Oil consumption after rebuild

[valantis544]

hello everybody.

My 95 E36 M42 had oil consumption of 1lt every 1.000km so i decided to take the engine apart to fix it since it had 200.000km. The head was serviced with new valve seals and guides as well as new piston rings. The guy from the machine shop measured the bores and said it was ok to procced without honing (i asked for not honing to avoid removing the engine block from the car) and that rings will take about 5.000km to seat and then consumption will be about 0,5lt or less every 5.000km. That guy is fixing engines 30 years now. So i have done now about 3.500km and the car is losing 0.8lt every 1.000km!! The guy told me that for the first 5.000km some oil consumption will be normal until the rings are seated, and is pretty sure that everything was done and measured as it should on my engine. i used 10w40 non synthetic oil for first use and did oil change again at 1.500km, and i didn't baby it while driving. Also replaced chain tensioner, guides and all gaskets. CCV valve is new and working for sure. No ECU faults. Compression is very strong in all cylinders and car drives fine.

When the car is on idle for some minutes and then i hit the gas it leaves from behind a big cloud of smoke which makes me think of the valve seals but it seems black so maybe the car is running a bit rich. Other than that no visible smoke like before.

Anybody else had a problem like this before? Rings will take so long to seat properly? Maybe some of the new rings are stuck on piston? Is that amount of oil consumption normal until now? I really dont want to spend any more money chasing ghosts. Is it possible to replace the valve seals without pulling the head on this engine? If it is then i can do it myself but i really want to avoid pulling the head off again.

Sorry for the big post (its my first).

[deansweet]

I'd do a cylinder leak down test?
Could a intake cam gear be off a tooth or two?
Just guessing as I am not a re-builder but have had head work done and haven't experienced this but considering the motor was burning oil before and after rebuild it might still be your rings...

Keep us posted on what else you can think of or find out.

[valantis544]

I'd do a cylinder leak down test?
Could a intake cam gear be off a tooth or two?
Just guessing as I am not a re-builder but have had head work done and haven't experienced this but considering the motor was burning oil before and after rebuild it might still be your rings...

Keep us posted on what else you can think of or find out.

Thanks for posting. The cams installed and timing where done by the book and checked many times by turning the engine before putting everything back together. Yes a leak down test should be done but it seems not many people knows what it is here where i live. Maybe i will buy the tool with the gauges to perform the test on my own. I think, allthough not sure, that the rings installed was Goetze if that helps.

[romkasponka]

IMHO if you replace rings you must do hone. I done rings replacement with hone and oil consumption was low like before rebuild. Never added oil and doing just replacement.  From the symptoms you say it looks like problems with valve seals or guides.

[valantis544]

IMHO if you replace rings you must do hone. I done rings replacement with hone and oil consumption was low like before rebuild. Never added oil and doing just replacement.  From the symptoms you say it looks like problems with valve seals or guides.

I am also thinking at valve seals which i can replace in a day or two. I hope it is something like that and not the guides but i trust the guy which did the work on the head. The engine gasket set was bought by me from pelican parts, which includes the valve seals, so no errors there like wrong seals, allready checked that.

[romkasponka]

Your engine is M42 and not M44? Are all the spark plugs looks the same?

[valantis544]

Your engine is M42 and not M44? Are all the spark plugs looks the same?

The engine is M42. Spark plugs replaced when the engine was fixed and again replaced 3 days ago and unfortunately was thrown away accidentaly (by a friend hehe) before i was able to have a look at them so i will check them in about 1.000km.

[valantis544]

Anyone replaced valve seals without pulling the head on a m42?

[keflaman]

Deansweet is right, a cylinder leak-down, aka pressure differential test, would be in order and will eliminate or confirm blowby. Where are you located? I lived in Italy and my neighbor was a mechanic. I bought him a leakdown tester and I don't think he ever comprehended the concept. His father had the shop and was a mechanic for decades. They were pretty resistant to towards learning anything new because "that's the way we always have done it."

I also heartily agree with romkasponka about honing and I think it was a mistake not to. The purpose of honing the cylinder bores is to eliminate glazing and establish a cross-hatch pattern to retain oil on the cylinder walls for lubrication as well as proper break-in for the new rings.

I believe you can replace the valve seals on the head in situ, but if you've already installed new ones...I think by process of elimination it points to the rings not seating.

[romkasponka]

IMHO if all spark plugs looks the same there can be only few things: rings/cylinder or head job is done not good or with wrong parts (tolerances valve stem/guide is too big or valve seals are damaged or not correct). If you say that head is done really good you have to hone cylinders and probably remove oval wear.

[valantis544]

Deansweet is right, a cylinder leak-down, aka pressure differential test, would be in order and will eliminate or confirm blowby. Where are you located? I lived in Italy and my neighbor was a mechanic. I bought him a leakdown tester and I don't think he ever comprehended the concept. His father had the shop and was a mechanic for decades. They were pretty resistant to towards learning anything new because "that's the way we always have done it."

I also heartily agree with romkasponka about honing and I think it was a mistake not to. The purpose of honing the cylinder bores is to eliminate glazing and establish a cross-hatch pattern to retain oil on the cylinder walls for lubrication as well as proper break-in for the new rings.

I believe you can replace the valve seals on the head in situ, but if you've already installed new ones...I think by process of elimination it points to the rings not seating.

i live in Greece. I know not honing the cylinders was a mistake but they were carefully measured and found fine with the factory cross-hatch well present. Mechanics here are just about the same don't want to know new techniques.

[valantis544]

IMHO if all spark plugs looks the same there can be only few things: rings/cylinder or head job is done not good or with wrong parts (tolerances valve stem/guide is too big or valve seals are damaged or not correct). If you say that head is done really good you have to hone cylinders and probably remove oval wear.

I must find an easy way to see if the problem is from the rings not seating or seals. Maybe the seals where wrong size what can i say. If someone tells me that it is possible for sure to replace the valve seals with the head on then i will go for it. Until then i will add some kilometres to the odometer and see if anything changes.

[colin86325]

It should be possible to replace the valve seals in situ using a tool like this one, and compressed air to hold the valves in place:

http://forums.bimmerforums.com/forum/showthread.php?602796-Custom-Valve-Compressor-Tool

[romkasponka]

I saw more easy way. Camshafts are removed. You can lower piston in particular cylinder and fill cylinder with rope fed through spark plug hole.  Lift the piston up till the rope did not let you turn the crank more (no brutal force) and you can do seals replacement because valves will be kept closed with the rope. It would  be smart to check that valve do not go in when you press on it.  I saw it on youtube

[valantis544]

Tnanks for the posts guys. Yes i am planning to use the rope method and also built a custom tool for compressing if i decide to replace the seals. This morning i told my brother to start the car and no smoke i mean none. I am curious where all that oil goes and i have no leaks. I hope the consumption settles down.