What's up with my cooling system?

[Porsche-O-Phile]

On the 951:

I've been losing coolant somehow. Here are the symptoms:

It seems to lose it during cool-down, not while the vehicle is in operation. Here's an example: I filled the expansion tank before I left work yesterday (engine was cool), then drove home. When I shut off the car I checked the expansion tank and it was right where it should have been - near the "max" mark on the tank. I let the engine idle for a few minutes as I looked around for any evidence of leaks with the engine hot and running - none observed. I shut the car off until this morning.

This morning I check the reservoir and it's slightly low. I add a little water, start the car and pull it forward about 15'. I get out and observe a little trail of coolant from underneath where the car was parked to where I pulled it forward. It wasn't the coolant I added prior to starting either (didn't spill any).

So sometime in the night, the coolant system leaked? I know there's an overflow drain on the expansion tank but I didn't overfill it and it's been doing this for a while. Radiator is new (less than 2,000 miles). It only seems to lose coolant when shut off/sitting. Once I start the engine cold I get a nice burning coolant smell for a while, just as if it's been leaking coolant onto the engine while cold and it's now burning off. No evidence of leakage once operating though.

Any thoughts? TIA.

[Razorback1980]

That sounds like a water pump to me. Check the hole in the bottom side for evidence of coolant leaking from there. Use a mirror and a light and look for signs of antifreeze or a rust color.

[armandodiaz]

I second the WP you should see some evidence of coolant on the front of the oil pan.

[Porsche-O-Phile]

May well be. Thanks for the tips guys. As a preventive measure, I've taken the 951 out of service for some repairs (including water pump replacement) and a whole slew of upgrades. I'll keep you all posted on the progress, but when it next graces the roads in earnest, it should be a 375-ish RWHP monster, hopefully with no leaks or quirky mechanical issues like this. . . I have a humongous pile of "go-fast" parts sitting in the garage that need boltin' on.

[bearone2]

you need to watch it over a couple of days after bleeding the system.

the water will be higher in the tank when at operating temp and wil be lower after the car sits over nite.

when the car is shut off the water temp goes up cuz it's not circulating and if you have too much water in the expansion tank, it'll leak someplace or break something.


it sounds like too much water.