BBC Overheating - Need Help

[Chevy1TonFun]

ITS OFFICIAL I AM STUMPED!! I just had the radiator rodded out and added some new 4000cfm fans. It was 102* today and she acted as if I hadn't done a thing, still got up to 230. What have I missed? HELP!!!!

Here is what had been done or checked.

Timing - 12* at idle/MSD HEI distributor
Thermostate - 160* - drilled a bypass hole
4000cfm puller dual fan kit
Newer OEM water pump
New hole for bypass hose.
No heater core or hoses
Using water and 2 bottles of Wetter Water, no antifreeze
4 core OEM radiator

 

[bp71k5]

Is the water getting pumped through the radiator? The upper hose will be hot and full of water if it is.

Check the thermstat, make sure the water pump hoses arent on backwards and that the pump is actually working, and then make sure the fans are turning on at the correct temp.


-Brian

 

[Greg72]

Serpentine or regular pulley setup? Remember the water pumps turn in opposite directions....

 

[folkenheath]

These guys have good points to check. Also...

Did something change? New engine? If so what heads, block, and head gaskets are you running?

Is it getting hot at idle? If so hook your vacuum advance up to full manifold vacuum, that will help some.

And how much mechanical advance are you running?

 

[Chevy1TonFun]

These guys have good points to check. Also...

Did something change? New engine? If so what heads, block, and head gaskets are you running?

Is it getting hot at idle? If so hook your vacuum advance up to full manifold vacuum, that will help some.

And how much mechanical advance are you running?

I had a 486 BBC built and have had overheating issues since the first start. A s for the hot idle, I don't think so. After driving around the block twice I let the truck sit running in the driveway for another 15 minutes and stayed at 209-210. But it seems to increase in temp in stop and go traffic. I am running a Black Mountain Performance cog belt setup. I believe the ratio same or close to stock pulleys.

 

[folkenheath]

What heads, block, head gaskets? Big blocks have 3 different Generations, using the wrong combo together can cause overheating problems.

 

[4X4HIGH]

Swap the t-stat for either a 180* or 195* and i'll bet your overheating issue goes away. Once you understand how the cooling system works then you'll know why a hotter t-stat should cure your problem. I'm heading to work in a few minutes and can't explain it now but I can later if you want or if noone else does before I get home tonight.

 

[folkenheath]

Swap the t-stat for either a 180* or 195* and i'll bet your overheating issue goes away. Once you understand how the cooling system works then you'll know why a hotter t-stat should cure your problem. I'm heading to work in a few minutes and can't explain it now but I can later if you want or if noone else does before I get home tonight.

Thats a myth, its a very common myth but it's not true. I run a 160 tstat and don't have a problem heck I even took it out once and it still cooled fine. The myth is the higher tstat will leave the coolant in the radiator longer to cool more. However, the longer the coolant is in the radiator, the longer it is sitting in the engine heating up. A higher thermostat will not make your enginer run cooler, if it does, then the other thermostat wasn't functioning correctly. To see how the myth started read the last two paragraphs on this page...

https://www.stewartcomponents.com/index.php?route=information/information&information_id=11

1tonfun, How confident are you on your temp gauge? At 230 the upper radiator hose should be too hot to hold onto for more than a moment. Be careful. If it isn't then it either isn't flowing or your temp gauge is wrong.

 

[4X4HIGH]

It's definately NOT a myth. Not everyone running a cooler t-stat has problems either BUT the ones that do have issues usually going to a hotter t-stat cures the problem (i've had personal experience with this over the years).

 

[folkenheath]

Well it's not worth arguing since you apparently know more than the people who make the stuff, so I'll only say thermodynamics and fluid heat transfer don't work that way.


Either way, I hope you get it fixed 1ton, let us know what you find out. BTW, what do you mean, "new hole for bypass hose"? Where did you tap the hole?

 

[Chevy1TonFun]

Ok, This is where I'm at now. After installing a 195* thermostat, I confirmed that at idle it stays at 210. Awesome, but the second (I do mean second) I rev (500+ RPMs) at all it jumps within a second to 225-230. Then it take 30 or so seconds (I counted) to come back down to 210-212.
ANYBODY KNOW WHATS WRONG????!!!! Thanks in advance. Also thank you to everyone who has been submitting your ideas and advice! I think I'm close.

 

[folkenheath]

Am I sensing some sarcasm with the "awesome" comment?

Who temp gauge do you have? I am wondering if your gauge is wrong if the temp is climbing 20 degrees in one second just from blipping the throttle. Have you tried a second gauge to confirm it?

You never did say what block, heads, and gaskets you have.

 

[Chevy1TonFun]

early 80s 454 bored .30 over and stroked (486ci), iron GM heads port and polish stage 2, fel-pro blue gaskets. I am running a new Autometer Phantom gauges. I think I already swapped out the temp gauge once before.

 

[folkenheath]

early 80s 454 bored .30 over and stroked (486ci), iron GM heads port and polish stage 2, fel-pro blue gaskets. I am running a new Autometer Phantom gauges. I think I already swapped out the temp gauge once before.

I mean more specific, casting numbers or year of heads and gasket part numbers. If the block is early 80s it's a Mark IV. So you have to make sure the heads and gaskets are compatible with that block. I'm pretty sure you can use the newer heads with the older block IF you use the correct gasket. Hopefully that's all fine but I would double check.

And where is this new bypass hose plumbed?