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at the end of my rope with overheating issues.

jmg222

NAXJA Forum User
NAXJA Member
Location
US
I'm running a 350 chevy in my '88 -- and can't shake an overheating issue. I had the truck running for a few years with a griffin rad, and it ran super cool, no matter what the temps -- dead of summer 95 degrees and humid, truck ran at a rock steady 190 degrees. Since then, the griffin rad sprung a leak, and I replaced with a novack kryo-flow, with integrated shroud with 3 e fans. I'm having chronic overheating issues on the highway... drove it yesterday in about 95 degree heat. It takes a while, but temps keep creeping around 210, then 230.. then I hit traffic, and I was done. Had to pull over and let everything cool off.

so, before I return this rad to novack, here's what I've done. Let me know if I'm missing anything:
1) pulled *everything* away from the front of the truck. I removed the Winch, lights, everything. nothing impeading airflow. didn't help.
2) drained, flushed, and replaced antifreeze. changed all hoses in case there was some blockage I was missing. no difference.
3) pulled the thermostat completely. Took a little longer to overheat, but other than that, no difference.
4) replaced water pump. No difference.
5) I *do* have a stock a/c condenser and trans cooler in front of the rad -- but I had the same set up using the griffin rad, and it didn't cause issues. Just to make sure, I drained the a/c, pulled the condenser, and tried running without it. No difference (can't really pull the trans cooler, since the kryo flo rad doesn't have a trans input,but that thing is pretty small)
6) I've confirmed all three e-fans are running properly, and kick on right at 190degrees.

is there ANYTHING else I can try? I'm sure novak will replace the rad, but I want to run down everything before I go this route.
 
If you had success with a griffin and you switched to a novak and now you have issues, I think you've found your problem.

It's obviously also a contributing factor that the coolant system and it's components are a few years older than they were when you first did your engine swap, but I think the issue is probably not enough radiator.
 
I'm grasping at straws here. You seem to have covered the basics.

Verify your ignition timing, especially your mechanical advance (higher rpm cruising) if your dizzy has mech advance. Too advanced will run hot.

Verify proper air/fuel mixture. Too lean will run hot.

Verify proper airflow direction. Make sure your fans are pulling through and not pushing air through the radiator (assuming your fans are on the back side of the radiator). Ive seen this before and it will cool fine at lower speeds and overheat at highway speeds.

Make sure you used the proper water pump for your application. Standard rotation versus reverse rotation makes a huge difference.

Have your radiator cap pressure tested at a Vatozone and make sure it seats properly on your rad. filler neck.

Thats all I've got...best of luck!!!
 
If you had success with a griffin and you switched to a novak and now you have issues, I think you've found your problem.

It's obviously also a contributing factor that the coolant system and it's components are a few years older than they were when you first did your engine swap, but I think the issue is probably not enough radiator.

To be clear, I got both rads from novack. They had qc issues with the griffins (they spring leaks constantly... which is exactly what happened to mine) and switched to kryo flows. I know a bunch of guys htat have the kryos in same application (chevy sb in a cherokee), and zero issues.
 
I'm grasping at straws here. You seem to have covered the basics.

Verify your ignition timing, especially your mechanical advance (higher rpm cruising) if your dizzy has mech advance. Too advanced will run hot.

Verify proper air/fuel mixture. Too lean will run hot.

Verify proper airflow direction. Make sure your fans are pulling through and not pushing air through the radiator (assuming your fans are on the back side of the radiator). Ive seen this before and it will cool fine at lower speeds and overheat at highway speeds.

Make sure you used the proper water pump for your application. Standard rotation versus reverse rotation makes a huge difference.

Have your radiator cap pressure tested at a Vatozone and make sure it seats properly on your rad. filler neck.

Thats all I've got...best of luck!!!

Thanks... should've added that:
1) proper air flow direction confirmed (I checked that off in the first round of fixes)
2) water pump is from an '88 silverado... which did not use reverse cooling
3) tried a brand new cap (13 pounds)

havne't checked timing/mixture issues...I guess since I'm not wheeling this weekend I can try that...
 
I have a novack in my 5.9 swap. I also have hot-running problems as well.

I'm using Derale 4000 cfm fans.. they draw a hell of a lot of air across that radiator. It stays @200-210 for the most part until I run a hill then it climbs towards 250 pretty quick, then cools back off after the climb is done. Runs hot with the ac as well.

it's tough dropping 700 bucks on a radiator that they say will cool a 650 hp engine and still have problems with only 215hp.. I think it's marketing BS.

I wanted a B-cool but they stopped producing the XJ rad.
 
Exhaust manifold gasket/donut? (Blowing exhaust gasses on the block)
Spark plugs? (Ive had spark plugs worn down so badly it caused a perpetual overheat)
 
Exhaust manifold gasket/donut? (Blowing exhaust gasses on the block)
Spark plugs? (Ive had spark plugs worn down so badly it caused a perpetual overheat)

I'll check the plugs, although they have less than 3k miles on them. No issues on the exhaust manifold. solid seal.
 
I think that may make it run a tad hotter... :)

get a mech fan, or move the rad to a place where you can get a larger E-fan. I don't care what the CFM on the fans says, there are not Efans available that fit in the front of a cherocar that pull enough air.
 
Didn't say if it was boiling over or not. But a 13psi cap is not going to help. The more pressure in the system the lower the boil over point will be.

The other strange thing is how it will still climb when at speeds. The air flow coming in at HW speeds will cool most motors. When on the HW the cooling air cools a stock mechanical fan clutch and it will begin to disengage so its better mpg. The fan turning at speeds is not need because the air flowing in is more than enough to cool everything. I take it the Thermostat is opening and making the Rad hot?
 
get a mech fan, or move the rad to a place where you can get a larger E-fan. I don't care what the CFM on the fans says, there are not Efans available that fit in the front of a cherocar that pull enough air.

This.

Ditching my triple elec fans and going back to a mech and aux fan setup was the best thing ever for my cooling system.
 
get a mech fan, or move the rad to a place where you can get a larger E-fan. I don't care what the CFM on the fans says, there are not Efans available that fit in the front of a cherocar that pull enough air.

I ran the same efans for three years on a griffin rad (and they worked fantastic (until the rad sprung a leak)-- kept the truck at 190 in the dead of summer, up hill, offroad .... so.....never say never :)
 
Didn't say if it was boiling over or not. But a 13psi cap is not going to help. The more pressure in the system the lower the boil over point will be.

The other strange thing is how it will still climb when at speeds. The air flow coming in at HW speeds will cool most motors. When on the HW the cooling air cools a stock mechanical fan clutch and it will begin to disengage so its better mpg. The fan turning at speeds is not need because the air flowing in is more than enough to cool everything. I take it the Thermostat is opening and making the Rad hot?

I put the 13 lb cap on only because I realized I had mixed and matched parts -- the upper hose has a fill cap in it, and came form a dodge truck that had a 20lb cap. The motor and pump came from an '88vintage chevy, which uses a 13lb cap. Agree the 20lb would actually raise the boiling temp, I was really just doing it to put on the cap I *should* have had since the begining.

I completly removed the theromstat.

I think it's an airflow issue, and convinced this is just a bum rad. I've contacted novack, and hopefully they'll stand behind their product and send me a new one (they built the shroud and fans, and say they have them on dozens of XJ's with 350s, so I'm going to just have to assume at this point I got a crappy rad)
 
Fix the Griffin and reinstall it

tried. spend $400 at a repair shop to re-epoxy it. that was the first thing I did. Never cooled the same way again once it burst (which I've been told is pretty common w/ aluminum rads)
 
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