discussion E36 318is white smoke above 3500 rpm

[Smell my finger]

Hi gents. I recently had a 1700km journey in a freshly rebuilt 318is(check my other thread for more info). The car runs fine but I have a persisting issue of white smoke above 3500rpm or generally when I do a pull or rev it up past that point. The only thing I didn't do when rebuilding the engine was valve stem seals. The head gasket and piston rings were done as well as the big end bearings. I know it's obvious that I should just do the valve stem seals and see if anything changes but I would like a few other opinions to confirm.

Thanks gents,
Stay safe

 

[husaindindar]

Idle the car for about 10 minutes, then give it a very hard rev.
If it shoots out a cloud of smoke, then it's valve stem seals.

 

[Mytfine]

Very hard to diagnose without a leakdown test, if its alot of smoke highly doubt its valve stem seals. How is the condition of the breathet system ?

 

[Smell my finger]

Idle the car for about 10 minutes, then give it a very hard rev.
If it shoots out a cloud of smoke, then it's valve stem seals.

Did your test...it does produce a puff of smoke. Bought the proper kit to do the seals the easy way just need an air compressor now😅

 

[Smell my finger]

Very hard to diagnose without a leakdown test, if its alot of smoke highly doubt its valve stem seals. How is the condition of the breathet system ?

I have replaced the pcv and accompanying hoses. Tested and restested. The idle rpm lowered and is more consistent than before. I am sure there might be a slight vacuum leak somewhere else tho

 

[Gordvisr]

It can be the valve stem seals yes but, when rebuilding the motor, did you measure bore, used pistons etc, before rebuilding? if not chances are that on higher revs, you still passing oil through the rings and not the valve stem seals.

 

[Smell my finger]

It can be the valve stem seals yes but, when rebuilding the motor, did you measure bore, used pistons etc, before rebuilding? if not chances are that on higher revs, you still passing oil through the rings and not the valve stem seals.

I did not measure. I did however do an "old mechanics trick" in which I was advised to leave 20ml atf on the piston heads after installing the new rings for 48 hours. If the atf is gone the piston will most likely have blowby. This obviously doesn't account for the seal at operating temperature but it passed this makeshift "test". I was skeptical and still am. I guess I'll see on friday after I've done the valve stem seals

 

[Gordvisr]

I did not measure. I did however do an "old mechanics trick" in which I was advised to leave 20ml atf on the piston heads after installing the new rings for 48 hours. If the atf is gone the piston will most likely have blowby. This obviously doesn't account for the seal at operating temperature but it passed this makeshift "test". I was skeptical and still am. I guess I'll see on friday after I've done the valve stem seals

goodluck, hope you get sorted.