thoughts on engine temps (1 Viewer)

[aclos3]

My "roar" went away some time ago which lead me down the fan hub clutch fluid path... I experimented with different levels of various fluids and ended up fairly close to stock, but with a bit more fluid and slightly higher weight oil (8000cst?). This got the engine roar back to the way I remembered it and helped keep temps in check at lower speeds, but the difference was not drastic.

Here are two examples of conditions that make my rig heat up:
-One of the quickest ways to get the coolant temp to shoot up is to drive up a steep grade at 20-30 mph. Think gravel, mountain roads with lots of twists and turns. In these cases, higher rpms seem to help a little, and cranking up the heat helps a lot.
-While towing an enclosed cargo trailer (2500 lbs?) at freeway speeds in hot weather with the A/C on going up a moderate grade. Turning off the A/C stopped the temp rise and, again, turning on the heat would bring the temps down quickly. On this particular trip I even tried running the rear heat and leaving the A/C on, but the results of this were inconclusive.

My conclusion, like others on this forum have stated, is that the cooling system is only just sufficient for these trucks. It keeps up fine under nearly all conditions, but throw in a steep hill and/or hot weather and you will watch the needle go up. You just have to keep an eye on it, much like any older vehicle.

 

[Tools R Us]

Another thing we have observed is; when very highly stressed, clutches giving up, becoming wimpy, when allowed to rest/cool, normal performance is restored. This is most common in the newer wimpy/neutered/reduced shearing area units, like the blue hub, etc, less on the early Aisin, have never observed it on an Eaton.

There is a characteristic of the fluid that explains this; when aggressively sheared at elevated temp, the fluid can have reduced ability to shear, like dropping to 10% or less of normal. This effect is temporary, when the load is removed, allowed to cool, full, original performance returns.

The best way we have found to reduce this is: Significantly stepping up in fluid viscosity and less on the valve. This makes the clutch more aggressive, reducing the chance of it getting to that mode. For a blue hub, in desert conditions, I have no problem with 30K, boosted rigs, may need 50K+.

The window to test is short, with tuned clutches, only reliably see it when hot and dry, so mainly June. Once the humidity comes up, even if hotter, the rigs are much easier to cool.

 

[bloc]

I get that the spring/thermostat moves quickly, but the holes are small and there isn't much force pushing the fluid into the relevant parts of the clutch. Especially with the viscosity of the fluids we are using. I'm also not saying it'll take an hour for this to happen.. my point was merely that it's not immediate. We can't expect the fan to react instantly when we drastically change the conditions that are telling it how to operate, and this can result in spikes in coolant temp.

On a different note:
I've mentioned this in another thread with zero response but I wonder.. would bypassing the radiator portion of the trans fluid cooler help keep engine temps down?

Obviously adding another trans cooler and maybe a fan would be called for.. but I remember the A343F in the 1KZ-TE hilux surfs contributing dramatically to engine cooling issues. Manual transmission guys never seemed to have issues. My 4runner ran a LOT cooler when I swapped to 5spd.

I understand that part of the reason for the stock setup is to help bring trans temps up to normal quickly.. but personally I'd rather drive carefully and keep the trans fluid temp in mind while reducing heat added to the engine cooling system over quicker trans temp rise. Personally.

 

[1973Guppie]

ok, now I am a bit confused. I had no idea that these clutches have an adjustment for "kick in" on them. I just bought mine from landtank and slapped it on, lol. Any info appreciated. @landtank

Noah

 

[Fireman]

If you got it from Landtank it is probably already "adjusted".

 

[1973Guppie]

If you got it from Landtank it is probably already "adjusted".

thanks, that is what I thought, I thought maybe there was an external adjustment on it or something......

can anyone tell me what temp an adjusted landtank clutch "should" kick in at? that would be beneficial info to have in future dealings....

 

[NLXTACY]

No, when you split it open there are two Philips screws. Adjusting those screws and plate adjusts the temp at which the plate opens.

 

[1973Guppie]

http://ajikoverlandexchange.com/products-page/landtank/80-series-modified-toyota-blue-fan-clutch/

according to the above it should be kicking on at 95 degrees?

 

[Fireman]

95 at the hub not the water temp

 

[1973Guppie]

95 at the hub not the water temp

gotcha, any idea what water temp factory specs it should kick in at?

 

[bloc]

It isn't that simple.

If your radiator water temp is 200 and barely any air is moving through it, that air might be close to 200. At the same rad water temp driving down the freeway with 80mph blasting through it, the air may only be 3*F (arbitrary number) over ambient.

This tendency is why we have a thermostatic fan clutch in the first place. The assumption is that independent of the water temp, if the radiator is working and if the air flowing through the radiator is cool enough, disengage the fan to save fuel and wear&tear. If for any reason the air flowing through the radiator is hot enough, engage the fan.

 

[Fireman]

Not sure. The threads I've seen show them opening at all sorts of temps. I'm doing this mod as we speak and the first hole didn't reach half open till 130f. The slot started opening at 151 and it opened to the notch at 175.

 

[Fireman]

Got my opening set at between 105-110. Temps in this area are up to 107-110 in the summer.

The warmest days on record are:

29 Jun 1980 117°F
15 Jul 1978 114.1°F
3 Jul 1980 114.1°F
28 Jun 1994 113°F
3 Aug 2012 111.9°F
The warmest months on average were:

July 1980 107.8°F
August 2011 107.5°F
July 2011 107°F
July 1978 105.4°F
June 2011 104.8°F

Hopefully this mod will help with running the ac.

 

[NLXTACY]

It was 108* today. Those temps look typical overall.

 

[Fireman]

Colorado is looking better everyday.

 

[bugsnbikes]

check your fan clutch belts. higher cst in blue clutches tend to create a bit of slippage in older semi glazed belts. tightening down my belt a bit resulted in a 10deg. top end drop.

 

[landtank]

I appologize for using such big words. It was a hot day. I was going very slow on the Rubicon trail. My water and transmission temps were normal and stable (unchanging). I turned on the AC at my wifes request. My water and transmission temps then increased a good bit. I then turned AC off. Water and transmission temps then decreased. Findings: Turning the AC on during periods of very warm weather while the enging is working under conditions other than flat cruising will cause water temps to increase which will then cause oil and transmission fluid temps to rise. Solution: Select AC to "OFF" mode and open windows.

I was making lite of all thermal data. But yes, as you begin to heat soak the cooling system it will effect everything in that system

 

[baldilocks]

I was making lite of all thermal data. But yes, as you begin to heat soak the cooling system it will effect everything in that system

I agree as engine water is used to control trams and engine oil temperature.

 

[surfpig]

It was 108* today. Those temps look typical overall.

It's been over 100 here for several days. 110 yesterday.

 

[Funner]

Got my opening set at between 105-110. Temps in this area are up to 107-110 in the summer.

The warmest days on record are:

29 Jun 1980 117°F
15 Jul 1978 114.1°F
3 Jul 1980 114.1°F
28 Jun 1994 113°F
3 Aug 2012 111.9°F
The warmest months on average were:

July 1980 107.8°F
August 2011 107.5°F
July 2011 107°F
July 1978 105.4°F
June 2011 104.8°F

Hopefully this mod will help with running the ac.

Ah Fall, how I miss thee. Can't wait for October so I can enjoy temperatures like those again.