Strange coolant vomit.

[ssimms]

Hi,

1992 535i 5sp. 146,000 well care for miles. Never overheated in my ownership, waterpump,radiator fine. Drove it home Friday last and Saturday morning came out to the garage to find coolant underneath (couple of quarts).
So I leave it alone until yesterday to troubleshoot problem.
a)
I find the overflow tank is empty (that explains the 2 quarts on the floor)
b)
I start the car and don't see any obvious leaks or hear any unusual noises.(only ran for 2-3 minutes)

So, since my wife has complained about the weak heat in the car lately I decide I probably need a new heater valve or aux water pump.
I take them out to find nothing wrong with either one as far as I can tell. The heater valves energize as they should and I can hear the pistons rise and drop as they should. I took it apart to verify nothing broken on the inside and no apparent leak on the outside like a crack or something.
The aux. water pump also will run when connected to 12volts and no strange noises or cracks in it either.
The hoses I removed at one end all look ok. So not any obvious broken hoses or splits etc.
Any ideas for my next steps? I would appreciate the assistance. I can't say that in my 26 years of BMW maintanence I have ever seen a car throw-up it's coolant without being hot or overheated.
Thanks in advance for any assistance or suggestions.

Scott

[dternst]

Checkout this thread:

http://www.bimmer.info/forum/showthread.php?t=19828

[ssimms]

Checkout this thread:

http://www.bimmer.info/forum/showthread.php?t=19828
Thanks, but, since my car hasn't been getting hot or overheated I don't think this is much help. by the way I searched through 60 or so topics before starting this thread.

[Blitzkrieg Bob]

the back of the engine? more towards the trans?

Could be the heater core.

It would leak out from the lower fire wall .

[ssimms]

Yes it was closer to the firewall. That would be a bummer. Does anyone know how to check their condition without removing center dash? The coolant return pipes are sitting full with coolant since I removed the hoses last night. I would have thought that if the heater core was leaking it wouldn't hold coolant.
Thank you so much for the ideas.

[Scott H]

the drains for the a/c evaporation and the heater core leaks are two tubes that run out each side of the tranny tunnel. Stick your head under there and see if those tubes have dried or evaporated coolant. Do you smell coolant in the cabin when you run the heater? The plastic lines that run to the heater core have been known to crack as well....


Yes it was closer to the firewall. That would be a bummer. Does anyone know how to check their condition without removing center dash? The coolant return pipes are sitting full with coolant since I removed the hoses last night. I would have thought that if the heater core was leaking it wouldn't hold coolant.
Thank you so much for the ideas.

[zmuff]

Did you take a good look at the overflow tank where the hose is attached? Mine had cracked about 3/4 of the way around but it was hard to see, the hose covered it up by about 1/8 inch. It definitely puked out it's guts on the floor. It would be a whole lot easier to fix too. Good luck.

[Alexlind123]

I recently replaced my expansion tank as well. The plastic give out after about 15 years.

[ssimms]

Thanks all, I have some more troubleshooting to do with all of your suggestions. Thanks again. As usual you are all aces in my book.

[ssimms]

the drains for the a/c evaporation and the heater core leaks are two tubes that run out each side of the tranny tunnel. Stick your head under there and see if those tubes have dried or evaporated coolant. Do you smell coolant in the cabin when you run the heater? The plastic lines that run to the heater core have been known to crack as well....
No it doesn't smell at all in the cabin. I am still at a loss.

[ssimms]

thank you. I will look at it closely.

[ssimms]

Well, three weeks have past since my last comment on this with a short vacation in between. I wanted to update this note as possible future help for someone else.
It seems that my water pump was the culprit. It was slowly dripping coolant past the bearing. So small that it wasn't even being thrown around the engine to spot on hoses or metal anywhere. Anyway, my car never overheated but, apparently when it decided to belch a couple of quarts through the overflow that fateful friday nite, it was just a air pocket that escaped from being low on fluid for some time.
My complete tear down at the firewall end was deceiving because that is where it looked like it was coming from. As I mentioned earlier the aux pump and heater valve, overflow tank etc. were in fine shape and are back in service. So after driving it for a week and still not being able to tell where it was leaking because I was checking it each trip with spare water in the car for an emergency it was holding it's water pretty well until the 5th day and then I noticed toward the front passenger side a puddle when I came out of work. So I topped it up and vowed not to drive it again until I had torn the front of the engine apart to check everything there.
Saturday I pulled the clutch fan and shroud off to get a better look ( I was going to run it until the thermostat opened so some pressure would help me find the leak) but, that wasn't necessary as the moment I stuck my head under the hood with the fan gone I caught a glint of water/coolant on the crank pulley. Closer inspection and I saw the drip ....... drip .......drip of the water pump bearing. So, the original water pump lasted 146,364 miles and wasn't making any noises at all when it started to drip past the bearing. The reason the leak wasn't obvious in front is because of the front engine cover which is still in place on my car and can hold a substantial amount of coolant before running off. Also, it was initially drip only when stopped I guess since it wasn't flinging coolant around the engine bay from the pulleys.

BMW coolant is awesome as the internal parts all look literally brand new. I was stunned because since I started driving BMW's in 1980 I have almost always had to replace waterpumps on a roughly 60-80,000 basis regardless of the model I owned. This is impressive and I will be replacing it with a Laso this week in addition to the thermostat and seals. Everything else appears to be in good shape so I expect things will go well after I get these things back together.
Thanks to all who commented and gave suggestions. I really appreciate this forum and everyone's willlingness to share.
Thanks again,
Scott