[KesslerR]

My 968 goes outside the normal temperature bars on the gauge when the outside temp is above 105 deg F and the AC is on. A check with a IR temp gun on the coolant outlet on the engine shows 235 deg. If I shut the AC off the temp slowly comes down to the top temp bar on the gauge.

I have flushed the system, put in new coolant, checked the bleed for air, checked that the fans are running right and have all the belly pans on.



Friends say that on a 20 year old car its the radiator all coated inside with what ever crud coats the inside of radiators and the answer is a new radiator, or......

remove it and fill it overnight with white vinegar and flush well with water. Anyone have the problem, tried one of the solutions, have a different solution, or .....

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[Cloud9...68]

I would recommend checking the temp of the fat hose on the passenger side of the radiator. If it's significantly cooler (not sure what "significantly" would mean - maybe a few tens of degrees) than that on the inlet, drivers side, it would indicate you have reduced flow, which could be caused by a faulty thermostat, a bad water pump, or a clogged radiator. From your description, your car is running WAY too hot - it should never get anywhere near the top bar, even on a 105 degree day. Personally, I wouldn't drive it until you get this sorted out. Good luck.

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[rl968]

How about temp switch failing?

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[Gotter]

You're talking about the top WHITE bar, not the red one, right????

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[SILVY968]

I have a water pump from my engine swap if that ends up being the issue.

Brian

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[blue968]

HI Guys



I just finished installing my Supercharger from Flash and it ran hotter than usual, it was up at the upper white line but I had the A/C on. I got a little nervous and turned the A/C off and the heat on. It was probably around 80-85 degrees. It definitly should not be that hot, I replaced my water pump about 2 years ago so Im thinking its my radiator. Does anybody know were you can get an aftermarket aluminum one?

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[Cloud9...68]

[quote name='blue968' timestamp='1347059869' post='132315']

HI Guys



I just finished installing my Supercharger from Flash and it ran hotter than usual, it was up at the upper white line but I had the A/C on. I got a little nervous and turned the A/C off and the heat on. It was probably around 80-85 degrees. It definitly should not be that hot, I replaced my water pump about 2 years ago so Im thinking its my radiator. Does anybody know were you can get an aftermarket aluminum one?

[/quote]

I would check a lot of stuff (measure temperatures of hoses, check thermostat, fan switches, temperature sender, air trapped in the system, remove radiator and check for clogs, etc.) before I bought a new radiator.

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[tamathumper]

Check the grounds to the instrument cluster as well.

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[Cloud9...68]

[quote name='tamathumper' timestamp='1347101963' post='132341']

Check the grounds to the instrument cluster as well.

[/quote]

Yes, great point - I would start there. Clean them all very well, and then spray them with contact cleaner, which you can get at any auto parts store. Unless your radiator is leaking, replacing it should be your absolute last resort.

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[tamathumper]

Don't forget to check Clark's Garage - there's a nice little troubleshooter there.



http://www.clarks-garage.com/shop-manual/cool-03.htm



And wouldn't you know it, a recent reference to those grounds, on that other list (take out all the .s in the word r.e.n.n.l.i.s.t:



http://forums.r.e.n.n.l.i.s.t.com/rennfo...ost19.html

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[RS Barn]

You mentioned car temp comes down when a/c turned off. You need to check fan operation. Low speed fans should come on any time a/c on. When coolant temp goes above 180 or so , high speed fans should kick on too. Check to make sure BOTH fans are running at both speeds. We've seen lots of cars with one dead fan motor.

One common problem is bad thermo switch not kicking on high speed fans early enough. Also replacing with 'low temp" thermo switch kicks high speed fans on earlier to help prevent climbing temps.

Radiators do build up crud and have reduced cooling .

Also possibility of composite WP impeller starting to slip.

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[Cloud9...68]

To add to Pete's post, mine was doing a similar thing - when driving on a medium-hot day (mid 80s, high humidity), my temperature gauge would rise alarmingly when I turned the AC on, and would slowly come down when I turned it off, but this required me to drive it very gently, and coast a lot. Soon afterward, I started my track car conversion project, so I haven't driven it in a year and a half. But as I was installing Pete's dual oil coolers, I stumbled into this:



   



The insulation around my fan switch wires had somehow gotten torn off, allowing the wires, I'm sure, to either touch each other, or maybe even a chassis ground point, as I was driving the car. Note: the above picture was taken midway into my repair, where I cut the wires completely and re-connected them using butt connectors - I thought I had snapped a picture of the wires before I started the repair, but apparently not. Before you spend any money on anything, you might want to take a quick look at all your fan's wires and make sure they're all intact.

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