383 LT1 Cooling Issue
Thread Starter
Instructor
Joined: Jan 2006
Posts: 100
Likes: 0
From: Fishers Indiana
383 LT1 Cooling Issue
I rebuilt my LT1 as a 383 last winter and I have taken it to 6 road course track events this year. At the last event (at Mid-Ohio), I started getting very high coolant temps. As the weekend progressed, it took less and less laps to get to about 255F. It only took two hot laps in the final session. By the time I got into the pits, the sensor was reading about 235 and I couldn't find a spot on the radiator hotter than about 165 (infrared thermometer). I initially thought to change the thermostat on the morning of the last day, but that was not the problem.
The water pump (AC Delco), radiator and upper and lower hoses were all new at the time of the rebuild.
When I put the head gaskets on, I noticed that the coolant passage holes in the gasket were only about 0.25" holes, and the passages in the head and block were a fair amount larger than that.
Is it possible that the gasket has come apart and the bits are holding things up? Bad water pump?
I've considered changing to an electric water pump, but I haven't done anything yet.
Any thoughts on this?
Thanks.
The water pump (AC Delco), radiator and upper and lower hoses were all new at the time of the rebuild.
When I put the head gaskets on, I noticed that the coolant passage holes in the gasket were only about 0.25" holes, and the passages in the head and block were a fair amount larger than that.
Is it possible that the gasket has come apart and the bits are holding things up? Bad water pump?
I've considered changing to an electric water pump, but I haven't done anything yet.
Any thoughts on this?
Thanks.
Thread Starter
Instructor
Joined: Jan 2006
Posts: 100
Likes: 0
From: Fishers Indiana
The gasket was part of the Trick Flow set from Summit.
When I filled the coolant, I added fluid until I got some out of the vent above the thermostat, closed the vent. Then I started the engine and added as necessary until the engine was up to normal operating temperature. Did I miss something here?
I did notice that the level was a little low after complete cooldown from a track session, so I filled it up (about a quart) before the next session. No change. Two hot laps to 255 degrees.
What should I be doing to "burp" the system?
Thanks.
When I filled the coolant, I added fluid until I got some out of the vent above the thermostat, closed the vent. Then I started the engine and added as necessary until the engine was up to normal operating temperature. Did I miss something here?
I did notice that the level was a little low after complete cooldown from a track session, so I filled it up (about a quart) before the next session. No change. Two hot laps to 255 degrees.
What should I be doing to "burp" the system?
Thanks.
Team Owner
Joined: Mar 2001
Posts: 30,847
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Ah, that's your problem.
You need to run the engine until the thermostat opens up, then crack that vent open.
Just make sure you don't get any on the opti
You need to run the engine until the thermostat opens up, then crack that vent open.
Just make sure you don't get any on the opti
Racer
Joined: Jun 2006
Posts: 408
Likes: 0
From: Elkton MD
High coolant temp
On my stock '95, it requires 3 full temperature cycles (full cold/full hot, etc.) before the temperature behaves 'normally'.
The service manual recommends three full temp cycles 'before any aggressive maneuvers' (they must mean gettin on it).
Good luck.
The service manual recommends three full temp cycles 'before any aggressive maneuvers' (they must mean gettin on it).
Good luck.
