Hello everyone, I got a lot of technical help on my last post, more than I expected. So I’m back with a new issue. My 2008 CTS DI has started overheating bad.
I already performed a combustion leak detection test, and the results were negative for exhaust gas. The cooling system is also holding pressure during with a radiator pressure test. The auxiliary water pump is definitely working, those little hoses have good pressure in them. When it’s running, either cold or at temp, I can squeeze the radiator hoses all the way shut bare handed. I already replaced the thermostat, that was a bitch and a half. It’ll idle for about 15-20 minutes before the temp needle creeps up above the 220 line, but it’s gotta be a dummy guage, because my scanner shows about 260 degrees before the needle moves above 220. I ran an actuation test on the instrument cluster, and all gauges are fully operational. I can drive for about 5 minutes after letting it cool down to “operating temp” on the dash before it shoots back up, fast. And since I’ve been using water, it just boils out of the system by then. I shot compressed air through the block water jackets, the coolant pipes, and the radiator. Less noise through the radiator than through the other plumbing. Fans are operational, I toggled them with the scanner. It seems to me that the water is just sitting stagnant until it boils out. Also noticed my STFT on both banks are -20 to -25% at idle. When I gas it at idle, it starts to push a lot of water out of the expansion tank with the cap off. I HATE throwing parts at cars, but I have a water pump on the way.
I’m wondering if there’s any way to test the water pump before I replace it. Any other tests or checks I can do to narrow it down would be greatly appreciated! Thanks, folks.
I already performed a combustion leak detection test, and the results were negative for exhaust gas. The cooling system is also holding pressure during with a radiator pressure test. The auxiliary water pump is definitely working, those little hoses have good pressure in them. When it’s running, either cold or at temp, I can squeeze the radiator hoses all the way shut bare handed. I already replaced the thermostat, that was a bitch and a half. It’ll idle for about 15-20 minutes before the temp needle creeps up above the 220 line, but it’s gotta be a dummy guage, because my scanner shows about 260 degrees before the needle moves above 220. I ran an actuation test on the instrument cluster, and all gauges are fully operational. I can drive for about 5 minutes after letting it cool down to “operating temp” on the dash before it shoots back up, fast. And since I’ve been using water, it just boils out of the system by then. I shot compressed air through the block water jackets, the coolant pipes, and the radiator. Less noise through the radiator than through the other plumbing. Fans are operational, I toggled them with the scanner. It seems to me that the water is just sitting stagnant until it boils out. Also noticed my STFT on both banks are -20 to -25% at idle. When I gas it at idle, it starts to push a lot of water out of the expansion tank with the cap off. I HATE throwing parts at cars, but I have a water pump on the way.
I’m wondering if there’s any way to test the water pump before I replace it. Any other tests or checks I can do to narrow it down would be greatly appreciated! Thanks, folks.
