Author Topic: Smoking after replacing valve seals  (Read 2347 times)

toneypenna

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Smoking after replacing valve seals
« on: December 26, 2022, 19:49:24 »
Hello to everyone, I'm back for some input on my current problem and would appreciate any help: 1964 230 SL -  Here is some history.: When I first got this car I replaced needed items like hoses, Motor mounts , got cold start functioning, installed new 123 electronic distributor etc. Never could get the F I adjusted to make it  idle correctly  Had a new top put on and the shop owner noticed the idle problem and suggested I take it to a local import car service he had used. They gave me a laundry list of things wrong with the car which I already knew, told me the valves should be adjusted, I agreed to the valve adjustment , got the car back and it did idle relatively well. They also told me the top valve area was loaded with sludge which they cleaned out. Wasn't to happy with that , thought it may make valve seals smoke, which it did. Car started smoking with the classic symptoms of bad valve seals. Engine did not smoke before this. I replaced the valve seals myself  with the head on the car which I have done many times before, but only on domestic cars never on an import. The result it smokes worse now than it did before I replaced the seals. I removed the valve cover and looked the best I could  through the valve springs and the  seals seem to be in place. Before I go any further, I thought I would post this to see if anyone had a similar problem and can point me in the right direction to solve this problem. Any input will be greatly appreciated.

teahead

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Re: Smoking after replacing valve seals
« Reply #1 on: December 26, 2022, 21:37:21 »
curious how they removed the "sludge".

May eventually burn off if it's the sludge that's burning.

Check your spark plugs
1970 280SL auto, AC - aka "Edelweiss"

Charles 230SL

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Re: Smoking after replacing valve seals
« Reply #2 on: December 26, 2022, 23:00:00 »
..Car started smoking with the classic symptoms of bad valve seals. Engine did not smoke before this. I replaced the valve seals myself with the head on the car which I have done many times before, but only on domestic cars never on an import. The result it smokes worse now than it did before I replaced the seals..
Hi Jim, since you stated 'classic symptoms of bad valve seals' I assume the engine now smokes (blue smoke) at start-up and smoking is reduced somewhat after it's warmed up. If the engine didn't smoke before changing the valve seals, it would appear that one of the new valve seals has worked loose - it only takes one intake valve seal to jump off the guide to cause smoke. When you replaced the valve seals were you able to check for excessive wear with each guide and valve stem - did the valve stems appear too loose or sloppy? If so, a valve seal may have jumped off. I know it's difficult to see between those valve springs but I'd take another look at the seals.
« Last Edit: December 27, 2022, 15:16:42 by Charles 230SL »

toneypenna

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Re: Smoking after replacing valve seals
« Reply #3 on: December 27, 2022, 16:26:11 »
Thanks for your reply, The engine smoked after the valves were adjusted and the  sludge was cleaned by a repair shop, got the car back smoking with bad valve seals symptoms, after I replaced all the seals, it now smokes worse than before, If all the original seals were worn, I think it would take more than one bad seal to cause the additional smoking.
I ordered more seals, and when I get time I guess I'm going to have to remove springs and check to see if and where I went wrong.

A question I had and forgot to put in the original post. I don't see any oil returns in the head thinking if they were plugged that could cause the smoke, all I can see is the oil returns up front through the timing chain area. Engine has a slight tilt rearward which makes me think oil may puddle toward the rear of the upper engine.
Looked in the tech area to find a schematic of the oil system, no luck.
Am I missing something?

toneypenna

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Re: Smoking after replacing valve seals
« Reply #4 on: December 27, 2022, 16:32:00 »
Thanks for the reply, don't know how they cleaned the sludge, Depending how bad it was, I would think they scraped out the heavy deposits and then used some sort of  cleaner. Don't see how the sludge residue if any could get into the combustion chamber to burn.
Thanks again

Charles 230SL

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Re: Smoking after replacing valve seals
« Reply #5 on: December 27, 2022, 19:01:06 »
..I don't see any oil returns in the head thinking if they were plugged that could cause the smoke, all I can see is the oil returns up front through the timing chain area. Engine has a slight tilt rearward which makes me think oil may puddle toward the rear of the upper engine..
I suppose the theory is, if the rear oil channel is plugged with sludge, oil could puddle to a point where it's level with the valve seals (?) That'd be quite a puddle but I guess its possible. I've attached a photo of a M127 head (complements of Por911t4) and it looks like there may be an oil return at the rear cam tower (I'm hoping someone has a better photo of a bare M127 head).
If this is indeed an oil return channel, it might be plugged with sludge; note the proximity of the #6 valve guides.
« Last Edit: December 27, 2022, 19:13:54 by Charles 230SL »

Charles 230SL

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Re: Smoking after replacing valve seals
« Reply #6 on: December 27, 2022, 21:18:24 »
Just found this post regarding the rear oil return: https://www.sl113.org/forums/index.php?topic=21603.msg157927#msg157927. There's an oil return at the base of the rear cam tower that may be plugged. Looks like it might be difficult to get to it with the cam in place (photo complements of "Watson"). A quick look at plug #6 should show whether oil is pooling in the head and getting past the intake seal.
« Last Edit: December 27, 2022, 21:59:56 by Charles 230SL »

ja17

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Re: Smoking after replacing valve seals
« Reply #7 on: December 27, 2022, 23:06:07 »
The chain gallery in the front of the engine will also return oil to the sump.  Read your spark plugs. If the spark plugs get oily, then it is an intake guide/seal problem or possibly a piston ring problem. If your spark plugs stay clean it is an exhaust guide/seal problem. If just the #6 spark plug gets oily, then it could be a problem with the modulator diaphragm in the automatic transmission. If it only smokes after warm up at idle it is again an exhaust seal/guide problem.

Be sure to run the engine vigorously on a test drive to burn off any oil which could have accumulated in the exhaust system previously. With an oil-saturated exhaust system, the oil smoke only begins when the engine and exhaust are good and hot.
Joe Alexander
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rwmastel

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Re: Smoking after replacing valve seals
« Reply #8 on: December 28, 2022, 00:06:42 »
... got the car back smoking with bad valve seals symptoms ...
For the novice readers on the forum, please describe "bad valve seal symptoms".
Rodd

Did you search the forum before asking?
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johnk

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Re: Smoking after replacing valve seals
« Reply #9 on: December 28, 2022, 12:14:13 »

Be sure to run the engine vigorously on a test drive to burn off any oil which could have accumulated in the exhaust system previously. With an oil-saturated exhaust system, the oil smoke only begins when the engine and exhaust are good and hot.
[/quote]

Make sure you do this after dark. I got a ticket trying to do it in the early morning for too much smoke. Letting the car idle in my driveway wouldn’t do the trick
John Krystowski
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toneypenna

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Re: Smoking after replacing valve seals
« Reply #10 on: December 29, 2022, 23:01:43 »
Just found this post regarding the rear oil return: https://www.sl113.org/forums/index.php?topic=21603.msg157927#msg157927. There's an oil return at the base of the rear cam tower that may be plugged. Looks like it might be difficult to get to it with the cam in place (photo complements of "Watson"). A quick look at plug #6 should show whether oil is pooling in the head and getting past the intake seal.

Charles, Thank you for your input, with your help I located the rear oil return, doesn't appear to be plugged but just to be on the safe side I'll run a piece of speedometer cable down. If it was plugged there probable would have been a puddle of oil when I pulled the valve cover. I guess I was just groping for an answer to my dilemma. Next step check plugs, then remove springs to check seals, then depending on what I find remove the head.
Thanks again Jim.                                                                                                                         

toneypenna

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Re: Smoking after replacing valve seals
« Reply #11 on: December 29, 2022, 23:22:38 »
The chain gallery in the front of the engine will also return oil to the sump.  Read your spark plugs. If the spark plugs get oily, then it is an intake guide/seal problem or possibly a piston ring problem. If your spark plugs stay clean it is an exhaust guide/seal problem. If just the #6 spark plug gets oily, then it could be a problem with the modulator diaphragm in the automatic transmission. If it only smokes after warm up at idle it is again an exhaust seal/guide problem.

Be sure to run the engine vigorously on a test drive to burn off any oil which could have accumulated in the exhaust system previously. With an oil-saturated exhaust system, the oil smoke only begins when the engine and exhaust are good and hot.

Joe, as always , thank you for your knowledgeable input. The car is a stick so I can rule out the trans modulator. My next step would be to read the plugs as you suggested, depending on what I find I will probable pull some or all of the valve springs to verify all is or isn't good there. I believe I already did the test drive to burn off any oil in the exhaust, however I can always try again with a longer drive. If I can't resolve it this way next step is to pull the head. Again always good to hear from you with your input. Thanks, Jim

toneypenna

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Re: Smoking after replacing valve seals
« Reply #12 on: December 29, 2022, 23:24:53 »
Be sure to run the engine vigorously on a test drive to burn off any oil which could have accumulated in the exhaust system previously. With an oil-saturated exhaust system, the oil smoke only begins when the engine and exhaust are good and hot.


Make sure you do this after dark. I got a ticket trying to do it in the early morning for too much smoke. Letting the car idle in my driveway wouldn’t do the trick

Thanks for your input and warning, I was lucky, did it during the day, no ticket. Thanks again , Jim

Kevkeller

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Re: Smoking after replacing valve seals
« Reply #13 on: February 15, 2023, 14:20:09 »
Did you figure it out?
1970 280 SL

mBdrvr

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Re: Smoking after replacing valve seals
« Reply #14 on: February 16, 2023, 18:08:19 »
I'm interested too.
Paul Greenblatt
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Benz Dr.

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Re: Smoking after replacing valve seals
« Reply #15 on: February 16, 2023, 18:24:55 »
230SL valve stem seals are difficult to replace. The end of the valve guide is smooth and the seal is supposed to stay in place by friction - they often won't. Having the guide perfectly dry without any oil on it is essential to making seal installation work.

Any significant wear in the guide and the seal will probably pop off. Generally speaking, a waste of time. :(
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JamesL

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Re: Smoking after replacing valve seals
« Reply #16 on: February 16, 2023, 20:22:36 »
Be sure to run the engine vigorously on a test drive to burn off any oil which could have accumulated in the exhaust system previously. With an oil-saturated exhaust system, the oil smoke only begins when the engine and exhaust are good and hot.


Make sure you do this after dark. I got a ticket trying to do it in the early morning for too much smoke. Letting the car idle in my driveway wouldn’t do the trick

Italian tune-up?
James L
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toneypenna

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Re: Smoking after replacing valve seals
« Reply #17 on: February 19, 2023, 20:19:33 »
Sorry id I haven't responded to the last few posts, but I pushed  the smoking problem off to concentrate on some other work that had backed up in the shop. To recap, when I last left off, I had replaced the valve seals only to have the car smoke worse than before the seals were replaced. Took it on two extended rides, and thought it  had started to clear up, but that was just wishful thinking. This is where I paused working on it. Here is the rest of the story that should answer any of your questions and I hope may help someone in the future.
When I ordered the first set of valve seals from Millers in Arizona, one seal was sent, I called and they sent me 11 seals not 12, taking one out of the package to make up for the one they had already sent. At this point I wasn't aware that the intake and exhaust valve stems are a different diameter. They came in one package with one part #, I could be wrong but I have never seen this, different size seals have different part #'s. We replaced the seals, by now you can see where this is going. My next step was to pull the head and have it rebuilt, but I try to think logically and kept thinking how the smoking got worse after the seals were replaced. I ordered another set of seals  , again from Miller's, only this time looked more closely at the seals and saw there was a difference  in the intake and exhaust.
After re doing the job ,finding one horizontally split seal and larger size seals where they shouldn't be, we put the car back together and as suggested in earlier posts it still smoked, however about 15 miles into a 40 mile ride on the interstate the smoking ceased. Thankfully problem solved. Going back to the first set of seals I ordered where Miller's  foolishly took one intake seal out,  the single seal they had sent was an exhaust leaving me with 5 intake and 7 exhaust seals. Naturally this made the problem worse.

toneypenna

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Re: Smoking after replacing valve seals
« Reply #18 on: February 19, 2023, 20:23:10 »
Ran out of room on the last post, just want to thank everybody that responded and shared there knowledge with mw to help solve the problem.

Jim

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Re: Smoking after replacing valve seals
« Reply #19 on: February 20, 2023, 03:10:26 »
That is helpful thanks.
DaveB
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toneypenna

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Re: Smoking after replacing valve seals
« Reply #20 on: February 26, 2023, 19:51:23 »
I guess my logical thinking in my last post wasn't what I thought it was. After all the smoke had cleared up on the 40 mile interstate ride, I left the car sit  for a little over a week or so, started it and guess what, the smoke has returned. I let it run for a while never cleared up, still not as bad as before the second seal replacement but no where near acceptable. At this point I see nowhere else to go except valve guides. I guess I'll be pulling the head and having it done over.
Hope this helps someone else in the future, however any input on this would be greatly appreciated.

Jim