Smell of burning

[charlieh34]

Hi can anybody advise me on this issue I have a 230TE which has had regular services and is in V good condition for 91 but if i kick her hard on an overtaking or just hard accelaration I often get a smell of burning afterwards and can see smoke coming out of the engine is this normal.
thanks all.

 

[mjtray]

Whats the mileage?

Are you having to top up with oil on a regular basis?

Does the smoke appear whilst accelarating or on the over-run?

With more info, it might help to point you in the right direction.

Cheers

 

[charlieh34]

The mileage is 120000 and the burning smell comes on the after run and when I accelerate she has just had a service and the oil is clean and does not need toping up when I open the bonnet after a journey when I have hard accelarated I can see the smoke rising up really strange as she is not overheating and I have good oil pressure!

 

[dieselman]

Valve seals need changing.

The smoke is after over-run condition as this raises the vacuum in the manifold and so sucks in oil.

 

[charlieh34]

thanks for the reply is this a big job and if so could you tell me how much this will cost me also is it okay to keep running her like she is or will this damage the engine
many thanks.

 

[flagstaff]

not a big job at all, you could do it yourself easily. it used to be the case that you would have to remove the cyl head to replace the valve seals (or fill the cylinders with string - like my uncle used to do!!) ... but this is no longer necessary. there is a tool you can get to keep the valve seated while you change the seal. don't forget to change the rocker cover gasket when you're done ...

 

[neileg]

If you're not too embarassed by the smoke, you can run the engine like this forever, almost. Topping up the oil now and again is a lot cheaper than changing the oil seals.

It is a straight forward job. I was quoted about £100 on my 190E which is basically the same engine. I decided just to run it on, and it got no worse over another 35,000 miles and two years.

 

[charlieh34]

Thanks for all your advise guys so it seems to be okay to keep her running as she is without damaging her further which I will probably do for now the problem is only noticable when i have really booted her apart from that she is fine ,

 

[Francois]

I always thought that valve stem seals would cause smoke comming out the tail pipe, not the engine itself.

Couldn't this be that the rocker cover casket is shot and this is spilling oil on a hot engine? Thus the burning smell?

 

[charlieh34]

this is quite interesting as I am not losing any oil to speak of and am certainly not blowing smoke from the exhaust could it be the rocker cover gasket leaking oil when the engine is pushed to high revs.? the smell of burning is only aparrent then

 

[flagstaff]

my money is on the stem seals. i took my '92 190e to france this summer, lots of high speed long distance stuff, and at stopovers there was plenty of oil smoke burning on the exhaust. naturally on the way home i kept the speed down :wink: oil smoke disappeared with lower engine speeds.

back in the uk, i started to get the burning smell you mention, even at low revs and general tooling about town. not all the time, but regularly. replaced the stem seals, problem gone. i don't have a scientific basis for saying this, but: my feeling was that the stem seals (when failing/failed) allow not oil but oil vapour out into the engine bay, where they will smoke on anything hot that they come into contact with.

on a long high speed run, the vapour pressure builds and busts out through (probably) the rocker cover gasket. later on, the (lower speed, lower pressure, town-type driving) oil finds it easier to escape, but in smaller amounts. hence the smell.

changethe stem seals, see what happens. they're cheap, and the job's no big deal. it can't hurt, can it?

 

[dieselman]

I always thought that valve stem seals would cause smoke comming out the tail pipe, not the engine itself.

Couldn't this be that the rocker cover casket is shot and this is spilling oil on a hot engine? Thus the burning smell?

I interpreted the problem to be smoke from the exhaust.

If the oil is leaking from the engine then firstly check the breather system is not blocked as this will cause oil to leak when driven hard due to the pressure build up in the crankcase.

 

[charlieh34]

thanks for your replies I will check the breather system is not blocked if it is okay then It must be the valve stem seals and I will have them replaced can you tell me how to check the breather system do you have to take the air filter off?

 

[Francois]

I would suggest that you try the breather and then the rocker cover gasket.

Only after this fails to work, would I change the valve stem seals.

Replacing the valve stem seals would propably solve the problem, since you would also replace the rocker cover gasket and this would obviously solve the problem if the gasket was the problem.

With my luck, if something like this happens, it is because the valve stem seals are shot and it is pumping oil vapour through an old and propably cracked gasket...

 

[charlieh34]

Could you please let me know how to check the breather not sure how to go about it, before I have the valve stem seals replaced
many thanks to all.

 

[dieselman]

You will have a pipe leading from the engine to the air filter, this is the breather. If you disconnect the pipe at teh air filter end you should be able to hear the engine internals and possibly see some smoke puffing out.
If there is no puffing the breather is blocked.

 

[charlieh34]

Many thanks for your advice.

 

[Impaler]

Don't you think smoke could be coming out of the engine because the exhaust manifold is cracked? Just a theory.