Cooling Concerns On A Hot Day (1 Viewer)

[Tachycardic]

Buy the new clutch on Amazon along with 20k cst fluid and do the mod yourself. Easy to do and way cheaper. If you have the money, I would buy a new radiator and cap as well.



RPM's are definitely your friend here. In warm temps I drive slower up the mountains with high RPM'S, 3.5-4K. It lowers the load on the motor and transmission, pumps the coolant faster with the pump and spins the fan faster. Doing this with 20k fluid, I sit at 184-189° on a hwy climb.

I've been read up on the fan clutch mod and everyone notes how their fans just roar when they first turn on the vehicle. my fan used to roar to life as well, but recently I also noticed how much quieter it became. I didn't think to replace it because I actually liked the quieter sound. I guess I'll go with a new clutch first.

 

[Azca]

I had problems with mine before I rebuilt it. Also had engine knock due to carbon build up. Actually overheated heading up the grade to Flagstaff in December if you can believe it. Some time after rebuild added a TYC radiator (based on Tools R Us recommendations) Already had modded the fan clutch. The combination has been great and not had an issue after. I have hood vents stuck on the shelf but had not cut the hood yet, may do that this winter. When I rebuilt it, there was crud caked around the oil cooler that no flushing could remove, cleaning it by hand took a considerable effort and was thicker than it looks in the pics. I must assume that crud was located in other areas of the coolant system I could not get to prior to the rebuild as evidenced by the pics below. Hot tanking it got rid of the rest when I brought the bottom end and heads in to get rebuilt.

If these were not fully maintained and coolant replaced regularly, I really don't think any amount of flushing is going to remove this build up. It will impact cooling system performance. I am willing to bet the cleaning of the block had more to do with keeping the temps down than anything else.

Oh, and remove all that insulating oil (rust prevention) from the block as well. A clean engine will run cooler.

 

[Tachycardic]

Would you all just buy a new fan clutch and mod it, or change the oil in the original fan clutch to 20K weight?

 

[AndrewInf]

I went with a new fan clutch for peace of mind and so I could do the swap without significant down-time. I had the housing hanging over a pan for a few days draining out the stock fluid; this much time is probably not necessary but I didn't have time to do the install right away anyhow.

I vaguely remember it was $60 or so at the time, looks like it's a little more expensive now on Amazon but not by much:

Amazon product ASIN B00829HAV8
Edit: hmm, link not showing on my end; you can search "AISIN FCT-004" on Amazon.

If your original is this model you can probably just service the one you have, although the big O-ring that goes around the edge may not survive the process. Breaking the + head screws loose could also be a problem on an old clutch. Note that the screws holding the two halves together are JIS and not Phillips head, slight difference and a Phillips driver may strip out the heads if you're not careful.

It is an easy mod and it's nice to know how to do it in case you want to go thicker with the special sauce. I did 15k with mine, if I were to do it again I would probably go 20 or 30k.

 

[Azca]

I went with a new fan clutch for peace of mind and so I could do the swap without significant down-time. I had the housing hanging over a pan for a few days draining out the stock fluid; this much time is probably not necessary but I didn't have time to do the install right away anyhow.

I vaguely remember it was $60 or so at the time, looks like it's a little more expensive now on Amazon but not by much:

Amazon product ASIN B00829HAV8
Edit: hmm, link not showing on my end; you can search "AISIN FCT-004" on Amazon.

If your original is this model you can probably just service the one you have, although the big O-ring that goes around the edge may not survive the process. Breaking the + head screws loose could also be a problem on an old clutch. Note that the screws holding the two halves together are JIS and not Phillips head, slight difference and a Phillips driver may strip out the heads if you're not careful.

It is an easy mod and it's nice to know how to do it in case you want to go thicker with the special sauce. I did 15k with mine, if I were to do it again I would probably go 20 or 30k.

Try the original 1st. Not hard to do. If you don't feel good about it, go with a vendors

 

[greentruck]

I saw engine temps hit 217-220F driving in and around town today in 109F ambient. Dropped to 204-207F on the highway. As far as I can tell, the fan clutch is original (I just passed 290K) and the radiator is a used brass one taken from another '94 donor vehicle with about 200K on it. Blue hub fan clutch first or get a new radiator?

It's not been that hot here, but if you're hitting 220F in town/207F on the road, then something is still amiss most likely.

You're dealing with the fan clutch, sounds like it's needed.

That used brass radiator? A potential problem. All the 80 series OEM radiators are a minimum 24 years old. Aluminum is better than brass at transferring heat, so a marginal brass radiator can be more an issue than the AL one. In any case, if you have a infrared remote reading thermometer, spot check the radiator at different spots. If you find patches where it's cooler, that's wheree it's clogged and not cooling effectively as it should. Time for renewal.

 

[baldilocks]

Would you all just buy a new fan clutch and mod it, or change the oil in the original fan clutch to 20K weight?

Do you know what fan clutch you currently have installed? What year 80?

 

[Heckraiser]

Would you all just buy a new fan clutch and mod it, or change the oil in the original fan clutch to 20K weight?

I modded my original black fan clutch (325k miles or something like that) with 20k and it still didn't perform, so I started over with the modded blue fan clutch from wits' end and that did the trick.

 

[Tachycardic]

Do you know what fan clutch you currently have installed? What year 80?

I believe the fan clutch to be original to the truck. It's a '94 with 290K. The brass radiator has about 210k on it. I blew the last on at 280K; this one came from a donor vehicle. I was thinking about just replacing the oil inside the clutch, but I am leaning towards a new fan clutch and 30k oil.

 

[Tachycardic]

I modded my original black fan clutch (325k miles or something like that) with 20k and it still didn't perform, so I started over with the modded blue fan clutch from wits' end and that did the trick.

Yeah, I think my clutch is tired and should be retired. I'm off to Korea soon and don't have the time to experiment. I'm just going to install a new and modded clutch. Thanks all!

 

[baldilocks]

I believe the fan clutch to be original to the truck. It's a '94 with 290K. The brass radiator has about 210k on it. I blew the last on at 280K; this one came from a donor vehicle. I was thinking about just replacing the oil inside the clutch, but I am leaning towards a new fan clutch and 30k oil.

I’ve owned only 93 ans 94’s. They have the fan clutch with a black hub usually. This clutch has a larger area for shearing the oil and is therefore considered to be more aggressive. Kevin recommended a max of 15k oil in the black clutch.

I have two of these clutches and both work well and one of them is just under 300k and the one I’m currently running has 307k miles. The one I’m not running sports 10k oil. I also did my best to reprogram it to begin opening up at about 100 deg f.

The one I’m currently running contains as much 15k oil as I could force into it which was about 50ml iirc. I think Kevin said to put in 45ml but I was able to get a little more into it. I did not set this clutch to open earlier and I like it best. Perhaps it seems to work a little better because it contains thicker oil. I can set the hand throttle to 1500rpm and let the engine run all day watching the digital temp gauge indicate the fan clutch kicking full on by 190 and shutting down completely by 185.

I read something written by an automotive engineer a few years ago where they explained that the fan clutch is set up to be timed with the thermostat. Pulling more air when the thermostat is barely open supposedly doesn’t net us much.

It would be a good idea to find out which clutch you now have and then decide which oil to put in it and do that before buying a new clutch. I ran a brass/copper CSF 2517 radiator for a couple years and during the summer in the Sacramento area 215 degrees was a common number on my Koso water temp gauge. I’ve since gone to an OEM plastic/aluminum radiator and it seems impossible to push it up to 200 deg.

 

[KC masterpiece]

I flushed out the cooling system in October 2020 and filled with Peak Final Charge Global. I have the OEM radiator, but I don't have the foam weatherstripping. I'll look into that. Thanks.

You can just get foam tape at any hardware store designed for automotive use and slap it in there. Just did that last weekend myself.

 

[LongDuck]

Just got back from a 3k mile road trip across 6hrs of desert (Flagstaff to Albuquerque) and back. I noticed a few things, but first my setup;

1. New TYC 1918 radiator installed last year, $127 on Amazon. New OEM radiator cap, new hoses, PHH, Heater Valve and various small hoses. Fresh Toyota Red, 50/50 mix. New Thermostat, Water Pump installed earlier this year.
2. Blue fan clutch, unmodified, OEM fan original to the 1996 truck.
3. New Factory short block installed in Feb, rebuilt head, valve lash set, etc.

Cooling performance at highway speeds - Ambient temps over 100F, IAT around 160F;

1. No AC load, temp stabilized at about 185F over level ground
2. AC on, temp stabilized at about 192F over level ground
3. Hill climbs dramatically increased temps, longer durations pushed it up to 208F
4. Turning off AC at bottom of the start of a climb helped to keep temps down, turning AC back on during the downhill portion helped. When above 210F, I'd let the teuck coast downhill which quickly dropped temps back to 199F or so.
5. As outside air temps climbed above 110F, engine coolant temp rises, stabilizing at about 212-214F at 72mph over level ground. This was concerning, and I limited AC use to keep it from rising.

On the trip back to Phoenix, Camp Verde has a hill climb that routinely tops out cooling performance. It was 117F in Phoenix, and this climb brought my temps up to 220F, AC off the whole way and STARTED the climb at 212F. Slowed down considerably, kept my RPMs up the whole way, and it didn't stay at 220 for more than a few seconds, quickly dropping down again to 214F for the rest of the climb. Over the top, it dropped back to 204-206F for the rest of the drive home.

I was expecting better cooling performance given the recent replacement of nearly everything related to the cooling system, combined with a new OEM short block, but there it is. It runs hotter than I'd like, but not enough to scare the pants off of me under normal conditions. On climbs, it definitely helps to have a live monitor of coolant temp data to help you adjust your driving style.

 

[Tachycardic]

Just got back from a 3k mile road trip across 6hrs of desert (Flagstaff to Albuquerque) and back. I noticed a few things, but first my setup;

1. New TYC 1918 radiator installed last year, $127 on Amazon. New OEM radiator cap, new hoses, PHH, Heater Valve and various small hoses. Fresh Toyota Red, 50/50 mix. New Thermostat, Water Pump installed earlier this year.
2. Blue fan clutch, unmodified, OEM fan original to the 1996 truck.
3. New Factory short block installed in Feb, rebuilt head, valve lash set, etc.

Cooling performance at highway speeds - Ambient temps over 100F, IAT around 160F;

1. No AC load, temp stabilized at about 185F over level ground
2. AC on, temp stabilized at about 192F over level ground
3. Hill climbs dramatically increased temps, longer durations pushed it up to 208F
4. Turning off AC at bottom of the start of a climb helped to keep temps down, turning AC back on during the downhill portion helped. When above 210F, I'd let the teuck coast downhill which quickly dropped temps back to 199F or so.
5. As outside air temps climbed above 110F, engine coolant temp rises, stabilizing at about 212-214F at 72mph over level ground. This was concerning, and I limited AC use to keep it from rising.

On the trip back to Phoenix, Camp Verde has a hill climb that routinely tops out cooling performance. It was 117F in Phoenix, and this climb brought my temps up to 220F, AC off the whole way and STARTED the climb at 212F. Slowed down considerably, kept my RPMs up the whole way, and it didn't stay at 220 for more than a few seconds, quickly dropping down again to 214F for the rest of the climb. Over the top, it dropped back to 204-206F for the rest of the drive home.

I was expecting better cooling performance given the recent replacement of nearly everything related to the cooling system, combined with a new OEM short block, but there it is. It runs hotter than I'd like, but not enough to scare the pants off of me under normal conditions. On climbs, it definitely helps to have a live monitor of coolant temp data to help you adjust your driving style.

Thanks for the info. I tell ya, hood louvres are looking better and better...

 

[TYM4FUN]

Just got back from a 3k mile road trip across 6hrs of desert (Flagstaff to Albuquerque) and back. I noticed a few things, but first my setup;

1. New TYC 1918 radiator installed last year, $127 on Amazon. New OEM radiator cap, new hoses, PHH, Heater Valve and various small hoses. Fresh Toyota Red, 50/50 mix. New Thermostat, Water Pump installed earlier this year.
2. Blue fan clutch, unmodified, OEM fan original to the 1996 truck.
3. New Factory short block installed in Feb, rebuilt head, valve lash set, etc.

Cooling performance at highway speeds - Ambient temps over 100F, IAT around 160F;

1. No AC load, temp stabilized at about 185F over level ground
2. AC on, temp stabilized at about 192F over level ground
3. Hill climbs dramatically increased temps, longer durations pushed it up to 208F
4. Turning off AC at bottom of the start of a climb helped to keep temps down, turning AC back on during the downhill portion helped. When above 210F, I'd let the teuck coast downhill which quickly dropped temps back to 199F or so.
5. As outside air temps climbed above 110F, engine coolant temp rises, stabilizing at about 212-214F at 72mph over level ground. This was concerning, and I limited AC use to keep it from rising.

On the trip back to Phoenix, Camp Verde has a hill climb that routinely tops out cooling performance. It was 117F in Phoenix, and this climb brought my temps up to 220F, AC off the whole way and STARTED the climb at 212F. Slowed down considerably, kept my RPMs up the whole way, and it didn't stay at 220 for more than a few seconds, quickly dropping down again to 214F for the rest of the climb. Over the top, it dropped back to 204-206F for the rest of the drive home.

I was expecting better cooling performance given the recent replacement of nearly everything related to the cooling system, combined with a new OEM short block, but there it is. It runs hotter than I'd like, but not enough to scare the pants off of me under normal conditions. On climbs, it definitely helps to have a live monitor of coolant temp data to help you adjust your driving style.

Now mod your clutch....

 

[DSRTRDR]

Would you all just buy a new fan clutch and mod it, or change the oil in the original fan clutch to 20K weight?

if you have the original black hub fan clutch that came on '93-'94, you'd want to stay at 10K-15K weight

if you are getting a blue hub fan clutch, you'd want to go to 20K or higher

we've had very good experience with the $130 TYC radiator off of Amazon in our 80

 

[DSRTRDR]

we went out wheeling on a 115 degree day in AZ just this week:

I took the LX - on the highway, the truck ran at 196 degrees (or less, lowest was 186)

on longer inclines, the Ultragauge-recorded temperature rose: with the A/C on, I couldn't stomach watching it climb beyond 213 - when I switched the A/C off, the truck would hold at 206, even on inclines - and quickly cool again to under 200 on downhills, even when going slow without much of a wind out there

stock radiator (with foam of course), black hub fan clutch with 10K fluid, OEM fan, green coolant - at the speed we were going, the S/C would not have been a factor

 

[LongDuck]

That's almost exactly what I'm seeing with my TYC1918 radiator and the same components you mention with the exception of running Toyota Red coolant in a 50/50 mix. With these summer temps we're seeing, I don't think you can get it much below 206-210F running AC.

 

[landtank]

we went out wheeling on a 115 degree day in AZ just this week:

I took the LX - on the highway, the truck ran at 196 degrees (or less, lowest was 186)

on longer inclines, the Ultragauge-recorded temperature rose: with the A/C on, I couldn't stomach watching it climb beyond 213 - when I switched the A/C off, the truck would hold at 206, even on inclines - and quickly cool again to under 200 on downhills, even when going slow without much of a wind out there

stock radiator (with foam of course), black hub fan clutch with 10K fluid, OEM fan, green coolant - at the speed we were going, the S/C would not have been a factor

If you are running a black hub on a S/C engine then the ringed fan or the 3FE fan you subbed in is part of the problem at minimum.

Both the black hub and the blue hub clutches are a 2 stage clutches. The difference is the amount of shearing in each stage. The black hub is designed with the idea that high speed driving will inherently force air through the radiator and lesson the need to drive to the fan in those conditions. So the primary stage favored more drive.

By now most have realized that the 80 series can idle all day in the hottest of conditions with out running hot. But ask the truck to drive down a stretch of road at speed and the temps climb.

The blue clutch shifted some of the shearing area from the first stage to the secondary so it would engaged more at speed. Unfortunately the oil CST used and the clutches timing fell short and we have trucks that still overheat at speed while suffering from poor AC performance at idle.

Draining the oil and filling it with some perceived ideal CST based on typical environmental conditions will likely yield varying results.

Best of luck to all.

 

[DSRTRDR]

If you are running a black hub on a S/C engine then the ringed fan or the 3FE fan you subbed in is part of the problem at minimum.

Both the black hub and the blue hub clutches are a 2 stage clutches. The difference is the amount of shearing in each stage. The black hub is designed with the idea that high speed driving will inherently force air through the radiator and lesson the need to drive to the fan in those conditions. So the primary stage favored more drive.

By now most have realized that the 80 series can idle all day in the hottest of conditions with out running hot. But ask the truck to drive down a stretch of road at speed and the temps climb.

The blue clutch shifted some of the shearing area from the first stage to the secondary so it would engaged more at speed. Unfortunately the oil CST used and the clutches timing fell short and we have trucks that still overheat at speed while suffering from poor AC performance at idle.

Draining the oil and filling it with some perceived ideal CST based on typical environmental conditions will likely yield varying results.

Best of luck to all.

I am running the OEM 80-series fan on the LX. NOT the ringed S/C fan.

I have not seen much difference between temperatures with the winged fan and the OEM 80-fan, but the latter is what I currently have on the LX - our 80 also has the OEM 80-series fan

between our 80 and the LX, the word is still out whether the black hub or blue hub fan clutches perform better - they both hold temperature within acceptable ranges even in 115 degrees, so

I don't quite see to what "problem" you are referring that I presumably have on my truck