if you have a good radiator shop near by, they might be able to improve it with hot chemical bath and pressure flush. Never tried that on a 944 radiator, so hard to say. And good radiator shops are getting harder and harder to find in our increasingly disposable world. Constantly needing to bleed could be a HG sign. If you don't keep bleeding, does it eventually spit out the overflow? That's a tell-tale HG sign...Poorsche44 wrote: Thu Feb 05, 2026 11:28 am I’m using an autozone rental coolant pressure tester, so it could be faulty. My spark plugs definitely aren’t steam cleaned, but I do get hazy exhaust on cold start. I’m wondering if that’s just to do with the cold or if there’s something else affecting that. I also struggle a lot bleeding all the air out of my coolant system. It seems like I can never get it fully bled, which makes me wonder if it is in fact a HG. If it is my radiator, do you think removing it and taking it to a radiator shop for a power flush would suffice in restoring it? It’s hard to find the plastic radiators for a reasonable price and I don’t trust aftermarket options.
Temp gauge testing
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Tom
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No, it doesn’t keep coming out of the overflow. I’ll peek at the cylinders this weekend to see if there’s any coolant in them and report back after. I still want to figure out why I can’t get any readings on my compression test either 
‘83 Platinum N/A 944
Well I took a look into my cylinders to find this
That streak down the cylinder wall is coolant puddling on top of the piston, there’s my smoking gun.
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That streak down the cylinder wall is coolant puddling on top of the piston, there’s my smoking gun.
‘83 Platinum N/A 944
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Tom
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Well, shoot. At least now you know.Poorsche44 wrote: Sat Feb 14, 2026 8:21 pm Well I took a look into my cylinders to find this8647468375765905512.jpeg
That streak down the cylinder wall is coolant puddling on top of the piston, there’s my smoking gun.
After replacing my head gasket my coolant temps seemed to get better, but then all of a sudden they jumped back up to the same amount of overheating I was getting as before. I’ve already bled the air out of the system 3 times with no sign of any improvement. I’m going to do some testing tomorrow but I suspect replacing the head gasket and getting the head machined wasn’t enough to fix the issue. My fan also aren’t kicking on at temp either for some reason, only when I turn the AC on
‘83 Platinum N/A 944
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Tom
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Ug, sorry. Maybe use the camera scope to make sure the HG is actually sealing now. How did you torque it? Did you clean and inspect the block deck for flatness and/or any defects/scratches that might prevent it from sealing?Poorsche44 wrote: Sat Mar 07, 2026 8:44 pm After replacing my head gasket my coolant temps seemed to get better, but then all of a sudden they jumped back up to the same amount of overheating I was getting as before. I’ve already bled the air out of the system 3 times with no sign of any improvement. I’m going to do some testing tomorrow but I suspect replacing the head gasket and getting the head machined wasn’t enough to fix the issue. My fan also aren’t kicking on at temp either for some reason, only when I turn the AC on
I'd check the thermo-switch in the radiator. Or just jump the pins to confirm the fans turn on when it triggers. If the fans do go on when you jump it, then most likely either there's air in the system preventing the switch from triggering reliably, or the switch itself is bad. If they don't go on, then most likely the relay is bad.
I’m going to look into with a scope today while having the coolant pressure tested hooked up to see. Since mine is an early model I followed the 15-37-66 lbft torque spec waiting 15 minutes between each stage. I didnt inspect the block for flatness and noticed some discolored/slighty rusty parts of the block, but I had no way of cleaning it without removing metal. I started with blue scotchbrite and eventually used a brass brush but some visual defects remained. I know this isn’t a scientific method but I did feel the entire surface and it was smooth. I’m also fairly confident the issue isn’t with my thermoswitch as I replaced it a few months ago. Here’s a photo of what the block looked like before I bolted everything back together
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‘83 Platinum N/A 944
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spacecad3t
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Do you motorsports the car? You wont really need something better than stock for everyday driving. Better fans go a long way too- but I would definitely start by figuring out if the radiator less efficient than it should be. Are your fans operating correctly? I don't have an early car, but the fan speed resistor wiring is ALWAYS trash and you may just be running on low speed fan and not getting the high speed fans.
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spacecad3t
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Emory cloth and a brick next timePoorsche44 wrote: Sun Mar 08, 2026 11:12 am I’m going to look into with a scope today while having the coolant pressure tested hooked up to see. Since mine is an early model I followed the 15-37-66 lbft torque spec waiting 15 minutes between each stage. I didnt inspect the block for flatness and noticed some discolored/slighty rusty parts of the block, but I had no way of cleaning it without removing metal. I started with blue scotchbrite and eventually used a brass brush but some visual defects remained. I know this isn’t a scientific method but I did feel the entire surface and it was smooth. I’m also fairly confident the issue isn’t with my thermoswitch as I replaced it a few months ago. Here’s a photo of what the block looked like before I bolted everything back together
