Suddenly-high temps

[baldilocks]

So, as for timing, I'm a little rusty on this sort of thing, and I certainly don't remember the correct terms, but I don't think the fluid dynamic shear effect we're talking about is linear... I know it's a curve with regard to speed, and I think with heat as well, so the valve timing is acting on a different part of the curve with a different viscosity anyway. Also, viscous clutches don't ever FULLY disengage and they don't ever really FULLY engage. As far as startup goes, honestly, it was every bit of two minutes (probably more) for the blue to stop pushing hard with 15k.

Another thing to consider, I'll bet there was a real "factory" spec for settings when these rigs were new, but I'm pretty sure they're just slapping them together roughly... *here* (waves hand toward a general area) these days. I assume the adjustment was there in the first place to allow for variance in the bimetal spring to match Toyota's opening spec, but I doubt they bother if you just buy a regular Aisin now. I've heard of a lot of variance in the "stock" setting mentioned in several of the threads. It seems to be all over the place.

As for mileage, when you're only getting 14, losing another 1 mpg hurts! I tried a few different timing settings on the 15k and my experience was that it really didn't matter where it was set, it was pushing a lot of air even when it was as fully disengaged as it gets... to the point where my OBDII gauge was showing the difference in temps, even with higher opening settings that I tried.

With the blue vs black comparison, I have no idea how that breaks down. Honestly, aside from how MINE behaves in MY RIG, it's all glorified speculation. I suppose we could build a fan clutch dyno... anyone want to slap some load cells onto one and fire up some data-logging software?

Anyway, I'll go back up if I ever feel the need, but I'm waiting on a few of those 100* plus days that we sometimes get to drive it hard with full AC. I've had it in and out like a dozen times in the last few months, just playing around with it. I'm not afraid to try again, but as noted previously, Toyota thought 10k was good enough for the middle east and Australia. I'm not too worried about it. Just sharing my experience.

Now you have me thinking I’ll at least put my new blue hub in a pan of water to see at what temp the factory “wave of the hand calibration” method has it opening up.

 

[landtank]

I’ve been getting a lot of questions on the subject as of late.

One in particular was asking what he might do as when pulling a hill with AC on his truck is starting to see some high temps. He added that the ambient temps were around 105*.

My recommendation was to turn off the AC.

When you have an engine operating temp of 185 and an ambient temp of 105 you only have a differential of 80* to cool the system.

Understand that in those conditions reaching optimum engine temps can be a challenge. Especially heavy loaded, foot to the floor with the AC cranked.

 

[Broski]

I’ve been getting a lot of questions on the subject as of late.

One in particular was asking what he might do as when pulling a hill with AC on his truck is starting to see some high temps. He added that the ambient temps were around 105*.

My recommendation was to turn off the AC.

When you have an engine operating temp of 185 and an ambient temp of 105 you only have a differential of 80* to cool the system.

Understand that in those conditions reaching optimum engine temps can be a challenge. Especially heavy loaded, foot to the floor with the AC cranked.

Although this makes perfect sense.

The hole idea is keep the AC running when it’s 105° out

 

[mudgudgeon]

Although this makes perfect sense.

The hole idea is keep the AC running when it’s 105° out

My wife did a road trip a few weeks back through SC, on a day where there was an extreme weather warning for temps up to 109⁰f
She got a CEL, and the code was for transmission over temp.
Got her to turn on code reader app before continuing, and after letting it cool down for 30 minutes or so.
Trans temp went up to 275⁰. Coolant to 240⁰.
Told her if she wanted to continue, turn off cruise control, turn off AC, and drop speed by 10-15 mph instead of keeping pace with SC divers, and watch the coolant and trans temperature like a Hawk. It didn't go any higher.

Reminds me! I gotta flush the trans fluid and refill. I'm sure 275⁰ cooked the ATF good!

 

[Broski]

My wife did a road trip a few weeks back through SC, on a day where there was an extreme weather warning for temps up to 109⁰f
She got a CEL, and the code was for transmission over temp.
Got her to turn on code reader app before continuing, and after letting it cool down for 30 minutes or so.
Trans temp went up to 275⁰. Coolant to 240⁰.
Told her if she wanted to continue, turn off cruise control, turn off AC, and drop speed by 10-15 mph instead of keeping pace with SC divers, and watch the coolant and trans temperature like a Hawk. It didn't go any higher.

Reminds me! I gotta flush the trans fluid and refill. I'm sure 275⁰ cooked the ATF good!

Last year on my way to the SAS event towing the 80 with my Super Duty F350 and with the cab over camper in the bed.
Going through Las Vegas all the way up into southern Utah it was 118° out.
The truck has engine temp and tranny temp gages with a bar graph once the temps reach 210°. They start reading out in numerals that Harley ever happens even with the load.
I watched the numbers climb. The engine reached 228 and the transmission reached 239. I have never seen anything like that.
got no check engine lights, no bells or whistles.
My wife asked me what I was going to do. I said it’s 118° out there unless the check engine light comes on or the truck gives me some kind of dire warning we’re gonna keep trucking and that’s what we did with the AC on max.

 

[COS80]

I suppose 20k May be overkill for an 80 that lives in northern areas and rarely, if ever, leaves it’s home area. As I stated before, I’ve had two black hub clutches open and the oil shearing area is at least double the area, if not more, than that of the blue hub based on photos I’ve seen of the open blue hub clutch. Anecdotally, then, 5k oil should be sufficient for a black hub clutch in hot climates as far as Toyota is concerned. In accordance with info posted by the experienced folks down in Arizona I filled my black hub clutch with 10k and she would pull some big air when hot keeping coolant temp under control. Start up plus two minutes is about how long it took to disengage after sitting over night.

Gas mileage? What’s that? I think mpg would be more adversely affected by modding the open up temp of the clutch thermostat leavening it engaged much more of the time. The way I see it, leave the timing as factory set, run an oil weight that will affect a strong clutch engagement to drop the radiator temp quickly so the clutch disengages as soon as possible.

I’ve been getting a lot of questions on the subject as of late.

One in particular was asking what he might do as when pulling a hill with AC on his truck is starting to see some high temps. He added that the ambient temps were around 105*.

My recommendation was to turn off the AC.

When you have an engine operating temp of 185 and an ambient temp of 105 you only have a differential of 80* to cool the system.

Understand that in those conditions reaching optimum engine temps can be a challenge. Especially heavy loaded, foot to the floor with the AC cranked.

The idea of very thick oil that engages later makes some sense to me. So how would one set the fan internals back to stock, if so Inclined? I would bet that I have one of the modded blue hubs from Land Tank. I found the instructions to mod, but I won't have a frame of reference for a starting point, if that's true.

 

[landtank]

Although this makes perfect sense.

The hole idea is keep the AC running when it’s 105° out

I get that, but sometimes you just can’t have what you want and have to settle for what you need

 

[landtank]

The idea of very thick oil that engages later makes some sense to me. So how would one set the fan internals back to stock, if so Inclined? I would bet that I have one of the modded blue hubs from Land Tank. I found the instructions to mod, but I won't have a frame of reference for a starting point, if that's true.

Not sure why you would want this. Having the clutch coming on later allows the system to run hotter until the clutch does finally come on stronger from the heavier oil and knocks the temperature down, possibly to a point where the clutch backs off some which starts the yo-yo cycle over again.

I personally prefer to time the clutch to stay ahead of the curve and a weight of oil that works most of the time.

And going with heavier weights of oils has diminishing returns. At some point all you are doing is increasing engine load, blade flex and the possibility of slicing you radiator open.

 

[COS80]

Not sure why you would want this. Having the clutch coming on later allows the system to run hotter until the clutch does finally come on stronger from the heavier oil and knocks the temperature down, possibly to a point where the clutch backs off some which starts the yo-yo cycle over again.

I personally prefer to time the clutch to stay ahead of the curve and a weight of oil that works most of the time.

And going with heavier weights of oils has diminishing returns. At some point all you are doing is increasing engine load, blade flex and the possibility of slicing you radiator open.

So whats your current rec? 6k? 10k?

 

[baldilocks]

The idea of very thick oil that engages later makes some sense to me. So how would one set the fan internals back to stock, if so Inclined? I would bet that I have one of the modded blue hubs from Land Tank. I found the instructions to mod, but I won't have a frame of reference for a starting point, if that's true.

Knowing that your clutch is a Landtank modded clutch gives you assurance that it’s not just a Willy Nilly setting. Experimenting with oil only costs a few cents plus knuckle skin. Land Cruisers are supposed to be fun so experiment away and “let the good times roll”.

 

[COS80]

I dont "know" it... I "suspect" it. It could also have been done all by the PO.

 

[Broski]

I get that, but sometimes you just can’t have what you want and have to settle for what you need

Or get the system working correctly

 

[COS80]

I bought a cheap anemometer. This current fan pulls ~5k cfm, and maybe more. With the narrow space, it's gonna be next to impossible to find an e-fan that can compare.

 

[COS80]

Actually, it occurred to me that it took 2,500rpm to get that figure. At idle, it only makes ~1,600 cfm. A cheap aux fan can beat that.

 

[landtank]

Or get the system working correctly

time to get to work on that superduty then I guess.

 

[Broski]

time to get to work on that superduty then I guess.

How’s that I never turn the AC off

 

[mudgudgeon]

A cheap aux fan can beat that.

Good luck with that

 

[Marvelicious]

Actually, it occurred to me that it took 2,500rpm to get that figure. At idle, it only makes ~1,600 cfm. A cheap aux fan can beat that.

Is your hypothetical cheap fan pulling that through a radiator, condenser and grill and forcing it into a cramped engine compartment, or just pulling it through a duct to get their rating? I'm pretty skeptical of aftermarket fan cfm ratings. All the fan in the world can only pull so much air into a tight space. Some of the forced induction guys have gone with thicker radiators (Ron Davis - $$$$$), but that comes with reduced clearance between rad and fan (as I think some of the guys in this thread have personally experienced). I don't know... much past 100* and I start looking at my weather app trying to find a cooler place to be! I'm far too Norwegian for that! If I lived in a part of the country that is afflicted with that kind of weather regularly, I might just keep a socket and a set of @Outsane hood risers in the glove box in case of emergency! As it is, every time we have a heat wave, I start thinking Alaska's winters can't be that bad.

 

[Andrew Bluemel]

I’m pretty anal about the coolant temps. Every time my truck hits over 200 it has my pretty dedicated attention. Usually after a long grade in the summer here in Colorado is when I see those 200+ numbers. As soon as I hit the downhill it cools right down into the low 190s.

In 100+ degree temps if it hits over 200, whenever I find a convenient spot I will pull off, put it in nutrial and hold revs at 2,000 (via handthrottle) till it settles into the low 190s or often times back to 186 (usually a good time for a bathroom break anyways). I attribute the quick cooling to having a solid fan clutch and also ripping off the Band-Aid and refreshing all the cooling system at once when I bought it back in 2014.

When I drive the cruiser (which is my DD), I want it to act like a car. Hold the speed limit (which it does pretty much everywhere thanks to the supercharger) and have the AC blasting. If it gets warmer then I want it (200+ for a sustained amount of time) I will pull off when it is convenient, but it is rare.

I haven’t run the numbers lately but when I did it, it was +/- $700 to do the whole cooling system. In my opinion don’t try to diagnose, just refresh the whole cooling system at once. Having owned my truck since 2014 with 190k, supercharged since 250k, and now having 314k, i can pretty confidently say it has never been over 210. I’m sure it can get hotter, but I don’t think heat helps anything.

it’s cool to find the exact problem in your system, but for peace of mind I think it’s cheaper to just bite the bullet and get the whole system refreshed and not stress about it no matter what you throw at it.

 

[COS80]

Good luck with that

Is your hypothetical cheap fan pulling that through a radiator, condenser and grill and forcing it into a cramped engine compartment, or just pulling it through a duct to get their rating? I'm pretty skeptical of aftermarket fan cfm ratings. All the fan in the world can only pull so much air into a tight space. Some of the forced induction guys have gone with thicker radiators (Ron Davis - $$$$$), but that comes with reduced clearance between rad and fan (as I think some of the guys in this thread have personally experienced). I don't know... much past 100* and I start looking at my weather app trying to find a cooler place to be! I'm far too Norwegian for that! If I lived in a part of the country that is afflicted with that kind of weather regularly, I might just keep a socket and a set of @Outsane hood risers in the glove box in case of emergency! As it is, every time we have a heat wave, I start thinking Alaska's winters can't be that bad.

You're both mistaking my meaning. I didn't mean that a cheap aux fan would be suitable to replace the factory fan; i meant a cheap aux fan that makes 1,601 cfm outperforms the factory fan making 1,600 cfm AT IDLE. Obviously, a blip of the throttle is all that's needed to destroy that cheap fan's performance (I posted that first), and the truck needs to do something other than idle for eternity, so an aux fan isn't going to replace a real fan.