71 Vette 350 overheating
Thread Starter
5th Gear
Joined: Jul 2013
Posts: 5
Likes: 0
From: York ME
71 Vette 350 overheating
Last year I decided to replace the lifters in my 350/270. I replaced the lifters, rocker arms and push rods. I also replaced a cracked passenger side exhaust manifold. The intake manifold was sand blasted and repainted. Now it will overheat while sitting at idle after about 15 minutes. I noticed two square burn marks on the intake manifold where the preheat channel goes into the intake manifold. What is causing it to over hear? It didn't overheat before I replaced these parts.
Racer
Joined: Jan 2010
Posts: 375
Likes: 21
From: London Ontario
I'm not a mechanic but my first guess is there Air trapped in the Cooling system?
Start it up cold and let it run with the rad cap off
as it warms up you should see coolant flow in the rad and maybe some air bubbles if you don't see any movement of coolant maybe a water pump or a plugged radiator
hope this helps
Barry
Start it up cold and let it run with the rad cap off
as it warms up you should see coolant flow in the rad and maybe some air bubbles if you don't see any movement of coolant maybe a water pump or a plugged radiator
hope this helps
Barry
Team Owner
Joined: Sep 2006
Posts: 31,285
Likes: 4,375
From: Westminster Maryland
Hi WW,
I believe the 'scorch' marks on each side of the crossover, near the heads, is very typical for an engine running at normal temperatures.
Using high-temp engine paint cuts down on the dark marks but usually doesn't eliminate them completely.
Regards,
Alan
I believe the 'scorch' marks on each side of the crossover, near the heads, is very typical for an engine running at normal temperatures.
Using high-temp engine paint cuts down on the dark marks but usually doesn't eliminate them completely.
Regards,
Alan
Last edited by Alan 71; Jul 12, 2013 at 02:58 PM.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
Could be an exhaust leak through the head gasket into the cooling system. You should see hot coolant expelled into the overflow reservoir (which is typical with any system, but very hot coolant, and at a more rapid flow), and bubbles at the radiator neck. When the engine cools down, there will be pressure in the coolant system.
Probably, not what you wanted to hear.
Probably, not what you wanted to hear.
Thread Starter
5th Gear
Joined: Jul 2013
Posts: 5
Likes: 0
From: York ME
The burn marks on the intake manifold; when I painted the intake manifold, I used High Temperature Chevy Orange. When I saw the burn marks, I knew that it was probably the cross-over channel, but, I also was having the overheating problem. I was thinking that something was causing the overheating and with the burn marks, that the engine was getting extremely hot to burn the paint.
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Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
That could easily be an overfilled system or a defective rad cap.
You need to know actual coolant temps and not guess at it.
You need to know actual coolant temps and not guess at it.
