85 red 5 speed - OK, here are the symptoms - had an errant coolant light come on a couple of times, then go out. Thought it was due to the common sensor failure, and just did not get around to cleaning the contacts. The coolant res was always at the full mark - to the seam. Coolant light was on again today - haven't driven the car for a couple of weeks. Drove to work - 20 miles, in traffic. No issues. Water gauge just above first white line where it always is. Drove home, coolant light still on. Very hot here today, and car never showed any sign of over heating. After dinner went to garage to check coolant - the res, for the first time, was low - pretty far down, but no sign of coolant anywhere. Filled it up with my usual 50/50 mix, took about a half a quart. Also pulled the plug on the sensor - it was green. Cleaned it well with DeOxit and plugged back in.

Drove 5 or 6 miles to the auto parts store to get more coolant and test the system. Light was not on - not sure if because I cleaned the plug or filled the tank. Came out of store and a little puddle of coolant behind the front passenger tire - fully expected an overflow, as I put a little extra in. For giggles, opened the hood to check it - the coolant was at the full mark, but coolant spray is all over the front of the engine Sprayed everywhere. Decided to drive home and listen carefully and watch things. No strange sounds whatsoever. None! Car temp never went above the normal mark for it - just above the low white line. Oil pressure fine, no unusual readings there. Drove home with no issue.

I got home and pulled the cross member and the air tubes and air box to get a good look at everything.. Took some pictures too. What could it be? No spray back by the overflow tank at all. It's all up front, by the water bridge, on the timing belt covers, belly pan and some in the vee. It looks like one of three things - o-ring failure? Water pump failure? Or worst case - head gasket failure?

Note - I did a full top end refresh last year in the spring - new o-rings, water pump, everything. Clean enough to eat off of too. Now covered in white crusty coolant. Looking for the wisdom of the board. Thanks!

 

Pressure tester...pump it up, follow the drip. Take 5min.

 

Second Speedtoys note, the engine fan blows the coolant around, so you cannot see point of origin.

 

I like the interesting leaks..

I vote for inner hose failure, coming out the end at the threads. That one was haunting me for a while before I got a pump. Flew around everywhere.

 

Wrong symptoms for this case, but my car rotted the passenger head casting plug and was leaking coolant behind the timing belt cover.

That was a fun one to locate.
I had to pressurize it from a regulated air source, because the game pump wasn't keeping up with the leak.

 

Don’t want to hijack this, but interested to see references to coolant pressure kits. I have such a tester, but none of the 15 or so adapters in the kit fit the 928 expansion tank!

Please can anyone post a pic of the adapter they have which fits, and/or any dimensions?

Thanks a lot

 

radiator ?

i once had a leaking oil cooler (BMW).... ( external oil/air) ... the fan was blowing oil up to the windshield.

 

based on the picture the water bridge center 1 inch ID hose has a damaged inner wall

 

I have one of those mega kits like you do and as you said, there isn't a good cap for the 928. This Stant kit fits and works perfectly so I have this for the 928s and the other for everything else.

 

I cheated and hooked directly to the vent hose, after disconnecting it from the reservoir and plugging the open port.

 

Borrowed a kit from autozone, one of the two universal (expandable) adapters worked perfectly, none of the other dedicated sizes came close. $0 =

 

Thanks for all the suggestions for a 928 compatible pressure tester. Maybe an expandable is the way to go - will investigate further.

 

I thought I had a photo of just this thing from last July doing service before a 5K mile drive..had this exact thing.

 

the little protuberance on the top of the outlet is what wears through the hose

 

Well, there you go:



The hose has a tear on the top. There appears to be sufficient slack to trim off an inch or two, and reattach it without getting a new hose. I will pressure test once I make the repair to ensure no other compromise to the cooling system, but I do think this is all it is. And of course, a big friggn mess to clean up from what was a very clean engine.