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...why could that happen...

Bummer. Can't see how the valve could have dropped into the cylinder during this particular test because the two tiny retainers that hold the valve to top of spring set were not disturbed. Also, the air pressure from the leak down test would have hold the valve up. Sorry to hear that but you seem to be more than a DIY to have your own shop. Please share your insight when you found out something.

Here are some E32 resources beyond what you can find in this forum. Below you can find a couple of posts I submitted for the piston-ring job and prior to that. Johan/Sean's masscom site has many instructions with photos; a summary of links can be found at e 3 8 dot org slash e 3 2. Also you can find more active e32 DIyers at the b i m m e r b o a r d dot com forum. The web links are spaced otherwise they would be censored.

http://forums.roadfly.com/forums/bmw...7475504-1.htmlPatrick C 88 750 159K

Re: That pressure buildup may be telling something

Ok looks like i will be pulling the motor out next weekend when i come back from Bavarians auto show. I did the pressure test and the results where i had leaking valves, bu that did not explain the oil burning. In the process of doing the leak down test i dropped a valve. I really have no idea how that happened. I was checking cylinder number five and as i had my ear to the throttle body listenng for air i heard the valve drop. I did not think much of it untill I went to turn the crank and it did not want to turn. So that is my story. I guess I will take pictures as i build the motor and post them up. This will be a quick build cuz I have my own performance shop and i dont like to take years to build a car.

Re: valve seals

I am doing a leak down test today. i will keep this post going till i figure out the problem. If i have to take the heads off i will just send them to the machine shop and put new valves and guides in. I might as well do a multi angle valv job.

valve seals

I have read that tested how tight the seal holds against motor oil by spraying WD-40 and exercise the valve up and down (head on the bench) and inspecting how much of the WD40 leaks through to the bottom side. I only read the post after I reassembled everything so didn't get a chance to try the technique myself.Patrick C 88 750 159K

Re: charcoal canister

Thanks for all the helpfull information, I will do the smoke test this weekend as soon as i have time. I have a smoke machine in my shop, its just hard finding the time to work on my own car. Right now I am swampped with work, I have three cars that i am building right now for customers. For some reason I have a strong feeling that the problem is with the new valve seals I put in, cuz even thou i got them from BMW. They gave me the wrong one's twice.

Start by using the right engine oil grade first.

ACEA A3/B3-B4 approved would be a good choice of oil.
Mobile 1 does not make any oil approved for our v12.
Try Castrol syntec 5w-40 or if you live in a warm area Total quartz 10w-50.Some people use 10w-40 gtx but that is not syntetic.
Use of Bmw approved specila oils makes your engine last longer. 1988 750il 128000km alpine white.
88 735i 272000km Da Silva(EAT) chip
91 318 5 speed 291 000 km stock

That pressure buildup may be telling something

The rings may be just strong enough to withstand combustion pressures commensurate with idling load. During an acceleration cylinder pressures are much higher and that might explain why there is blow-by buildup. I actually didn't see oil spill around my oil filler cap before I changed rings so to this date I have a doubt that my present oil leaks into cylinders 1 2 and 3 are coming from the valve stem seals (which were new and I replaced a third time). BTW I also noted oil streak marks down the intake valve stems, and oil crum accumulated on the exhaust valve stems. Just don't have enough experience to conclude from these observations.Patrick C 88 750 159K

Re: Patricks glass oil 'cannister' is shown here

Any one else have any other sujestions? Or has anyone ever had this problem. Also I noticed that after driving that when i check under the hood there is alot of oil on the valve cover right where the oil cap is. It is not the valve cover gasket. It seems to be coming out the oil cap but i cant see how cuz i just put a brand new one there. I am thinking that somehow a lot of pressure is building up inside the valve cover and pushing out the cap.

charcoal canister

I, and many people as well on this forum, share your feeling of having been taking great care of the car, and wonders why certain engine failure still occurred in spite of the TLC? May be 21 years of service do cause something inside the engine to weaken even though the car had not accumulated mileage. You can pay a modest fee for a good mechanics to conduct a leak down test to see if excessive pressure is leak past the rings, and on which cylinders. I did a DIY leak down test with a harborfreight tester and that told me all 12 cylinders were good! Partly that was because the tester used 35 psi, and partly because I didn't know what to look for.

Technically the rings can wear out--this you can verify by measuring the end gaps and compare the old and new rings. During the compression stroke hot gas pushes between the ring and cylinder wall and enter the crank space as blow-by so no oil can get in. But during the intake stroke the cylinder space is under a vacuum. Thus whatever oil splashed on the sidewall may be sucked into the cylinder. When I removed the heads of my M70 and looked inside, all 12 pistons had a layer of oil on top. This was despite 9 spark plugs were relatively free of oil.

As for the canister, I had noted that after I blocked off the breather valves some gray exhaust also disappeared. Basically the DMEs have a way to meter the breather valves so they open for three seconds to suck in and burn off gasoline vapor collected inside the charcoal canister. Both valves are mounted on the side of the two air filter housings. I believe the old canister was sending out too much gasoline that had caused a different kind of exhaust problem. At the end that fix didn't help the oil-burning problem enough but at the time the idea gave me some hope.

You can try a couple of things to eliminate the extra things hanging off the combustion cycles: Block off those breather valves, and block off the VCV valves and non-return valves with friction tape. Look into the rear mirror often while driving to see if oily exhaust lessens. Too bad there's no good way to block off oil supply to the valve stem seals because they can still be the source of your oil leak into the cylinders.Patrick C 88 750 159K

Re: Patricks glass oil 'cannister' is shown here

every gasket possable on my car is fixed uupper and lower oil pan gasket, valve cover gasket, vcv gasket, intake manifold gasket, throttle body gaskets, and new oil cap.

Patricks glass oil 'cannister' is shown here

http://forums.roadfly.com/forums/bmw...7423953-1.html

but you mention:
Every time i pull the plugs there is lots of oil on them, I cant see how the rings would cause oil on the plugs.
------------------
is that coming from inside the cylinders or from outside, leaking valve cover? and from there dropping into the spark plug holes?

Shogun E32 Tech Tips: http://twrite.org/shogunnew/topmenu.html

Re: I did try a lot of fixes

yes the smoke is very embarrassing,especially the way I have My car set up. I am trying not to lean toward the rings as the problem but it might just be that. I realli dont see how cuz i really take car of this car. oil changes on the regular and i only use sunnoco 93. I keep her parked in the garage and i dont drive her in the winter. You metioned something about the cannester. What cannester are you talking about? Every time i pull the plugs there is lots of oil on them, I cant see how the rings would cause oil on the plugs.

I did try a lot of fixes

and until this last year I changed out the rings and no more blue smoke. However, I can't declare victory because cylinders #1 2 and 3 are still having problems. A professional mechanics performed a leak-down test that used 100 psi pressure (versus my DIY tester that used 35 psi) and he reported that he heard air leaks into the crank space when testing those 3 cylinders. I also measured roundness of those cylinders but couldn't find anything--as a shadetree I didn't know what to look for. It still burns oil, but more discretely.

So what I want to say is, based on my limited experience, after exhausting all other possibilities (canister/breather valves; VCV; valve stem seals) changing the rings has brought limited success and has since prevented embarrassing blue smoke.Patrick C 88 750 159K

Re: make a plastic bag test

I did the plastic bag test already and it sucked the bag in just a little. I also rechecked the VCV's and they are good so are the old once's.

make a plastic bag test

let engien run in idle, open the engine oil cover, put a plastic bag straight over the opening of the oil cover so that it is sealed. If it blows out, not good, if it sucks the plastic in a bit, o.k.

For sure Patrick C750 will chime in, he had the problem for years and made sveral tests with VCV valves etc.Shogun E32 Tech Tips: http://twrite.org/shogunnew/topmenu.html

burnning oil 750il 1988

Hello guy's i am having a little issue with My 750il. She is throughing a lot of blue smoke and I cant figure out what is wrong. everything was fine untill i did the valve cover gaskets and the oil pan gasket. After I did the valve cover gasket I stated noticing a little smoke when I got on the gas heavy, over one months time it gradually got worse. to the point where it will smoke as soon as i started it up in the morning. I figured it must be my valve seals after reading a couple of right ups about blue smoke from a 750il. so i parked the car for about two months until I got the seals and found time to do them. (yes everything on my car i do myself) So now after changing all the valve seals and replacing the VCV's and hoses along with fresh plugs, distributor caps and rotors. The car still Smoke like a chimney. As soon as you start it up it smokes and idles ruff, let it warm up and drive and you see smoke. After the car is really warm you do not see smoke anymore and she idles very smooth, but as soon as you floor the gas peddle nothing but pure smoke out the exhaust. The car is burning about one quart of oil a day an when you pull the plugs they have a lot of carbon build up on them and oil. Today I desided to do a compression test and the results are as followed:
Cyl 1- 145, 2- 160, 3- 165, 4- 145, 5- 170, 6- 160, 7- 160, 8- 160, 9- 160, 10- 145, 11- 145, 12- 145
I dont know what the compression is suppose to read I just know that these motors are 8.8:1 I do know that this is not a good sign of compression. I just wanted to hear what you guys think the problem might be. I am going to do a smoke down test this week, but I am thinking its my oil rings.( I could be wrong) The car only has 127,000 miles on it I am the second owner and I do take care of he car. Only use mobile 1 full synthetic 5w30. Any help would be appreciated.