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Thread: Is oil in the cylinders normal?

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    Is oil in the cylinders normal?

    I'm getting ready to smog my car which barely passed last time on the hydrocarbons. One thing I want to do is run seafoam to clean up some of the carbon so I wanted to see a before of the pistons before I ran the seafoam using an endoscope and I found some oil in 5 of the cylinders. First time looking in the cylinder so I don't know if this is normal for this engine. The car is stock with 68k miles. Runs strong, no codes.



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    Wow, I would think not, and I would think leaky valve seals..

    If it is maybe you could run it, and then scope it immediately, and watch for a while to see if the oil is coming down from the valves..

    Are the valves closed on the one cyl with no oil? If so maybe turn the crank a bit to open those valves and see if you then get oil out of them..

    That is awfully low miles though, maybe it is coming from your intake via the crankcase breathing device..

    I don't think you would get that from bad rings..
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    Faulty CCV/separator would be my guess given the mileage. When they fail they tend to allow some oil in via the intake, and it can certainly accumulate over time.
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    I turned the crank to lower the pistons and get a better look and didn't notice any new leak in the clean cylinder. I don't think so many valve seals would fail at the same time especially will such low mileage.

    I was just thinking about the ccv allowing blow by back into the intake. Here's the thing. About 2 years ago I noticed the car was consuming more oil than usually. I've owned this thing since it was almost new and it's always burned about 1 quart every 1k miles. 2 years ago it started to burn 1 qt every 300 miles. I replaced the ccv to see if it would help. I thought it did but honestly I haven't even driven it long enough to be sure. One thing I noticed when replacing the ccv was the port that connects to the intake definitely has oil in it and there was oil in the intake. I could not see a trace of oil in the port/tube that leads to the dipstick. I took the old ccv apart and there were no tears in the rubber membrane. Is it possible there's a clog in the dipstick tube? I'll have to remove the ccv to check for oil in the intake.

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    Quote Originally Posted by ax77 View Post
    I turned the crank to lower the pistons and get a better look and didn't notice any new leak in the clean cylinder. I don't think so many valve seals would fail at the same time especially will such low mileage.

    I was just thinking about the ccv allowing blow by back into the intake. Here's the thing. About 2 years ago I noticed the car was consuming more oil than usually. I've owned this thing since it was almost new and it's always burned about 1 quart every 1k miles. 2 years ago it started to burn 1 qt every 300 miles. I replaced the ccv to see if it would help. I thought it did but honestly I haven't even driven it long enough to be sure. One thing I noticed when replacing the ccv was the port that connects to the intake definitely has oil in it and there was oil in the intake. I could not see a trace of oil in the port/tube that leads to the dipstick. I took the old ccv apart and there were no tears in the rubber membrane. Is it possible there's a clog in the dipstick tube? I'll have to remove the ccv to check for oil in the intake.
    It sounds like you're getting somewhere.

    I was just going to note that you could potentially have a leaky valve cover gasket letting oil get into your plug wells. If you didn't notice it, it would run down into the cylinder. Though I don't know how you wouldn't notice a spark plug that looked like it had been dipped in oil.

    I can see the CCV not functioning properly even if it's not ripped. Your miles are so low I can see something like that failing from sitting more than wearing.

    You could always pull the new one and see if there's fresh oil in the dipstick tube now. There will always be oil in the intake side - it separates most of the oil out, but there will always be some vaporized oil that makes it back into the intake.

    -Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.

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    You sure this isn't oil coming in from the spark plug wells having oil in them due to a faulty gasket?

    S52 were known to have bad oil ring control with 2.5 quarts of oil burn per 1000 miles being normal to BMW (it's in your manual, look it up). I guess with your motor being on the extreme oil burn side, maybe they could be that wet. Typically late model M3 do not have this issue.

    Obviously the CCV system needs to be addressed if it is suspect.

    I'm guessing you had oil in your spark plug wells. Considering your carbon buildup is very MINIMAL, this is not a long term issue you have had.
    Last edited by Braymond141; 03-12-2019 at 04:29 PM.

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    there was no oil in the spark plug wells. I'm going to pull the ccv drain tube

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    the ccv doesn't look to be doing its job. There's no trace of any oil being returned to the dipstick.

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    Quote Originally Posted by blckstrm View Post
    I was just going to note that you could potentially have a leaky valve cover gasket letting oil get into your plug wells. If you didn't notice it, it would run down into the cylinder.
    Wait, how does oil into the cylinders from the plug wells?
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    Quote Originally Posted by MauiM3Mania View Post
    Wait, how does oil into the cylinders from the plug wells?
    Because he removed the spark plugs.

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    Just an update if it can help anyone in the future.

    After looking into my oil consumption deeper I found that the ccv was working fine. The vacuum was to spec, there were no clogs and the intake didn't show signs of oil pooling. After cleaning up the engine I did find I had a leak from the oil filter housing that was difficult to notice. I replaced the gasket and it looks to have cut my oil loss in half from 1 qt every 300mi to 1/2qt which is still too much.

    The cylinders still show about a teaspoon of oil on the piston tops. I guess it's obvious that it can't be normal. I attached a mirror to my endoscope to see perpendicularly in the cylinder and I could see oil dripping down the top of the cylinder walls and with the valves open I could make out oil on the valve tops. So looks like my problem is the valve seals. I'm relieved to find the cause and that it's not the rings but still amazed how the seals could go bad with such low mileage. I know maintenance will come to mind but with 67k mi, this thing is a garage queen that's never had an oil change interval go past 3000mi, usually around 1k. I don't get it. So I'll be changing those seals soon. Heck my consumption may even go below the 1 qt per 1k mi it was doing when I bought the car at 17k mi. They may have been leaking for ages.

    oh also a $10 usb endoscope is the best diag tool I've ever bought. The car doesn't exhibit the usually signs of leaking valve seals. Doesn't smoke at startup or downhill deceleration. The only thing I did notice was quick soot buildup on the exhaust tips.

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    Quote Originally Posted by ax77 View Post
    The cylinders still show about a teaspoon of oil on the piston tops. I guess it's obvious that it can't be normal. I attached a mirror to my endoscope to see perpendicularly in the cylinder and I could see oil dripping down the top of the cylinder walls and with the valves open I could make out oil on the valve tops. So looks like my problem is the valve seals. I'm relieved to find the cause and that it's not the rings but still amazed how the seals could go bad with such low mileage. I know maintenance will come to mind but with 67k mi, this thing is a garage queen that's never had an oil change interval go past 3000mi, usually around 1k. I don't get it. So I'll be changing those seals soon. Heck my consumption may even go below the 1 qt per 1k mi it was doing when I bought the car at 17k mi. They may have been leaking for ages.
    I've only done this with the head outside of the car, but this is the best video I've seen with the head still on the block:

    https://www.youtube.com/watch?v=KzzXE1o6NeE
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    Quote Originally Posted by Hova View Post
    I've only done this with the head outside of the car, but this is the best video I've seen with the head still on the block:

    https://www.youtube.com/watch?v=KzzXE1o6NeE
    thanks. I do plan on replacing them with the head on.
    Last edited by ax77; 04-15-2019 at 11:00 PM.

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    Ax77, why don't you go take your smog test, after you get the engine really hot. If you pass, I'd forget about what you saw, and just drive your car. Sometimes, it's better not to know.

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    Quote Originally Posted by Braymond141 View Post
    You sure this isn't oil coming in from the spark plug wells having oil in them due to a faulty gasket?

    S52 were known to have bad oil ring control with 2.5 quarts of oil burn per 1000 miles being normal to BMW (it's in your manual, look it up). I guess with your motor being on the extreme oil burn side, maybe they could be that wet. Typically late model M3 do not have this issue.

    Obviously the CCV system needs to be addressed if it is suspect.

    I'm guessing you had oil in your spark plug wells. Considering your carbon buildup is very MINIMAL, this is not a long term issue you have had.
    This is my thinking too. VCG leak, leaked into the wells, leaked into the cylinder when he took the plug out

    AFAIK based on the information given, the only other place oil could get in is through the valve stem seals

    Also, valve stem seals would be the most logical reason why 5 of the 6 had oil pooled. The one that didn't had all the valves completely closed.

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    Are you actually sure it's all oil and not just condensation? I don't know for sure this happens, but it seems logical some condensation might form inside an engine that has cooled from operating temperature. If there were truly that much oil in your cylinders I'd think you'd be seeing clouds of blue smoke at start up.
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    Quote Originally Posted by marvinstockman View Post
    Ax77, why don't you go take your smog test, after you get the engine really hot. If you pass, I'd forget about what you saw, and just drive your car. Sometimes, it's better not to know.

    I actually did pass smog a few weeks ago but barely again. The hydrocarbons were at the limit because of the oil burning. At least I can drive it in the meantime but the car is in pristine condition and I can't just let it be. It'll also kill my cats if I don't fix it not to mention extra money on feeding it oil. I've already bought all the parts just waiting on some tools.

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    Quote Originally Posted by RightYouAreKen View Post
    Are you actually sure it's all oil and not just condensation? I don't know for sure this happens, but it seems logical some condensation might form inside an engine that has cooled from operating temperature. If there were truly that much oil in your cylinders I'd think you'd be seeing clouds of blue smoke at start up.

    It is oil. At first I thought it was gas and had leaky injectors which was causing me to run rich and cause the high hydrocarbons but I was able to get a drop on the tip on my endoscope. It's definitely oil. Also confirmed by my abnormally high oil consumption. There's no leaks anymore, including the spark plug seals. It's not coming from the intake manifold so it must be coming from the valves. I still shocked how a car with 67k mi could have bad valve seals. I'll be confirming it soon though

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    Quote Originally Posted by Hova View Post
    I've only done this with the head outside of the car, but this is the best video I've seen with the head still on the block:

    https://www.youtube.com/watch?v=KzzXE1o6NeE
    interesting, I had seen this video before but just noticed that he's not pressurizing the cylinder or stuffing it with rope or something else to keep the valve from falling. He just put the piston at tdc and the valve dropped only a bit.

    Can anyone who's done a valve seal job without removing the head on a s52/m52 confirm pressuring or stuffing the cylinder is not needed? I've searched. I guess it's easy enough to pressurize it. Just worried if my compressor were to cut out I'd lose the valve and be screwed but knowing that tdc would prevent that as a fail safe would put my mind at ease.

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    As the guy in the video showed, at the top of its travel the piston is definitely high enough to block the valves from falling into the block. Notice he even needed to crank the piston down slightly later to give himself a little easier time with the pliers with less valve stem sticking out.

    This is also why you have to worry about piston to valve clearance if you're machining your head and whatnot. The pistons are fully capable of hitting the valves if timing or clearance is off. If they can hit the valve, it means the valve has nowhere to fall to when the piston is up. They move a couple mm and then they're resting on the piston. Look at pictures of the underside of an S52 head and then the top of the block and you'll see there's nowhere for them to go.
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    Quote Originally Posted by TostitoBandito View Post
    As the guy in the video showed, at the top of its travel the piston is definitely high enough to block the valves from falling into the block. Notice he even needed to crank the piston down slightly later to give himself a little easier time with the pliers with less valve stem sticking out.

    This is also why you have to worry about piston to valve clearance if you're machining your head and whatnot. The pistons are fully capable of hitting the valves if timing or clearance is off. If they can hit the valve, it means the valve has nowhere to fall to when the piston is up. They move a couple mm and then they're resting on the piston. Look at pictures of the underside of an S52 head and then the top of the block and you'll see there's nowhere for them to go.

    This. Though I would highly recommend you use air pressure, or some other method to make sure the valve does not drop. You can scratch the piston or the valve, it makes sense not to let the metal on metal contact while working.
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    You should always put piston at TDC on the cylinder you are working on when doing valve stem seals. That way if the air pressure cuts out the valve doesnt fall all the way in. Its like that for almost every engine. Ive seen someone drop a valve into an N62. It did not look fun taking that head off

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    Be sure to lock the crank real good if you are going to use air pressure so you don't kick the crank over and really cause a catastrophe.. Put it in 5th gear with the parking brake on or something..

    The bottom surface of the valve and the top surface of the piston are not precision surfaces so I wouldn't worry much about scratching them.. I mean, you regularly put a C-clamp on the bottom of a valve and poke the top of your piston with a screwdriver or tap it with a hammer etc, they are not that fragile in that aspect.
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    thanks for the input everyone

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