Help Needed Diagnosing Coolant and Oil Leak

[6MTGirl]

I took another look today. There is definitely a leak coming from the timing chain tensioner - there were all kinds of oil and grime under it. I tried snugging it up and didn't get it to budge, but I had to use a weird combination of a 32mm deep impact socket, 1/2 to 3/8" adapter, u-joint and ratchet. That didn't provide the best of leverage. Do you guys use a short 32mm, or a 1/2" u-joint and a deep socket? I will need to get the correct tools for this job, especially if I'm to replace the washer. I also tried to inspect the bolt behind the thermostat housing. It appeared dry from what I could see.

sapote asked if sealant was used on the VCG - there is some at least in the corners. I've read that's where it's supposed to be applied anyway. However, the VANOS itself looked pretty grimy on the exhaust side.

See photos below. Would you guys say the VANOS could be the cause of the timing chain tensioner leak? Thanks again for the help!

[BlAikenstein]

I use a harbor freight pivoting ratchet thing with a short 32. It’s awkward but works well.

I’m betting vanos *gasket. Mine leaks down to the tensioner and then drips on top of the ac compressor. If you clean all the grim off and take it for a quick drive with redline pull you’ll see fresh oil under the vanos

*Sealing plate is between the valve body and vanos. My leak is coming from the steel gasket between the vanos and head

[PetrolM3]

There is also an oil ‘freeze plug’ (hole is used for machining during manufacturing then plugged) under the Vanos solenoid which can leak or literally fall out. Mine was leaking and made a serious mess in that area. You’d have to remove the solenoid and thermostat housing to get to it. I agree with doing a thorough clean up of the area to be able to pinpoint the culprit.

[erickhoyos]

I took another look today. There is definitely a leak coming from the timing chain tensioner - there were all kinds of oil and grime under it. I tried snugging it up and didn't get it to budge, but I had to use a weird combination of a 32mm deep impact socket, 1/2 to 3/8" adapter, u-joint and ratchet. That didn't provide the best of leverage. Do you guys use a short 32mm, or a 1/2" u-joint and a deep socket? I will need to get the correct tools for this job, especially if I'm to replace the washer. I also tried to inspect the bolt behind the thermostat housing. It appeared dry from what I could see.

sapote asked if sealant was used on the VCG - there is some at least in the corners. I've read that's where it's supposed to be applied anyway. However, the VANOS itself looked pretty grimy on the exhaust side.

See photos below. Would you guys say the VANOS could be the cause of the timing chain tensioner leak? Thanks again for the help!

When my timing chain tensioner was loose and had no way of fitting a wrench in there, what my dad and I did was use a pair of locking pliers and locked the socket really tight so it wouldn’t slip when tightening. Probably one of the worst ways to ruin a socket but it worked really well.

[2004LSB]

This tool should help tremendously with getting the timing chain tensioner off or to tighten down:

https://www.harborfreight.com/3-piece-square-drive-socket-caps-67011.html

Just get a deep socket, use this tool, and a wrench and you should have just enough room to get enough leverage

[6MTGirl]

I use a harbor freight pivoting ratchet thing with a short 32. It’s awkward but works well.

I’m betting vanos *gasket. Mine leaks down to the tensioner and then drips on top of the ac compressor. If you clean all the grim off and take it for a quick drive with redline pull you’ll see fresh oil under the vanos

*Sealing plate is between the valve body and vanos. My leak is coming from the steel gasket between the vanos and head

Thank you for sharing. I am going to start compiling a parts list for when I get around to bulletproofing the VANOS and I'll be sure to replace every nut, bolt and gasket. I won't be driving the car until I fix the coolant leak for fear of overheating, but I'll clean up the grime as best as I can for now. Mine drips on the high pressure power steering hose, making me think that's leaking too (which is not out of question, haha).

[6MTGirl]

This tool should help tremendously with getting the timing chain tensioner off or to tighten down:

https://www.harborfreight.com/3-piece-square-drive-socket-caps-67011.html

Just get a deep socket, use this tool, and a wrench and you should have just enough room to get enough leverage

That's pretty cool, thanks! I'll pick up a set of these and a 3/4" wrench. I happen to have a deep 32mm socket that I needed for the axle nuts on my racecar. I had stashed it away not thinking it would be used for anything else, but here we are.

[bigjae46]

VANOS sealing plate

But don’t listen to me...


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[sapote]

The VANOS high pressure oil line is usually the culprit - - the insulated section that is slightly bendable usually develops a small fracture (I'm assuming through repeated heat cycles) and spews oil all over the headers, exhaust side of the block, and even chain tensioner when the car is running. Replaced it and no more pesky leaks!

I thought about the same oil line, but this leak is very little and if the VANOS line leaked then it should be a big mess with high pressure oil (115 bar = 1668 psi) ; therefore I don't think it's the source.

[6MTGirl]

The VANOS high pressure oil line is usually the culprit - - the insulated section that is slightly bendable usually develops a small fracture (I'm assuming through repeated heat cycles) and spews oil all over the headers, exhaust side of the block, and even chain tensioner when the car is running. Replaced it and no more pesky leaks!

The stuff on the belly pan though...that looks almost coolant-like. When was the last time the car had its coolant drained out? With age and repeated heat cycles, the O ring on the lower radiator hose temp sensor usually flattens out and causes a leak once the system becomes pressurized.

The stuff on the belly pan is coolant indeed. I saw the coolant dripping on the ground and that's what prompted me to remove the belly pan and look around. That's how I discovered the oil leak at the front of the engine. The coolant leak turned out to be from the temp sensor. Leaks galore!

[sapote]

The other potential source of oil leak is the right side upper chain guide pivot bolt with sealing washer. It's right under the VANOS. Make sure it's not loose.

[sapote]

Oil's on the chain tensioner doesn't mean the tensioner is leaking -- leak from above can make it look dirty. I would remove the VC and if reuse the gasket if it's still soft. Clean all RTV and redo again, making sure to add some at the VANOS/head seams, and the cover corners. I don't use RTV on all gasket surface.

[Grke46m3]

I use a harbor freight pivoting ratchet thing with a short 32. It’s awkward but works well.

I’m betting vanos *gasket. Mine leaks down to the tensioner and then drips on top of the ac compressor. If you clean all the grim off and take it for a quick drive with redline pull you’ll see fresh oil under the vanos

*Sealing plate is between the valve body and vanos. My leak is coming from the steel gasket between the vanos and head

The vanos gasket can be replaced without messing with the timing or fully removing the vanos unit right?


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[6MTGirl]

The other potential source of oil leak is the right side upper chain guide pivot bolt with sealing washer. It's right under the VANOS. Make sure it's not loose.

This guy? From what I can tell from above, it seems dry and I can't spin it with a screwdriver like that.

Oil's on the chain tensioner doesn't mean the tensioner is leaking -- leak from above can make it look dirty. I would remove the VC and if reuse the gasket if it's still soft. Clean all RTV and redo again, making sure to add some at the VANOS/head seams, and the cover corners. I don't use RTV on all gasket surface.

That is the case for me - I re-checked that the tensioner is tight. I will pull the VC for the VANOS bulletproofing, which is a job much too big for me to undertake without more expert supervision, so it will have to wait a bit. So, you use RTV in the corners and on the half moons (front and rear)?


In the meantime, I have a new coolant temp sensor on the way and would like to flush and bleed the coolant since it's pretty old. What is the best place to drain it from, other than at the sensor? I figure that's the lowest point, but I've heard most of the coolant is in the block. I'd like to avoid touching the engine block plug if I can help it.

[BlAikenstein]

The vanos gasket can be replaced without messing with the timing or fully removing the vanos unit right?


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Yeah for sure, you’ll have to wiggle the cams to get it to push off the head but it only needs to come out a little. If you haven’t replaced the o rings on the sealing plate that’s an easy job to knock out at the same time