Still overheating...everything replaced. (1 Viewer)

[goaticus]

So, I brought this up a while back and am now even further stumped. Still having overheating issues on long steep grades, when weather is anything but cold, particularly when cruiser isn't able to keep highway speed. Can usually keep it under control with full blast heaters but have had to pull over and let cool at idle. I live on the coast so it's usually not an issue until I go inland on road trips taking me over mountain passes. My last suspect was waterpump. Pulled it (Aisin) and it looked perfect, replaced it anyways with new Aisin. Here's the list:

-New 3 core all brass radiator (realize not the conductivity of Al, but can't be that bad).
-New Mr T T-stat
-Full Transmission flush
-New blue Aisin clutch
-Fan looks good
-Shroud in place
-Timing on spec
-Tested negative for CO2

Out of ideas. After pump replacement last night, I reduced coolant ratio way down and added a bottle of Water Wetter. Thinking of doing the HD clutch oil upgrade, adding additional push fan/fans, adding additional trans cooler.

 

[jpoole]

The next step that I'd take is to mod the fan clutch. I'd adjust / set the opening temp and change the oil per this thread:

Blue fan clutch mod...Thread has gone to hell, read at your own risk

History: On my first drive this summer after replacing my transmission I was having an overheat condition with the truck. On the following weekend while towing a camper it was real severe in the 230* range. After returning I was able to confirm that my Blue hubbed fan clutch was to blame...

forum.ih8mud.com

Note that these days folks are running 15000 CST and heavier oils in most cases.

My clutch is set to be halfway open at 110 degrees F and is running 15000 CST oil. I'm curious is 120 to 125 wouldn't be a better pairing with the tstat temp but I'm still learning/experimenting.

The modded fan clutch may make a huge difference and is easy/cheap to try. Beyond that you don't mention the foam around the radiator being in place but it could make a smaller difference and help with AC performance as well.

From what I know you should be able to make your system work with just the fan clutch changes, if no engine tuning issues are at play, but when the time comes an aluminum radiator will help cooling performance as well.

 

[goaticus]

From what I know you should be able to make your system work with just the fan clutch changes, if no engine tuning issues are at play, but when the time comes an aluminum radiator will help cooling performance as well.

I'll do what I have to, but that would be a real bummer to replace the Rad. I paid big bucks for the all brass because it's repairable. Figured it would probably outlast the truck. Sigh...

 

[jpoole]

Get some air flowing through it and see where you are before you worry about replacing it and hopefully you can rock that all brass Rad. indefinitely.

One other item I forgot to mention and didn't see in your list is cleaning the AC condenser. Air has to flow through it first, for the most part, before it hits the engine radiator so a clean condenser without a ton of bent fins is going to help.

That being said, these trucks are pretty fan dependent, even at speed, so getting your blue hub to the point where it's roaring when things are hot could make a huge difference depending on where you are now. I ran my new Blue hub clutch for a while before adjusting the temp and changing the oil and the before/after difference was huge. Out of the box the blue hubs seem to be set at a variety of opening temps and the oil is pretty thin so you may primarily have an underperforming fan clutch right now.

 

[MoJ]

Is the radiator OEM Toyota? I only ask as I’ve previously ran the 93-94 brass without issue. I wouldn’t rush to replace it. I assume you’ve already cleaned the condenser? You’re certain there’s no air in the system?

I’ll add that many of us have ran non-modified, but properly working, fan clutches and maintained cool temps. 80’s didn’t run hot from the factory.

 

[thedoughboy]

x2 on modding the fan clutch. I too had similar overheating issues. If you read around this forum, the blue clutch performs well at 25K +. I bought a blue Aisin clutch and put 20K in it. Still had some issues. Drained it and replaced the fluid with 30K. So, I probably have about 28K in there. It works well at that viscosity. It pulls a lot of air!

 

[Marco Lau]

how do you know you are overheating? do you have aftermarket gauge? If so, what are the readings??
Overheating due to slow traffic resulting in insufficient air thru the radiator usually means your fan clutch needs upgrade. If you are overheating on highway 75mph, usually your radiator is the culprit..consider all other parts of the cooling component is up to par.
I am running 30k fluid in my clutch (15K previously) and my temp drops 5-10 F

 

[inkpot]

As your rigs slows down, are you manually downshifting the transmission in order to keep the RPM up higher?

 

[Marco Lau]

As your rigs slows down, are you manually downshifting the transmission in order to keep the RPM up higher?

4L keeps my rpm between 2.5-3k range, and i can see the temp. drops per my digital gauge. The problem for me is usually rock crawl at idle up steep hills for an extended period of time.

 

[Tools R Us]

... 80’s didn’t run hot from the factory.

But, they weren't saddled with that wimpy blue hub! My guess, it depends on the climate and load they were operated under? Mine had sevreal complantes of running hot, the fan clutch and radiator replaced at about 20K miles.

 

[Tools R Us]

...
Note that these days folks are running 15000 CST and heavier oils in most cases.
...

First "fan clutch" needs to defined. I would not bother opening a blue hub for less than 30K.

 

[rghouse]

Got oil in the coolant? I suspect the head is warped/cracked. Fan clutch problems are at idle/traffic. Won’t always see the oil in coolant FYI. If you are at wits end pull the head. That was my same story

I have some extra R/C car gear oil for ya too, about 20 ml...

 

[ccslider]

Have the foam that goes around the radiator? Top, bottom and sides

 

[MoJ]

Fan clutch problems are at idle/traffic.

Is that true?

 

[Marco Lau]

Is that true?

Yes, on highway, should have enough air moving thru the radiator

 

[MoJ]

Yes, on highway, should have enough air moving thru the radiator

Seems logical but contrary to previous statements that the fan plays a very significant role in drawing in air at highway speeds.

 

[NorCalFJ100]

I think you should do a leak down test if you are thinking there could be head warpage. Pressure testing the coolant system will be helpful. Sorry if I missed it, but have you done the super flush to your cooling system?

 

[Marco Lau]

Seems logical but contrary to previous statements that the fan plays a very significant role in drawing in air at highway speeds.

I never said that...

 

[MoJ]

I never said that...

OK, the prior post seemed to imply that at highway speeds there would be enough air moving through the radiator that the fan clutch wouldn’t be a key contributor to thermal management.

 

[80t0ylc]

So, I brought this up a while back and am now even further stumped. Still having overheating issues on long steep grades, when weather is anything but cold, particularly when cruiser isn't able to keep highway speed. Can usually keep it under control with full blast heaters but have had to pull over and let cool at idle. I live on the coast so it's usually not an issue until I go inland on road trips taking me over mountain passes. My last suspect was waterpump. Pulled it (Aisin) and it looked perfect, replaced it anyways with new Aisin. Here's the list:

-New 3 core all brass radiator (realize not the conductivity of Al, but can't be that bad).
-New Mr T T-stat
-Full Transmission flush
-New blue Aisin clutch
-Fan looks good
-Shroud in place
-Timing on spec
-Tested negative for CO2

Out of ideas. After pump replacement last night, I reduced coolant ratio way down and added a bottle of Water Wetter. Thinking of doing the HD clutch oil upgrade, adding additional push fan/fans, adding additional trans cooler.

1st question: Are you running oversize tires? 2nd question: Have you added armor or significant weight? I'm running a '94 also, which means that the stock radiator was brass with plastic tanks. I replaced this with an all brass CSF when one of the seams started leaking on my OEM radiator. I was also adding armor, bumpers, sliders, skidplate and larger tires - 33" and finally 35". Had same problems you're having and not able to run A/C when I needed it the most. Messing with fan clutches helped slightly, but still couldn't get the temps down in hot summer weather. Part of my problem was that with all the mods made to my rig I had exceeded the limit of what the brass radiator could provide. It was suggested to replace my CSF with a TYC 1918. It's available on Amazon at a very reasonable price. Also says it's for '95-'97, but it fits '93 & '94 as well with no modification. It's aluminum with plastic tanks but was what I needed to get my engine temps down in the hot weather and on long grades. I know that's not what you want to hear, but for the price, it's worth a try. That's how I approached it and the thing is - it works!