So had some time today to finally try and diagnose the system.


Put in a gallon of water into the expansion tank and about a minute later it started leaking from underneath the car, back of the motor area.

Seems to point to the metal cross over pipes and or the O Rings that go with them.

Does the part that the cross over tubes insert into fail ever or probably just the metal pipes and O Rings?

I think you are correct with that being the problem. Is there ever any issues with that accumulator breaking?

That cross over pipe is a heavy casting. Can't imagine it leaking. It has gaskets on each end (the two heads) and then the orings for the metal tubes in the middle.

The heater hoses run behind the block. Probably worth taking the engine acoustic cover off and looking around with a mirror to localize the source better.

The accumulator is heavy casting or the pipes that go from one end to the other are? I thought someone mentioned it being a good idea to replace those along with the O Rings

After looking into everything I am tempted to order the Valley Pan service kit from ECS which includes the new valley pan and associated gaskets, the two gaskets for the for the water accumulator and then the o-rings for the coolant pipes as well as a few other gaskets I believe.

They have a BMW one listed which includes the BMW valley pan or one assemblies by ECS with an upgraded valley pan. I was pretty sure the Valley pan was bad so would the upgraded one be the better option?

Also while I am doing that anything else besides the oil separator that I should switch out while I am there and ordering parts? No other mechanical issues with the car as of now, so this would be preventative

Valley pan is different. I thought you were asking about the crossover - the metal casting that the metal tubes slide into at the rear of the engine. That cross over is heavy. The metal tubes are pretty lightweight. The valley pan is medium, but corrodes at the gasket sealing surface over time, so the putted gasket surface becomes the limiting factor.

I wouldn't buy the valley pan kit or what ever your looking at. It's a rip off. Total price for a VP gasket repair should not exceed 15 bucks (this doesn't include the ccv). Buy yourself a tube of black rtv sealant instead of a new VP.

You could replace the ccv diafram, rear coolant hoses, intake gaskets, ect ect.

Been real busy at work lately, but I'm trying to follow this thread. I've done this procedure 2-3 times now and know this area well:).

I wouldn't be buying parts on a seems to conclusion. The key here is a sudden loss of coolant and I assume with no prior indication of a coolant leak. If the leak showed without starting the engine that indicates a major leak that doesn't even need the system pressurized. I suggest you do what you need to do to confirm the source and start with eliminating all hoses. Have you removed the plastic cover under the engine and jacked it up so you can take a flashlight and look up toward the top to of the engine?

He needs to pull the top cover and might as well pull the intake. And confirm the lower radiator hose is not leaking.

Before buying anything.....

VP leaks are real easy to diagnose..... You'll have coolant leaking down the back of the engine You can also see the VP from the top too with a flashlight.

I have not gotten underneath the car yet. It was a really cold day in Indianapolis my last day off.

I am going to get under it this sunday and actually get it off the ground so I can see where from the rear its leaking but its definitely coming from the back of the motor and the system didn't need to be pressurized before it started leaking.

I appreciate you keeping an eye on the thread Helihover! And every one else

It seems the possible culprits that need to be checked through are the Valley Pan gasket, the o-rings and gaskets off the accumulator and the hoses back there, just want to go through a check list so when I get under the car I know exactly what to look for.

As the car was never turned on and therefore no pressure in the system, does that rule out the Valley Pan gasket as the culprit? Dont exactly understand what the valley pan does or necessarily where it is but it seems to be higher up in the system where water might not get to by simply being put into the expansion tank.


Thoughts?