Cooling System Running Hot What Next? (1 Viewer)

[FirstToy]

Frank,
Sorry to hear it's bumping into the AC cutoff. I'm sure it's frustrating with no clear solution and time/money spent on unfruitful PM...

I have 7K cst for my fan clutch to do (read up on tools r us informative posts)
Offroad lights had no measurable effect on cooling - I measured before and after.
My temps flux with ambient temp, like yours. When it's cooler, engine temp drops, etc.
I don't come into the bumping off AC cutoff though.

One thing is that 200F is not hot. Ideally you want an engine to get to 200 as fast as possible and stay there. I guess the logic is that 190F will give you a larger buffer before you hit AC cutoff.

The only time it really strains is on freeway grades (where the fan clutch has no effect, correct?) or heavy trail work where the fan clutch does effect it.

My AC is not ice cold when it's really hot outside and i'm tooling around town. I got the 7k cst to hopefully improve that.

When the engine is working on the freeway grades, temps will build up but stabilize.

I could easily imagine it bumping off 220F+. Going up to Big Bear in 100F+/10%humidity and thin air... people overheat, I see it. That is what I want to avoid but is that a limitation of the cooling system and just drive slower as the solution or is there something wrong?

I had a thought that airflow is reduced with the ARB bumper and lift because airflow is creating a high pressue zone behind the radiator, not allowing normal flow. I was going to add a "spoiler" of sorts to test the theory- might be good to try in this heatwave we have.

Another theory was that the newer HG somehow routed cooling differently so it reads hotter but is normal- however, it seems like a false logic if you are bumping off the AC cutoff.

On the fan clutch- I am confused on which requires what:
-orig oem clutch - requries heavier fluid for eqiv results? or is it the blue clutch that does?
(I read that cruiserdrew went with 6k cst and noticed a stronger fan so I got whatever the shop had- that was 7k cst)

All thoughts and observations... don't really have answers and too lazy to work on the truck in 105F temps!

(oh and fwiw, my temps have been around 195-205F (can go 180-185 in cool weather, on a downhill) and felt it to be normal except my AC as described)

 

[Cruiserdrew]

(I read that cruiserdrew went with 6k cst and noticed a stronger fan so I got whatever the shop had- that was 7k cst)


(oh and fwiw, my temps have been around 195-205F (can go 180-185 in cool weather, on a downhill) and felt it to be normal except my AC as described)

And, I have since gone to 10k fluid after some temps near 220 on a day I was climbing the grades on highway 4 and it was 111F outside. No issues since but it has not been that hot. I was alarmed because it always reads 188-195 and suddenly it was much hotter. I suppose 220F is still in the normal zone and it didn't overheat or shut off the AC, but I still did not like it. James-I still have 1/2 bottle of 10k fluid if you want to give it a try. I'll be in Claremont next weekend.

Stats: 1 year old radiator, fan clutch, thermostat etc.

I actually have considered lowering the percentage of antifreeze, as water has a higher specific heat capacity than ethylene glycol.

In many ways I was happier before modding the temp gauge or running Tom's scan gauge.

As long as the outside temp is below 100F, the usual temp is 190F or so, but once the outside air gets really hot, the temp climbs in a noticable way, especially on steep grades.

 

[FirstToy]

Andy,
thanks I'll take you up on that. Give me a call when you are in town

I hear you on the scangauge... i think Toyota was really smart to have it dead in the middle!

I have the same experience with regards to temps relating to outside temps above 100F

Maybe it's just the limit of the cooling system and can't shed heat fast enough in those constant heat generating conditions?
I wonder if the Ron Davis radiators would be much better at maintaining engine temps during those situations..

 

[Romer]

I've never bothered to bleed the cooling system the few times I had it open. Since the coolant flows into the rad at the top and out at the bottom, any bubbles will stay at the top and eventually be released out through the radiator cap IMO. I tend to fill the cooling system from the U-shaped pipe at the firewall with the rad cap off. YMMV of course!

He replaced the radiator, so bleeding is something that is needed.

When you have done your flush and fill, where you on level ground or at an angle.

I had a problem before the SC when I flushed in my level garage that was fixed by bleeding

 

[landtank]

have you considered a restricted exhaust? As a cat fails it starts to increase the back pressure which in turn backs heat up into the engine straining the best cooling system.

 

[unwiredadventures]

I got a couple tubes of 7K cst fluid you can have if you're interested. Won't be needing it because I'm happy w/ 10K fluid.

From what I'm reading I may need 10k or 15k

If operated in desert conditions I wouldn't even put 10K in them, 15K minimum

I'll try out 15k

Also when you replaced the thermostat, did you make sure the hole was at 12 0'clock?

Doh! no, I'll pull and re-orient.

I'm sure it's frustrating with no clear solution and time/money spent on unfruitful PM...

I was going to do most of it anyway with almost 160k miles.

Ideally you want an engine to get to 200 as fast as possible and stay there. Going up to Big Bear in 100F+/10%humidity and thin air... people overheat, I see it. That is what I want to avoid but is that a limitation of the cooling system and just drive slower as the solution or is there something wrong?

My wife's LX450 has the old, non-blue clutch. And never has reached the AC cutoff.

And, I have since gone to 10k fluid after some temps near 220 on a day I was climbing the grades on highway 4 and it was 111F outside. No issues since but it has not been that hot. I was alarmed because it always reads 188-195 and suddenly it was much hotter. I suppose 220F is still in the normal zone and it didn't overheat or shut off the AC, but I still did not like it.

Mine cuts off at 220F. Interesting that yours does not.

I actually have considered lowering the percentage of antifreeze, as water has a higher specific heat capacity than ethylene glycol.

You're the 2nd that has suggested this.

have you considered a restricted exhaust? As a cat fails it starts to increase the back pressure which in turn backs heat up into the engine straining the best cooling system.

Good point. I had exactly this problem on an Izusu Trooper many years ago.

I have my old non-blue fan clutch in a box in my garage. It was working perfectly when removed. I'll put it back in tomorrow for some testing.

I very much appreciate all the ideas I'll try the easy stuff first to narrow this down. I'll do them one at a time.

1. Bleed cooling system.
2. Make sure thermostat is correctly oriented.
3. Swap in old non-blue fan clutch.
4. Lower percentage of Red antifreeze.
5. Remove driving lights.
6. Change fan clutch oil.
7. Diagnose catalytic converters.

 

[FirstToy]

Frank,
remember you are pushing a lot more air than a stock 80.
it is also trying to roll a good 65lbs more per wheel in rotating weight. I have to think that is a significant issue... but I also think there could be something amiss. keep us informed on your progress!

 

[Cruiserdrew]

I believe the AC shut off is 226 or there abouts.


I don't think you can really bleed the system. That function is accomplished by a functioning radiator cap and an overflow that you keep on the full side. I do try and fill it nose up a little, but really don't sweat it. This only makes any difference the first couple of temp cycles, after that, all the air is purged and you're just dealing with fluid that expands and contracts.

BTW-If your cap isn't new, I'd replace it.

Having the jiggler at 12 o'clock simply makes it eaisier for air to be purged as you fill the motor with coolant.

 

[Tools R Us]

...
The only time it really strains is on freeway grades (where the fan clutch has no effect, correct?) or heavy trail work where the fan clutch does effect it.
...
When the engine is working on the freeway grades, temps will build up but stabilize.

There will always be a temp increase with load and highway speed is no exception. Some have said that highway driving is possible without a fan, guess that depends on you definition of “normal highway driving”. If it’s cold, heater on (acting as a radiator) and relatively flat road, it’s possible, even likely depending on temp. In the southwest normal highway driving often includes warm temps, A/C on (dumping heat in front of the radiator) and extended mountain climbs. Under those conditions if your clutch it’s up to par you will be seeing big temp increases or be parked on the shoulder cooling it off.

...
On the fan clutch- I am confused on which requires what:
-orig oem clutch - requries heavier fluid for eqiv results? or is it the blue clutch that does?
(I read that cruiserdrew went with 6k cst and noticed a stronger fan so I got whatever the shop had- that was 7k cst)

All thoughts and observations... don't really have answers and too lazy to work on the truck in 105F temps!

(oh and fwiw, my temps have been around 195-205F (can go 180-185 in cool weather, on a downhill) and felt it to be normal except my AC as described)

The earlier clutches (Eaton, black and early blue Aisin) have more shearing area, are naturally by design more powerful. My observation is; with a row of rigs idling long term in hot weather, A/C on, all with 10K fluid, it’s easy to tell the ones with the earlier clutches. Stand in front of a rig with an early clutch and it will try to pull your laundry into the grill, the later clutches are wimpy in comparison, it’s very obvious. Not saying that late clutches are bad, but to get them to perform on par with the early, requires about 1.5-2 times the viscosity. My criteria for selecting fluid viscosity is; the max temp, load that the rig will possibly see and type of clutch.

In the big clutch mod thread there was much prediction of doom, FUD, with some experience those have proven to be baseless conjecture. Most all of the rigs in our club have moded clutches, some have had several different setups, early on I was conservative with other’s rigs and advice, this summer the lowest viscosity that I have done was 10K in a Taco and a Sequoia. The ’80’s have been, Black and early blue Aisin at 10K, Eaton at 12.5K and the later blues at 15-20K, with great results. Another observation; A/C temp and motor temp are somewhat related, if your vent temps have a big variance with engine/vehicle speed, the motor temp will have a big variance. When there is enough airflow to keep the A/C happy at high temps and low speed, the motor will also be happy.

IIRC one of the engineers that I talked with, sent some pix to, at the time of the big thread said something about a big viscosity number (16K maybe?) possibly being the best in our clutches. At the time I was , but now after 3 summers of messing around, that’s about where some are having great results, some of those engineer types know their stuff!

Disclaimer; these observations are based on experience in desert conditions. I have run a few snow trips and the lowest parked overnight temp ~20F with no issue. I’m happy, ready to have a good time at 100F and miserable at 50F, so it’s on someone else to test arctic performance.

 

[Tools R Us]

...
I don't think you can really bleed the system. That function is accomplished by a functioning radiator cap and an overflow that you keep on the full side. I do try and fill it nose up a little, but really don't sweat it. This only makes any difference the first couple of temp cycles, after that, all the air is purged and you're just dealing with fluid that expands and contracts.

That agrees with my experience. I run it easy the first couple of heat cycles and check/fill the overflow before each drive. When the overflow bottle level stabilizes your good to go.

BTW-If your cap isn't new, I'd replace it.

Agree if the cap is leaking it wont properly bleed.

Having the jiggler at 12 o'clock simply makes it eaisier for air to be purged as you fill the motor with coolant.

Agree, that's it only purpose.

 

[unwiredadventures]

Another observation; A/C temp and motor temp are somewhat related, if your vent temps have a big variance with engine/vehicle speed, the motor temp will have a big variance. When there is enough airflow to keep the A/C happy at high temps and low speed, the motor will also be happy.

I'm experiencing this in my 80. At idle AC is not very cold. With more engine/vehicle speed is gets much colder.

My wife's 80, with the old non-blue clutch AC is always very cold, idle or at higher speeds.

 

[Tools R Us]

I'm experiencing this in my 80. At idle AC is not very cold. With more engine/vehicle speed is gets much colder.

My wife's 80, with the old non-blue clutch AC is always very cold, idle or at higher speeds.

Change the fluid, it's inexpensive, a relatively simple job, that's reversible. If you don't get the effect that you want, it's easy to change to another viscosity, haven't found a downside, just cooling performance increase.

 

[landtank]

if you think it might be the clutch you could just swap in the one from your wife's truck to test.

 

[NLXTACY]

if you think it might be the clutch you could just swap in the one from your wife's truck to test.

There ya go. And its only 15 or so minutes off and on.

And BTW I have the Temp Gauge mod and the Scan Guage and they match each other perfectly. I've noted on my own threads about this issue and my A/C shuts off at exactly 227º, never before.

Also, my truck has been running around 200º on the freeways these past few 100º days and narry an issue.

 

[unwiredadventures]

if you think it might be the clutch you could just swap in the one from your wife's truck to test.

I have a perfectly good working non-blue fan clutch in a box. I'll swap that one in so this has no effect on the

...and my A/C shuts off at exactly 227º

Strange, mine does it at exactly 220º

I just showed the (princess) to my wife. She said "don't forget it".

 

[OGBeno]

Get rid of the Scangauge.

Seriously. None of this was a problem until the Scam-gauge was introduced into the mix.

 

[unwiredadventures]

I Also when you replaced the thermostat, did you make sure the hole was at 12 0'clock?

I took a look at the thermostat on Monday, I had it installed at the 9 0'clock position, moved it to 12 0'clock. Later in the day I drove to the top of the San Bernardino Mountains. It's a paved road that goes from about 1000' to ovey 5000' on wide switchbacks. My coolant temps never went above 205º with AC on. Ambient was in the low 90's.

Ambient temps are cooler now. So I don't know if this completely solves it.

I'm going to proceed with changing the oil in the blue fan clutch.

 

[Romer]

I hope thats it. That would be a simple fix

 

[Brian894X4]

The thermostat is suppose to be oriented straight up or at least within 15 degrees of straight up, so the little air valve thing can vent. Sounds like that was exactly your problem.

By the way, normal scangauge temps in a normal cooling system with normal ambient temps (around 70) and normal driving should be 181 degrees. I think our thermostats are set to fully open at 180 degrees.

As far as lights affecting airflow as mentioned earlier in the thread, I have a lot of things blocking the airflow to my radiator including lights and I'm very surprised at how little affect it has on the cooling system. I think a normally operating cooling system on the LC is way over capacity and can handle plenty of blockage. Besides, you're not actually blocking airflow, unless something is actually resting up against the radiator. The fan is still sucking in air and while it may not come from straight ahead it can still come from other directions and still provide heat transfer.

There are many applications in everything from vehicles, to boats to locomotives, where the radiator is nowhere near direct airflow, but the fan is enough to draw in air from various directions to provide heat transfer.

I think where radiator flow blockage becomes an issue is when the clutch on the fan starts to fail.

 

[FirstToy]

It's been quite a bit cooler lately so I don't think the tstat has anything to do with Frank's overheating.

The conditions in socal can be very hot and very dry.