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Post by Hurricane87 on Sept 1, 2015 8:10:19 GMT -6
I had my thermostat changed last month (paid someone to do it because I couldn't figure out how to get the radiator hose off without tearing it). While doing that, the mechanic also replaced the overflow tank cap with a regular radiator cap.
Everything ran perfectly for three weeks. Now I'm getting slight overheating (3/4 up on the temp gauge, when before it pegged at 1/2). It only happens at long idles, so it looks like the electric fans, except they're running fine.
I saw a "only use AC/Delco caps" on another thread. Is this possibly being caused by the radiator cap? If so, why only at idle? And while we're on the subject, why isn't there a radiator cap on the actual radiator?
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RCA1186
Administrator 
Rob
Go Pack Go!
Posts: 4,837 
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Post by RCA1186 on Sept 1, 2015 12:31:44 GMT -6
As far as I know a lot of newer cars don't have a radiator cap on the actual radiator anymore because of the pressurized surge tank. How's your coolant level?
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Post by Marc on Sept 1, 2015 14:01:19 GMT -6
Replace the cap that the mechanic put on with the cap specified for the surge tank. And like rca99aurora said, check the coolant level.
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elgato
Aurora Newbie
Posts: 17
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Post by elgato on Sept 1, 2015 17:33:03 GMT -6
Take a look at my thread just above this one. Very similar.
I had an older GM cap that would violently leak around the seal when the car was warm.
Replaced it with an 18 lb Autozone cap that looked more like a standard radiator cap.
The next time it got warm the cap would loudly snap open blowing coolant everywhere.
The gauge would be at about 3/4 when the problem would show up.
Did you replace the housing and thermostat or just the thermostat?
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Post by Hurricane87 on Sept 3, 2015 13:05:15 GMT -6
Checked everything out. The cap has not popped, and the coolant level is fine.
Any other ideas?
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Post by Hurricane87 on Sept 8, 2015 0:54:01 GMT -6
Bump.
Does anyone have any ideas on this?
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elgato
Aurora Newbie
Posts: 17
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Post by elgato on Sept 8, 2015 14:15:01 GMT -6
On a hot day mine would run closer to 3/4. Take a look at the pic of my thermostats. There is a huge difference between aftermarket and GM. Now it runs right at the 50% line. There was also a Tech Bulletin 01-06-02-001 regarding the thermostat and housing. The newer housing is 12570247. The number is stamped on it where you can see it. Just to make sure you could borrow a block/head gasket tester from Autozone.  |
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Post by Hurricane87 on Sept 10, 2015 9:38:48 GMT -6
On a hot day mine would run closer to 3/4. Take a look at the pic of my thermostats. There is a huge difference between aftermarket and GM. Now it runs right at the 50% line. There was also a Tech Bulletin 01-06-02-001 regarding the thermostat and housing. The newer housing is 12570247. The number is stamped on it where you can see it. Just to make sure you could borrow a block/head gasket tester from Autozone. Of course, I wouldn't know how to use one, or interpret the results if I did, but thanks for that. Anyone else? |
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Post by Toronado3800 on Sept 10, 2015 14:22:42 GMT -6
On a hot day mine would run closer to 3/4. Take a look at the pic of my thermostats. There is a huge difference between aftermarket and GM. Now it runs right at the 50% line. There was also a Tech Bulletin 01-06-02-001 regarding the thermostat and housing. The newer housing is 12570247. The number is stamped on it where you can see it. Just to make sure you could borrow a block/head gasket tester from Autozone. Of course, I wouldn't know how to use one, or interpret the results if I did, but thanks for that. Anyone else? What is the complicated part of the headgasket test? I've never done it but if ya post the directions lets see if we can figure it out. The fans come on high @225ish. On my 98 that is 2/3rds up. I figured out the number correlation by using a $10 blue tooth code reader I got off fleabay. I don't think 225 was a great idea on GM's part but it is as designed. I say have a scanner pull your actual temp when the needle is there amd post the directions for this test and we'll get to the bottom of it. |
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tigger
Administrator
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Post by tigger on Sept 10, 2015 17:50:07 GMT -6
I have a theory, but you won't like it... Worn water pump impeller. At idle, the pump can't provide adequate volume to keep the engine cool. Compounded by the lack of airflow through the radiator. Once you get the revs up and some air through the rad, temps come back down to normal, correct? Just a theory... |
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elgato
Aurora Newbie
Posts: 17
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Post by elgato on Sept 15, 2015 16:27:28 GMT -6
Borrow the Block Tester from Autozone. Very simple instructions are included.
You simply use a bulb to pull air from the cooling system through blue fluid. If it changes color
you have exhaust gasses present.
Search Block or head gasket test. There are tons of Youtube videos of people doing it.
Mine turned out to be a small crack in the brass filler neck on the plastic coolant bottle.
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Post by Hurricane87 on Oct 5, 2015 10:22:16 GMT -6
Found it at last. Verrrrrrrrrrrrrrrry slow leak from the infamous crossover gaskets. As I don't have a spare $600 lying about, I have fed it coolant tabs and am watching the levels and the bottom of the engine to see what happens.
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