radiator size differences

[sb69chevy]

What are the differences between the 2, 3 and 4 core rads? I'm having a little overheating prob (not bad) but think I may have a 2 core rad since the engine was originally a six cyl. Would it be better to buy a new 4 core or go w/ used and have it cleaned? Thanks, sb

[jb4short]

Originally Posted by sb69chevy

What are the differences between the 2, 3 and 4 core rads? I'm having a little overheating prob (not bad) but think I may have a 2 core rad since the engine was originally a six cyl. Would it be better to buy a new 4 core or go w/ used and have it cleaned? Thanks, sb

It's the number of rows of tubes running from tank to tank. The more tubes the higher the capacity for flow (and volume). Properly mixed coolant, and a good water pump make a big difference. You can also get a slight overheating problem with air-pockets in the system.

[sb69chevy]

Thanks. The odd thing is that it gets hottest on the highway. Would that be air or coolant flow prob??

[ERASER5]

Take off the radiator cap and look inside. From front to back you can count the number of rows. I you do not have shroud (most Six’s did not have a full shroud) you can just look closely at the core/ end sheet. The two-row and three-row rads use the same end tanks so the two-row rad will have extra space on the end sheet. The four-row rads are fatter and require bigger mounting tabs. I just cut into my mounts and bent them wider, but my truck is pretty messed up. A full shroud will help if you don’t have one.

Price a new copper four-row rad then look at Summit Racing’s two-row aluminum radiators. The Aluminum rads out cool the copper rads hands down.
Take off the radiator cap and look inside. From front to back you can count the number of rows. I you do not have shroud (most Six’s did not have a full shroud) you can just look closely at the core/ end sheet. The two-row and three-row rads use the same end tanks so the two-row rad will have extra space on the end sheet. The four-row rads are fatter and require bigger mounting tabs. I just cut into my mounts and bent them wider, but my truck is pretty messed up. A full shroud will help if you don’t have one.

Price a new copper four-row rad then look at Summit Racing’s two-row aluminum radiators. The Aluminum rads out cool the copper rads hands down.

[sb69chevy]

Will look inside. I did get a shroud for it last year. Like I said, this happens mainly on the highway, and when it's high 90s-100s outside. Once I get the rpms and speed down, the temp starts falling again.

[jb4short]

Originally Posted by sb69chevy

Will look inside. I did get a shroud for it last year. Like I said, this happens mainly on the highway, and when it's high 90s-100s outside. Once I get the rpms and speed down, the temp starts falling again.

Could be a clogged radiator. Did you take out the thermostat? Some people take them out thinking it will run cooler but it actually will raise the temperature slightly at highway speeds (too much flow and the coolant doesn't get cooled before re-entering the block).

I'd try a simple system flush, new coolant, and a new thermostat before buying a different radiator. If it doesn't fix it you can recover the coolant for reuse anyway.

[sb69chevy]

I have a stat, but the truck didn't have one when I got it...I have a 165 in there, maybe need to go up to 185?

[jb4short]

Originally Posted by sb69chevy

I have a stat, but the truck didn't have one when I got it...I have a 165 in there, maybe need to go up to 185?

You said it was originally a 6cyl....was the motor swap done when you bought it? If it was and the PO was running W/O a thermostat then this might not be a new issue

[sb69chevy]

yes, swap was already done. this is only a late summer thing. today it got around 210 on the highway, which, to me, is high. Maybe not? Either way, it should be running a little bit cooler I would think.

[68gmsee]

Originally Posted by sb69chevy

Will look inside. I did get a shroud for it last year. Like I said, this happens mainly on the highway, and when it's high 90s-100s outside. Once I get the rpms and speed down, the temp starts falling again.

Just for grins, check the lower radiator hose to make sure it hasn't collapsed on you. I had one doing the same and found the coiled wires inside had rusted and the higher suction at high speeds would collapse the hose...

[sb69chevy]

Okay, I'll check that too. Just replaced it about a year ago or so.

[68gmsee]

Forgot to mention... not to scare you, but I also had another car that would act up similarly and it turned out to be a leaking head gasket. The higher speeds created more pressure and it would slowly force hot gasses into the water jackets (thats the way the mechanic explained it to me). We found that one by doing a leak test.

If it gets bad enough, it will suck up water into the engine when it cools off and you can see it when you start it up after sitting for a while and or loosing coolant.

[sb69chevy]

I don't think it's that bad, but you never know. Thanks for the heads up.

[Longhorn Man]

you have plenty of air flow at speed (stick your hand out the window, you'll feel it )
You (most likely) either have a coolant flow problem, or a detonation problem that you can't hear at speed.

[sb69chevy]

Longhorn Man, what would cause the detonation problem? Incorrect timing or something like that?

[Longhorn Man]

that, or runing too lean

[Longhorn Man]

or too much carbon build up in the combustion chaimbers

[sb69chevy]

If carbon build up, is there anything to help w/ this w/out a teardown?

[Longhorn Man]

warm up the engine, then up the throttle to about 2000 RPM.
Take a bottle of tranny fluid, and slowly pour it into the carb. If the RPMs start to drop, you're dumping too much in.
It'll smoke like crazy, but this cleans it out.

[sb69chevy]

okay, I'll have to try that. Thanks, again.

[GREASEMONKEY72]

tranny fluid or water (both done the same way) seafoam you can do the same way but once its all in you want to shut it off and let it sit for 5-10min then start it up again till the smoke goes away

and 210 aint really that bad

[Longhorn Man]

no, 210 is ideal for engine longevity.... but can hurt performance.