M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: B318M42W on November 08, 2008, 11:55:36 AM
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I have a few questions and concerns with my engine...
1) some coolant finds it's way into the oil, but the engine isn't burning abnormal oil quantities or any coolant. Last know compressions were about 210 psi, where's the leak???
2) how reliable is the timing chain on the M42? car has about 175 000 miles ont it. do they break a lot? are the sprockets subject to failure wear? any operational restrictions until it's fixed??? and in the event it snaps, how much does a head go for these days???
Thanks for any imput!
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bump
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if your timing chain snap's you will need alot more then just a head lol
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Stock timing chain is double row, it's not bad, just keep the tensioner replaced when needed, there is also a guide that sometimes needs to be replaced.
I am no big expert on the coolant in the oil, but it could be a head gasket or timing profile gasket (the 1 big flaw) among other things I suppose.
Most profile gaskets failed within 100,000 miles from the factory and many were replaced under warranty, haven't really heard from a replacement failing.
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Coolant leak may be coming from the profile gasket.
sprockets and chain are prone to wear... never heard of a chain snapping though. Just make sure to keep up on the tensioners.
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Thanks for all the input! Tensioner was replaced about 5K miles ago... should be good for a while...
coolant flush with a thing that seals holes in the cooling system will hopefully buy me a few months until I decide to undertake the replacement of the profile and head gasket...
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Never mind how reliable the timing components have been for other people. Have you pulled the valve cover and done an inspection of the sprockets? Have you pulled the oil pan and looked for loose bits in it? At 175k, it's definitely time for you to undertake those two activities. Check for properly torqued upper pan bolts while you're in there -- that's another M42 killer.
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I was thinking on having a look at the chain/sprockets when i get a chance in about 2 months, (car is not a DD...) How can I tell if it's excessively worn out? places that are more a good idea to check out?? to take out the lower oil pan, do i need to remove the subframe crosmember??
Thanks again!
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The new sprockets are flat on the outermost diameter. This flat spot is about 1.5 mm wide. The worn out sprockets don't have a flat spot, they come to a point.
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I have a few questions and concerns with my engine...
1) some coolant finds it's way into the oil, but the engine isn't burning abnormal oil quantities or any coolant. Last know compressions were about 210 psi, where's the leak???
2) how reliable is the timing chain on the M42? car has about 175 000 miles ont it. do they break a lot? are the sprockets subject to failure wear? any operational restrictions until it's fixed??? and in the event it snaps, how much does a head go for these days???
Thanks for any imput!
1) Are you sure it's coolant.. what season are you in? It could be condensation. If you're not loosing coolant it might not be coolant, but condensation... It might also be coolant in a small quantity. Your leak might not be large. It really can be hard to tell. Can you really tell if you loose 50-100cc ?
2) I've never heard of a chain snapping. But i have experienced a failure of the tensioner, together with the rails. I have heard a lot of others experience this. Actually on my desk right now i have a oilpump housing with evidence of a failed intake side chain guide "It has chain scuffing marks, that would not be possible with an intact guide". When the engine i'm now driving had this incident i drove it home approximately 50km. It sounded awefull, but it didn't do any other damage to my engine.. But if you can avoid driving when it fail i would prefer that.
The timing chain on a M42 comes cheap, so if it has an unknown history and high mileage i'd change it out. as a comparison the timing chain assembly on a S14 engine is very expensive you can pay above 700 USD just for the essentias.
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the reason why i think that it's coolant that just seeps though is that normally when i redline it a few times, the oil get a little more clearer, and seems to have a small change in viscosity (more water like feeling to it). also, after an oil change, i skim an object at the surface and it leaves behind a trail, that's lighter in colour and then resorbs itself back to the "original" state. I did notice last winter that the coolant level went down a little (about 1cm per 400 miles). also, (maybe not related...) the oil smells bad, a bit like exaust and gas. oh and the engine has a tendency to groan upon starting and then a little bit around 1500-1800 RPM.
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the reason why i think that it's coolant that just seeps though is that normally when i redline it a few times, the oil get a little more clearer, and seems to have a small change in viscosity (more water like feeling to it). also, after an oil change, i skim an object at the surface and it leaves behind a trail, that's lighter in colour and then resorbs itself back to the "original" state. I did notice last winter that the coolant level went down a little (about 1cm per 400 miles). also, (maybe not related...) the oil smells bad, a bit like exaust and gas. oh and the engine has a tendency to groan upon starting and then a little bit around 1500-1800 RPM.
water often produces a brown gue / sludge inside the engine...
try (with the engine turned off) to stick your finger inside the engine through the oilfiller hole and see if theres any such deposits to be found....
Alternatively you can remove the cam cover and inspect it this way..
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interesting! i'll remove the vavle cover and keep an eye out for the deposits at the same time as the timing components inspection... (that should be after x-mas.. don't have the car right now :( )
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I replaced my valve cover gasket 2 days ago, since I was going to change the oil anyway and some of the bolts on the valve cover were not properly torqued, and I also checked the lower oil pan while I was at it, and found 3 screws lying on it. I heard it is not uncommon, nor good, since it may affect the oil pickup, depending on which bolts are loose, I believe. It all took longer than I would have wanted, but in the end I managed to put it all back together. No apparent damage or anything wrong when removed the valve cover. Engine was running smoother afterwards, but to my surprise now thereīs a leak. Not from the valve cover gasket (as it was before, thatīs what led me to this), havenīt been able to pinpoint where from since it has been raining for the last 2 days. What weirds me out is the yellowish/greenish-oily stuff that leaks from my car. Iīm assuming thereīs coolant leaking into the engine. But whereīs it leaking in there through? and where is leaking it out from? I might be able to figure all this out tomorrow īcause I donīt have to work. It smells very lightly like burnt oil, thereīs no overheating. Is it too bad to drive a few miles here and there before I get this fixed?
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I also have that kind of burnt/overheated oil smell from the oil. I've tried lubromoly 10w40 semisynthetic oil and a more "regular" oil and it still smell... It's been running like that for the past year or so (or about 15K miles). In my opinion, I think that the oil gets that smell from the blowby exhaust gases from the cylinder???
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Also, if you have any leaking oil that gets on your exhaust manifold, that could induce such smells.....
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roundel318, youīre exactly right. I figured out I had a leak through my valve cover gasket only after the smell caused by oil dropping on the exhaust manifold. I only noticed it when I parked, as I turned off the engine but the exhaust pipes are still very hot. I didnīt smell anything as I was driving. Right now Iīm trying to figure out where is it leaking from, from the top everything looks clear and dry, and from the bottom everything looks dark and wet. And with all the hoses is hard to look in between. So far I could not find any traces of coolant leaking into the oil. Iīm heading out to remove the valve cover, wish me luck!
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Well, no coolant is leaking into the oil, and no oil is leaking out the valve cover, thatīs the good news. Now, my spark plugs were somewhat oily, and cylinder #3 makes a soft rattling sound and I could feel the bumping on the spark plug boot as I touched it. What does that mean, and more importantly, how do I fix it?:confused:
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then oil is leaking through the valve cover down in the spark plug wells? When mine needed to be replaced, this was happening to me.
Also, I have some light oil leakage from the oil pan that sometimes will get on the exhaust a bit and cause a smell.
Thoughts?
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well, the leaking of oil into the spark plug wells most probably comes not from the outer, rectangular-shaped part of the gasket, but from the gasket "rings" in the middle. Most likely, theyīre not fully seating where they should, either because of their position or because of wrong amount of torque on the bolts. I thought at first: the tighter, the better, right? since weīre trying to avoid leaks. I was told thatīs not necessary true, and that by not tightening the bolts too much, you are just leaving the room the gasket needs to expand (due to temperature increase) thus keeping the oil from leaking out. Although I have no number for the amount of torque used on these bolts. Iīm keeping a close eye on my valve cover, havenīt seen any leaking so far. But I know itīs leaking from somewhere else. Iīm going to keep on replacing gaskets to see if it stops. The one I took from the valve cover looked just fine, but it was leaking, so I guess we canīt tell just by how it looks (at least I canīt). Next one up is the lower pan. I need to get me a torque wrench.
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Don't overtorque those bolts on the cam/valve cover! They are only like 8-10 lbs; the head is aluminum, too tight and you will strip them out. Then you will get to find out how much fun it is to helicoil! :)
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There is documentation around on the internet with Torque values for EVERYTHING on the M42.
Might want that :)
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coolant in oil sounds like head gasket, and as for the oily plugs the seals on the plugs wells for some reason always go. Idk why but for some reason it happens often.
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German's didn't know how to make gaskets before the mid 90's.
The Japanese called with suggestions :)
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I just replaced my cam cover gaskets. They were leaking but there was no obvious reason for it. Comparing the new ones to the old, the rubber apparently gets much stiffer over time.
coolant in oil sounds like head gasket, and as for the oily plugs the seals on the plugs wells for some reason always go. Idk why but for some reason it happens often.
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tru story.. lol
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:eek:
I just replaced my cam cover gaskets. They were leaking but there was no obvious reason for it. Comparing the new ones to the old, the rubber apparently gets much stiffer over time.
I don't wanna go on and on, but the "obvious reason" is just pre mid 90's german gaskets ;)