Running Hot

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Aug 31, 2019
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Dallas
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.
If you have an unmodded blue hub then that's probably 100% of your problem. Mine's been modded 3 times now. First with 10K fluid, then 15k (or 20k?), and now with 30k.

I guess my thermostat could also been only half-opening, since you're not the first to report that either... new t-stat is ordered, probably arrives early next week.
 
Joined
Nov 9, 2012
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Olathe, KS, USA
If you have an unmodded blue hub then that's probably 100% of your problem. Mine's been modded 3 times now. First with 10K fluid, then 15k (or 20k?), and now with 30k.

I guess my thermostat could also been only half-opening, since you're not the first to report that either... new t-stat is ordered, probably arrives early next week.
I have been debating about the CST of oil I am planning on running.

I DD my truck, so I don't really want to totally kill my gas mileage by running too heavy of CST oil, but too light and I will overheat.

Since the Kansas City area is not as hot as Dallas (usually) or as AZ or CA, then I'm thinking I can go lighter oil than what everyone in those areas is doing. However, with the fact that it's been almost as hot here as it has been in Dallas in the last few weeks, I want to do this once.

What info did you use to get to the levels you did at the time? 10K, then 15K, now 30K? You mentioned ToolRUs, anyone else?
 
Joined
Aug 31, 2019
Messages
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Location
Dallas
I have been debating about the CST of oil I am planning on running.

I DD my truck, so I don't really want to totally kill my gas mileage by running too heavy of CST oil, but too light and I will overheat.

Since the Kansas City area is not as hot as Dallas (usually) or as AZ or CA, then I'm thinking I can go lighter oil than what everyone in those areas is doing. However, with the fact that it's been almost as hot here as it has been in Dallas in the last few weeks, I want to do this once.

What info did you use to get to the levels you did at the time? 10K, then 15K, now 30K? You mentioned ToolRUs, anyone else?
I just started with the max viscosity toyota made, which was 10k. I decided that wasn't powerful enough (my stock 60 has a louder fan). So I went with 15k from amazon. And now I'm still getting toasty so I'm trying 30k. It's all pretty arbitrary to your rig. I'd say 15k is a safe starting point on a stock blue hub. 30k is what arizonans use reportedly.
 
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I DD my truck, so I don't really want to totally kill my gas mileage by running too heavy of CST oil, but too light and I will overheat.
Maybe try out an electric pusher fan. Might give you the boost you need without unnecessary drag the rest of the year.
 
Joined
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Olathe, KS, USA
Maybe try out an electric pusher fan. Might give you the boost you need without unnecessary drag the rest of the year.
There's actually a factory fan that can fit on the front of the radiator that I had considered installing. I have no idea of the CFM it can push, but I want the system set up to operate correctly, but you make a very valid point.

I had an electric fan on my old Chevy truck years ago and I set it so I could turn it on ahead of time if I knew I was going to start working it hard. I had actually eliminated the water pump fan altogether.
 
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There's actually a factory fan that can fit on the front of the radiator that I had considered installing.
I've got a pusher fan laying around that I didn't reinstall after replacing my condenser. I'll see if I can get the fan and bracket reinstalled and see if it has any effect during the heat wave we're having in Oregon. I'm not overheating, but after finally wiring up my Koso temperature gauge, I'm seeing some temperature spikes in certain situations. Seems to be a stop and go thing, or rather a go and stop.
 

fj80pb

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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.

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.
FWIW, I have the same aux fan (12” Spal) installed quite some time ago. I decided to keep manual control of it instead of a thermostatic switch. It sure helps in pushing air through the AC rad- particularly while at idle or stop-and-go traffic.
However, I doubt it will help you with cooling system. For that, nothing beats a clutch and a cooling system in top shape
As other members have mentioned, make sure your rads are as clean as possible of dirt, grease, bugs, etc...anything that minimizes the flow of air is kinda critical in these hot days
Cheers!
 
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When I first installed the new, untuned blue hub fan on my '97 it would run hot under fairly hard conditions. For instance if I pushed it hard, climbed the hill to my house and let it sit idling w AC on it would break 220-whatever and the AC would shut off.

I setup that blue hub so that the small hole is 50% open at 110 degrees and then added 45 ml 15k CST oil. That was years ago and it's run pretty cool ever since. If I push it hard while towing 3kish pounds, with a rooftop box and a lot of gear inside, I can get it to go up to 205ish but it's yet to go over 210 I don't think. When not towing it stays under 200 in all conditions I've monitored. Temps are via an odb2 reader. If I drive relatively unloaded and keep speeds below 70 the 80 get's around 15mpg, and if I pedal pretty lightly around 16mpg.

I could see adding heavier oil if I were going to do a lot of hot weather rock crawling. The combination of going heavy on the skinny pedal followed by lots of idling seems like one of the more challenging cooling scenarios and tougher than the towing/cruising my 80 does.

I'm not sure if having the fan open earlier (lower temp) would change things much as the clutch on my 80 clearly is engaged when it needs to be at this point. For that matter, it may open a touch soon? I did play around with opening temps a bit and settled on 50% at 110 for some reason (it's been too long for me to recall and I lost my test notes it appears) but I think others have had luck with other temps.
 
Joined
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When I first installed the new, untuned blue hub fan on my '97 it would run hot under fairly hard conditions. For instance if I pushed it hard, climbed the hill to my house and let it sit idling w AC on it would break 220-whatever and the AC would shut off.

I setup that blue hub so that the small hole is 50% open at 110 degrees and then added 45 ml 15k CST oil. That was years ago and it's run pretty cool ever since. If I push it hard while towing 3kish pounds, with a rooftop box and a lot of gear inside, I can get it to go up to 205ish but it's yet to go over 210 I don't think. When not towing it stays under 200 in all conditions I've monitored. Temps are via an odb2 reader. If I drive relatively unloaded and keep speeds below 70 the 80 get's around 15mpg, and if I pedal pretty lightly around 16mpg.

I could see adding heavier oil if I were going to do a lot of hot weather rock crawling. The combination of going heavy on the skinny pedal followed by lots of idling seems like one of the more challenging cooling scenarios and tougher than the towing/cruising my 80 does.

I'm not sure if having the fan open earlier (lower temp) would change things much as the clutch on my 80 clearly is engaged when it needs to be at this point. For that matter, it may open a touch soon? I did play around with opening temps a bit and settled on 50% at 110 for some reason (it's been too long for me to recall and I lost my test notes it appears) but I think others have had luck with other temps.

This is also a concern of mine. Landtank's guide mentions setting the valve to 95*, but wouldn't that mean the fan would run non-stop in ambient temps above 100? So I'm thinking that would add a lot of heat to the fluid, maybe it gets super hot after 30-60 min of driving, then when I go to idle, the fan is acting wimpy?

I don't know exactly how the valve operates or where 95* comes from, but even at 110 it sounds like it would still be on all the time. If ambient is 100*, surely the air passing thru the radiator and condenser would heat up by more than 10*, so the fan clutch would just be on all the time... right?

Does anybody know where setting the fan clutch to 95* comes from? Should I consider setting mine higher?
 

Broski

I love Wheelin my 80
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Yes mine is modded and seems to be fairly accurate. I like knowing what's actually going on (can rev engine to cool her off when it gets close to red)

I don't have OBD2 so don't have the ability to digitally read the temps
Toyo com has a obd1 reader
 

77mustard40

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Been a pretty darn hot summer in Texas with 50+ days above 100 and about a week of temps in the 106 - 110 range. I’m running an unmodified blue hub clutch and OEM radiator. I did take the time to flush my cooling system when I picked up my 80 which included a couple of cycles of Thermocure and distilled, followed by a couple days of distilled only. I never washed out heavy soot but it seemed both flushes were productive. Followed this with all new hoses and thermostat. My 80 is my DD and I put about 40 miles a day on it. My 80 runs right at 186 in the mornings with ambient temps of 80, and has peaked in the afternoons at an observed 203 on the ScanGuage with temps above 105. I’ve got 20K on the shelf and will probably modify my clutch eventually, but overall I’m pretty happy with how the 80 has held up this summer. BTW I never max my AC but it’s plenty cool set about an inch from full AC.
 
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30k fluid installed, no change. Still climbs up to about 215* or so stopped at a light in gear, AC on, heat soaked, hot day.

No problems whatsoever when moving. Towed 3000 lbs in 100* heat today and yesterday, saw normal temp when driving on roads or highway (180-190ish?).

Thermostat is next, will probably change it tomorrow and test both in a pan of water.
At this point I'm thinking, if it's not opening all the way the increased flow resistance may be too hard for the water pump to overcome at 650rpm. Once I get moving, the higher speed of the water pump is able to overcome the restriction... just a theory.

Also interesting to note that the temp doesn't climb if I put it in park. But this isn't always practical at a stop light, and there have been some scenarios where even in park it climbs, but it takes much longer (~30 minutes) as opposed to a few minutes when in gear.
 
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Albuquerque NM
I'm pretty much in the same boat as @iansplatinum. I have 30k fluid in blue fan clutch and it roars like crazy, replaced radiator with TYC, replaced thermostat with OEM, have foam around radiator, etc. I even tried Redline water wetter. Still get high temps (up to 220s) when crawling with the A/C on. I've never had the A/C cut out though. If I turn off the A/C then the temperature holds basically steady in the middle of the modified temp gauge, even crawling in 120 deg F weather. Would love to figure this out. I did see a little improvement after I added the foam--it helps prevent hot air from recirculating and the temperature seems to recover quicker when I rev up the engine, but temps still creep up when crawling at low RPM.
 
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I'm pretty much in the same boat as @iansplatinum. I have 30k fluid in blue fan clutch and it roars like crazy, replaced radiator with TYC, replaced thermostat with OEM, have foam around radiator, etc. I even tried Redline water wetter. Still get high temps (up to 220s) when crawling with the A/C on. I've never had the A/C cut out though. If I turn off the A/C then the temperature holds basically steady in the middle of the modified temp gauge, even crawling in 120 deg F weather. Would love to figure this out. I did see a little improvement after I added the foam--it helps prevent hot air from recirculating and the temperature seems to recover quicker when I rev up the engine, but temps still creep up when crawling at low RPM.
This describes my experience exactly
 
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Albuquerque NM
I also have a small electric pusher fan like this:
 
Joined
Aug 31, 2019
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Dallas
I also have a small electric pusher fan like this:
I bought the fan (OE toyota), fabbing up the bracket soon.
My 80 used to have a larger condenser fan on it but the PO removed the center support to fit it, which caused my hood latch to get sketchy so I replaced the support and removed the fan... surely that wouldn't be the difference between approaching red and not?

My AC has never shut off either, just trying to be proactive since she's got 278k on the odo and we're gonna be driving it to wyoming in 28 days
 
Joined
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My AC has never shut off either, just trying to be proactive since she's got 278k on the odo and we're gonna be driving it to wyoming in 28 days
AC shuts off at 227 deg. Toyota must have felt semi-comfortable with getting that hot, otherwise the AC cutoff would be lower? 🤷‍♂️ I still would like to crawl and not get that hot though.
 
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At this point I'm thinking, if it's not opening all the way the increased flow resistance may be too hard for the water pump to overcome at 650rpm. Once I get moving, the higher speed of the water pump is able to overcome the restriction... just a theory.

Why are you idling so low with the AC on @ 650? My rig idles around 800-1000 with AC on. Lower idle, means lower fan speed and less air being pulled across the radiator for cooling. I'd check on your IAC valve to get your idle to bump up some and beyond that you may look into an aux fan to boost your idle cooling.
 

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