Thoughts on oil leak diagnosis?

[schnell944]

Hi, all. Been trying to track down a moderate oil leak at the front/driver-side area of my M62TU engine (2003 540iT) for a little while now. I cleaned the area as best I could and used UV dye. I read as many threads as I could on oil leaks in this general area. As with oil leaks like this one, it was at first hard to figure out exactly where it was coming from since it ran down onto the engine support/mount, control arm, and even the oil pan area. After cleaning and using a UV light, the circled area in the picture below seems to be highest point at which I've been able to see new oil. This is a view from directly under the engine, looking up at where the lower part of the upper timing chain cover meets the block on bank two of the engine. The valve cover gaskets are not leaking (they're relatively new and I checked all around with a mirror). Given all this, I think it's most likely the upper timing chain cover gasket that's the problem. Just wanted to try to confirm my theory or hear thoughts on any other possibilities before I dive into replacing the gasket. Thank you!

IMG_9593[7383].jpg

[R Shaffner]

I can't tell from the pic, but my first guess would be a leak from the upper timing cover, along the bottom edge. (I'm thinking of the bottom section that is horizontal. Oil gets thrown at that area constantly by the chain, and it sits there on that seam.) Also, as you might know, those gaskets start out as soft, pliable rubber, and with heat/time they shrink into brittle pieces of ____. So leaks there are common.

When I bought my '02 with 150,000 miles a few years ago, the leak was clearly coming from there (no higher). I wondered if it was nuts to replace just that gasket and the one for the cam cover, without replacing them all. I tried it and it's worked fine. No leaks from the other upper timing cover or the one below.

There is another place oil can come from that you should check first. It's the tube for the CCV that runs lengthwise along the inside of the V, from that area to the CCV valve at the back of the intake manifold. If you remove the top plastic engine cover and shine a light down between the intake runners on the driver's side, you can see the tube. Look at the front, under the front runner for cylinder #5, and you can see where the tube enters the engine. That's for blow-by gasses that have oil in them, so that tube can leak oil. If you have oil in that area, that might be the problem. If it's clean (dry), then the upper timing chain cover gasket is the top suspect.

[MSporting]

I just went through a similar process tracking down a leak that was situated on the passenger side of my M62TU - so, not the same as your issue, but I’m chiming in because of how you described the surprisingly large area these leaks can cover. My problem was the timing chain tensioner, but that little leak from where the tensioner enters the block (passenger side) had oil all over the bottom of the car, even clinging to the oil pan and the drain plug. I actually thought the plug was leaking at first.

Dealt with the tensioner problems and back to zero leaks... I know you’ve most likely got this narrowed down to your driver side, but if you haven’t already, check that tensioner because I couldn’t believe how far that leak traveled through my engine bay.


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[Chedley]

+1 Msporting.
Most likely, it is the timing chain tensioner...Start there.
Have you replaced it recently ? Did you forget to remove/replace its washer-crusher ??

[msvphoto]

+1 Msporting.
Most likely, it is the timing chain tensioner...Start there.
Have you replaced it recently ? Did you forget to remove/replace its washer-crusher ??

OP said driver's side. Unless this is a RHD car I think that might rule out the tensioner since it is on starboard.

[schnell944]

Thanks, all! Funny enough, I just replaced the timing chain tensioner as preventative maintenance (and used a new washer) last week. Engine’s just a touch over 80k miles. Everything looks good and dry in that area. Right, msv, the leak is on the opposite side (bank2, drivers side of a LHD car).

Shaffner - will double check the CCV tube. Thanks for the suggestion. Quite sure it’s dry but worth another look. Looking like I’ll be doing the upper timing cover gasket. If anyone in the NOVA area has a VANOS solenoid tool and/or special tool for leveling the new gasket I can borrow, that’d be great. Thanks again, all!!

[98OrientBlue]

Thanks, all! Funny enough, I just replaced the timing chain tensioner as preventative maintenance (and used a new washer) last week. Engine’s just a touch over 80k miles. Everything looks good and dry in that area. Right, msv, the leak is on the opposite side (bank2, drivers side of a LHD car).

Shaffner - will double check the CCV tube. Thanks for the suggestion. Quite sure it’s dry but worth another look. Looking like I’ll be doing the upper timing cover gasket. If anyone in the NOVA area has a VANOS solenoid tool and/or special tool for leveling the new gasket I can borrow, that’d be great. Thanks again, all!!

Mine is pre-Vanos M62, but I believe that leveling process will be the same. After installing new UTCCG use the valve cover itself as the leveling tool. Just put it on with no valve cover gasket and tighten evenly around. That will force the UTCC down to the right level. Tighten UTCC bolts and you're done. Remove valve cover and reinstall with gasket as normal. Worked for me and no more leaks many years since!

[schnell944]

Thanks, 98!

[schnell944]

Hi, all. Just an update with some better pictures of the highest point I've been able to identify oil coming from. See circled area in the picture below. The hole/threaded protrusion seems to collect a big drop of oil on it that then falls below to the engine support, etc. To the right of the circle (and below it) is the engine support/engine mount. To the left is the seam where the timing cover meets the block. The second picture provides better perspective relative to the timing chain cover seam. Still thinking it is the upper timing chain cover (oil running from seam on the left and collecting on the circled area)...unless there is a possibility oil could be coming from the hole that is circled? Appears to be threaded for mounting/attaching something, but I'm not sure of its purpose. Welcome any additional thoughts/theories. Thank you!
image1.jpeg
image2.jpeg

[RosieE39]

The LH engine mount bracket has oil passages for the Oil Filter Housing with 2 “O” Rings where it mates to the block.



No. 10 in the picture.
P/N 12311718712 x2

[schnell944]

Thanks, Rosie! I thought (feared) the o-rings might have been a possibility initially, but it appears that the leak starts higher than this point. The circled area in the picture is above where the bracket mounts to the block. Does this seem like a correct assumption?

[RosieE39]

Thanks, Rosie! I thought (feared) the o-rings might have been a possibility initially, but it appears that the leak starts higher than this point. The circled area in the picture is above where the bracket mounts to the block. Does this seem like a correct assumption?

Well, unless the block is porous which I highly doubt, it’s the closest, most likely place the oil is coming from, especially considering that the oil in those passages are pressurised.

[schnell944]

Hmm. Could be. Could also be that oil is running down from where the upper timing chain cover meets the head, which is just a bit higher and to the left of the circled area..it’s a bit damp in there but unclear this is the origin of the leak. ...or it could be both. Perhaps I just need to dive in and tackle one or the other at this point. If it’s the bracket I-ring, that seems like a horror to replace. Appreciate your advice!