'85 overheating
Thread Starter
3rd Gear
Joined: Aug 2003
Posts: 3
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'85 overheating
when car is cold and start it up ,runs fine. can drive it for as long as i choose with temp. staying btw. 182 to 192, but if i shut it down then restart after 5 minutes the temp will show about 205 then drop to 199 then begin climbing steadily to an overheat unless i shut it down for an hour or so. again this only happens after a restart with normally warm engine.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: '85 overheating (JIW)
What do you consider an overheat? GM says shut the engine off at 260 F. Does your main fan come on at 228 F ?, its supposed to, and your auxilliary fan (if you have one) comes on at 238 F, does it? Idling with no fans on will cause the engine temp to continue to climb. Does your low coolant light come on?, if so, burp your cooling system. If you restart with the engine hot and drive it over 35 mph does it cool off?, if not you have a defective thermostat. Hope this helps.
Team Owner
Joined: Sep 2001
Posts: 62,099
Likes: 1,724
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: '85 overheating (JIW)
Check to see that the fans are coming on at 228 and 238 as he suggested, and your thermostat doesnt open til 195F. If temps dont hold at 195 for a few minutes (the digital readout is off by a couple degrees) then its probably stuck.
When these engines get warm, they continue to rise in temps like a runaway freight train unless you do something to help it out. high temps are normal
When these engines get warm, they continue to rise in temps like a runaway freight train unless you do something to help it out. high temps are normal
Le Mans Master
Joined: May 2003
Posts: 5,203
Likes: 0
From: Las Vegas Nevada
Re: '85 overheating (vader86)
i recently replaced my thermo but I think its sticking by the way the temps rise and fall and at what point. It was an el-cheapo.
what would be a good reliable stat that works as advertised? :cheers:
[Modified by Southern Comfort, 9:35 AM 8/16/2003]
what would be a good reliable stat that works as advertised? :cheers:
[Modified by Southern Comfort, 9:35 AM 8/16/2003]
Thread Starter
3rd Gear
Joined: Aug 2003
Posts: 3
Likes: 0
Re: '85 overheating (jfb)
usually shut down after reaching 245-250. main fan does come on at 228. no aux. have to replace motor. coolant light does not come on, there has been no loss of coolant. do drive it over 35 after warm restart & temp still climbs to overheat. also have new rad., new hoses & thermo. with no luck. again, from cold start i can run for as long as i want with no problem. thanks for the reply.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: '85 overheating (JIW)
I suspect a defective thermostat. Normally, you will see the coolant temp go above the opening temp (from a cold start) and then suddenly cool down to the opening temp and stay there if you are driving over 35 mph. But the temperature never dropping from a hot start and driving over 35 mph, the thermostat must be closing and sticking due to hysterisis when coming from a high temp, but cooling further (letting the car sit ) the thermostat will jump closed and then act normal from a cold start. I would replace the thermostat.
Robertshaw thermostats are high quality and thats what I would install.
[Modified by jfb, 6:25 PM 8/16/2003]
Robertshaw thermostats are high quality and thats what I would install.
[Modified by jfb, 6:25 PM 8/16/2003]
