Running Hot

Joined
Jun 30, 2009
Messages
21
Hi all - I’m having similar problems and believe my issues are two fold: 1) no foam around the radiator/fan shroud and 2) a modified fan clutch that may be malfunctioning.

For #1, does anyone have pics for where the foam should go? I get the foam should go between the shroud and the radiator, but where specifically? There isn’t much room between the shroud and the radiator for foam around the sides and top of radiator.
 

lumbee1

Native American
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Sep 21, 2011
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Holly Springs, NC
Hi all - I’m having similar problems and believe my issues are two fold: 1) no foam around the radiator/fan shroud and 2) a modified fan clutch that may be malfunctioning.

For #1, does anyone have pics for where the foam should go? I get the foam should go between the shroud and the radiator, but where specifically? There isn’t much room between the shroud and the radiator for foam around the sides and top of radiator.
I don't have pics of where I installed it but I did buy some D channel neoprene foam off Amazon that was a perfect fit.

www.amazon.com/gp/product/B00NL4BUMY

The foam goes between the front of the radiator on the top and the sheetmetal cross member. When the OEM foam is missing, there's a 1/2" to 5/8" gap for air to blow over the radiator rather than through it.
 
Joined
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New Idria 95043
I don't have pics of where I installed it but I did buy some D channel neoprene foam off Amazon that was a perfect fit.

www.amazon.com/gp/product/B00NL4BUMY

The foam goes between the front of the radiator on the top and the sheetmetal cross member. When the OEM foam is missing, there's a 1/2" to 5/8" gap for air to blow over the radiator rather than through it.
It also goes on the lower tank
 
Joined
Jan 29, 2019
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Portland, Oregon
Changing oil in my fan clutch to 15K made the biggest impact. On average 7-10° cooler on the same hills at the same outside temperature.
 
Joined
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Portland, OR
FWIW, I've seen many 80s running well within temp range without a fan shroud, radiator skid plate or foam gasket. While that's obviously mot the best condition, I don't think it's the difference between "normal", warm and hot. Maybe you would see it on a digital gauge as a couple of degrees, one way or the other...

I'm with @Malleus on this one. I doubt a little bit of foam is going to make the difference between cooling and not. I too have run some of my own vehicles without fan shrouds and it didn't make much difference. The fan clutch on the 80 is pretty strong when it's in working order.
 
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sSart the car and let engine comes up to operating temp, at around 180F, you should hear the fan clutch engaging with a noticeable roar.....
 
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Charlotte, NC & Alexandria, VA
I had similar issues. Fan clutch was bad. I modded it with 12K fluid in 2017. Recently noticed that sitting in drive thru's the temp would spike. I picked up a blue hub from a friend and pulled mine off. Side by side I couldn't tell a difference but the blue hub had more fins and was known good so I installed it. While walking back to my garage, I spun my fan hub once last time and don't you know it spun like it had bearings installed in it. The hub would engage sometimes but then spin freely like it was low on fluid.
I have some 10k cSt silicone on the way. I'm going to add that to the new thermostat and see if that'll bring to operating temps in line with the JAN 95 80 in the driveway.

@iansplatinum I apologize for highjacking your thread. The silicone I ordered is:
1658948827525.png

fleabay was the only source I could find within a month's delivery window :(

FWIW, my thermostat replacement didn't totally fix my heating problem. The JUL '95 is running better, but not equivalent to the engine with the unrepaired head on my JAN '95. I'm adding the clutch repair to see if that's a part of my problem. I couldn't find a testing procedure in the FSM for the water pump, so I resorted to spraying the radiator with cold water, assuming that if I cooled the radiator and the engine subsequently cooled, the pump must be moving water. It did, so I crossed that item off my troubleshooting list.
 
Joined
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Dallas
No worries. It's all useful discussion. My fan clutch is not audible at idle when the engine is at operating temperature. That's how every other car I own (4 others, 5 total) with a mechanical fan clutch operates. If it's not up to temp and you rev, you just hear engine noise. If it's up to temp and you rev, you hear engine + fan. I've never been able to hear a fan clutch at idle, I always figured they're just moving too slowly to produce much noise.
 
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Dallas
I found this thread useful: Hot temps when crawling - https://forum.ih8mud.com/threads/hot-temps-when-crawling.1221455/

I drained my 20k fluid yesterday and put in 30k fluid. According to ToolsRUs, the blue hub needs 30k minimum. I did notice that my 60's fan is a little louder than my 80's modified blue hub... One would think they'd be similar.

Planning on seeing how that performs... Then I'll move on to tape and foam.

Then I'll try a new thermostat but now I'm doubtful it's my issue. After reading the above thread, I've come to realize that the raventai temp gauge mod puts the temp range in a more conservative reading scale. I typically don't do above 217*F, and have yet to hit 226*F. Those are hot, but apparently others run their 80s and have the AC shut off on them (happens at 226*F) when towing or climbing.

So maybe I'm being overly cautious and maybe my 80 acts more or less how others' 80s act.

I just don't want to pop a HG in Wyoming when I'm 3000 miles from home :rolleyes:
 
Joined
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Portland, OR
For reference, when we drove the 80 and 200 from Oregon to Arizona at the end of June, I had my wife drive the 80 while towing a trailer weighing about 2500lb full of our belongings. I was towing the larger trailer with the 200. We were in constant radio contact and we crested some pretty long(10 mile/30 minute) hills. One particular hill, it was about 102 out, we were in high elevation and the wife said the temp gauge was at 198. We were both in 2nd gear going about 45mph. She said she never saw over 198 the whole drip down.

A super strong fan clutch can hide a broken cooling system. I had overheating problems for years with a 3 row copper Koyo radiator. I kept throwing higher and higher CST oil into the fan clutch until I eventually replaced the radiator with an aluminum 2 row. All my overheating problems went away and now the fan clutch was way too strong and I also had to take out the 170f thermostat. The truck would have a hard time getting over 160 while running around town in 70-80 weather. I'm not one of the well established voices on this forum for cooling issues but I've silently battled my own for quite a while. In my opinion, a good working aluminum radiator and a healthy fan clutch are all what's needed to keep this rigs running cool. Cool as in, straying not far from the thermostat opening temp around 185. If you're seeing 217 on the regular, a stronger fan clutch will only mask a failing radiator for so long. Food for thought.
 
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I found this thread useful: Hot temps when crawling - https://forum.ih8mud.com/threads/hot-temps-when-crawling.1221455/

I drained my 20k fluid yesterday and put in 30k fluid. According to ToolsRUs, the blue hub needs 30k minimum. I did notice that my 60's fan is a little louder than my 80's modified blue hub... One would think they'd be similar.

Planning on seeing how that performs... Then I'll move on to tape and foam.

Then I'll try a new thermostat but now I'm doubtful it's my issue. After reading the above thread, I've come to realize that the raventai temp gauge mod puts the temp range in a more conservative reading scale. I typically don't do above 217*F, and have yet to hit 226*F. Those are hot, but apparently others run their 80s and have the AC shut off on them (happens at 226*F) when towing or climbing.

So maybe I'm being overly cautious and maybe my 80 acts more or less how others' 80s act.

I just don't want to pop a HG in Wyoming when I'm 3000 miles from home :rolleyes:
I start to freak when my temp hits 215F on freeway....something is definitely not right if i see those kind of temp. 195-205F is most i see even on steep climbs w/ AC on full blast @ 95F out. When wheeling, 200-215 is pretty normal on 4Hi, but as put in 4Lo and keep the rpm up, the temp will drop almost immediately back to ~200F and that tells me the fan clutch is working as it should. 225F or above you are playing with fire IMO highway or tow...
 
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I start to freak when my temp hits 215F on freeway....something is definitely not right if i see those kind of temp. 195-205F is most i see even on steep climbs w/ AC on full blast @ 95F out. When wheeling, 200-215 is pretty normal on 4Hi, but as put in 4Lo and keep the rpm up, the temp will drop almost immediately back to ~200F and that tells me the fan clutch is working as it should. 225F or above you are playing with fire IMO highway or tow...
I have never hit 226*F. I peaked at about 220*F crawling up a 4 star trail and getting pinned on a rock for 30 minutes trying to dislodge myself. That's when I really started to try to figure out what was up. I generally cruise at 190F on highway AC on with 100-105*F ambient temp. It's when I pull into a drivethru and idle that it starts to climb to about 215*F before I take action and rev up to run the fan clutch.

For reference, when we drove the 80 and 200 from Oregon to Arizona at the end of June, I had my wife drive the 80 while towing a trailer weighing about 2500lb full of our belongings. I was towing the larger trailer with the 200. We were in constant radio contact and we crested some pretty long(10 mile/30 minute) hills. One particular hill, it was about 102 out, we were in high elevation and the wife said the temp gauge was at 198. We were both in 2nd gear going about 45mph. She said she never saw over 198 the whole drip down.

A super strong fan clutch can hide a broken cooling system. I had overheating problems for years with a 3 row copper Koyo radiator. I kept throwing higher and higher CST oil into the fan clutch until I eventually replaced the radiator with an aluminum 2 row. All my overheating problems went away and now the fan clutch was way too strong and I also had to take out the 170f thermostat. The truck would have a hard time getting over 160 while running around town in 70-80 weather. I'm not one of the well established voices on this forum for cooling issues but I've silently battled my own for quite a while. In my opinion, a good working aluminum radiator and a healthy fan clutch are all what's needed to keep this rigs running cool. Cool as in, straying not far from the thermostat opening temp around 185. If you're seeing 217 on the regular, a stronger fan clutch will only mask a failing radiator for so long. Food for thought.
What would be broken about my cooling system though? Everything is brand new except the engine. That's what I don't understand.

No exhaust gasses in coolant either. Tested about 3 different times.

I have no issues at speed. The problem only presents itself when I am not moving, not revving, in gear @ 650rpm w/ AC on, heat soaked engine bay, sitting for 15+ minutes. That's when I see 217*F. Highway cruisin, probably max 190F eyeballing it (OBD1 so no scangauge readout)
 
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I have never hit 226*F. I peaked at about 220*F crawling up a 4 star trail and getting pinned on a rock for 30 minutes trying to dislodge myself. That's when I really started to try to figure out what was up. I generally cruise at 190F on highway AC on with 100-105*F ambient temp. It's when I pull into a drivethru and idle that it starts to climb to about 215*F before I take action and rev up to run the fan clutch.


What would be broken about my cooling system though? Everything is brand new except the engine. That's what I don't understand.

No exhaust gasses in coolant either. Tested about 3 different times.

I have no issues at speed. The problem only presents itself when I am not moving, not revving, in gear @ 650rpm w/ AC on, heat soaked engine bay, sitting for 15+ minutes. That's when I see 217*F. Highway cruisin, probably max 190F eyeballing it (OBD1 so no scangauge readout)
Everything you described points to the fan clutch not working properly at idle. It needs to be engaged and pulling air when at a stop.

Also check to make sure that your radiator isn't clogged from the outside with mud, grass, whatever between the multiple coolers.
 
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Portland, OR
What would be broken about my cooling system though? Everything is brand new except the engine. That's what I don't understand.

No exhaust gasses in coolant either. Tested about 3 different times.

I have no issues at speed. The problem only presents itself when I am not moving, not revving, in gear @ 650rpm w/ AC on, heat soaked engine bay, sitting for 15+ minutes. That's when I see 217*F. Highway cruisin, probably max 190F eyeballing it (OBD1 so no scangauge readout)

I thought you were alluding to reaching 217 regularly in hot temps(100+ even while moving). If you start moving and temps lower back down to 190, radiator is most likely fine. I would agree with @BILT4ME that the fan clutch could use some more CST to counteract the heat creep at idle on hot days.

I'm heading a different direction on my rig. Ordered a 12" spal fan off amazon for about $100 and plan to wire it in to kick on around 195-200. I like the idea of keeping 7k CST in alongside the aux fan for a year round solution over swapping out fan clutches or fluids throughout the year.
 
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Everything you described points to the fan clutch not working properly at idle. It needs to be engaged and pulling air when at a stop.

Also check to make sure that your radiator isn't clogged from the outside with mud, grass, whatever between the multiple coolers.
Cracked it open last night, 1 yr old blue hub unit, verified valve opens and closes with heat. Set to halfway open at 95*F like the Landtank bluehub thread recommended.
Took out the 15k (or was it 20k?) oil and replaced with 30k. Went for a drive, sounds similar, maybe a little more roar. Heat did start to creep at idle but I didn't get the chance to sit long enough to stress test.

Radiator is band new, condenser is less than a year old. Neither has dirt, the condenser was washed from a safe distance with a power washer.

My trans cooler looks like hell but sits far enough away from the condenser that it shouldn't really make a difference at idle.

How does one verify the fan clutch is fully engaged at idle? I shut the car off and immediately opened the hood and spun the fan, it had plenty of viscous resistance.
 
Last edited:
Joined
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I thought you were alluding to reaching 217 regularly in hot temps(100+ even while moving). If you start moving and temps lower back down to 190, radiator is most likely fine. I would agree with @BILT4ME that the fan clutch could use some more CST to counteract the heat creep at idle on hot days.

Just put in 30k, we'll see. In my original post I tried to describe as best I could that it only happened when:

  • in the sun, hot day (100+ F)
  • idling in gear (@650rpm)
  • AC on
  • heat soaked engine (been driving 30-60+ minutes)
  • not moving
If any of those conditions are not met it seems to do fine. But there are lots of situations where all 5 are checked off: sitting in traffic, in a drive though, wheeling with a group, etc. I almost always have my dogs with me and am not OK with simply turning the AC off. It shouldn't be that way
 
Last edited:
Joined
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Just put in 30k, we'll see. In my original post I tried to describe as best I could that it only happened when:

  • in the sun, hot day (100+ F)
  • idling in gear (@650rpm)
  • AC on
  • heat soaked engine (been driving 30-60+ minutes)
  • not moving
If any of those conditions are not met it seems to do fine. But there are lots of situations where all 5 are checked off: sitting in traffic, in a drive though, wheeling with a group, etc. I almost always have my dogs with me and am not OK with simply turning the AC off. It shouldn't be that way
Everything you just described is what happened with mine last week.

I just went out and checked and the new fan clutch I installed is an Aisin, blue hub (I have not modified it) and I have a new fan on there. I am going to swap out my hub and change the oil in the blue hub and modify it per Landtanks' notes to see what I get.

When I spin the fan by hand on a cold engine, I get about 1/4 turn before it stops.

I have NEVER had an issue for cooling prior to this, so I am very concerned. Nothing has changed on my engine to bring this on, other than finding the old T-Stat only half open. I cannot imagine what the folks in AZ deal with on a regular basis.
 

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