cannot stop coolant leaks, new ones keep popping up
 

944 S2 1990
I've changed ALL coolant hoses, fan switch (at radiator), thermostat and I consistently
have to tighten leaks that continue to occur at different places. Engine does not overheat it goes just slight past 2nd mark (about 9:00). AC condenser fins are clear and not blocked.
I'm afraid if I continue to tighten clamps at leak points that eventually it could adversely affect the radiator or worse heater core.
FYI coolant level is about 2inches above min. mark when cold, and respectively so above the max. when hot.
System is not expelling any coolant from the cap overflow.
Zero modifications.
Bled properly.

What happens if you leave the cap off or loose?

Have you tried replacing the cap, with the correct pressure rating of course?

cap is stock and likely original, spring isn't seized so i assume it's not causing excessive pressure as a spring is likely to become weaker rather than stronger through age. I have not ran the engine cap off as I had no reason to. Replacing the cap is easy enough of course but I don't see a reason to.

What was the condition of the surfaces where the new hoses conected like when you replaced them? I had a similar issue with a Land Rover. I had to spend way more time than expected cleaning the metal below where the clamps went to get a good seal.

All surfaces were well cleaned because they needed it, especially where there was metal present.

Are you using good quality clamps or just some picked up from your FLAPS?

Could you define good quality clamps?
I re-used original Porsche clamps, and used new clamps from Lordco (same stuff as NAPA) or any car garage would carry / use when I was a mechanic. I don't believe it's the clamps that cause the issue.

It's just that if your surfaces are clean and intact and you are using new hoses there is little else that can cause a leak.

Maybe the clamps you are using on the joints that leak are worn out and loosen under vibration. Cheap insurance to replace them with factory Porsche clamps.

Is the lip on the pipe where the hose attaches in good condition and is the clamp attached adjacent to and not on the lip?

Lips and all fittings are in good condition. It's pretty much a full restoration where I took the time to clean everything, if needed. Clamps are adjacent and not on lips.

it would be nice to know what kind of pressures you are seeing.

i use hylomar but too much is a bad thing.

ok, any recommendations for a coolant pressure gauge?

Stant ST 270. Do you have the 100kPa or 150 cap?

I pump the system full of air and squirt every connection with soapy water to find small leaks. It will hold a vacuum for a month or so. I don't drive it much and temps stay a needles width below the first hash mark under normal driving.

per the first post, i don't see any mention of coolant on the ground, nor any mention of coolant loss, either of which would indicate a leak. it sounds like there is air in the system. was it properly bled?

I had a small leak that took me a while to find. It was on the reservoir where the small return hose connects to it. There was a hairline crack in it on the back side. I had fired it up and gotten it hot one day and was checking the clamps. As soon as I touched the clamp with the screwdriver, I saw a small stream shoot out from behind.. Replaced the reservoir and no issues since.

Coolant leak is present because coolant is either on the ground or under hose.

150cap. I'm not looking for a unknown leak, I'm looking for the cause of consistent leaks at consecutive areas.

Please read first post, I'm not looking for leaks. Im looking for cause of constant leaks after fixing previous ones.

Seems like no one has an idea I didn't already think or tried. I will decrease the coolant to min. mark at cold, then drive and bleed just for a trial an error. If that doesn't work I'll purchase a pressure gauge and or change the cap with same rating.

Try gently tightening the clamps with the engine warm. The rubber is softer and the clamps will seat better. Also make sure you don't have a stripped clamp. I have had one of the larger clamps strip. don't overtighten it will damage the hose.

If something leaks in multiple places all at once, inexplicably, it is either pressure or something is compromising the seals. Or the fluid is not what was expected (like hydrogen in a helium balloon) but this is not likely in your case.

If your cap is lifting check the overflow hose maybe? Grasping at straws but honestly what could it be other than pressure? I can't remember the last time I had a coolant leak caused by a loose clamp that *wasn't* a result of someone just forgetting to tighten the clamp.

Some sort of solvent in the coolant that is softening the hoses is the next crazy notion. That certainly causes problems with power steering and fuel system leaks at the clamping points.

My money is on something like a blocked overflow and a head gasket leak and it's a wonder the reservoir has not cracked yet.

Idling with the cap loose to see if it chooches out coolant would be my next step.
-Joel.