Smoke cloud!! - PeachParts Mercedes-Benz Forum

lilblkbnz · #1 03-20-2007, 10:21 PM

I just got my 87 420sel on the road after fixing a bunch of little things. Some of you may remember that I bought this as a parts car from a guy that said that the tranny was frozen. Fixed a leaking line near the radiator and it's been good to go ever since. Now for the first problem. The car runs good, no misses, good idle and seems to get pretty good mpg. I've only driven it about 400 miles since I got it. I replaced the plugs, cap, and rotor. Today I took it out for a little exercise and pushed it up to about 80 and had to stop fpr a red light. I noticed what looked to be blue smoke from the exhaust. Crap!! The car ran rough for a few seconds as I pulled away from the light and left a big cloud of smoke. I continued to drive normally and didn't see any more smoke. So I decided to push it again. The same cloud of smoke appeared again when I came to a stop and then pulled away. It seems to only do this after hard acceleration. I didn't notice any smoke while accelerating, only after slowing down to stop. I'm not getting any smoke on startup. Also, I had the wife drive while I followed in the other car and didn't see any smoke during normal driving. Any ideas?? The only issue I've found with the engine is there is a clicking that seems to be on the drivers side that comes and goes at will. Cam oilers maybe?? Could these two be related?? Thanks guys.

Rockman59 · #2 03-20-2007, 11:06 PM

Worn valve stem seals can cause that blue smoke. Very common on older Benzes.

deportes · #3 03-20-2007, 11:38 PM

stem seal posible, i replaced mine to find out it was a valve guide after i reassembled the head. removed again and rebuild it and now there is no smoke. good luck

david s poole · #4 03-21-2007, 10:16 AM

based on your description i too would go for the trans modulator[it has a vac conn]if it were valve stem seals there is usually smoke at start which goes away after warm up.

lilblkbnz · #5 03-21-2007, 10:53 AM

Thanks guys, I'll check the modulator vac hose. Right now I'm in the middle of replacing the cam oilers, one on the drivers side was broken. I'll post what else I find while I'm in there. So far everything else looks normal. Hey, this car hasn't been driven in over a year so I think it's doing pretty good. Thanks again.

psfred · #6 03-21-2007, 01:44 PM

Blue smoke on trailing throttle and after sitting at a light is diagnostic for bad valve guide seals. A pain, but not really horrible on that car.

Can cause oil consumption as high as a quart in 1000 miles above normal, too, maybe even more. Likely if the cam oiler fitting were broken, it needs guide seals.

Check the plugs, too -- if one has significant oil ash accumulations, you may have a guide loose in the head (I've seen this on a cast iron block M117).

Transmission fluid smoke is white, and a blown modulator will make it shift funny as well. It stinks something horrible, too, not like burning motor oil.

Peter

lilblkbnz · #7 03-21-2007, 03:11 PM

Update:
I replaced the cam oilers and found that the tube was bent a little bit. Just enough so that the plastic parts could not seat properly. I pulled one off my other car and installed new plastic parts. Started the car and no ticking. I took it out and drove it hard. No smoke. I drove it just like I did yesterday, accelerated up to 80 mph and slowed to a stop at a light. No smoke. I tried it several times and haven't seen any smoke yet.I'll keep an eye on it, but it looks good for now. Thanks for the inputs.