Car overheats, turn heater on and guage goes down??
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Car: 91 RS and 88 IROC-Z
Engine: 305 TBI and 383 Carb
Transmission: 700R4/2200 stall & 700R4/3500 stall
Axle/Gears: 3.42 posi and 4.11 posi
Car overheats, turn heater on and guage goes down??
I've replaced the thermostat, radiator cap, coolant temperature sensor and heater valve. When I have the a/c on the temp gets to 240-250. If I put it on high vent or heat for 15-20 seconds the guage drops back down to normal and I can put it back on a/c and the temp wont rise back up. If I turn the car off and let it sit for a little while, the process repeats. This only happens with the a/c on, without the a/c on the temp never gets over 210-220. Is there any other valves that could be sticking??
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Car: 88Fbird,88Formula,04 GP,04 Durango
Engine: LO3,L98,3800,HEMI
Transmission: 700r4, 4l60e, 545rfe
Re: Car overheats, turn heater on and guage goes down??
Have you ever flushed your cooling system? What type of fan do you have? electric or clutch
#3
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Car: 91 RS and 88 IROC-Z
Engine: 305 TBI and 383 Carb
Transmission: 700R4/2200 stall & 700R4/3500 stall
Axle/Gears: 3.42 posi and 4.11 posi
Re: Car overheats, turn heater on and guage goes down??
The radiator is about 6 months old, it has the single fan. I just ordered the dual 11" spal fans, they will be here Friday.
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Car: 88Fbird,88Formula,04 GP,04 Durango
Engine: LO3,L98,3800,HEMI
Transmission: 700r4, 4l60e, 545rfe
Re: Car overheats, turn heater on and guage goes down??
Did you flush out the engine block? A new radiator wont do any good if you have a lot of build up of rust and other junk inside the block. Check the water pump too. When GM water pumps go bad they usually start to leak water. Check it while its running.
#5
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Car: 91 RS and 88 IROC-Z
Engine: 305 TBI and 383 Carb
Transmission: 700R4/2200 stall & 700R4/3500 stall
Axle/Gears: 3.42 posi and 4.11 posi
Re: Car overheats, turn heater on and guage goes down??
If it was the waterpump or dirty block it would overheat all the time, not with just the a/c on.
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Car: 88Fbird,88Formula,04 GP,04 Durango
Engine: LO3,L98,3800,HEMI
Transmission: 700r4, 4l60e, 545rfe
Re: Car overheats, turn heater on and guage goes down??
normally, at least with my car, when i run the ac the car tends to run little hotter. If your getting poor circulation or the water pump is getting weak then that would make it really hot. And 210-220 without the ac running sounds a little hot too. But then again i have 160* stat.
#7
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Re: Car overheats, turn heater on and guage goes down??
my car use to overheat to 240 or so while sitting in hot traffic when it was stock and NO AC.. Fans dont turn on till high temps anyway as set from factory but 240 was ridiculous. I turned my heater on and the car cooled off....not sure why that happened. maybe it kicked a fan on early? i dont know
i since replaced the thermostat and programmed the fans to come on at a lower temp and its fine! rarely gets above 180-190 anymore
i since replaced the thermostat and programmed the fans to come on at a lower temp and its fine! rarely gets above 180-190 anymore
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Car: 97 Z71
Engine: 350 Vortec
Transmission: 4L60E
Re: Car overheats, turn heater on and guage goes down??
Originally Posted by Orr89RocZ
my car use to overheat to 240 or so while sitting in hot traffic when it was stock and NO AC.. Fans dont turn on till high temps anyway as set from factory but 240 was ridiculous. I turned my heater on and the car cooled off....not sure why that happened. maybe it kicked a fan on early? i dont know
Factory fan doesn't come on until I think 238°.
#9
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Car: 91 RS and 88 IROC-Z
Engine: 305 TBI and 383 Carb
Transmission: 700R4/2200 stall & 700R4/3500 stall
Axle/Gears: 3.42 posi and 4.11 posi
Re: Car overheats, turn heater on and guage goes down??
My fan turns on way before 238. My dual 11" fans from Spal will be in tomorrow. I have the stock 195 thermostat, should I run a lower one and buy something like the JET thermostat switch to make them come on sooner?
#11
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Car: 86 ta ws6 silver and gun metal
Engine: 305 fi lb9 eng code f
Transmission: 700 r4 with shift kit
Axle/Gears: lim slip not sure gears
Re: Car overheats, turn heater on and guage goes down??
is the car act boiling at 240 it would be boiling bubbling making steam if not .check the act temp of the eng .running the heater should not drop the temp that fast it might help after a while i would check the sending unit and check act temp of eng most shops have temp check tools .i wouldnt take out the stat it will cause prob jwith fuel injection system run ritch
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Car: 1987 Firebird
Engine: Present=350/4brl, Future=455 H.O.
Transmission: Present=700R4, Future=Richmond 6Spd
Axle/Gears: Now Stock, Later 3.73
Re: Car overheats, turn heater on and guage goes down??
this happens because the water pump hoses go from the pump to the heater and back so it has more time to cool and thats why, because i took my heater and a/c out of my 1987 bir and thats what it looked like. so thats whats up.
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Car: 91 RS, t-topped, man trans.
Engine: 350cid 350Hp crate motor
Transmission: t5 with new stock clutch and parts
Axle/Gears: 3.08 stock -RS
Re: Car overheats, turn heater on and guage goes down??
160* t-stat here! no problems on the cooling except i keep filling the damn thing up. dont no where the coolant goes.....
but in traffic with the 160* stat, my block heats up to about 190. im still below stock which is good. i think.
im ging to say that your water pump needs care or your block flushed. when i bought my car it baffled me how it would reach 250*+ on interstate 15. The block had a family of dragonflies in it.... after the flush....it sticks at 160*
but in traffic with the 160* stat, my block heats up to about 190. im still below stock which is good. i think.
im ging to say that your water pump needs care or your block flushed. when i bought my car it baffled me how it would reach 250*+ on interstate 15. The block had a family of dragonflies in it.... after the flush....it sticks at 160*
Last edited by 1991ON20's; 11-26-2007 at 03:01 AM.
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