Planned Engine Rebuild

[mkbull]

Hello and all the best for 2008

I have now stripped the engine from the car.
Hopefully getting the body ready for some blasting treatment in January.

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I wanted to strip the car engine down and make some assessment of its condition and planned refurbishment.
I would be grateful for any advice and thoughts from the vastly experienced here.

Here are the details.

Car 1966 230sl RHD Manual.
Engine No. 127-981-20-002724
I think this looks original for the car.

Odometer reads 52000 miles (obviousely could be 152k,252k..etc although previous owner(s)told me they thought the milage to be genuine at only 52000)
Car has not been on the road since 1988.

First Assessment

Before carrying out the strip down I decided to get the car running. I briefly did the following
Replaced Oil and Plugs
Replaced Fuel Filter
Flushed out Fuel lines/tank.
Preliminary repair to Fuel Pump(plan to do a more thorough job).
Repaired Fuel Injector (thankfully did not need much persuasion to get a couple of stuck valve seats moving)
FIP rack movement was very smooth and injectors all looked to be performing fine (visual inspection whilst cranking engine).

Before attempting the start up, I put engine oil in the pots and turned the engine with the plugs out several times.
The engine sounded very smooth indeed and I concluded the engine must at least have been turned over a few times during its very long stand?
Checked compressions cold and got consistant readings although a little low this would be expected I thought.

Started the engine and she runs very smoothly.
Engine starting was surprisingly easy and sharp and the car ticked over like it had never been in a coma.
After several starts checking oil water etc. I let the engine tick over to warm up a little and then check Compressions again.
Compressions were again consistant around 130s.

Following this I briefly did some work on the clutch to get it working and took the car for a short drive (not on the public road )
and again all felt very normal - my first drive in a pagoda and I like it!

The Strip Down

I removed the engine follopwing advice I found here ,ie. with transmission (BTW my son did a video of the engine lift out and I can post it if anyone is interested
but it was actually a very easy process.)

Unbolted the transmission and bolted the engine on the engine stand
I found the head bolts extremely difficult to remove and after snapping the 3rd one I used the pressure on and hit/tap with hammer technique. this worked for the remainder of the bolts without misshap.
Generally good news once inside.
I think the pistons are standard size (stamped with 81.99 and 81.98) and there was no signs of piston bore scoring or excessive wear.
The Camshaft and Crankshaft also shows almost negligible signs of wear. I plan to chech the Crank Dia. with a micrometer next week but judging by the bearing shells and the look of the cranshaft(they are stamped STD and have minimum wear) I think things are looking very standard.
A mechanic friend who works for Renault was amazed at the overall condition inside the engine and said in his opinion he has seen more general wear on a Renault with 20,000 miles on the clock!

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What Next

I plan to rebuild the engine as soon as possible so that I can get back on with the major work (the body) without having a box of engine part lying around my workshop.
If, as is looking promising, the piston bores are still within tolerences I would plan to de-glaze and fit standard 82.00mm rings,
new Standard Cranshaft bearings, new seals/gaskets all round, de-coke and seat valves new timing chain then put her back together?

I think these rings are standard but here there is a little discrepency in what I have researched and Haynes manual(which doesnt specifically cover the 230sl).
The Haynes manual qoutes the standard bore as 81.750 to 81.772
SLS link below shows the STD bore as 82.00mm

http://www.sls-hh-catalogue.de/bin/dbframes.phtml?mid=IN02

My pistons also have 4 rings instead of the 3 I would have expected for a 1966 model (the table at SLS suggests only generation 1 early 230sls have 4 rings).


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Any thoughts appreciated

Thanks for your help
Mark
(reading and learning)
UK

[glennard]

Mark, In the process of doing the same for a 127.982 engine grafted into  a '65 113.  Unfortunately it sat for 20 years-nos 4 and 5 pistons were frozen, a ball stud was bent, a valve pressure piece was missing, FIP was frozen, water side is corroded, etc, etc.  Makes  it a challenge to disassemble! Let alone get to run.....

[pauldridge]

Thanks for those encouraging comments... I'm just about ready to yank my engine also, and expecting a similar-style "rebuild"... mine has 3 cylinders w/ compression @ 175-180, but the other 3 at 100-130.. Crankcase blowby is so severe that it literally belches oil from under the valve cover gasket and tach drive area at higher rpms, so it has to go.  My pro-mechanic adviser thinks I'll find bearings in good condition, and can get by with cylinder de-glazing and new rings... Hope springs eternal!

Your video would be extremely helpful... maybe a Youtube posting?
Phil


230SL soon to be 180G Silver/blue interior. Auto/AC

[mkbull]

quote:Originally posted by pauldridge

Thanks for those encouraging comments... I'm just about ready to yank my engine also, and expecting a similar-style "rebuild"... mine has 3 cylinders w/ compression @ 175-180, but the other 3 at 100-130.. Crankcase blowby is so severe that it literally belches oil from under the valve cover gasket and tach drive area at higher rpms, so it has to go.  My pro-mechanic adviser thinks I'll find bearings in good condition, and can get by with cylinder de-glazing and new rings... Hope springs eternal!

Your video would be extremely helpful... maybe a Youtube posting?
Phil


230SL soon to be 180G Silver/blue interior. Auto/AC

http://uk.youtube.com/watch?v=cBEyCH24uL4

sorry about the audio
Thats my son saying "I've got your arm in it - doing that dad"

[ja17]

Hello,

All but the latest 230SLs had four ring pistons originally as did the other Mercedes engines of the era. 82mm is standard bore for the 230SL some of the M127 sedan engines of the era had a slightly smaller 80mm bore.

Original Mercedes piston rings are extremely hard. Most often the rings are not worn out until the cylinders are shot. In these cases complete oversize piston , piston ring and piston pin sets are ordered to be installed in overbored cylinders.  In this way all wear is removed. Of coarse this is the most costly solution also.

For slightly worn engines, many difficult choices must be made.  Most often replacing just the piston rings is a bit risky. Putting nice new round piston rings in slightly worn, egg-shaped cylinders can cause oil consumption problems. Original equipment rings (ATE) are very, very picey and often too hard to "break in" on slightly worn cylinders. Best success and mcuch less expensive can be an aftermarket softer ring set. I am sure you can get some good recomendations from some owners here. Deves is one choice.

Mercedes is very conservative with the permissable cylinder wear specs. The book says 0.10mm (0.004") wear ! So if you feel a ridge at all you are most likely out of specs! I suspect softer rings would accomodate more cylinder wear than a new  original ATE set of piston rings. Decisions, decisions!

Consider evaluating your originals. They have already adapted to the wear in your engine. You can remove some rings and install them in the cylinders and measure ring gap against original specs. This will give you the combined wear of the rings and the cylinders as a functional unit. Another quick observation ... the fourth ring is one-piece cast iron. Notice it has an upper and lower ridge with a "valley" between. If the ridges are worn down level or close to level with the valley the rings are shot. Judging from your photo your rings seem to be in good condition.

Removing perfectly good rings and installing new inferior rings that do not quite fit the slightly worn cylinders, may not be your best choice?  Hard decisions!

Replacement ring sets are usually softer and easier on cylinder walls. In addition they will wear or break in easier than harder rings. The fourth oil ring may be a three piece steel ring instead of a cast iron ring as original. They can work fine and may even work better in a worn engine, when you must replace the rings. A steel oil ring will damage easier during accidental overheating (loss of  temper). The original cast iron oil ring seems to resist heat damage better. It all comes down to the amount of wear and the decisions you make.

Be sure to check the clearance between the piston ring and its ring groove. The skinny top ring can twist and break if the ring groove is worn too wide.

You can do a visual check on the bearings and measure them with plasti-gauge. Here again, this will give you the combined wear of the crankshaft and the bearing together as a functioning unit.

Keep us up to date, good luck!

Joe Alexander
Blacklick, Ohio

[mkbull]

Thanks for looking at this joe
I have done a lot of reading but its difficult to get concise information like this.

I have aquired a set of micrometers and an imperial bore gauge.
The crankshaft dias all look great with readings of 47.95+ all round on all big ends.

I am having a little more troble with the bore gauge as it doesnt seem to calibrate accurateley with the metric micrometers (which I know are very accurate), notwithstanding this the bores dont look too bad since they are not very different from top to bottom. I'll report back with definite figures tomorrow.

From what you say about " Choices" I am more swayed now towards a rebore and next size pistons and hopefully will get these ordered over the next few days.

Thanks again
Mark

[ja17]

Hello Mark,
Yes often times it is easiest just to measure the wear of the cylinders by reading the unused part at the very top and the area of most wear below. This will give you and idea of the actual wear. Compare it to "permissable wear specs" in the manuals. Make sure to clean the carbon off the upper paart of the cylinder before making the measurement.

A good digital caliper is most often the easiest measuring tool to use these days. They easily switch back and fourth from metric to inches, and zero out just by clicking a button. Measuring deep down in cylinder bores is not possible but it will work on most anything else including the top of the cylinder bores and the wear area just below.

Joe Alexander
Blacklick, Ohio

[gdpmv152]

I am now slightly concerned regarding my compression in my 250SL.
I took the car to a very reputable German shop that has done work on our cars for years. After my tune up and valve adjust, the compression in each cylinder was between 130 and 135. Is this exceptable or am I on the low side. The car runs great.

[ja17]

Hello Gregory,

I believe that the compression ratio on your engine should be 9.5 to 1. This ratio is cast on your head below #3 spark plug, just above the block.  You should see the head casting number and the compression ratio under it (9.5).  So If my math is correct 9.5 times one atmosphere (9.5 X 14.7) is about 140. lbs.  You are very close.  Often times engine display higher compression because of the cylinder head being "cut" or carbon build up in the combustion chambers.

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Copmpression guages will give false readings. Sometimes a small carbon particle will  lodge itself in a gauge and stay there. Readings with a warm engine can also help readings slightly. I remove all spark plugs before taking the reading. This allows the engine to turn over easily and usually improves the readings.

The rule of thumb is to be concerned when the cylinders deviate more than 20%. Cylinders fail one at a time normally, good even reading like yours are usually a good sign.






Joe Alexander
Blacklick, Ohio



Joe Alexander
Blacklick, Ohio

[gdpmv152]

Joe, great information and a relief as well. My friends at the shop where the car was serviced were not concerned with the compression readings, now I know why.
Many thanks for your input.

Greg

[mdsalemi]

Mark,

My 2 cents here:

If you are going to attempt to do this yourself, and it sounds like you are, you should at least take a cue from the professionals like Metric or Noels.

A consistent process leads to consistent results.

Many shade tree mechanics when attempting something as major and complex as an engine rebuild will attempt to "find out what's wrong" and "correct it" in the rebuild rather than taking the approach of performing a consistent process, albeit one that is more expensive and perhaps more time consuming as well.  However, there is NOTHING more expensive than finding out AFTER the engine is back together and BACK inside the car, that something is amiss.  Anything you think you might have saved by not doing becomes rather moot.

For example, you may think your head is in perfect condition due to the testing that you've done on the engine as a whole.  So you attempt a partial rebuild of the bottom end, perhaps rings and or pistons.  You get it back together and find there's a small crack in the head.  Now what?  You can draw all kinds of similar scenarios and the only way to prevent these "Murphy's Law's" from happening is to provide a consistent process in a rebuild.

Metric Motors of California, a noted engine rebuilder says the following:

"The Metric System"
Every engine gets the same complete treatment-
No short Cuts=No Weak Links

While you may want to do it yourself, and the cost of shipping an engine from UK to CA is prohibitive, there are UK rebuilders as well, and you can follow the rule that these pros have established, and that is provide a consistent process to what you are doing.  You'll get a consistent result and prevent problems down the line.  You can check both Noel's and Metric's websites for information on what they do to each engine; Crewe, too.

http://www.mercedesengines.net/default.asp  (Metric)
http://www.noels.com/About%20Noel.htm
http://www.creweengines.co.uk/remanufactured1.asp  (A UK Source for your greater amusement.  Look at what their process is too.)

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[Benz Dr.]

It's possible to use the original pistons by installing new rings if nothing is worn out. Even if the top ring groove is worn a spacer can be installed to set the top ring square to the piston but that requires machining of the top groove. In most cases you will be replacing with new pistons if things are that bad.

I would not install new bearings without having the crank journals polished nor would I do any of this without a new oil pump.

I would also not intall the head without new valve guides if they show any wear. Even small amounts of play will cause all kinds of trouble. New valve stem seals won't work very long with worn valve guides. If there's not too much wear it's possible to install sleeves in the quides. These are very thin and are installed by pushing a ball through the guide which squeezes the shim out leaving a perfectly sized hole for the valve stem.
The critical area of these engines is the cylinder head. It's where the most mistakes can and do take place during rebuilds. Everything has to be perfect and there's a lot more to a high end rebuild than you might ever believe. Anyone can do and average job. It takes very specialised tooling and a lot of skill to do it right.
If the engine smokes after a rebuild I can pretty much tell you it's a problem with the head. The valve rockers MUST be level or the the valve quides will be damaged very quickly - before the engine is warmed up and it's too late by then. If you run out of adjustment on the ball studs the valves are worn out or the seats have been cut too deeply. Did I mention about using worn out valves? I use .015'' cam shaft shims on engines with this kind of wear to bring the adjustment back for the ball studs.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[mkbull]

I managed to calibrate the bore gauge today and have carried out further measurements.

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I am now fairly confident of the readings I am obtaining.
The bore at the bottom in the (no wear zone)is measuring exactly 82.00mm further up near the top it measures 82.200  and at the top just below the lip the widest measurement I am obtaining is 82.245.
All cylinders are very similar.
The crankshaft big ends are reading very close to orig spec.
at 47.95

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I do understand and appreciate your views on my self help approach, but really guys -Have you seen the bodywork of this poor old car?
(I posted pics on the bodywork forum). Although I am not a pro mechanic I am an engineer (civil), If I am going to have any chance of recovering this old lady then it can only be through my own hard work (and hopefully some excellent knowledge/advice from this group)- my pockets simply dont extend to what it would take to put her right with professional help, I simply do not believe it would be economically viable. (not that a lottery win wouldn't change my mind in a nano-second.)

Notwithstanding this I appreciate that I will need to be outsourcing some of the work and I do not wish to take any "short cuts" especially with the engine overhaul. I think Joes comments and the measurements above suggest that the rebore and new piston route is the way to go. I received a quote from Northern Rebore Services today £70.00.(seems quite cheap)I liked the fact that the chap I spoke to asked me to bring the crankcase over to him before ordering any pistons as he said "0.5mm (next size piston up) does not leave a lot of room for error at 10 thou each side".
Pistons and rings and gaskets will be another £1500.00 from SLS.
I would replace the timing chain and oil pump, polish the crank and renew all bearings.

The Cylinder head now that sounds a little scary..... I would be delighted to replace those guides but I have not done that before and it is not described in my manual - do they push out?
Is it ok to replace these without replacing the valves themselves?
How do you ensure the rockers are level? where do the camshaft shims go? oops I'm having an overload ....

Why did I fall for a Pagoda???  

[psmith]

Mark,

I say "go for it" I can appreciate needing to keep the cost down and you can get advice from this site.  Maybe Cees will share some tips as I think he has been collecting engines to rebuild ever since he and Joe rebuilt his.  Let us know how its going and post lots of pictures.

By the way, nice to have another civil engineer on the board!

Pete S.

[ja17]

Hello,

If you review what you get from Metrix in a rebuild, you will see plenty of options also. The secret to sucess is good judgement from experience. Knowing what to look for, what can be re-used or replaced and how to put it back so it stays together for a long time.

There are all different degrees of re-build from them also. Always ask to see what parts are being replaced and what parts are being re-conditioned, what parts are being inspected and re-used as is. You will get many possible combinations.

It doesn't take much experience to replace every moving part with new, but it takes a lot of experience to make the decision on which moving parts can be re-used or reconditioned. This experience comes from seeing many engines and from seeing which parts fail and why. The actual re-assembly is textbook and less intuitive, but also must be done correctly.

Joe Alexander
Blacklick, Ohio

[mdsalemi]

quote:Originally posted by ja17

Hello,

If you review what you get from Metrix in a rebuild, you will see plenty of options also. The secret to sucess is good judgement from experience. Knowing what to look for, what can be re-used or replaced and how to put it back so it stays together for a long time.

There are all different degrees of re-build from them also. Always ask to see what parts are being replaced and what parts are being re-conditioned, what parts are being inspected and re-used as is. You will get many possible combinations.

It doesn't take much experience to replace every moving part with new, but it takes a lot of experience to make the decision on which moving parts can be re-used or reconditioned. This experience comes from seeing many engines and from seeing which parts fail and why. The actual re-assembly is textbook and less intuitive, but also must be done correctly.

Joe Alexander
Blacklick, Ohio

Joe,

Under "normal" circumstances, what Metric offers for our engines are quite simple, and there really are not options as you put it.

  > They offer a complete or longblock rebuild
  > They offer a partial or shortblock rebuild
  > They offer a rebuilt cylinder head

Due to popular demand, they now offer (they didn't some years back) crankshaft kits and engine parts by quotation, as well as some machine shop service.

That's it.  On the rebuilds, they list completely and in great detail exactly what is replaced as new; what is inspected and reused.  It is a consistent process.  All this information is on their printed brochure and on their website as well.

For example, all of their rebuilds include NEW pistons.  My guess is that they have determined, based on their experience, that that is what is needed regardless of the condition of the pistons that come out of the core.

Connecting rods are cleaned and inspected; I assume if they found a problem, they'd let you know and would replace it or repair it if possible.

However, if you had some kind of special needs I'm sure they'd accomodate them.  For example, on my rebuild, what they wanted to do was to simply exchange my "core" for an off the shelf, already completed engine.  I preferred--time was not an issue--that they simply rebuild my engine.  They did that without a problem, and even sent the custom crate ahead of time so we could ship it.

They are not inexpensive--what is on these cars right?  However, they are approachable (I've spoken with Mike Elias many times); and their attention to detail impressed me.  I'm sure Noel's is quite similar though they don't provide as much detail on their website or in their brochure.

But since this thread didn't start out with someone looking for someone ELSE to do a rebuild, I'd offer that simply, some of the information Metric provides on what they do is useful and instructive, and is a means to take advantage of someone else's experience.

Since they now also offer parts, it is perhaps another good source to add to one's list when you need engine rebuilding parts.

You'll note that their price for the M127 is $300 more than for the M130!  This goes along with Dr. Benz's observation some time ago about 230SL engine parts getting harder to find...

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[mkbull]

quote:Originally posted by mdsalemi

quote:Originally posted by ja17

Hello,

If you review what you get from Metrix in a rebuild, you will see plenty of options also. The secret to sucess is good judgement from experience. Knowing what to look for, what can be re-used or replaced and how to put it back so it stays together for a long time.

There are all different degrees of re-build from them also. Always ask to see what parts are being replaced and what parts are being re-conditioned, what parts are being inspected and re-used as is. You will get many possible combinations.

It doesn't take much experience to replace every moving part with new, but it takes a lot of experience to make the decision on which moving parts can be re-used or reconditioned. This experience comes from seeing many engines and from seeing which parts fail and why. The actual re-assembly is textbook and less intuitive, but also must be done correctly.

Joe Alexander
Blacklick, Ohio

Joe,

Under "normal" circumstances, what Metric offers for our engines are quite simple, and there really are not options as you put it.

  > They offer a complete or longblock rebuild
  > They offer a partial or shortblock rebuild
  > They offer a rebuilt cylinder head

Due to popular demand, they now offer (they didn't some years back) crankshaft kits and engine parts by quotation, as well as some machine shop service.

That's it.  On the rebuilds, they list completely and in great detail exactly what is replaced as new; what is inspected and reused.  It is a consistent process.  All this information is on their printed brochure and on their website as well.

For example, all of their rebuilds include NEW pistons.  My guess is that they have determined, based on their experience, that that is what is needed regardless of the condition of the pistons that come out of the core.

Connecting rods are cleaned and inspected; I assume if they found a problem, they'd let you know and would replace it or repair it if possible.

However, if you had some kind of special needs I'm sure they'd accomodate them.  For example, on my rebuild, what they wanted to do was to simply exchange my "core" for an off the shelf, already completed engine.  I preferred--time was not an issue--that they simply rebuild my engine.  They did that without a problem, and even sent the custom crate ahead of time so we could ship it.

They are not inexpensive--what is on these cars right?  However, they are approachable (I've spoken with Mike Elias many times); and their attention to detail impressed me.  I'm sure Noel's is quite similar though they don't provide as much detail on their website or in their brochure.

But since this thread didn't start out with someone looking for someone ELSE to do a rebuild, I'd offer that simply, some of the information Metric provides on what they do is useful and instructive, and is a means to take advantage of someone else's experience.

Since they now also offer parts, it is perhaps another good source to add to one's list when you need engine rebuilding parts.

You'll note that their price for the M127 is $300 more than for the M130!  This goes along with Dr. Benz's observation some time ago about 230SL engine parts getting harder to find...

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

Hi Michael and thanks for your input. The list is indeed useful.
there is no doubt looking at Metric's offer that they do a fantastic job and I hope to emulate it as best I can. There is hardly a day goes by that I do not envy you guys in the US. Prices aside I do like your country - cant help wish we had never lost that little scuffle on July 4th.

Mark

[mdsalemi]

Mark,

I'd ring up Crewe engines, too--they seem like decent folk, and worth a chat.  Between them and Metric or Noel's you should have great sources of parts too.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[ja17]

Hello Michael

I see this as a contradiction, the fact that they do not include new vertical and horizontal timing gears, connecting rods, rocker arms, valves, camshaft, cam towers, and a lot of other items in the standard metric rebuild imply options or possible additional cost to the owner if needed or requested. Yes they do quote prices for standard procedure but there are many variables with rebuilt engines. With this said, I condsider Metric one of the best and most likely the best in the business. Their experience and reputation is undesputable. There is also a huge advantage when a rebuilder does their own machine work "in shop" (as Metric does) under their supervision.



Also let's face it Michael,

Anything but a new engine from Mercedes is "cutting corners". You may not like the term "cutting corners" but the goal is to save money by re-using some good slightly worn parts.
You will not likely find a Mercedes Dealer even interested in rebuilding your engine at any price. Mercedes' approach is, that if you can get the originial manufacturer to supply you with a fresh factory new engines, you cannot do any betterthan this. Anything else is "cutting corners" and just a cost saving measuresure.

In this sense I have always believed in re-building engines (cutting corners so to speak). Many engine componants will last our lifetime while others need occasional attention. There is no reason a good quality rebuild will not last as long as a new factory engine.

It all boils down to good judgement and important decisions during the rebuild.


Joe Alexander
Blacklick, Ohio

[mkbull]

quote:Originally posted by mdsalemi

Mark,

I'd ring up Crewe engines, too--they seem like decent folk, and worth a chat.  Between them and Metric or Noel's you should have great sources of parts too.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

I'll try them monday (they are closed until the 7th)and keep you posted. Thanks Mark

[mkbull]

quote:Originally posted by ja17

Hello Michael

I see this as a contradiction, the fact that they do not include new vertical and horizontal timing gears, connecting rods, rocker arms, valves, camshaft, cam towers, and a lot of other items in the standard metric rebuild imply options or possible additional cost to the owner if needed or requested. Yes they do quote prices for standard procedure but there are many variables with rebuilt engines. With this said, I condsider Metric one of the best and most likely the best in the business. Their experience and reputation is undesputable. There is also a huge advantage when a rebuilder does their own machine work "in shop" (as Metric does) under their supervision.



Also let's face it Michael,

Anything but a new engine from Mercedes is "cutting corners". You may not like the term "cutting corners" but the goal is to save money by re-using some good slightly worn parts.
You will not likely find a Mercedes Dealer even interested in rebuilding your engine at any price. Mercedes' approach is, that if you can get the originial manufacturer to supply you with a fresh factory new engines, you cannot do any betterthan this. Anything else is "cutting corners" and just a cost saving measuresure.

In this sense I have always believed in re-building engines (cutting corners so to speak). Many engine componants will last our lifetime while others need occasional attention. There is no reason a good quality rebuild will not last as long as a new factory engine.

It all boils down to good judgement and important decisions during the rebuild.


Joe Alexander
Blacklick, Ohio

Thanks for sharing your views joe - as always things are never black and white - I agree with your earlier comments - making the right choices is perhaps the most difficult part of the work. This is where sharing views on this forum is most helful.
I do not need or intend to cut corners but everything always comes back to the same science - "cost/benefit analysis".

Mark

[mdsalemi]

Hi Joe,

Actually they do put in new valves and valve guides on every rebuild.  Check their details!  But jeez, Joe!  If any rebuilder put in all new items as you indicated it could hardly be called a rebuild; it would be called a re-assembly of new parts!

You have to remember that their normal mode of operation is "on exchange" with a core deposit; they do indicate upcharge for non-rebuildable cores.  If they find a bad rod or something it might be long after the deal is done!

Noel's advertises that they supply MB dealers...I wonder if that's "official"?

By cutting corners I simply mean not performing a "consistent process."  Don't assume ANYTHING is OK, but put everything through a process and procedure to ensure integrity before you put it all back together.  They've come to a system after years of experience; you have too.  Your average person here has no such experience and must rely on the experience of others if it is to be done correctly and last.  Does "Joe Smith" have Magnaflux equipment in his garage?  Does he know how to use it?  Does his machine shop down the street know the limits of decking our heads?  Do they have the equipment to do it right?  theengineer has a head that was decked different amounts in the corners!  Dr. Benz has a headed decked a bit too much, he'll say, on the Red Rocket.  Mike Elias found a small crack in my head and welded it up (at no additional charge) during my rebuild.  These are the kinds of things where experience of you and professionals comes in handy; your average machine shop might not know this; your average shade tree mechanic might not know what to look for or where--there's no substitute for all those years of experience and all those engines apart...

With the cost of parts and labor skyrocketing, cutting corners either by commission or omission can be a very costly mistake.

After reading the detail of Metric, and seeing YOU in action, the very last thing in the world I'd ever do is rebuild my own engine!  I simply know too much of its complexity and what can go wrong if you don't do it right!!

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[ja17]

Yes Michael,

There is no easy substitute for years of experience. The pros have all learned by their mistakes and paid for their mistakes!

A nother consideration is the cost of tools to do the job yourself.  Make a parts list first and get prices to see what you are in for.

You will have to find a good machine shop you can trust. One which is familiar with Mercedes engine parts. Do not depend on them to have all the right specs at their fingertips, no mater what they say. Gather all the information and leave it with the parts. they will apprecaite it. Consider them looking up a 280SL in there generic spec books.!  Well there are three 280SL engines, will they know which spec to follow. (early and late M130 engines and the later 280SL W107 with the M110 twin cam engine). Do the homework for them. Others may assume clearances are the same as in other engines. In fact clearances in these engines are "trighter" than what they are used to. Do the hoomework for them.

If your engine suffered catastrophic engine failure before the rebuild or was severely overheated other parts will need  closer inspection.

A wise man is one who realizes his own limitations!

However some owners  find that the satisfaction of such a project part of the joy of ownership. Definately not for everybody. For those I would advise, read a lot, and ask a lot of questions so the experience here can help guide you around bad information and pitfalls. Plan on set backs and if not consider yourself fortunate!

Joe Alexander
Blacklick, Ohio

[mdsalemi]

quote:Originally posted by ja17


Another consideration is the cost of tools to do the job yourself.  

Amen to that.  AND, how to use them all.  Measurement tools in the .0001 range?  Ouch.

quote:Originally posted by ja17


A wise man is one who realizes his own limitations!

Well, than I'm a friggin genius!

I've been in many a private plane with private pilots, and that's one of the first things I ever decided I could NOT do.  Multi-tasking on steroids, with death possible for a slight mistake.

I spend my time finding the experts, not trying to be them!!!


Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[hauser]

The nice thing about a Metric rebuild is you get a warranty along with it.  I know Gernold uses them exclusively and has been very pleased with the results.

1969 280sl 5 spd
Gainesville, Fl.