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Running Hot

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R

roca

Freshman Member
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I have a 1980 TR-7 that was running as beyond the half way
mark and despite replacing the radiator, cap and thermostat it still can reach the 3/4 mark after 15 minutes. Needless to say, I am only testing it within 1 mile of my house. There isn't any noise or leakage from the pump. Should I replace the temp transmitter unit since it is a low cost item. Also, there is a wire with a connector that attaches to the res coolant tank. You will have to pardon my ignorance but what is the function of that component and could that be the problem? Any thoughts are most appreciated.

Rich
 
Here's a couple ideas...
First, are you still using the OEM viscous fan? If so, is it actually working?
Probably a doumb question, but all the hoses are good? If a hose is pinching off, if can slow the flow.
Are you really sure it's running that hot? If you can get access to one of those remote temperature "guns" shoot the thermostat housing and see what the temp really is. I know that the one time my car got that hot (during safety and emissions, when the bonnet was up) it was blowing antifreeae out the expansion tank.

The wire to the expamsion tank is for the coolant level sensor. If you have insufficient coolant, that's what will light up the light on the dash. Wouldn't have anything to do with running hot.
 
Hello Rich,

what is the graduation at 3\4, because I would expect that to be a normal reading. As long it is not in a red band or more than 85 to 88 degrees (if you have a degree gauge) then that sounds OK.

Alec
 
Thanks for your responses. It used to consistently read 1/2
or just below. The fan daes work. It did not appear to be overheating @ the 3/4 reading, however, I wouldn't risk driving it based on all I've read. I didn't see coolant
blowing out anywhere and levels appeared normal. Visually,
the hoses look okay. The bottom radiator hose does not have
a spring but looks okay(ie I don't notice any collapsing)
The temp rose gradually over about 15 min. Would this definitely rule out the temp transmitter? I don't have access to a temp gun. The radiator (used) was pressure tested before I bought it

Puzzled in Scarborough, Me

Rich Obi did you find out if the autozone in your area tests the ignition modules? /ubbthreads/images/graemlins/confused.gif
 
Check the easy stuff first. Put a thermometer in the radiator. I spent about 600 dollars to find out my gauge was incorrect.
 
Not exactly sure what the actual temp at 3/4 is, but am guessing that at the 1/2 mark it's around 180 degree F. The reason is that I've got a brand new 180 thermostat in mine, and you can tell by watching the gauge when it opens, and it opens just about right at the 1/2 way point.

Roca...Just started a new job and haven't had a chance to find out. Do want to tho...I think I have 3 of them laying around here and no use keeping any that are bad.
 
Hello Bill,

So you would sick a thermometer in the expansion tank when
it reads 1/2 and expect about 180? If the temp rises over 15m on the guage would this rule out the temp sending unit? Also,
is there a way to check whether nthe lower rad hose is pinching while the car is running?

Thanks,

Rich
 
I appreciate the offer but I'm all set. I was just passing the info along since it saved me $30 and I pulled it in 10 m

Rich
 
My tr3 doesn't have an expantion tank so I just stuck it in the radiator neck. You can buy a thermometer for about 50 dollars. I used my wife's candy thermometer and washed it off before she noticed it was missing.
I dont think I would open anything hot I let mine warm up without a cap on it.
 
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