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Unread 07-16-2009, 09:32 AM   #1
valkadesh
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Cooling Question 258 - high temps!

I recently put a rebuilt 258 in my 85 CJ7. It was performed by a local shop and a new water pump was installed at the same time. After i got everything back, i went ahead and installed an autometer electrical temperature gauge so i could see exactly what i was running at.

Driving around town, i'm sitting pretty constantly at 210. My sending unit is on the drivers side of the of the engine block right near the firewall. EGR is hooked up

However, when i get going at a good speed ~60 or so, for any period of time, the temperature starts to creep up. After a brief 5 minute drive at that speed, i was already up to 225 and climbing.

I'm assuming the thermostat is working (and new), because when it heats up around 210, i can see it move back a bit telling me the thermostat has opened up and coolant is flowing.

I have what looks like a 6/7 blade fan (not sure if it's a clutch fan or not). Shroud is installed.

I'm really scared to take it on the interstate for any period of time. Prior to putting in the new engine, my last motor overheated on the interstate and boiled coolant everywhere!

I'm thinking it's the radiator perhaps, but i'm not sure. Also i have a warn 8274 up front which sure isn't helping the air flow.

Ideas? bigger radiator?

Thanks!

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Unread 07-16-2009, 09:47 AM   #2
Jon In Tucson
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This is a basic question, but I didn't see it addressed in your original post. Has the radiator been boiled out? New hoses? Have you taken the thermostat out and run for a while and watched the gauge. My first thought is that the radiator is partially plugged or the fan is not movinig enough air. Air movement is not as a big an issue at highway speeds though. Good luck and God bless.
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Unread 07-16-2009, 09:55 AM   #3
valkadesh
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The hoses are fine from what i can tell. I haven't touched the actual radiator itself nor do i know how old it is. I'm thinking my next step is to remove it and get it checked or just replace it.
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Unread 07-16-2009, 10:13 AM   #4
swatson454
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Every time I've seen the temp just creep up at highway speed it's been a plugged radiator. Fan, shroud, clutch is all irrelevent at that speed.

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Unread 07-16-2009, 12:33 PM   #5
valkadesh
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Thanks for the post. I'm thinking i'm going to just go ahead and replace it. I can get a 3 core locally for like $180. Considering how much i just spent on a new motor and fuel injection, it seems like a wise investment!
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Unread 07-16-2009, 05:22 PM   #6
Jreedpete
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before you go and buy a new radiator, you might consider some back flushing. there may just be some debris in it, or your engine block, thats clogging it a bit.
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Unread 07-16-2009, 07:27 PM   #7
valkadesh
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Well i did some research tonight. First i took the rad cap off and warmed up the engine, i can see the coolant moving up and down so i'm assuming that the thermostat is working correctly. Also with the cap off, my gauge was on 195 with the engine warm.

I replaced the cap and the temperature immediately moved up to the 210 range when it stayed indefinitely when idle.

I then took it out on the interstate and ran it for about 5 miles. I was near 225, and when i exited the interstate it shot up to 240. Once i idled for a while at a nearby gas station is returned to 210.

I also picked up a temperature gun tonight and shot the thermostat housing while it was idling (temp gauge showing 210), the housing read between 195-200. Assuming the coolant inside is a bit warmer, i assumed this to be correct.

Going through receipts tonight, apparently i put in a new radiator about 2 years ago with new hoses, and i had only put 2500 miles on the jeep since. The radiator is the kind with the drivers side off-center fill cap. It appears to look like new upon inspection. I also appear to be running a clutch fan.

Any other thoughts? I'm kinda stumped at this point as to next step....

Last edited by valkadesh; 07-17-2009 at 06:45 AM..
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Unread 07-16-2009, 10:22 PM   #8
ACAD_Cowboy
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The problem might not be the cooling system. If the engine is leaning out at highway speeds, chamber temp rises which would drive overall system temps up. I would think about an aftermarket AFM and o2 sensor. Not a bad investment to aid in tuning.
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Unread 07-17-2009, 06:37 AM   #9
valkadesh
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I've got the howell fuel injection system installed, so i would think that if things got too out of specs, it would turn on the check engine light.
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Unread 08-03-2009, 08:33 PM   #10
valkadesh
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Well i thought I'd update this and solicit some more help. As you can see from my profile, I've got a Warn 8274 winch installed which is massive. I took the winch off and took the jeep for a drive, temps stayed constant at 210. So I'm guessing at highway speeds i'm not getting enough airflow through the grill and the clutch fan is not working hard enough.

So i went ahead and spent the big bucks and ordered a flex-a-lite 575 which is supposed to be fit the CJ like a glove.

I removed the clutch fan and shroud, and I went to install the new electric fans. Problem: I've got maybe 1/4 to 1/2 inch clearance between the water pump and the fan grill, and there is a big gap at the top of the radiator. Any thoughts? I'm stumped at this point. I've read the directions about 10 times and i'm pretty sure i've got everything setup correctly....

pictures enclosed (the wiring isn't hooked up, so ignore that)



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Unread 08-04-2009, 08:08 AM   #11
PavementPounder
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Quote:
Originally Posted by valkadesh View Post
Going through receipts tonight, apparently i put in a new radiator about 2 years ago with new hoses, and i had only put 2500 miles on the jeep since. The radiator is the kind with the drivers side off-center fill cap. It appears to look like new upon inspection. I also appear to be running a clutch fan.
When you replaced the radiator, I assume you replaced it with another 2-core? That's your problem.

From what you have posted about the Jeep getting hot when on the highway (when coolant is passing though it much faster than when at idle), I suspect you have insufficient heat exchange occurring due to insufficient dwell time. That means that the coolant is not remaining in the radiator long enough to be cooled due to the increased coolant circulation rate. Doesn't matter how much air you try to move across the radiator at this point. Your radiator just doesn't have the required cooling capacity. You need more surface area and more coolant volume. The only way you're going to get that is by installing a larger radiator.
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Unread 08-04-2009, 08:42 AM   #12
valkadesh
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I believe that i have the "high performance" 2 core model (with the driver's side rad cap). There is a 3 core that is actually cheaper, but people claim the 2 core actually works better. I know the 3 core is quite a bit thicker and has a center cap.

I guess i could drop the $200 on the 3 core radiator, but even then i don't think my new fans will fit. I'm assuming the 3 core will have the same..or less clearance!

Maybe i'd be ok with the clutch fan and the new radiator. I'm about out of options.

You'd think a stock 258 even with a big winch wouldn't be this complicated
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Unread 08-04-2009, 08:52 AM   #13
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One way to get more fan clearance is to remove the studs in the water pump pulley flange and use short bolts to keep the pulley on.

I'd agree about the radiator capacity though. I have the 3core on my '75 with an 8274 in front of it. My engine is the 258 with EFI and never has a problem with cooling even in 100°+ temps wheeling in Moab.
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Unread 08-04-2009, 09:20 AM   #14
valkadesh
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CSP, are you running the clutch fan and shroud, an electric fan, or something else?

Thanks.
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Unread 08-04-2009, 09:50 AM   #15
CSP
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Direct drive fan (no clutch) with a shroud. Clutch fans weren't used yet when mine was built.
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