[Joe White]

I've been battling an overheating issue for quite some time. Now I do understand it is 100+ degrees out right now, but I'd like to believe the engine should still be able to cool itself off.

I've got a big three core aluminum radiator, with dual electric puller fans, and smaller electric pusher fan. Running a 195 thermostat at the moment, was running a 180 (no change). There is ac in the truck, but the overheating problem still exists with the ac off. I am able to open the hood and let it idle and it will cool down to around 210. Doesn't seem to matter if I idle or drive around, if anything heats up faster when driving around.

The trucks radiator appears to keep up for the first 3 or so openings of the thermostat, keeping close to 195. But after than it seems to overpower the radiator, and the fans are just blasting 200 degree heat constantly.

Here are some picture for reference.

 

[Rhotpursuit]

A couple of things...you need a shroud for the pullers. The pusher is probably doing more harm than good. You also need to seal the perimeter of the radiator to the core. It also looks like you cut out part of the trim across the front of the radiator. All that high pressure when you're driving goes up thru that gap instead of thru the radiator.

 

[oldeerslayer]

There is a long running discussion as to whether a 3 core or a 2 core cool better. I agree with the school of thought that says 3 skinny little cores don't cool better because the passages are so small water doesn't flow well enough. There are a lot of swaps using both the original 4.3 rad and C4 Corvette rad that are 2 core and nearly identical in cooling ability. Both have been used successfully many times from Maine to Mexico.
Fans are another area of debate. Personally I don't like shallow after market ones. Yours don't appear to have enough distance from the radiator to facilitate good airflow. They also don't have enough room for much pitch to the blades. Propeller driven aircraft use variable pitch propellers and increase the pitch for better performance because a steeper angle creates more airflow. I also agree ^ the pusher is probably restricting air flow at speed. Factory fans from various cars seem to work better than aftermarket ones. The old standby was the Ford Taurus fans, which actually came in numerous versions. Those are less popular these days because they are such amperage hogs. But lots of amps translates to lots of air flow. Probably more than necessary. Next came the Dodge Intrepid fans. Which fit the S10 4.3 rad real well and weren't quite so hard on the electrical system. Lot of guys including me who've had good success with them. Current trend sems to be Grand Am rad and fans. You'd think they're smaller, but they've been used quite successfully.
One thing to check is that your wiring to the fans on the 30/87 side of the relays is 10 AWG. Anything less could be slowing the fans. And as mentioned above sealing the rad to the support and shroud to the rad are important so that all air flows thru the core. Most later S10's also had a deflector in front of and below the front of the rad to increase airflow.
Those get left off quite often resulting in decreased air flow.

 

[bk2life]

heats up faster when driving

you've answered your own question right there. Every vehicle, with any engine combo should be able to completley remove all cooling fans and be able to drive above 45 mph and have zero cooling issues. this is due to the forced air being pushed through the radiator.
On my v8 swap i had a climbing temp issue above 65mph. I had the V6 rad and the intrepid fans. II removed the interepid fans and went for a blast down my local highway. What i ended up finding is i had an air pocket underneath my engine bay where the hot air leaving the rad would turn and go back into the radiator. I brought a few pieces of carboard and sheetmetal with me and put various 'airducts' taped to my truck under the bumper and on the sides of the rad until i found the issue. I could then drive from 55 to 105mph without any issues.

GM has put air dams under vehicles for a while. 3rd gen camaros (think KITT) have a very necessary air dam under the core support that if not there, will over heat. Just that one simple piece causes that much issues. thats where i got the idea for the duct work under my truck .


Also, all the red arrow hot airs are just going right past your rad..
remove the pusher fan its not needed.
check your puller fan specs, they might not be good fans.

make sure the fans are sealed to the rad

and block off or redirect all air (red arrors) that are escaping around the rad. youcan easily bed a piece of sheetmetal and direct the air through the bumper towards the radiator

 

[Brawndo]

OP i see you are using the 4.3 belt routing. Is the waterpump a reverse rotation pump? I believe that causes all the problems if it is not.

A bit tedious vid below but you get the idea.

 

[Joe White]

Every vehicle, with any engine combo should be able to completely remove all cooling fans and be able to drive above 45 mph and have zero cooling issues. this is due to the forced air being pushed through the radiator.

I think your right on forcing more air into the radiator. I'll try to seal up the radiator some more. I'm still just worried about it working well on idle. It is a slow overheat, so I'm fine at stoplights as long as I'm not at one for 5 minutes.

Here is what I did the other day trying to see if it would help with my overheating issue. It appeared to help, around 207-210 while driving around like 30mph. Before hand it would slowly climb to about 220 before I would come back home and open the hood to let it cool off.

I'll try to fix up some of the gaps where the air might be recirculating, see if that helps. Just trying to find a good way to do it and it not look too terrible.

 

[Joe White]

OP i see you are using the 4.3 belt routing. Is the waterpump a reverse rotation pump? I believe that causes all the problems if it is not.

A bit tedious vid below but you get the idea.

I've been wondering this too. I didn't do the original engine swap. Is there a serial number on the waterpump to look up. I didn't see one on top. Also whenever I was toping off the coolant, the coolant appeared to be bobbing up and down quite rapidly. Not something I've really ever seen before.

 

[Rhotpursuit]

The air dam/scoop that bk2life mentioned will help a lot. Time to hit the PickNPull. You can use backer rod to seal around the perimeter or the radiator....or a slice of foam pipe insulation. It's closed cell so it won't soak up or retain water. All of that along with ditching the pusher, and getting a good set of puller fans and you'll be golden.

 

[Brawndo]

I've been wondering this too. I didn't do the original engine swap. Is there a serial number on the waterpump to look up. I didn't see one on top. Also whenever I was toping off the coolant, the coolant appeared to be bobbing up and down quite rapidly. Not something I've really ever seen before.

I am about 98% sure the 4.3 pump will fit the SBC. Around a 90 91 water pump should work and it is reverse rotation. Changing the pump will most likely take less time than putting in the extra fans. I think what you are seeing with coolant rise and fall is the pump impeller causing cavitation.

 

[Brawndo]

https://www.oreillyauto.com/detail/c/masterpro-water-pump/engine-cooling/water-pump/d916446a6bad/masterpro-water-pump-new/owp0/c301620/v/a/3652/automotive-suv-1991-chevrolet-s10-blazer?pos=0

Rotation Direction: Reverse

 

[Brawndo]

 

[Brawndo]

Sorry for mult posts admin, cant figure out how to add text to picture. In any case the above is belt routing that requires reverse rotation water pump.

 

[Joe White]

I am about 98% sure the 4.3 pump will fit the SBC. Around a 90 91 water pump should work and it is reverse rotation. Changing the pump will most likely take less time than putting in the extra fans. I think what you are seeing with coolant rise and fall is the pump impeller causing cavitation.

I'm not 100% ruling out the waterpump, but I don't believe it to be the issue. I drove the truck again tonight, only about 90F outside plus its dark. But I am able to run the AC at somewhere probably about 1/2 max ac. Otherwise at max ac the truck slowly, over a couple of miles, rises about 10 degrees. When I turned the ac down it managed to slowly go back down and start cooling normally, and staying at 195F (the thermostat temperature).

The air dam/scoop that bk2life mentioned will help a lot. Time to hit the PickNPull. You can use backer rod to seal around the perimeter or the radiator....or a slice of foam pipe insulation. It's closed cell so it won't soak up or retain water. All of that along with ditching the pusher, and getting a good set of puller fans and you'll be golden.

I did make some small improvements with putting some of that backer rod around the rad. Glad you recommended that, never would've known what to use. I'm not done putting the backer rod in to seal up some of the air gaps that could be recirculating all the hot air. Also need to close up the big opening in front of the radiator, which is more than likely a big cause the heat "recycling". Might look into getting another set of puller fans, the ones in it seem to work good, but I noticed the shroud is pretty cut up in a couple of places. If you know of any good brands or fans that would be good for this please tell me, I got no clue.

Also just coming to terms that idling in 100+ degree heat might not be that feasible with such a big engine, with limited cooling capacity.

 

[FLORIDA BUTCH]

At one time I had the same problem you do. Here in Florida it would ride at 200 to 210. I found out one of my fans wasn't working {I have 2}. Also in order to have fans that cool enough to cool your engine they have to be fans that need a relay switch. My fans produce 2000CFM each. Fans that don't need a relay switch don't put out any more CFM than a hair dryer. Without those fans I wouldn't be able to use my truck. I don't go over 190 on the hottest days. Next time I get a radiator I'm going to get a 2 row. The tubes are larger and cool better. Dera

le is the brand I used.

 

[Joe White]

Did some research on the fans, they appear to be a dual fan kit, Maradyne MJS22K dual 12in fans. This is the first car of mine to have electric fans, to me they appear to move a lot of air, but maybe when it comes to electric fans they are on the slow side. Didn't see anything about CFM but the wattage was 225W. Is that enough? I'd be fine upgrading, it is just another jap into my wallet I don't want to do.

Edit: looked up the fan itself, a single fan appears to be 225W with a CFM of 1565.

 

[Rhotpursuit]

Get the Intrepid fans...6 blade.

 

[bk2life]

Did some research

have you tried a second temp gauge? just to make sure youre not chasing the dragon?

 

[Brawndo]

have you tried a second temp gauge? just to make sure youre not chasing the dragon?

+1

 

[oldeerslayer]

Get the Intrepid fans...6 blade.

I do agree. Never heard anyone complain about overheating with those fans.
Problem with replacement Intrepid fans is they aren't necessarily configured like the originals. Chrysler had basically 2 models. The standard duty which pretty much went on 4 bangers and had the 5 blade fans. Then there was the heavy duty, severe service, and a couple other beefy names. The better fans had better motors and 6 blades. Most replacements now have 6 blades and the standard motors. They claim to fit everything.
I know where there is a Chrysler 300 in a junkyard with the original HD fans still on it. They look to be a beatch to get off, is why they're still there.
Good thing is they all move enough air to do the job. I think the pitch of the fans is the trick. That's why they aren't the skinniest one out there.
One problem I suspect with his current setup is it has no MPH shut off like GM has in the 0411 and later PCM's. At highway speed the spinning fans actually create a wall that limits airflow to what the fans can deliver. If they'd stop, the amount of air blowing in at highway speed is way more than any fan can produce. I'd try putting a kill switch on the fans that you can flip in the cab. I'm willing to bet he'll see his temps go down by shutting them off above 50 mph. Just don't forget to turn them on when you slow back down.
I also think his fans look too shallow to seriously move enough air. CFM ratings from the manufacturer need to be taken with a grain of salt. 225 watts at operating 13.8 volts is 16 amps. At Battery voltage of 12 volts it's 18.75A.
I run my Intrepid fans with a 30A fuse on each. And a separate 10A on the control side of the relays. For all 3 relays.
I use a controller that is soft start helps. It starts slow, then increases speed to what's needed. Easier on the whole electrical system. Just not a cheap setup.
My 377 inch ZR2 has a DCC PWM controller. My LQ9 2wd has a factory blue/green 2003 P59 PCM running the fans at stock Caddy temp settings. Both trucks use Intrepids. Although the ZR2 is an OEM HD one. While the LQ9 has a Rockauto closeout Intrepid fan setup that had to have a 3rd relay installed because they were wired incorrectly when manufactured.
There's a whole thread on what the problem was and how to cure it by adding a 5 wire 87A type relay.
I used GM fuel pump relays from the 90's because they're built to last forever. Not like the little imported ones on eBay.

 

[Rhotpursuit]

Here's a thread from V8S10 on Intrepid fans.

V8S10.ORG • View topic - Intrepid Fans