Engine Rebuild/Overhaul

[n/a]

All:

I have a bit of bad news, my M127 engine is on its last leg and in need of a major overhaul. It appears that a complete tare down / rebuild is in order. The car will not stay in time, nor idle at stops, and she is going through at least a liter of oil per month and I only drive on weekends, less than 1,000 miles/month. I have called SL tech but have also read, where other shops do this kind of work. Has anyone gone through this experience recently, using SL Tech for a rebuild and if so what was your experience like – good I hope. Experience/recommendations for other shops? Does anyone know what a typical rebuild cost? I've seen prices from $5K -$10K.

I'm also considering having the engine detailed back to original as pictured in the Meredith book. Is it worth the extra cost? - Now would be the time to have it done.

Any insight is much appreciated. Thanks

Scott
1966, Signal Red, 230SL

[Cees Klumper]

Hello Scott - please see the following thread on my own engine rebuild that Joe Alexander and I did over the past two weeks (well, Joe did it and I watched and videotaped most of the time!). There is a lot of relevant info for you there:

http://index.php?topic=389

You should consider also getting in touch with Metric Motors. Michael Salemi got his replacement engine from them; I drove his car at the tech session and it runs very well, Michael told me he is very pleased with it. I believe they advertise exchange engines for around $5,000 which is what a full rebuild should cost most of the time. The only time you are facing higher costs is if major components need to be replaced (such as the cylinder head, but in that case get a donor one off a sedan rather than buying it new). I would expect Gernold Nisius' shop to do an excellent job at rebuilding one of these engines, and you can also check with Will Samples of S&S Imports in Texas (see vendor table on the home site for contact details) - he is specialized in engine rebuild work for the W113 and would for sure also be a good option for you.

Altogether other alternative: you could try locating a good used engine off a donor car, could run you no more than $1,000. Then you can keep your current (original?) engine for a later rebuild, e.g. when Joe and I finish our engine rebuild manual ...

Good luck!
Cees

white 1969 280 SL

[n/a]

Thanks Cees:

I noticed your and Joe's rebuild thread right after I posted my question.  That looks like it was a lot of fun!!!!  My girlfriend’s farther and I were considering rebuilding the engine ourselves but we decided to have a pro do it, as it would take us twice the time to complete, if not longer.  So while the engine is out we are going to renew the entire engine compartment and be ready for the engine's return a couple of months later.  I'm hoping that I can save a little money by pulling and re-installing the engine ourselves.  Did you or will you plate the linkages/other detailed items on your rebuilt engine?

Scott

Scott
1966, Signal Red, 230SL

[Cees Klumper]

I am still thinking about getting things on the engine plated. If I go that far, I will want to do a full detailing of the engine bay otherwise the engine will literally look out of place. Normally I am not that interested in the cosmetics, but I must admit that seeing a couple of the super-duper cars at last weekend's tech session (e.g. Tom Sargeant's and Michael Salemi's) sure left me impressed. Besides cost and time constraints, also the fact that the plating will inevitably come off again keeps me in doubt. To be continued ...

[ja17]

Hello Scott,
What is the history on the engine? Has the cylinder head ever been reconditioned? Most of the time this will solve most problems with oil consumption.


Joe Alexander
Blacklick, Ohio

[n/a]

Joe:

Don't know that much about the engine's history, other than it is original.  Most of the records that came with the car only show routine service and up keep.  If I had to guess nothing has been done to the engine, and from it’s appearance I'm sure it's never been pulled.  


Scott
1966, Signal Red, 230SL

[ja17]

Hello Scott,
Consider reconditioning the head first. If this solves the problem you save big time. If it does not help you will be out only the price of a head gasket and labor, since head work is a must during a major rebuild anyway. First time headwork will often solve oil consumption and compression problems. You may even want to tackle the headwork yourself! Check the compression and the spark plugs. Are you getting hard crusty oil deposits on the plugs?

Joe Alexander
Blacklick, Ohio

[Naj ✝︎]

Scott,
Joe's idea is worth persuing - you'll be able to tell a lot from the condition of the bores etc. once the head is off.
naj

naj
'Kloines Scheisserle'
65 230SL
68 280SL

[n/a]

Joe/Naj:

I am getting oil deposits on the plugs, but it's not hard and crusty.  I would describe it as a very thick film.  It looks similar to the plug oil deposit photo in the Haynes Manual.

The oil consumption is only one of my problems; I can't keep the car in proper time.    I can’t set it at 8deg BTDC as documented in the BBB, well I can but when I reconnect the vacuum the car retards so much that the engine dies out.  The best I was able to do was 27deg BTDC w/o vacuum, at times the car will idle properly, and then suddenly start to die out while sitting at a stop.  The distributor appears to be working correctly, it retards and the bearing/spring are strong - rotor snaps back when I turn.  Points were just renewed and checked for dwell-39deg.  It's been suggested that the timing chain is slipping and/or has stretched out.  And after almost 40 years if might be time to renew.  

I’ve consider having the chain/front end renewed, and the reconditioning the head first, but my concern is what if that doesn’t fix the problem.  Then my only option is an overhaul, and now I’m out even more money b/c of the first front end and head work.  Any thoughts?  


Scott
1966, Signal Red, 230SL

[rwmastel]

Regarding chain stretch and timing problems:
Isn't there a way to measure chain stretch using the position of the crank shaft compared to the position of the cam shaft?  Also, last year at Joe's tech session we had my cam cover off.  Joe was able to examine my chain tensioner and note that it was fully extended, meaning that my chain was stretch to the limit of the tensioner.  Perhaps he could elaborate on this procedure.

Regarding oil consumption:
Can't you combine a compression test, a leak down test, and maybe some other diagnostic procedures to see if your leakage is around the valves or the rings?  This would give you a hint as to what may need rebuilt.  As said before, with the head off you can learn something about the bottom end of the engine.

My car has high oil consumption, but fairly good timing even with the stretched chain.  I plan change the timing chain at my first opprotunity and have the head reconditioned this winter.  When the head comes off, the cylinders, pistons, rings, etc will be checked for indications of bottom end wear.

Rodd
1966 230SL Euro
1994 E420

[Cees Klumper]

Have you checked your distributor - is it correct for your engine? I am asking because when I bought my car, it had the incorrect-type ditsibutor on it and would dy at idle once the engine was warmed up. When it was replaced, the car ran fine. There is a listing of the various types of ignitions in the BBB if I am not mistaken.

[n/a]

Cees:

Yes the distributor is the correct one.  according to the BBB/other reference I should have an 051 distributor and that is what is on the enigne.  Thanks for the suggestion.  Please keep them coming!!!  I'm hopful that I've missed something which will fix these nagging/expensive problems.

Scott
1966, Signal Red, 230SL

[Tom]

Since you are encouraging all thoughts, let me pose a question and venture a guess.

Have you checked your valve clearances? I would guess that your valve clearances cannot be maintained (throwing off timing as the clearance changes) as the ball sockets that the rocker arms sit in are loose.  They should hold 20 lb/ft of torque (I think-check the specs).  You may be seeing wet plugs from oil seeping from the top of the head through the loose ball socket threads into the spark plug tunnel.  Just another thought.

Best,

Tom

[ja17]

Crusty Deposits on the spark plugs are usually oil deposits. Black wet plugs usually is a result of unburnt fuel. If your engine uses oil and you do not get these crusty deposits on the spark plugs, then your exhaust valve guides in the cylinder head are usually the cause. Oil leaks through the guides and drops into the exhaust port in the head and exits through the exhaust system as smoke and never enters the combustion chamber. Time for headwork!

Joe Alexander
Blacklick, Ohio

[Ricardo]

Joes advice is the same as he gave to me a couple of years back. Head work with new guides/timimg chain etc. cured my smoking engine and oil consumption problem completely. Really not too expensive to have done as I hauled the complete eng. to a shop and had them do the tranny seals and front main seal at the same time for about $2200 cdn. including all parts (no new valves).
Tom's point about ball adjusters is interesting as I was considering changing mine to hopefully cure a hot engine rattle that sounds like noisy valves. The shop owner where I go is a retired MB trained mechanic, and pagoda owner. When I spoke with him recently about the idea of changing out the ball adjusters, he stated that the rocker arms should be changed too, or the new adj. would wear prematurely.
Costly I thought....but actually the adj. are $50 the rockers are $60 ea. not exactly pocket change for a dozen of each but.... any thoughts about re-using the rockers
Ricardo

[Benz Dr.]

There's some things to consider here.
 If your engine is useing a lot of oil and has low compression ( 110 psi or less ) you may want to do a full rebuild. All of my expirience tells me that you will loose the bottom end once yopu bolt the fresh head back on. If the whole engine is worn the bearings will fail within months as they won't be able to handle 20 to 40 psi more compression held in by the top end.
 
 A chain as strong as the weakest link.

 However, if the oil pressure is good and the compression is higher ( 130 or more ) and is just uneven from leaking valves then a head rebuild will probably be quite sucessfull. I do a number of tests before, during and after I have the engine running to monitor compression and overall eveness of the cylinders. I'm looking for nice close numbers -  the higher the better ( up to about 165 to 175 max )  Even 150 across the board is OK if they're even.
Dan c

Daniel G Caron