96 LT4 overheating no circulation
Thread Starter
Cruising
Joined: Jul 2002
Posts: 14
Likes: 0
From: woodstock ga
96 LT4 overheating no circulation
Hi All
First off I hate to ask for help unless I really need it as I own a C4 Corvette salvage shop for over 15 years and been doing business with 100% positive feedback on Ebay a lot of you have probably bought parts from us vette!
Anyway here it is on my 1996 LT4 I built my LT4 from the heads up I used AFR 1031 heads, a pretty big ISKY cam, TPIS 58mm throttle body, TPIS full length headers, B & B 3" triflow exhaust, 30# injectors, 7 quart race oil pan, forced air induction ect...
It runs like a champ but for the last 3 weeks it has been getting hot to about 235 digital and 250 analog in about 30 minutes of sitting still and it used to always run a consistant 185-195 due to the fact that I have a Griffin aluminum radiator, 160 thermostat, both fans are working as they should and I got rid of the Dex Cool and run regular green.
I have bled the coolant system several times and I put a new mechanical water pump on it less than 1500 miles ago when I built the engine.
Yesterday when I cranked it I left the radiator cap off and noticed my coolant was not moving around in the tank ot was just sitting still and just going up and down slightly and even when the thermostat should have opened it still was just going up and down until it started to overheat and then it was flowing out pretty good.
So what do you thing defective pump or thermostat?
Any help is greatly appreciated.
First off I hate to ask for help unless I really need it as I own a C4 Corvette salvage shop for over 15 years and been doing business with 100% positive feedback on Ebay a lot of you have probably bought parts from us vette!
Anyway here it is on my 1996 LT4 I built my LT4 from the heads up I used AFR 1031 heads, a pretty big ISKY cam, TPIS 58mm throttle body, TPIS full length headers, B & B 3" triflow exhaust, 30# injectors, 7 quart race oil pan, forced air induction ect...
It runs like a champ but for the last 3 weeks it has been getting hot to about 235 digital and 250 analog in about 30 minutes of sitting still and it used to always run a consistant 185-195 due to the fact that I have a Griffin aluminum radiator, 160 thermostat, both fans are working as they should and I got rid of the Dex Cool and run regular green.
I have bled the coolant system several times and I put a new mechanical water pump on it less than 1500 miles ago when I built the engine.
Yesterday when I cranked it I left the radiator cap off and noticed my coolant was not moving around in the tank ot was just sitting still and just going up and down slightly and even when the thermostat should have opened it still was just going up and down until it started to overheat and then it was flowing out pretty good.
So what do you thing defective pump or thermostat?
Any help is greatly appreciated.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,008
From: Texas
Probably a bad t-stat. I'd pull the t-stat out, toss it in a pan of boiling water with a thermometer and see if the t-stat opens (and at what temp).
Havings said that, I know on mine I don't see a lot of coolant flow in the fill reservoir. I run Dexcool with no issues and the temps are fine (mid 170s while cruising). FWIW I have a 383 with ~500hp at the crank.
Havings said that, I know on mine I don't see a lot of coolant flow in the fill reservoir. I run Dexcool with no issues and the temps are fine (mid 170s while cruising). FWIW I have a 383 with ~500hp at the crank.
Thread Starter
Cruising
Joined: Jul 2002
Posts: 14
Likes: 0
From: woodstock ga
Thanks for the reply.
Well I did some shade tree cooking today
on my thermostat and unfortunately my Hypertech 160 thermostat is indeed in perfect working order.
Now I am guessing I am having a water pump failure, or water pump drive shaft or any other ideas?
Well I did some shade tree cooking today
on my thermostat and unfortunately my Hypertech 160 thermostat is indeed in perfect working order.Now I am guessing I am having a water pump failure, or water pump drive shaft or any other ideas?
Race Director
Joined: Apr 2003
Posts: 17,698
Likes: 1,667
From: moraga ca
If you really have no radiator circulation and the radiator coolant is near cool until the motor overheats, it has to be a bad waterpump (or collapsed hose, but you would have seen that). A motor with a bad head gasket or cracked head will overheat but the radiator water will get hot as well as the coolant in the block.
