Smoke at start up? To do, or not to do..

[Allen F]

Hi Folks,

I have a 66 230 SL and it smokes at start up.  I have been told by many that this engine pumps oil into the fuel system, and this is normal, and others say I probably need valve guides.  I have restored the rest of the vehicle, inside and out, and I am now detailing the engine and I was thinking it might be time to do the head.  It runs excellent, smoke or otherwise.  I noticed when I pulled out the intake manifold that a lot of oil had collected in the bottom of the tube between the throttle plate and the filter housing.  This seems odd.  Any guidance is appreciated. If anyone has any suggestions on putting a later model alternator in, that would be great too.  

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[rwmastel]

Allen,

Hi.  Great picture!  What is the color code and name for your paint?

This engine doesn't pump oil into the fuel system directly, but there is a breather tube on the valve cover that allows oil vapor to be pushed back to the intake manifold by pressure in the top end of the engine.  People here can elaborate on what might cause this pressure.

Regarding the smoke, you should not be getting smoke at start up.

Regarding the need to replace your valve guides & seals, you might be ready for that.  How many miles are on the engine?  Has there been any other engine work done on the car?  Have any other tests been done (compression test, leak down test)?  How much oil does your engien use?

I have a worn engine that uses oil and smokes and here's how I determined that I could use a rebuild:

1.  Burns lots of oil, a quart every 300 to 400 miles.  Your owners manual will tell you the acceptable rate of oil use.
2.  Not leaking oil to speak of, so it must be getting burnt.
3.  Changed timing chain & found that the worn out one was not the  factory original endless chain (it had a master link).  At about 100,000 miles per chain, the car must have over 200,000 miles on it.
4.  Joe Alexander looked at the valve seals and suggested that they may be factory original or at least very old replacements as they are made from the older white material.
5.  I dropped my oil pan and removed the bottom half of the front two crank shaft bearings.  They were somewhat grooved and they were worn unevenly, showing some of the second layer of metal.
6.  At idle with a hot engine, my oil pressue is only about 1 bar (15 psi).  It is at full pressure by 1,500 rpm or so.
7.  I don't get much smoke at startup, but I do sometimes get oily water spattered out onto the garage floor at startup.  Also, I do get significant smoke when pulling away from a stop or when down shifting to accelerate.
8.  When I bought the car, the compression was on the low end of acceptable in all cylinders.

I strongly suggest you get a local expert to check out your engine.  If you tell us where you live, we can recommend shops in your area.

Best of luck!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[Cees Klumper]

Compression check (as Rodd points out) and a leak-down test will tell you / your mechanic a lot. The factory specs are pretty generous when it comes to oil usage: 1 liter per 400 km's is considered within spec. That equates to roughly 1 US quart per 250 miles!
If the leakdown test indicates a head rebuild is in order, don't let the shop mill the head as a matter of routine, only when it is absolutely necessary. There is only one millimeter of permissable material to be removed, and heads are very hard to come by / expensive on the M127 (230 SL) engine.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Allen F]

Thanks for the guidance Rodd.  The car has 114k, and had an engine (long block) at 15k.  I have all the original books and history.  It smokes some under heavy acceleration, but use no oil really. I could have a local guy do the project, but since I need to detail and replate all the parts under the hood, I prefer to do it myself.  I did the whole restoration on the car by hand, including refinishing, so I would like to finish it.  If the collective opinion is that these cars shouldn't smoke at startup (a puff, it doesn't fill the neighborhood) then I will yank the head.  I need to find a decent service manual, the 1968 manual for 113's doesn't cover this operation on the 6 cylinder variants.  


Here is a shot of the interior.  I guess the photo sizes must be pretty small to get them up?

Thanks,

Allen


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[Cees Klumper]

That's a very nice interior - why do you make us jealous ;-)

Maybe it's a simple as one or more of the valve seals. There is a way to replace these without taking the head off. There should really be no smoke on start-up. I believe it may also be caused by transmission oil making its way into the wrong places. Maybe Joe Alexander or Dr Benz will comment more 'knowledgeably' ...

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[ja17]

Hello Allen,
Smoke during start-up can be caused by worn valve guides or hardended or out- of-place valve seals.  A ruptured transmission diaphram in an automatic may also cause smoke during start and warm up. In this case #6 spark plug will collect deposites also.

Start with the inexpensive things first. Take the valve cover off and with strong light look in each valve spring to see if the valve seals have jumped off the valve guide. You may have to turn the engine to uncoil some springs. Valve seals outr-of-place, can be re-seated or replace.

Valve seal replacement is another option. This fix will not last if the valve guides are worn.

Sometimes valve seals get hardened from long storage. They may begin to work again when the car is put back into use.

Valve seal replacement is tedious and difficult without some special tools.

Depending on which route you take we can help out with more information and photos. Keep us up to date.



Joe Alexander
Blacklick, Ohio

[Ben]

One thing I would try to find out is what is the source of the smoke, is it definitely oil (blue grey) is it excess fuel (brown black) or water/brake fuid (whitish).

Does the car start easily ?

I'd be surprised if it were anything else but worn valve guides and stem oil seals but a leakdown test will confirm.

My rebuilt engine, done last year, has popped two stem seals off. The were new items, to original white plastic spec, and I'd really love to fit a different type if I'm going in there !

Is there a different type available for a '64 230SL ?? If so where and $ ??


Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Allen F]

Thanks for all the tips...  It starts and runs great, so I suspect that it is bad valve guides.  It's a little embarrassing when a crowd gathers around your classic car to check it out, only to have it belch smoke at start up.  If I start it within 5 minutes of shutting it down, it doesn't seem to smoke.  

Here is an infrared camera photo of the car taken with an Agema IR camera.  



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[Ben]

quote:My rebuilt engine, done last year, has popped two stem seals off. The were new items, to original white plastic spec, and I'd really love to fit a different type if I'm going in there !

Is there a different type available for a '64 230SL ?? If so where and $ ??

Anybody .......?

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Cees Klumper]

Yes Ben, me. When I put on my new valve seals last year I took a lot of care to clean the (new) valve guides with kerosene etc. before putting on the seals. Clean hands etc too, to make as sure as possible there would be no oily film between the contact surfaces. I don't know if this is effective since once the engine gets going, there will be oil all over - but maybe not between the seal and the guide. Also it may be a case of "you only get onse shot to put it on just right" (straight, far down enough etc) ? Just a guess.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Ben]

Thanks Cees, but did you use the later type, the rubber ones instead of the white plastic ones ??

I believe the inlets are still white plastic !!

Regards,
Ben in Ireland.
'64 230SL 4sp.
'03 CLK Kompressor

[Cees Klumper]

I'm not sure now Ben, it's been over one year. I will have to check next time I have the valve cover off. As I recall, they are all of the *new* rubber type.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[W14]

Allen,

In one of your posts you also mentioned: "It smokes some under heavy acceleration..."  
This would would indicate piston-ring wear as well.

Will W14
1965 230SL 4spd
Victoria,BC

[Allen F]

Thanks for pointing that out...

I have the accessories pulled off the block, so I can't easily get it hot enought to do a compression check.   But I guess I could squire some oil in there and do it.   It seems that they were all pretty even when I checked them a couple years back, but I know even doesn't mean "not worn."

Thanks again, as usual, the project grows, but I have no discomfort with throwing money at this car!

[Allen F]

I pulled the head yesterday, and no question the valve guides on some cylinders (or at least the seals) are gone, as I can see some of the stems are loaded with oil and debris.  

I ran a compression check, and it was about 120 in all.  Looks like I am off to the machine shop.

Allen

[Benz Dr.]

Tsk tsk tsk........

the 127 engine ONLY uses white valve stem seals - intake and exhaust. The later cars use the black rubber ones on the exhaust valve guides but there's no grooves on either of the valve guides to hold the seals on the 127 engine so getting them on right is really important.

The valve guides have to be perfectly clean and dry BEFORE you put the seal on. If they aren't the seal will likely pop off.

I use a special tool to install the valve stem seals on the guide. This requires having the valve in the guide and then slowly working the valve stem through the seal. There are these special valve stem condoms that come with the seals but I find they don't work all that well. Once I have them started I use the special tool to carefully tap the valve stem seal on to the guide.

Note:
The intake and exhaust seals look the same but are different sizes. It's not all that easy to tell them apart so I use a set of calipers to make sure I have the right ones. Once I have them on I use a bit of cam lube (red stuff) to lube the valve stem so that it slides easily in the guide and on the seal. At this point the seal should never come off the guide if it's installed properly. If the guide is worn a new seal won't help for very long so the guide should be replaced.

Anyone figure out how to test the roto caps yet? The time to test them is when the head is off.

Daniel G Caron

[Benz Dr.]

Oh yeah, one more thing.
 There isn't even close to enough oil going into the injection pump elements to ever cause the engine to smoke. There's enough to seal and slightly lubricate the elements but that's about it.
Any smoke is oil coming through the engine past the rings or valve guides.

Daniel G Caron

[ja17]

Hello Allen,
These threads will have some more information and photos on your task;

http://sl113.org/forums/index.php?topic=1668

http://sl113.org/forums/index.php?topic=1113,head,


Joe Alexander
Blacklick, Ohio

[Allen F]

Thanks to all for the continuing guidance.  Here are a few more questions....

Should I get the engine overhaul parts from MB or is there an aftermarket source?  

Someone told me that I should use the latter type seals vs the early type seals?

My cylinders look great, but I am sure the rings are gone. I assume they can bore the block a minimal amount and reuse those pistons?

Thanks again!

Allen Frechette

[Cees Klumper]

Dan - how about just turning the camshaft with the head off by hand, to see whether the rotocaps are working properly?

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Benz Dr.]

You can't see them moving that slowly Case. They need to be moved quickly enough so that you can actually see them move. It takes a minuet or more at idle for the valve to make one complete revolution.
The easy way is to just tap the valve retainer hard enough with a brass hamer to make the valve open. You can see the valve spin by doing this.

You can't bore out a cylinder and use the old pistons. You can deglaze the cylinders, use new rings and maybe be OK if the pistons are in good shape and there's minimal wear in the cylinders. I use only Deves piston rings for this purpose. You won't have the same compression as you would with new pistons and bored cylinders but you should be able to get 90% ( 165 PSI x 90% = 148 PSI ) which is still within useable limits.

 I'd take 90% of most things......

Daniel G Caron

[ja17]

Hello Allen,
Don't count the rest of  the engine out yet, unless you plan on spending about $2500.00 to $3500.00 on parts for a major overhaul. Machine work may cost you another $1000.00. Mercedes only allows about .005" cylinder wear before replacement and boring the block. So if you can feel a ridge at the top you are probably already beyound re-ringing the pistons.

If your car seemed to run well, had good oil pressure and if you find problems in the head, you may want to recondition the head and re-install it. 90% of the time this will be all that is needed. It is taking a slight chance that the engine may need more, but all you have to loose is the cost of a head gasket and a little labor. The alternative is $3500.00 minimum for a total rebuild, if you do the labor. You will miss out on the summer driving also.

Shop around for the parts, the dealers may be reasonable on some things and outrageous on others. Pistons with rings are a big expense. Expect to pay at least $100.00 for each piston assembly. the dealer will want quite a bit more for these. Make a list and send it out for pricing. Consider using some of the list suppliers who can help you with information also.

Joe Alexander
Blacklick, Ohio

[Allen F]

Thanks for the input Joe,

It seems like the cylinders are in excellent condition, and I can't detect even the slightest ridge.  I was prepared to yank the engine, and I found a machine shop that is familiar with them, but even he asked if I had done a leak down test.  I would rather pop the head back in and get back to driving it, I just wish I could tell if my rings were bad without total dissasembly.
 
Have you ever used those plating kits for replating the metal parts in the engine bay?  I just ordered a kit, since the objective of this exercise was to detail the engine.  

Allen

[Joe]

An old motorcyclist's trick to deglaze cylinder walls is to remove the air cleaner, rev the engine, and toss a handfull of borax into the air intake. This abrasive material is said to reseat the rings. I've never tried this, but have heard of it from multiple credible sources.
I assume it then gets into the oil and "reseats" the bearings, too!
Joe

[Cees Klumper]

One comment on the piston & rings: here in Europe these are now typically over 250 euro per set! So about $1,800 for six of these sets. Last year in the US I paid around $108 per set, although even then the European prices were already up there. Probably older stock in the US pipeline. Get them while it lasts?

Cees Klumper in Amsterdam
'69 white 280 SL automatic