Overheating

Ls5bigblock

Well Known Member
Supporting Member 3
I have a QB block 4422 with 690 heads rebuilt by Carl Maquillen. It has been bored .40 over and stroked.
Changed water pump tried different fan blades clutch no clutch. Unable to bleed air from system. Does have heater.
Any ideas on what else I can do. Center dump exhaust from showcars, new radiator 4 core. Correct fan shrould.
Thank you in advance for any help.
 

wristpin

Well Known Member
PVS409 had a similar problem that had much discussion awhile ago and his issue was resolved. Maybe you or someone with more tech savie than me can locate it with the search mode.
 

427John

Well Known Member
I just looked at that thread,and the OP did too,he never did say what he found to resolve the issue.For the OP do you have a thermostat in the engine,and if so do you have the bypass and heater hoses hooked up?
 

427John

Well Known Member
Is the radiator upper hose and hose connection higher than the thermostat housing on the intake?This is not an aftermarket crossflow radiator right?
 

4speedman

Well Known Member
Supporting Member 2
Fan should be half in half out of the shroud you do have the 409 shroud if not the small block can be cut down to size and the timing if is is slow it can cause overheating i had this problem a few years ago
 

Ls5bigblock

Well Known Member
Supporting Member 3
Thanks I do have correct fan shroud. I have checked timing I think I may have a cracked head.
 

El Rat

Well Known Member
How do you know that the system has air? if so then where is the air coming from (ask yourself)? Were the heads pressure checked? Find the air “leak” and you will find the problem!
 

MRHP

 
Supporting Member 1
These engines are not known for trapping air in the coolant system. Either faulty thermostat, water pump, etc.... or combustion gasses entering the coolant system.
 

427John

Well Known Member
Thanks I do have correct fan shroud. I have checked timing I think I may have a cracked head.
That may be,but I would get one of those testers and check before I pulled the heads.Even if the test shows combustion gases you may get lucky and just have a head gasket leaking compression into a coolant passage.
 

Don Jacks

Well Seasoned Member
Supporting Member 3
If you want to know which sides leaking remove the fan belts and thermostat.Make a partition[the top of an oil filter box works well for this],fill the thermostat opening,start engine and let idle.The bubbles will tell you which head needs to come off
 

Junky

Well Known Member
Friend had a similar problem, and it was the lower radiator hose was collapsing. He found an old hose that had a spring in it, and put the used spring into his new hose, and problem resolved. If you truly have combustion gasses in the coolant, then the spring won't help. I would start with a radiator tester, and pressure test to see if it holds pressure. If you find it doesn't, then it could be a bad head gasket, so I would do a leak down test on each cylinder till I found which one it is. It could be more than one cylinder if the head gaskets were defective from the manufacturer. I certainly don't have the experience of many of the others that give advice, however, I have learned from them, and like a good parrot, I can repeat what they have taught me.
 

Toms63SSQB

Well Known Member
Supporting Member 8
I have been in contact with Tony regarding his overheating problem. He has had both head gaskets replaced to fix that problem. He still has an overheating problem the motor runs at about 230-240 degrees. The fan is not centered on the shroud, the back of the fan is pretty much flush with the back of the shroud, nowhere near centered. He has a clutch fan that bolts directly onto the wp which he purchased from SC. He does have the correct shroud. Attached are some pictures, they are a little dark and kind of hard to see.
 

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59apachegail

Well Known Member
I have a 283 that would heat my truck up so much after half an hour you couldn’t touch the sheet metal on the front. It would vapor lock, have hot start issues, electrical issues etc...

After all the fixes I threw at it the final fix was correcting the fan depth. Before the fan was flush inside the shroud. I removed the spacer and it was now half in and half out of the shroud. Heat issues went away, for good measure I upgraded to a 5 blade from a 4.

I know it isn’t a 348 or a 409 but from what I gathered (definitely not an expert nor do I play one on tv) the fan needs to be set correctly or it won’t spread the air around properly under the hood.
 

blkss64

Well Known Member
Since I only know about 64 409 shrouds, as I have one, they are one year only and are completely different from the early design. But, from memory, the 59-63 W fan shroud doesn’t have the large ribs on the shroud. The pictures are hard to tell but the shroud looks too wide, as it seems too long from the radiator upper tank to the end of the shroud. Maybe another member that has an early shroud can measure this depth and post it. I am not doubting that the shroud is not correct because it did bolt up with the radiator, it just looks different than what I remember the early shroud to look like. The 64 shroud has those large ribs but is not that deep. Maybe cut the shroud to have the fan blades half in/ half out?
 
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