Hello new here, I own a 4 wheel drive shop in Florida and specialize in Jeep conversions to chevy engines.Some are stock others more performance. Now onto the problems I seem to keep having cooling problems with these conversions. They get up to around 220 degrees and can climb higher but I shut them down or bring them back to idle and they will cool down.
The engines seem to be overheating in higher RPM ranges sitting or driving and pulling like up mountian roads , all idle very cool, all have the same radiators aluminum from a place called Novak, and Flex a lite 3000cfm electric fans, and all are Automatic TH400. one is a 350 with iron chevy heads and I don't know what kind of cam but sure does run great. the other is a built 383 with E-Tec Edelbrock 200 heads a lunati Voodo cam and a Proform electric water pump, neather of these can run at standing still at 2000RPM or driving down road with out running hot takes a little while depending on outside temp 30 to 45 mins. Both have Edlelebrock carbs 650CFMs. All is new in both just can't figure it out. So I am looking for help. Have played around with differant Thermostats higher flows, stock ,160 to 185, timing, and distributor curves. have not checked spark plugs for richness, but both have had Holleys on them also and did the same thing. Any input would be great.Thanks

Do you have high flow water pumps on there and are you sure the radiator is big enough. The entire system should hold about 4 gallons of Coolant to be safe. Is this a 4 row or 2 row radiator?

Here's a decent high volume aluminum pump that's inexpensive.
http://store.summitracing.com/partd...-1888&N=700+4294908216+4294840140+4294889107+400299+4294903574+115&autoview=sku

Also, long shot, is the water pump rotation correct? Some pumps have different rotation than others so the belts/pulleys need to be correct. Serpentine vs. V groove.

 

I beleive they are 2 row and no it does not hold 4 gal of coolant about 2 gal

 

I beleive they are 2 row and no it does not hold 4 gal of coolant about 2 gal

I think you need more coolant. 8 quarts isn't enough IMO. I betcha a higher capacity 4 row radiator would do it.

I'm talking 4 gallons in the WHOLE SYSTEM, not just the radiator. Just to be clear. You better check that, I think you're wrong on the 2 gallons.

 

yes that filling radiator more than likely

 

yes that filling radiator more than likely

OK I have to ask. You said:

Hello new here, I own a 4 wheel drive shop in Florida and specialize in Jeep conversions to chevy engines

and you don't know this stuff cold?

 

What do you mean?

 

With all the info you have given and seeing the size of the radiator, which is the only thing they both have in common other than the fans, I might take a guess and say that perhaps the radiators are too small.

Also if they run fine at highway speeds but start to get hot when you slow down then you might want to take a look at your fan shroud arrangement.

Do you have a shroud other than the one that came on the fan?
If you are indeed using the shroud that came with the fan is it mounted directly on the radiator.

Any space between the radiator and shroud will cause air to flow in through that gap and not through the radiator.

Are they all running electric water pumps?
A lot of these pumps are designed primarily for drag use and were never really indended for the street.
That could also be a problem.

I would say start with the shroud issue as that would be the cheapest thing to rig up and see if it works.
Then maybe slap a stock belt driven water pump on it and see what that does.
If you are still having problems then the radiator might be the culprit.

I also would do what has already been mentioned and make sure the pumps are flowing the right direction.
A friend once had an overheating issue that was eventually traced back the a reverse flow pump on a standard flow system.

Thats all I can guess at this point.

 

Both fans are mounted dirrectly to Rad. One has a machanical water pump, both have same radiator. And it is running at higher RPMs sitting or down road, just put a new cam in one the other day and breaking in cam started to overheat at 2000 RPM. That one has the electric pump.

 

What do you mean?

Are these the first two to have the problem. If this swap is your specialty don't you know what it takes?

That being said...to the post above. I made the assumption you had a decent quality aftermarket fan installed correctly.

As noted, if it were at idle, I'd suspect the fan. Since it's under load I lean coolant quantity or water pump.

As to the high volume pump, there are some for drag racing. The one I referenced is a fine pump for street or off road use.

The other issue is too if you have a high volume pump, and a small radiator, it could get hotter as the coolant doesn't sit long enough in the radiator and it will run hot. To me, a four row radiator is in order. Again, this is internet advice I've never seen the vehicle. The reason I say this is at higher speed the coolant runs through the system faster which cools less in the radiator. With the electric pump, the coolant doesn't get as hot at idle, so the short stint in the radiator isn't as punishing.

This is really engine trouble shooting 101 at this point. There's nothing to a cooling system. It's the pump, radiator, and t-stat. That's it.

 

Both fans are mounted dirrectly to Rad. One has a machanical water pump, both have same radiator. And it is running at higher RPMs sitting or down road, just put a new cam in one the other day and breaking in cam started to overheat at 2000 RPM. That one has the electric pump.

Roller cam? Rollers don't require breakin. I expect that all new motors will be rollers.

 

Yes I do have a few out there these are the two with more performance engines and yes thes two have the same radiator, the others have have conversion radiators stock style, they were bought used soI don't know how many core they are. and they also have clutch fans and shrouds. thats why the other aluminum rad. was purchased for these engines, the water pump elecric is a Proform 35 gal min pump, One of the Jeeps have a stock 350 1972 block never beeen touch that we could tell, pulled pan a check bearings, with a new set of built vortec heads and a lunati 268 cam Conversion rad, brass or copper and a 6 blade fan and clutch and big shroud runs 180 all day. All depends on buget of customer

 

Both fans are mounted dirrectly to Rad. One has a machanical water pump, both have same radiator. And it is running at higher RPMs sitting or down road, just put a new cam in one the other day and breaking in cam started to overheat at 2000 RPM. That one has the electric pump.

I would then say that the radiators are probably the issue.

Once the coolant in the system gets saturated with heat it is probably not in the smaller radiator long enough to cool it down and it just keeps getting hotter and hotter.

 

I wish rollers no flat tappet, I make daily driver Jeeps and budget doesn't let them get into rollers.

 

Thats where I am headed too , the radiators I bought for these came from a place that I buy my adapter from. now they are making a HD Rad, for performance engines, they made sound like the ones i bought would work for performance. Just trying to make sure before spending more money. Didn't know if there was something else to check. I build 4X4s noit engines.

 

I wish rollers no flat tappet, I make daily driver Jeeps and budget doesn't let them get into rollers.

OK, you also said it was a 72 block, which left out rollers anyway.

I re read what I wrote, and I'm even a little unclear, let me re phrase:

I think in both cases, the coolant is moving through the radiator too fast at speed and does not have time to cool off, so the radiator needs more capacity.

The fans should be plenty. Did you speak to the fan manufacturer about the application? One big fan can be more effective sometimes than two smaller ones. I have dealt with that company, they are pretty good if you call and tell them what you're trying to do.

Still boils down to the same issue though, either a bigger radiator, or better flow, or combination of both.

Again, total system capacity should be about 4 gallons.

 

I build 4X4s noit engines.

Ah ok, answered my question. :welcome:

 

Slap some factory radiator in there and see if that does the trick.
Maybe something from a full size chevy truck would work if you can get it to fit.

I would try that before I bought new radiators.

 

I only have one fan, and I think I will try another radiator i have one for a Jeep conversion that is stock for a jeep Chevy fit. Thanks for all the help.

 

(I think in both cases, the coolant is moving through the radiator too fast at speed and does not have time to cool off, so the radiator needs more capacity.)

Remember its a closed system...Common though process though. Seems to make sense at first but if you realize that water is always touching the block or the rad you'll see it doesn't matter how fast it going....it's always touching something. Now, a bigger pump helps, but not by speeding up the flow but by creating turbulence in that flow. The "stirring" of the water as it travels through the tubes allows the water in the center of that tube to be moved closer to the walls of the tubes and it will pickup heat it wouldn't staying on in the middle. Installing a bigger rad will reduce the turbulence sometimes creating a problem that just seems like it too slow. In essence, your right, just and but by different reasons than what your thinking.


My opinion is to get rid of those eletric fans and get a good GM four blade fan on it. Then your gonna have temp problems the other way...

 

4x4, here's a link to a wiki article that many of us have contributed to and may be helpful to you....
http://www.crankshaftcoalition.com/wiki/Bulletproof_cooling_system

Agree with johnsongrass1 about the speed of coolant through the system. I have never thought that it makes a heck of a lot of difference. If the water moves through the block at X speed and through the radiator at X speed, the heat picked up and heat rejected will be on the same ratio as if the water went through the block at XX speed and through the radiator at XX speed.

 

4x4, here's a link to a wiki article that many of us have contributed to and may be helpful to you....
http://www.crankshaftcoalition.com/wiki/Bulletproof_cooling_system

Agree with johnsongrass1 about the speed of coolant through the system. I have never thought that it makes a heck of a lot of difference. If the water moves through the block at X speed and through the radiator at X speed, the heat picked up and heat rejected will be on the same ratio as if the water went through the block at XX speed and through the radiator at XX speed.

I'm sticking with speed of coolant. Here's why. ANY radiator will work if you leave the coolant in there long enough. The practical problem is that the capacity of that radiator may be too small to cool fast enough. Until we know the BTU rating of both the radiator and the heat coming from the engine, there's really no way to answer either way. Either way, the answer is the same.

I also have to respectfully disagree on the fans too. I think electric fans are one of the greatest additions to cars in terms of reliability in recent history. I remember as a kid sitting in traffic overheating all the time. Not being able to run the AC because it may over heat if we weren't going fast enough. Fan clutches going bad. IDK, I like electric fans and they work well when appropiately specified.

 

"ANY radiator will work if you leave the coolant in there long enough."

I don't know, if you leave the coolant in the radiator for a certain length of time, the other half of the coolant is in the block/heads for the same length of time, picking up additional heat that must be rejected and pretty soon, you're into a vicious cycle.

The way I see it, you've touched on the correct answer, BTU production versus BTU rejection. Makes sense that if the radiator is rejecting XX heat and the motor is producing XXX heat, she ain't gonna operate so well after everything comes up to operating temp.

 

well I understand about leaving in the Rad. long enough and also therefor leaving it in the block to long, I have tried low flow thermostat from miloden and it didn't help, and as far as electric VRs machanical fans, 4x4s alot of the times is slow pulling engines and other times as we have here in Florida is mud ,water. So thats why I picked a electric fan great for idling and can be turned off in high water, I have broke fan blades,bent them and cooked engines puttin around and going thru water. I am going to try a rad. I have for my personal Jeep when I tear it down to put my stall convertor in. Also I may change fans, have any of you tried the Ford Taurus 2 speed fan, supposed to put out 4000cfm on high, have put these in couple of 4x4 trucks and the guys love them reall cooled them down.

 

"ANY radiator will work if you leave the coolant in there long enough."

I don't know, if you leave the coolant in the radiator for a certain length of time, the other half of the coolant is in the block/heads for the same length of time, picking up additional heat that must be rejected and pretty soon, you're into a vicious cycle.

The way I see it, you've touched on the correct answer, BTU production versus BTU rejection. Makes sense that if the radiator is rejecting XX heat and the motor is producing XXX heat, she ain't gonna operate so well after everything comes up to operating temp.

Well, yeah, that's my point. I started writing it but at this late date after a long weekend it didn't come across. Clarity is not on my side right now.

Still, if the radiator is too small, that's what you're going to get. Too much in the block, not enough in the radiator, and effectively not sitting there long enough to cool, in addition to not having enough volume to cool. Makes far more sense to me than turbulence.This is a closed system.

 

well I understand about leaving in the Rad. long enough and also therefor leaving it in the block to long, I have tried low flow thermostat from miloden and it didn't help, and as far as electric VRs machanical fans, 4x4s alot of the times is slow pulling engines and other times as we have here in Florida is mud ,water. So thats why I picked a electric fan great for idling and can be turned off in high water, I have broke fan blades,bent them and cooked engines puttin around and going thru water. I am going to try a rad. I have for my personal Jeep when I tear it down to put my stall convertor in. Also I may change fans, have any of you tried the Ford Taurus 2 speed fan, supposed to put out 4000cfm on high, have put these in couple of 4x4 trucks and the guys love them reall cooled them down.

At one time, I had all the info on using the electric fan arrangement from a Mark VIII Lincoln. Supposed to be the double-throwdown setup. If you google it, maybe you'll be able to come up with the info.