Coolant and possibly oil leaking at front of engine

[BennyM]

Just noticed a puddle today under the front of the engine. I followed the leak up the engine to right under the thermostat housing. I didn't have enough time to pull the fan and really get in there, but when I slid my fingers around the area, it seemed like there was oil seeping down as well. So, now I'm a little freaked out since oil doesn't flow through the thermostat housing, but does, I believe, flow through the timing case --and isn't that supposed to be sealed on top by the head gasket?!

Has anyone else ever experienced this?

[whiskychaser]

Are you sure the water pump isnt leaking? If so you might find it feels wet behind the water pump pulley or you may see a trace of spray on the side of the air filter box.
The timing chain cover conveys coolant down from the head and butts up to it. Any sign it has been off? If the timing chain cover is positioned even slightly off from the level of the top face of the block, you can put in new HGs and torque the bolts down as many times as you like. You will get nice compressions but it will still leak at the joint. No prizes for guessing how I know

[BennyM]

Ugh, I wont have time to check for a few days. I'll just have to keep it topped off in the meantime. The belt, pulleys, and airbox are dry. It also feels dry below the water pump. Everything seems to be running down the exhaust side of the front of the engine. How would the timing case be off if it wasn't off before, especially when there's like 50 bolts holding it in place? If that is the case joint, I'm wondering if there might be a way I can seal it with some gasket goop. Thanks for the quick insight, though.

[whiskychaser]

How would the timing case be off if it wasn't off before, especially when there's like 50 bolts holding it in place? If that is the case joint, I'm wondering if there might be a way I can seal it with some gasket goop. Thanks for the quick insight, though.
Thats why I was asking if it had been disturbed:) The hole in the top of the timing chain cover is actually on the opposite side to the exhaust:
http://www.realoem.com/bmw/showparts.do?model=HD68&mospid=47405&btnr=11_0157&hg=11&fg=10
But as the engine is cranked its possible it could run down the exhaust side. If you 'just' take the timing chain cover off, you wont be able to get at the joint between the top surface of the HG and the head. I ended up putting a smear of sealant on both sides of the HG round that hole and all was well. Hopefully my experience is totally irrelevant and someone else will chime in with an easy fix.

[BennyM]

Reporting back.
So, I checked the engine with the fan off and determined that coolant is leaking pretty freely from the thermostat housing. The housing is metal, but if the price is low, I'll replace that with the gasket. I know #10 in this diagram is seeping, but I can't figure out where else oil is coming from. http://www.realoem.com/bmw/showparts.do?model=HD53&mospid=47404&btnr=11_1282&hg=11&fg=15

I noticed that #9 was stripped and loose (PO had the wrong sized bolt in there and had over-torqued the few threads it was grabbing), so perhaps that allowed the vanos gasket to open on that side. I'm guessing I would have to replace that gasket (and the valve cover gasket) to really eliminate it as a possible leak.

Also, judging by the Bently, it may be possible to re-install the timing case without removing the head gasket. Is that true?

[Ross]

Recently I've seen two seperate M20s with horrific oil leaks up front and high. Both turned out to be the oil pressure sensor down at the bottom of the block. The pressurized oil was going up the covering on the wires then dripping down.
Unplug the connector. If it is full of oil and a bunch more comes running out of the disconnected dangling wire you've found it. Start the engine with it disconnected and observe the sensor to confirm.
12 61 1 730 160 is the part # should your problem be the same.
This one made me nuts the first time and feel like a genius the second time.

[BennyM]

That's a good tip, Ross. I can relate to the frustration. I don't think that fix applies to the M50TU, though.


Recently I've seen two seperate M20s with horrific oil leaks up front and high. Both turned out to be the oil pressure sensor down at the bottom of the block. The pressurized oil was going up the covering on the wires then dripping down.
Unplug the connector. If it is full of oil and a bunch more comes running out of the disconnected dangling wire you've found it. Start the engine with it disconnected and observe the sensor to confirm.
12 61 1 730 160 is the part # should your problem be the same.
This one made me nuts the first time and feel like a genius the second time.

[whiskychaser]

Also, judging by the Bently, it may be possible to re-install the timing case without removing the head gasket. Is that true?
Yes. Thats what I did first. But the timing cover is wedged very tight between the head and the sump. You can get it off if you drop the sump, drive out the 2 locating pins that go through the front of the cover, and undo all the bolts that secure it top/front and bottom. In an attempt to ensure I didnt get a coolant leak at the HG, I tightened the 3 sneaky bolts that come down through the head first. Still got a leak at the joint:( So I took the head off and made sure the top of the timing cover was bang on with the top of the block. For good measure I used some sealant but only at the joint with the timing cover.
Thankfully, you dont appear to have this problem :D