1995 LT1 overheating

[Nucman]

Hello All, I have posted here before about this same problem and thought i had it solved but its back !!! I have a 95 vette LT1, that intermittantly says its overheating. I have replaced the radiator, thermostat ( new 180 degree) new radiator cap, kit to turn on fans at 200 degrees.

I still have a problem of where i get on the road for a hour or so and all of a sudden the analog gauge will start creeping up and then bottom out to 270 degrees but the digital will only go as far as 244 degrees, if I drive 1/8 mile down the road the temp will drop down to around 220 degrees.

I drove today from Baltimore to Norfolk Virginia, I guess about 200 miles. When I first got on the road the car ran about 205 degrees for a hour or so and then all of a sudden then temperature rose to 220 and then bottomed out at 270. About 1/8 of a mile it went back down to 212-215 for the next hour or so. I then pulled off the highway for food and and soon as i got off the ramp the tempurture rose again to 270 and then came down again. I got my food and pulled out of the parking lot and the temp rose to 270 again but after 1/8 mile came down again and stayed at 205. After driving a while the low coolant light came on but the car was running cool. I drove about 20 more miles and pulled of the road and went to check the coolant. The resorvare was between cool and hot, I twisted the radiator cap and the coolant started to rush in the resorvour, so I retighted it and just continued on. I got back on the highway and the car ran between 201-209 degrees for the last 80 miles of my trip. Has anyone else had this issue ??? I have no leaks, no white smoke from the exhaust, no water in the oil. I will say the heater never gets hot, just luke warm. Not sure if that is related.

Thanks

 

[93Rubie]

Your heat being lukewarm got my attention. Has this car ever had nasty old coolant in it? How old is the water pump?

Reason I ask is I had a car kick my butt it would run down the road just fine but had poor heat output and when sitting would overheat. After many hours messing with it I figured it out, water pump was bad, internally the pump vane was all ate up from the old nasty coolant in it. Replace the pump and problem solved.

Not saying this is what you have but like I said it caught my attention.

 

[Hib Halverson]

I wouldn't worry too much about the engine overheating but, if you still stress about it get a IR temp gun and read the thermostat housing when the gauges are saying 270.

My guess is you have a problem with wiring, connections, the coolant temperature senders or the IP display.

 

[Nucman]

Re: Lt1 Overheating

Thanks for your replys, yes I removed the hoses from the heater and there was quite a bit of old coolant rust and grime in the lines. However this overheating happens at 70 mph or sitting still, there is no situation that it allways overheats. Yesterday when I returned from my trip, I toped off the radiator resouvor (took about 1/2 gallon) and started the car and let it sit for about 1/2 hour. Right at 201 degrees reading on the digital read out the fans kicked on, of course the analog gauge read about 212. But after sitting for a half hour the cars temp stayed at 202 degrees. So i am just not sure what is happening.

 

[SnakeOiler]

Sounds like an air pocket in the system.

Did you fill the system using the correct procedure?

 

[boomdriver]

Hello All, I have posted here before about this same problem and thought i had it solved but its back !!! I have a 95 vette LT1, that intermittantly says its overheating. I have replaced the radiator, thermostat ( new 180 degree) new radiator cap, kit to turn on fans at 200 degrees.

I still have a problem of where i get on the road for a hour or so and all of a sudden the analog gauge will start creeping up and then bottom out to 270 degrees but the digital will only go as far as 244 degrees, if I drive 1/8 mile down the road the temp will drop down to around 220 degrees.

I drove today from Baltimore to Norfolk Virginia, I guess about 200 miles. When I first got on the road the car ran about 205 degrees for a hour or so and then all of a sudden then temperature rose to 220 and then bottomed out at 270. About 1/8 of a mile it went back down to 212-215 for the next hour or so. I then pulled off the highway for food and and soon as i got off the ramp the tempurture rose again to 270 and then came down again. I got my food and pulled out of the parking lot and the temp rose to 270 again but after 1/8 mile came down again and stayed at 205. After driving a while the low coolant light came on but the car was running cool. I drove about 20 more miles and pulled of the road and went to check the coolant. The resorvare was between cool and hot, I twisted the radiator cap and the coolant started to rush in the resorvour, so I retighted it and just continued on. I got back on the highway and the car ran between 201-209 degrees for the last 80 miles of my trip. Has anyone else had this issue ??? I have no leaks, no white smoke from the exhaust, no water in the oil. I will say the heater never gets hot, just luke warm. Not sure if that is related.

Thanks

First, there is no point is guessing if the cooling system is known to be dirty. get it flushed and cleaned. Also, the most common problem with overheating is simple trash inbetween the radiator and condenser. Pull the top shroud off the access that space and remove debris. It cannot be seen or done from the front.



If its still inconsistant then I'd have to believe the problem is electrical. The gauges and sensors all operate on varying electrical resistance. Dirty connections, corrosion and even grease can alter a signal. Clean all the related connectors and go find all the electrical grounds on the car and clean those as well.
If it were really at 270 degrees...you'd know it.