Overheating at idle ... 1979 c10

[QBuff02]

if you have any doubts, for a quick and dirty cut up some cardboard to fill in the gaps of that radiator and wrap around the corners of the fans that aren't covered currently so it directs the air THROUGH the fans from the whole radiator. but the trouble I see in that pic is there is an awful lot of real estate not covered by a fan or a shroud, and a shroud to cover all of that is going to look like trash and probably be more of a hindrance than a help. But i'm also not a fan of electric fans for these very reasons. I'm making 500ish hp out of an iron headed big block with a stock radiator, shroud and a mechanical fan and last weekend when the temp was above 90 degrees here the hottest it got was just tickling 200 degrees and that was after a 10 mile steady drive at average 3,000rpm (65ish mph, speedo cable broke) with about the last mile of that pull being probably around 30% grade coming straight up out of the river valley. No need to fix what ain't broke, but there are some guys that know which fans and relays and shrouds and such to use and have good luck with them. And I will add one thing to look at if you still have a/c components in place make sure the condenser is clean and free of bugs and dirt/debris, I've seen many times where even though they aren't hooked up they were hanging out behind that grill dirty and plugged up and that also restricts the air flow through the radiator and the fans.

 

[Bextreme04]

@Cu1n81,

Man, if I saw my temp go to 215 I would freak out!! The only time I've seen temps over 200 was one time I was in a group of hot rods going to Longview, Texas to a car show on a very hot summer afternoon on interstate and the lead car was doing over 80 mph. Running, my temp showed 205 and I was freaking then. I almost pulled back and slowed down. I would have thought a head would crack at 215! Or a blown head gasket or something else equally as bad.

215 is actually normal operating temp for most OEM V8 applications, its not even close to overheating. A 195 Thermostat will keep the engine locked right around there. Modern LS computer controlled fans will kick one fan on at high AC pressure or at around 205-215, with the second fan coming on at 225 or so. 50-50 coolant mix wont start boiling until about 265 and the higher coolant temp isn't what will cause head warpage or damage, its the coolant boiling to create steam pockets that greatly exceed that temp and create high pressure or a complete lack of coolant at all that can allow the engine to get 100's of degrees hotter than that. Steel won't start to have a significant reduction in tensile strength until it hits 1,000 degrees or more.

 

[Bextreme04]

Here is my current setup:

Thanks for the replies so far. I will definitely check these items. Currently these fans run all the time. I haven’t put the fan thermostats on yet. Once I realized I had too little air flow from these fans, I figured it wouldn’t hurt it to run all the time.

I’m looking for a shroud now. If anyone has a link to one they suggest I’d be appreciative.

And to be clear the truck handles 99% of driving fine. I drove thru traffic just fine the other day. It was stop and go. But I had runs where the air could get thru it and kept it cool. I definitely can’t let this truck idle for an hour or something like that. It would over heat.

The truck isn’t stock. It has a mild cam. A few other mods. I just bought it about 2 months ago.

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That is exactly your problem... those fans are tiny, and as others have stated they are not pulling through the majority of the radiator. Go down to the local pick and pull and get some 2007-up Silverado 2500 electric fans. They will cover that entire radiator, flow way more air, and they only cost about $40-50 used. You can get a brand new set for about $140 also if you dont want junkyard ones, but you will also need to order pigtails if you get a new one. If you get a junkyard unit you can get the harness with it as well and then just get a temp switch and two 40 amp relays.

 

[RecklessWOT]

Go down to the local pick and pull and get some 2007-up Silverado 2500 electric fans.

Are you sure about that year range? I'll admit despite owning one I don't know much about the newer trucks and what options different configurations came with, but I have a 2008 2500 (albeit it's a GMC, but I thought they were more or less the same) with a 6.0 an it most certainly has a clutch fan. Is it just the diesels that have electric fans? Maybe it's only the 1500s with 5.3s?

 

[Bextreme04]

Are you sure about that year range? I'll admit despite owning one I don't know much about the newer trucks and what options different configurations came with, but I have a 2008 2500 (albeit it's a GMC, but I thought they were more or less the same) with a 6.0 an it most certainly has a clutch fan. Is it just the diesels that have electric fans? Maybe it's only the 1500s with 5.3s?

I'm not sure. I just know that in 2007 and up, they were optionally available.

 

[DoubleDingo]

Why no shroud? You need a shroud. Install a shroud. Shroud is your friend.

 

[Raider L]

Also, it's very important that the shroud cover the sides of the radiator as well as air will pass right around that sucker at street speed. It has to be enclosed on all sides so the air is captured going through the radiator, and the air is going only through the radiator to get maximum cooling. And it will cool significantly better at low speeds the more captured the air is. NO leaks, on the sides or anywhere.

 

[Rusty Nail]

Why no shroud? You need a shroud. Install a shroud. Shroud is your friend.

Fan Shrouds are all the rage this year! We were just talking about fan shrouds..

Good pix!

 

[Cu1n81]

Thanks guys. Bigger fans with a shroud and I can now idle for days it won’t overheat. Thanks for all your comments!

 

[potent rodent]

install a shroud and a good fan clutch and 7 blade fan

 

[Rusty Nail]

Thanks guys. Bigger fans with a shroud and I can now idle for days

No pics?

 

[Bextreme04]

Also, it's very important that the shroud cover the sides of the radiator as well as air will pass right around that sucker at street speed. It has to be enclosed on all sides so the air is captured going through the radiator, and the air is going only through the radiator to get maximum cooling. And it will cool significantly better at low speeds the more captured the air is. NO leaks, on the sides or anywhere.

I know this is an old thread, but this post is not really correct. You don't need a shroud at all at street speed. In fact, any kind of shroud or fan is actually hurting your cooling at anything over about 35-40mph. A shroud is absolutely critical for keeping air flow through the radiator when stopped though. The rest of this post is totally correct, just not the street/highway speed part.