Large coolant leak after stopping
 

I drove the 968 to work today...fine on the way there and on the way home, everything seemed fine.

When I pulled into the garage, I thought I heard the sound of water spilling (not dripping) so I briefly looked under the car and everything was fine. Fast forward a couple hours and I see coolant running out from under the car...lots of it. From what I can see, it looks like two separate leaks and there is quite a bit of coolant missing from the reservoir. Both leaks look to be coming down from below the water pump area.

Could this just be a loose coolant line? Last time it leaked it was a couple drips and it was a loose clamp. This was about 1/3 of the coolant. I had the water pump changed a couple months ago so it's still under warranty.

Well yes, it could be, or it might not. Asking us to diagnose a leak requires more info or some pics or both. It could be a hose has come loose or partially off. You mentioned a recent h2o pump replacement. So perhaps the shop forgot to retighten all the hose clamps after the job, so check all of them. Just because the leak appears to be coming from a particular area can be misleading, coolant leaking will follow the structures just like a rain gutter so you need to get the car up on stands and follow the leak back carefully to determine the source. Up on jack stands you can start the engine and see exactly where it's leaking from. Could also be a split in the bottom of the coolant reservoir, they have a record of cracking with age. Get it up on stands and report back.

Cheers
Mikey

Are you guys affected by very cold temps? Cold temps can do a number on coolant hoses and their clamps. Most probably it's a loose clamp but as suggested, you are the best person to trace the coolant.
The fact that you recently had waterpump swap performed makes me believe it's something related to that job.

I took some pictures but they came out terrible. I'll try and take some more once it's up on jackstands today. No cold weather here, I'm in Sacramento.

about a month after the h2o pump change there was a small leak that ended up being a hose clamp. I left the lower body panel off after that so I could see leaks right away and there has been nothing for the last 4+ months. I did see some wetness near the top hose connecting to the water pump so I'll go through all the clamps tonight. Just caught me off guard because it was not a couple drips like I would expect.

Did you do the water pump yourself, or did a shop put it on. If a shop did it, take it back to them. They'd probably be glad to check it out for you.

If you are checking it out yourself, as in driving to get it hot, checking, driving etc. Make sure you keep enough coolant in it, and make sure you keep air out of the system via the vent screw on the top of the engine. Overheating may lead to a lot of other issues.

Shop did it, however the shop is about 20 miles away so if it's a simple fix, I'd just assume do it myself. Anything more and it will go back.

So I didn't make much progress tonight and now I'm confused. I went around and tightened the hose clamps, but none of them had wetness around them. I filled the coolant tank up and started the car and let it run.

I let it run for 10+ minutes, revving the engine until it showed warm on the gauge. Not a drip anywhere. I checked all the hose clamps, nothing running down the hoses, everything dry under the reservoir....not sure what to check now?

Two ideas:

Is it possible that it burped it out. I had a case on my KL (Mazda) engine, where I thought for no reason it started to overheat. I later found out that I hadn't properly filled the coolant, allowing all the air to get out of the cylinder head. When the system built up enough steam in the head due to the lack of water filling all the passageways, it burped it out, causing the overheat. I didn't know until later that this was why it over heated. I properly filled the system, and never had an issue again.

Along this line, do the fans come on like they are supposed to, and stay on after stopping when the engine is really hot. If the fans didn't continue to run after you stopped, and it was hot enough, it could have gotten over the boil point and pushed out the coolant.

As suggested, most probably air in the system. It came out through the overflow tube in the expansion tank.

Where is the expansion tank located?

I did see quite a lot of crusted pink stuff around a hose clamp almost directly behind the distributor...haven't had a chance to check that out closely though.

It also appears I have an early car because I do not have a bleeder screw where I've seen there are supposed to be. Where were they located on the early cars?

Well thanks to Jay, I'm 99.99% sure the heater control valve took a dump. I looked up a picture and what happens when it goes and I have all the same symptoms. That hose clamp I said was "behind the distributor"? Yep, goes the the HCV. I'll make sure when I get back to the garage Monday but I'd bet this is it. What a mess it makes, dried pink coolant everywhere in the engine bay!

You also get coolant flow out of the overflow hose after shutdown if you have a bad pressure cap. It's pretty scary as it looks like a blown head gasket symptom, in fact I might have gotten my black car cheap because the owner thought it had a BHG. It had this problem which I discovered when I first stopped with a hot engine on my way back from picking up the car in Nebrahoma.

Sounds like a different problem than yours but worth a mention for posterity (and searches.)
-Joel.

Joel..what do you mean "bad pressure cap"? Are you talking about the coolant reservoir cap?

Yes. Boiling over after shutdown can be a bad coolant tank cap that is not holding pressure.

So I got the new heater control valve today and went about putting it in. First stupid move, I thought I could get away without draining the coolant first, thought maybe since the cap was off and the system wasn't pressurized, it wouldn't spill out too much. I was wrong...the coolant is now drained the messy way.

Anyways the new HCV went fairly smoothly. I made sure to turn all the hose clamps so they can be easily tightened now, they were a pain on the old one and very hard to get to. Everything is re-attached and tightened down so I think I'm ready to refill and I want to make sure I do it the right way...here's what I got:

1. Pull drain plug to make sure as much old coolant is out. Car tilted downward in the front.
2. Fill reservoir
3. Start car with heater on full, car tilted up in front.
4. Pull vent screw under upper engine cover (early car)
5. Add coolant once HVC opens until it pours out of vent, screw vent closed.
6. Go for a drive, come back and repeat system vent.

Anything wrong, out of order or needs to be added?