blue smoke under accelaration merc 380 sec - PeachParts Mercedes-Benz Forum

paddy42 · #1 06-01-2009, 04:09 PM

hy my merc 380 sec is blowing blue smoke under accelaration in the sports mode (b button) but is completly fine to drive standard mode, it revs with plenty of power in neutral and no smoke , only when its driven in kick down b button. ive taken off the air box lid and saw some oil on the pan and sludge in the crank breeder pipe cleaned all of this , also changed oil and filter to 5-30 semi syntetic, please help as im new to this site and cant afford to spend alot at the moment regards

david s poole · #2 06-01-2009, 06:39 PM

if it is blowing blue smoke under acc and not just high r.p.m.then you have oil ring problems.much more likely is that the valve stem seals are history and need replacing.to check this drive car in low gear[b]up to 4000rpm and take foot off acc,look out rear vision mirror and look for the smoke.i think [and hope for your sake]that this what you will find.

RSA560 · #3 06-02-2009, 03:33 AM

...Use thicker oil as well

arvy · #4 06-02-2009, 03:43 AM

If your valve stem seals are gone, you will also notice blue smoke on startup.

paddy42 · #5 06-02-2009, 02:40 PM

Thanks for your reply David
Yes you are right , when in b button at 4000 rpm foot off blue smoke. I am not a mechanic but handy so please tell me where valve stem seals are 0n a 380 sec w126. hence there is no blue smoke on start up and when its in neutral it will rev to 6200 rpm with no smoke and also engine sounds fine , im stuck not knowing what to do now.think ill buy a service detail manual and start stripping starting with the airfilter and see whats underneath , do you agree or otherwise.

pawoSD · #6 06-02-2009, 02:57 PM

Quote:

Originally Posted by paddy42

Thanks for your reply David
Yes you are right , when in b button at 4000 rpm foot off blue smoke. I am not a mechanic but handy so please tell me where valve stem seals are 0n a 380 sec w126. hence there is no blue smoke on start up and when its in neutral it will rev to 6200 rpm with no smoke and also engine sounds fine , im stuck not knowing what to do now.think ill buy a service detail manual and start stripping starting with the airfilter and see whats underneath , do you agree or otherwise.

Whoa there!

....valve stem seals are not a job for someone who is "handy".....they are inside the head of the engine under the valve train and springs. This job should be left to a MB mechanic. At the same time it might be a good idea to have them replace the timing chain and guides on that engine if it hasn't been done recently, since they will have it all apart anyways.

Don't start removing stuff from the engine. This is not a task for the average DIY'er, even I don't think I would attempt it, and I've done some major stuff on these cars.

paddy42 · #7 06-03-2009, 05:42 AM

Hi , i dont even know if it is stem valve seals as i said there is no blue smoke under normal driving conditions, MB tell me that if they were causing problems it would under perform with constant blue smoke, anyway ive started cleaning the the filter and breather pipe to the crank with the result of alot less smoke and only at very high revs, doesn`t seem to burn oil either, there must be some one who experienced this on there car, i dont think this is a major problem and im not going to MB as been quoated 88 uk pounds per hour just to diagnose problem, whole car only cost £510 and in otherwise good condition with 12 month mot.think ill just drive with light foot in future.pity though as i would really like to fix.

david s poole · #8 06-03-2009, 10:06 AM

until the valve stem seals get worse you can just replace spark plugs[which btw if you pull them out you will see evidence of oil burning]this situation will eventually foul the plugs and you will need to replace them.also keep a good check on oil level as it will go down.

paddy42 · #9 06-03-2009, 02:31 PM

Thanks David

Top man , ill have a look at plugs tommorow and change them out. ill let you know , funny thing is it doesn`t seem to be using any oil but probably will over time, since i cleaned the sludge out of the breather pipe in the air filter and cleaned all round there is llittle or no oil burning, well im saying this convincing myself , but in the end ill have to have an overhaul £££££

olpos · #10 06-04-2009, 03:33 PM

One way to stop a car from smoking is to run syntec oil.For me its mobil 1 15-50
Do not use a syntec blend,must be full syntec.If you use a stop smoke addative it will stop smoking or get much worse.Do not use with the syntec oil, must be pure syntec.You most likley need valve guide seals.Some only smoke on deceleration,not start up.Although this is a patch it works very well.Cars do not die from bad valve guide seals.When the seals get bad enough it becomes cheaper to fix the seals.Depends on how much oil you use.
Thanks
Rich

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