Coolant Overheating Issue

[Gorilla57]

@Plongson that last pic you posted really solidifies the issue with the Jeep and the diesel. That stack of intercooler, condenser, radiator is sooooo tightly packaged, it’s a miracle air even moves through the front end. Thanks for that pic and hope the radiator was worth it. ??

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[Plongson]

Oh man...you are so right on...Imagine that turbo spooling up boost, the induction air hot as HELL and trying to dump that heat...straight into the punky little radiator...it's amazing these things don't burst into flames...

I'm at 50k miles and there was just a little bit of oil residue in the intercooler...Prolly normal for the mileage. I'm going to take a little test run today up the mountain and see how it performs.

 

[Gorilla57]

Oh man...you are so right on...Imagine that turbo spooling up boost, the induction air hot as HELL and trying to dump that heat...straight into the punky little radiator...it's amazing these things don't burst into flames...

This is probably one of the reasons why my 1500 ED doesn't heat up as bad as a Jeep. The truck has the intercooler below the radiator and the radiator is huge.

 

[Wrangler man]

FINALLY...got the new Mishimoto radiator for the rig. It took three weeks and they gave me an additional 5% for the delay.

The radiator looks very well made and is an additional 5/8" thicker where the OEM is only a puny 1" thick. There is not much radiator on these stock units.

Mishimoto says 4 hours to install...it took me 7 and it is not easy...in fact it's a total pain in the arse requiring the dissembling of the front end...nothing is easy on these rigs.

The stock radiator is 25" wide and the Mishimoto is 25 1/4" wide and that impacts the intercooler...it just won't fit without some "field work" on the new radiator and grinding on the intercooler. Seriously not cool...GRRR.

All the components "stack" on the radiator like a club sandwich and getting them all together is a real PITA. Really two man job.

For the money and work involved, this sucker better make an improvement. It's a big gamble...

This is REALLY not the job for a novice or apartment carport mechanic...just say'n

Installed mine a week ago. I also included their tranny cooler. I was shocked on the $1,000 labor install charge. But your post reassures it was money well spent. I don't want to spoil your results on performance. But will chime in once you share.

 

[Wrangler man]

The thermostat is pretty easy to access but you are going to loose coolant just checking it...on top of that, "burping" the air when refilling takes a while and patience

 

[Wrangler man]

I asked the installer when I installed the upgraded radiator if it was a good time to check and or replace the thermostat. His reply was "on a diesel its not a good idea. If it's not broke don't touch it. I did replace the three hoses, upper and lower with new ones. Kept the old ones as spares.

 

[Deleted member 59498]

Good info here thanks to both!

@Plongson is that your FJ? Had to ask, FJ40? Love those old guys.

 

[Plongson]

The FJ40 belongs to my good friend who helped me wrestle in this mess. It's a full stock 1979, except for power steering.

As for the new radiator...I'm still testing. Without the Tazer fan override, there is not much difference. Kick the fan on manually on high speed, and the temps drop rapidly. Time will tell if this is a viable solution to the temp issue.

As for the fan, some of you will remember clutch fans. If you had a bad clutch fan, it didn't matter how much radiator you had, it was going to overheat. It seems now the key is kick on the fan to get the air flow through a larger and more efficient radiator. The manual fan override is absolutely necessary and crucial to control heat on these rigs.

As they use to say, "Film at eleven"...lol

 

[zouch]

the question i have is related to how that new Rad works when it's been on the road at speed in the heat for a while; that's the only place i've ever seen mine start to get warm.
at 70+ MPH there is already what should be adequate air flow.

if we're not finding as much of a difference in those conditions with the upgraded Rad, but kicking up the fan speed makes a difference, i would think that would indicate that the problem is not the capacity of the Rad to exchange heat, it's a matter of adequate airflow through the Rad.

The FJ40 belongs to my good friend who helped me wrestle in this mess. It's a full stock 1979, except for power steering.

As for the new radiator...I'm still testing. Without the Tazer fan override, there is not much difference. Kick the fan on manually on high speed, and the temps drop rapidly. Time will tell if this is a viable solution to the temp issue.

As for the fan, some of you will remember clutch fans. If you had a bad clutch fan, it didn't matter how much radiator you had, it was going to overheat. It seems now the key is kick on the fan to get the air flow through a larger and more efficient radiator. The manual fan override is absolutely necessary and crucial to control heat on these rigs.

As they use to say, "Film at eleven"...lol

 

[Plongson]

My thought is, the fan being on the rear or back side of the radiator is more efficient at "sucking" the air through the radiator rather than forward airflow simply being "pushed" through" the front of the radiator. Any obstruction deflecting the laminar flow will simply find the easier path and go elsewhere. As we know, there is plenty of obstruction forward the radiator and air is lazy.

This is a primary reason why electric fans are positioned behind and not ahead of heat exchangers as in slow or stationary equipment.

Forward motion will have less effect on heat transfer than auxiliary fans pulling air from behind heat exchangers...until you get into relatively high speed air flow as in aircraft.

Essentially, induced draft vs forced draft...

 

[garykk]

I have the steel bumper with the winch insert. Was thinking of removing the plastic insert, putting a black mesh in the hole. Directly to the rear of the hole is the bottom of the cooling stack. A little more air could help.

 

[Deleted member 59498]

She never came back to finish the story! Were you guys mean?

Or did I miss it?

@Jwobes

 

[CO2Wrangler]

@Plongson @Wrangler man

Any follow-up on the radiators? Any difference?

 

[Plongson]

Actually, I'm very happy with the new radiator. Daily running around there is little difference but when the coolant temperature rises and you switch on the fan (tazer), the temperature DROPS fast... like 10⁰f to 15⁰f in 60 seconds...so fast it sometimes drops below the thermostat for a few seconds.
It's a total PITA to install but it's worth the price and hassle. It should have come from Toledo like this.

 

[Steph1]

You seem to be running quite a heavy wheel/tire combo. What size tires and which axle gearing are you currently running?

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