Carpokes

I finally got around to testing the gauge accuracy, and I can confirm that it is operating as intended. I did however go on a short drive to find that my radiator isn’t getting hot even though the car did overheat. I’m not quite sure how to differentiate the issue between my thermostat and my water pump though. Any ideas?

Thermostat, or it is really, really, really hard to get these car's coolant system bled completely. Like really hard.


Did I mention it is quite possible that the coolant system is not completely bled?

Poorsche44 wrote: Tue Mar 24, 2026 8:02 pm I finally got around to testing the gauge accuracy, and I can confirm that it is operating as intended. I did however go on a short drive to find that my radiator isn’t getting hot even though the car did overheat. I’m not quite sure how to differentiate the issue between my thermostat and my water pump though. Any ideas?

Can't say I am surprised at all about the gauge being accurate, but at least you can cross that off the list with confidence. If the car overheats and the radiator never gets hot, it could be a stuck thermostat or a non-pumping water pump. Given your history, it could also just be so much air in the system that the pump can't get to any coolant to pump. In fact, that might be most likely under the circumstances? Do you get sustained strong heat in the cabin if you turn your heater on? If so, that would suggest the pump is working and circulating coolant, but it's just not getting through the thermostat to the radiator...

I’ll check the heater and see how it behaves. I cracked the bleeder screw after the little test drive I did yesterday and found very little air came out though. I’m hoping it is just a faulty thermostat, but it was replaced with a wahler unit about a year ago.

Had the heater on for several minutes and it stayed consistently hot when it got up to temp. This time I’m buying an oem thermostat and not aftermarket

Tom wrote: Tue Mar 24, 2026 8:39 pm

Poorsche44 wrote: Tue Mar 24, 2026 8:02 pm I finally got around to testing the gauge accuracy, and I can confirm that it is operating as intended. I did however go on a short drive to find that my radiator isn’t getting hot even though the car did overheat. I’m not quite sure how to differentiate the issue between my thermostat and my water pump though. Any ideas?

Can't say I am surprised at all about the gauge being accurate, but at least you can cross that off the list with confidence. If the car overheats and the radiator never gets hot, it could be a stuck thermostat or a non-pumping water pump. Given your history, it could also just be so much air in the system that the pump can't get to any coolant to pump. In fact, that might be most likely under the circumstances? Do you get sustained strong heat in the cabin if you turn your heater on? If so, that would suggest the pump is working and circulating coolant, but it's just not getting through the thermostat to the radiator...

Trying to figure out which thermostat to buy based on the water pump I have, and I could use some help. I have a uro 944.106.021.22 “new” style non-turbo water pump. If I refer to my PET I find the thermostat listed for my car is 944 106 129 05. When I look that number up on pelican parts, there’s a note that says “For all models with updated water pump, (Turbo Style), use thermostat # 944 106 019 00.” My car has an “updated” pump, but it is the non turbo model. the paragon parts page that I bought it from says it’s a non turbo model, which I would assume is correct because I do not have the block off plate. The thermostat PN I have had installed in the car for the past year is the 944-106-019-00-M2. I wonder if I’m not getting coolant to the radiator because the thermostat is faulty, or because it was the wrong one for my style of water pump.

Sorry, it took me a while to find this. I thought it was an official TSB, but it was actually a Tech Bulletin in the back of the old printed spare parts catalog. If you measure the groove in the throat of your water pump, you can confirm if it is the new style, needing the parts listed below. There is a groove in the throat and a lip that the thermostat sits against. I just confirmed on a new style pump that the 7mm is the distance between that lip and the top of the the groove. I'd be quite surprised if you have the old style pump, but this way you can confirm.

Well after several days of driving after installing a new thermostat the car works as intended! The wahler thermostat I removed said made in Brazil so I wonder if that could be part of the problem. The OEM one I purchased had a made in Germany stamp so I’m confident about this one lasting longer.