Last Lemming

I have a 951, and about 6 months ago I was replaced my heater valve behind the engine while I was replacing my clutch. So I drained the system to install this piece, installed the piece and put the car back together and bled the system. So I thought at least. Went for short drive - say 15 min. - to test out the new clutch. Everything seemed fine. I parked the car and right after I shut off the engine I heard weird sound and coolant started gushing out. It turned out that both the top rubber coolant hose and the large lower rubber coolant hose that goes to the water pump were cut through not just burst but cut through by the cooling fans. I surmised that the steam or pressure in the system caused the hoses to balloon up until the made contact with the fan. The fan nicked the hoses and from there they gave way. I check to see where the split and it was in the correct relative position it need to be for the fan to have nicked both hoses. You could see visible marks the fan had made in each case.

So after replacing the hoses and bleeding the system several times, I thought all is well. I noticed the first few times I drove until the car until it was fully warmed up and then parked the car the fluid was just a bit down. I assumed it was just finding its level. I topped it up and until a few days ago it stayed where it was. The other day I took it for a drive and the next day is was down a tiny bit again.

I checked my oil dipstick, no milkshake. I checked the underside of my oil cap and it is dry and clean. I don't have any white smoke and if anything my car is running cooler than ever, not overly cool but cool like people say it should be running. Before it was always nearer the second white mark, now it rides between the two marks while stopped in traffic. On a hunch I checked under my car tonight and noticed a small puddle, say 4" x 4" of coolant that has been sitting there at least a week near the back of my front tire. Directly under the fuse box. However the puddle could have been there from before and I just pulled in further into the garage. I was thinking my overflow line from the tank. The thing is when I park my car in the garage I pop the hood, I check the coolant level every time and it has never been near the cap to allow it to overflow. So where is this coming from?

The car had a fresh top end rebuild and head gasket and runs perfectly fine.

V2Rocket

a bad radiator cap gasket can let coolant (steam) escape.

jbrob007

Hmmmm.... good question. It took me a couple of tries until I got out all the air (via the vent bolt) out and the liquid level consistent. BTW, not to hijack the thread but speaking of the radiator cap venting, what psi should the radiator cap be ? Mine appears to be an after market, but it fits perfectly and is rated at 13 psi...

Last Lemming

the radiator cap is for this car, I don't know who makes it. But the car was steaming out of the cap there would be traces of on top of the reservoir. There isn't, nothing. My temperature never rose even when the hoses burst. When I park the car and look at the engine bay, no smoke or steam.

V2Rocket

the steam could be venting out the drain hose rather than out through the "fill neck" under the cap.

snb13

Do you have the small bracket in place that holds the top radiator hose off the alternator fan?

Last Lemming

I think so, why do you ask?

Last Lemming

I checked my compression tonite and I was within a few pounds of what it was a year and a half ago. I will need to do a pressure test to the coolant system next. I know once I pressurize it it's supposed to hold pressure fore one hour right? How much pressure are you allowed loose in that hour, if any?

Tom M'Guinn

Get a pressure test kit. It will pinpoint a coolant leak (or confirm none) in minutes, and very easy to use. Some auto parts stores will loan them out, though the bladder style one linked below is worth every penny to have when needed.

Last Lemming

Ok, pumped up the presser to the coolant system to 10.5 psi. Lost only .5 psi over 10 min. Not sure that indicates an issue or not but I think I’m good.

NoRush993/951

When the coolant tank starts to fail, it develops hairline cracks in the plastic. If you are lucky, they are visible on the top side. But if they develop on the bottom side, you won't see them. The cracks start leaking little droplets that will enlarge over time as the crack(s) expand. If you have an old yellowish tank, it's a good suspect to check out.

mrgreenjeans

^^^^^ this ^^^^^

if you are confident it's not a head gasket failure.

And make sure you have a BEHR pressure cap with the correct rating on it; they ARE different between the series one and two 944s. EPA changes apparently to raise the boiling points slightly to make emissions certification on the later cars

Tom M'Guinn

I usually got to 15psi and let is sit longer. I look mostly for drips vs pressure drop, since the seal at the reservoir isn't necessarily perfect (nor the pinched overflow line) and since a small drip/leak won't show on the gauge for hours sometimes.

Last Lemming

The 10 lbs psi held for half an hour. This morning I jacked the car up and have set the presure to 15 lbs psi. I noticed that the sway bar has coolant on the bottom of it just below where overflow tube is. However the inside of the tube is completely dry and the air duct that runs to the alternator and just under the overflow tube isn't wet at all. You would think if the coolant was coming out of the overflow tube the top of the duct would be soaked.

Also there is no coolant coming from the water pump, though there shouldn't be, it's relatively new.