Today my daughter pulled over because the 960 was "smoking." Temp normal. But she saw the coolant level light flash on and off once. By the time I got there, no steam or obvious leak, but some trace coolant on the ground. Her description implied it was between the engine and firewall - heater hose I presumed. The coolant reservoir seemed to be at the correct level. No apparent leaks in heater lines, even pulling on them. Static run, sustained revving at 2500+ rpm, all normal. I followed her home about 10 miles. I had her leave it running in the driveway. No problem. Then she took another 20 mile round trip. As she neared home, she called to tell me it was blowing steam again, and that the coolant level light was on. I had her check the temp, it was good - had her continue home. In the driveway I let it run, revved, up, tried to tax the cooling system. Heater on and off, etc. The reservoir was near-empty, but the level did not change while I observed. Nothing on the ground. Checked the oil - clean and clear. I brought the coolant to the fill line and let it run another 20 at idle and with some rpm for a couple of minutes. No hint of a problem, aside from a residual coolant odor. Both occasions that my daughter observed an apparent coolant discharged were at a sustained 65 mph on the freeway. The whole time the car is running tip-top with the temp at 12 o'clock. I'm perplexed. I'd appreciate any thoughts.

- Rich

 

Actually a car at 65mph in winter should not be stressing the coolant system at all... I'd run it at idle, fan disconnected, A/C on if possible, to get it to overheat. Hopefully in a heated garage... Or do a pressure test on the system. Or both...

 

By the way, it was about 60F ambient air temp when this all occurred (in Vegas, sorry for all of you in the single digits right now! ). I'll try to heat it up w/o fan. I don't have a pressure test set-up, but that may be my next tool purchase if I cannot figure this out. Since the heater hoses seem good, I'm fearing a head gasket issue. It just doesn't make sense that it's intermittent and so far has happened for just a couple of minutes, 3 different times, in a total of almost 2 hrs. of driving. I've added maybe a quart of coolant.

 

Could be the HG, always a possibility in a hard to figure overheating cases...
Keep posting!

 

The heater supply hose (the one with control valve in-line) had a small crack at the clamp. It was intact enough to hold until a certain pressure spike. Not sure why peak driving temp, accelaration, higher rpm, etc. didn't necessarilly trigger a blast of coolant, which we saw as steam because it hit the exhaust manifold. It most often happened after sustained cruising, and then didn't really continue when driving resumed. Always, by the time we could get the hood up, there were no clues except for residual coolant odor. It was so odd that I was resigned to it being a head gasket. It took pressurizing the system with a hydraulic bladder to find the breach. Even then, it was hard to tell which of two heater huses was leaking at the rear of the head. In fact, I broke the return hose man-handling it to see if there was a leak. So ultimately, it was not only sensible, but necessary to replace both heater hoses. They are probably the original hoses ... so not bad for 18 years! Due to being a weekend and a long way from a proper foreign auto parts house, I just went with semi-generic hoses (what Autozone had cataloged for a 960) that only had a molded 90 degree at one end, which I used on the heater core at the firewall. So now the routing is above the head, not so clean compared to the factory-bent hoses the neatly took the heater hoses between the head and the firewall, mostly out of sight. One of those "I should go back and make it right when I have the time" moments, that will probably never happen due to function outweighing aesthetics. I'm pretty excited to be back on the road without a head gasket issue. Wheeew!