Strange temp issue
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From: weems va
Strange temp issue
My normal ride into work with outside temp around 40/45 ill get up to 190 degree temp ok im happy with that. But when i put the heat on it will go UP? to 196/198. Didnt notice this last year because i was working on alot of things and it wasnt on the road much during the winter. I have a 93 with c-68 auto heat/a/c. On my other older cars the temp would come down a little with the heat on. Dave
Last edited by davewhtt; Oct 29, 2013 at 07:25 AM. Reason: /
Safety Car
Joined: Aug 2002
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From: SANTA CRUZ CA
Originally Posted by davewhtt
....... On my other older cars the temp would come down a little with the heat on.
A suggested solution to overheating on a very hot day is to roll down all windows, and turn on the heater (defroster) to the max position. This directs coolant across the heater fan during the flow cycle which will lower the coolant temp.
Are you certain that cooling system is full? Is the system acting as a 'closed' system i.e. - expanded coolant flows to the overflow bottle when hot, and returns to the surge tank/radiator via a siphon during cool-down?
Check the surge tank level - when cold - before your next drive.
Safety Car
Joined: Aug 2002
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From: SANTA CRUZ CA
Originally Posted by davewhtt
......... Is it possible a blockage in the heater core would cause this? .....
if there was blockage in the core.
Last edited by don hall; Oct 29, 2013 at 02:27 PM.
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Thread Starter
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Joined: Oct 2012
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From: weems va
Dont jinx me engine and tranny sound good. When i got car i had the flashing led and it turned out to be low freon. I had it charged and its been fine since. Thats when i found out that car had been updated with new freon. I havent had flashing since. Checked coolant last night and it was full. Coming in this morning the only thing i noticed was way to many deer on side of the road!
Safety Car
Joined: Aug 2002
Posts: 3,842
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From: SANTA CRUZ CA
Originally Posted by davewhtt
...... Coming in this morning the only thing i noticed was way to many deer on side of the road!
Might want to check the condition of the catalytic converters, before you are left stranded.
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Joined: Aug 2002
Posts: 3,842
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From: SANTA CRUZ CA
Originally Posted by davewhtt
...... Checked coolant last night and it was full.
'full', do you mean the coolant level is at the max level in the neck of the surge tank leading to of the overflow bottle?
Some owners consider the surge tank 'full' when it is an inch below the level of the exit tube leading to the overflow bottle. That is not full.
If there is a breach in the coolant 'closed system', expanded coolant will not return to the surge tank via a siphon during engine cool-down. In this case, expanded coolant will continue to flow out of the engine until enough coolant has been expelled to accommodate the expansion. Without a return of coolant (or the owner adding coolant), the cooling system will always be low on coolant causing elevated temps.
I'm stressing the importance of a 'closed system', as I have experienced deformed surge tank cap gaskets, split or loose hose ends, and even a tiny split in the surge tank neck, which was only detected by running my fingernail over the surface:
Crack in neck hi-lited:
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From: weems va
Don how fast you forget.. You suggested this a few months ago and you were correct the brass had split. I got new tank and it took care of it. At the same time i flushed system,new thermostat and new cap. The water level is up to the cap. The picture you show looks like it was taken on my car. It was hard to see the crack/split like you said i could feel it more that see it. Dave