High engine temp under load

[80t0ylc]

Since I installed RT's temp gauge mod, I've had concerns that my engine temp on hills is climbing too high. It doesn't matter what the air temp is, it seems to be load dependant. I can just about tell if I'm on an incline by looking at the gauge. Flats and down hill and it'll drop back down. Seems like normal average reading on highway now is a needle width above halfway. Seems higher than it should be

Before the temp gauge mod, it barely moved. Stayed a needle width or 2 under half, which was normal. Now, the engine will warm up to same spot in about 5 min. Then if driving on the flat, it will climb to halfway. If I pull over and let it idle, it will drop back just under half. On long hills the gauge will keep climbing to a needle width or 2 under the red area and drop down to half way or less as I'm descending other side of hill. The longer the hill, the farther it climbs.

----What has been replaced so far:
-Fan clutch: New OEM Blue hub & fluid replaced with 10K
-Thermostat: OEM
-Radiator: CSF 3 row all metal & new 13 lb cap, weather stripping installed
-Flushed and new coolant
-All hoses new including phh and all heater hoses
-Rear heater bypassed
-New OEM belts & idlers

Was thinking maybe water pump for a while, but it isn't noisy and doesn't leak. Plus the temp doesn't climb running on the flat, even at highway speed. It's a '94 OBD I, so no scan gauge possible. Stock tire size; 2.5" OME lift; Lots of armor; weighs about 6400 lbs. Mileage is 240K. I want to put a RTT on and tow my Mini with it, but it's not even summer yet and I'm concerned that warmer weather, running A/C and/or towing might push it into the red or worse on passes this summer. Any ideas because I'm just not sure if this is normal, considering the weight? Or how far I can push it into the red with the temp gauge mod?

 

[landtank]

I wouldn't be surprised if it's the fan clutch. In my experience a dump and fill is a crap shoot as to whether or not it will improve it's ability to get the job done reliably.

 

[LandCruiserPhil]

For best prformance 10K in a Blue hub is too light for AZ

 

[McDowra]

First thing I would do is put a temp gauge on it so you can tell exactly how hot it is getting. Go to any parts store buy a cheap one install it temporarily and get some real numbers and see what is really happening.

 

[80t0ylc]

I wouldn't be surprised if it's the fan clutch. In my experience a dump and fill is a crap shoot as to whether or not it will improve it's ability to get the job done reliably.

Thanks, Rick! I was hoping you'd see this. Would upping the CST to say 15-20K improve performance or not? If not, is adjusting going to gain anything?

For best prformance 10K in a Blue hub is too light for AZ

Thanks, Phil! I'm wondering now if it's too light for anywhere

First thing I would do is put a temp gauge on it so you can tell exactly how hot it is getting. Go to any parts store buy a cheap one install it temporarily and get some real numbers and see what is really happening.

Thanks for reply! You know, I had similar idea. I have one of those Laser digital readout thermometers, you know - point and shoot. Just don't know where to read on engine block. Thinking about where existing temp gauge sending unit sits. Just to confirm, isn't it near thermostat housing? So maybe run it up a hill to where the gauge starts climbing uncomfortably high. Pull over and pop hood and read on thermostat housing. I have a chart on my sunvisor that I made from RT's gauge mod thread to give ball park idea what gauge is telling me. I'll compare to see if gauge is lying to me or not. Sound like a good plan?

 

[landtank]

Thanks, Rick! I was hoping you'd see this. Would upping the CST to say 15-20K improve performance or not? If not, is adjusting going to gain anything?

My first brand new blue clutch behaved just like this. Under load the truck would over heat but it could idle all day long and maintain temperature. I tried a few things and the only way to get it to work the way I wanted was to advance the timing and put in thicker oil.

I now advance the timing and use 15k oil.

There has been a few threads out there and others who had swapped out the oil ended up needing to advance the timing as well. Not everyone but some had to.

In my experience the timing set by the factory does seem to vary from clutch to clutch and sometimes that can be quite a bit.

 

[80t0ylc]

Well after a drive with my laser thermometer, I'm convinced the modified temp gauge is accurate. Rick, I'm coming to the same conclusion about the fan clutch. I think since the engine has to work harder due to all the extra weight from armor, bumpers, 2nd battery, winch, wench and my fat ass . It's probably equivalent to running in the high temps the AZ, SoCal and other sunbelt 80 owners are dealing with. I'm going to start with changing the fluid. Since I'll be adding the extra weight of a RTT and towing load, I'm going to jump to 20K - 25K CST, maybe even 30K. I checked the timing when I installed it and it was OK.

 

[OGBeno]

I've never had any issues with the stocker blue hub fan clutch.

I've run it now since 2007 and I've run some pretty tough trails: Rubicon/
Death Valley/Southern Utah in some very hot temps, running the AC, slow and very low, high rpms, slow speeds very heavy engine loads and have never had any issues with the stocker CST weight with the silicone.

Like Rick, my timing is advanced to 9 degrees.

That said, my entire cooing system is all OEM and new (as of 2007).

YRMV.

 

[elhombre]

Your gauge preforms pretty much the same as mine. When I drop it into 2nd, and pull a hill at 50mph 3k rpms, it shows 2 needles less than red also, Nothing more. (I turn the A/C off )

What I did was run the truck at home and put a towel over the front of the grill. I then turned the A/C on and waited for the truck to heat up. The modified Temp guage went right up to the beginning of the red. At that point, the over temperature switch which Toyota put in there to drop the A/C as a load, cut off my compressor. I looked at the guage and knew that the water temp in the head was 219 (verify this temp up in the FSM, I am at work and cannot remember the exact cut-off temp). Either way, I saw where the guage now read where Toyota engineered a specific temp. For 3 years now, my guage moves around but never into the red. And only once did I see it move closer than 2 needle widths but I was wheeling in the summer with the A/C blasting on South Padre Island National Sea Shore ie. deep sand. I turned the A/C off and all was well. Now I "know" what the modified temp guage reads at where Toyota decided the engine is getting too hot.

I started running a brand new blue fan clutch with 10k at the same time as the guage mod. About 18k miles.

 

[fj4068]

I now advance the timing and use 15k oil.

Like Rick, my timing is advanced to 9 degrees.

I think LT was referring to timing in the sense of clutch initial opening temperature.

 

[OGBeno]

I think LT was referring to timing in the sense of clutch initial opening temperature.

Yup. Now that I re-read what Rick wrote, its become clearer.

 

[80t0ylc]

I've never had any issues with the stocker blue hub fan clutch.

I've run it now since 2007 and I've run some pretty tough trails: Rubicon/
Death Valley/Southern Utah in some very hot temps, running the AC, slow and very low, high rpms, slow speeds very heavy engine loads and have never had any issues with the stocker CST weight with the silicone.

Like Rick, my timing is advanced to 9 degrees.

That said, my entire cooing system is all OEM and new (as of 2007).

YRMV.

Onur, is that an early blue hub, or one of the current ones? I'm not sure, Tools would know, but I think the early ones had thicker or higher weight oil. Also is your temp gauge stock or "RT" modified?

 

[half k cruiser]

Everthing these guys said ^ and x2 on the aftermarket temperature gauge. I can't tell you how much nicer it is to know the exact temperature instead of guessing with the factory gauge or using a temp gun. I recomend the KOSO digital if you want something nice.

 

[FastCarGuy]

Probably a dumb question...but where can I buy a Blue hub kit?

 

[80t0ylc]

Your gauge preforms pretty much the same as mine. When I drop it into 2nd, and pull a hill at 50mph 3k rpms, it shows 2 needles less than red also, Nothing more. (I turn the A/C off )

What I did was run the truck at home and put a towel over the front of the grill. I then turned the A/C on and waited for the truck to heat up. The modified Temp guage went right up to the beginning of the red. At that point, the over temperature switch which Toyota put in there to drop the A/C as a load, cut off my compressor. I looked at the guage and knew that the water temp in the head was 219 (verify this temp up in the FSM, I am at work and cannot remember the exact cut-off temp). Either way, I saw where the guage now read where Toyota engineered a specific temp. For 3 years now, my guage moves around but never into the red. And only once did I see it move closer than 2 needle widths but I was wheeling in the summer with the A/C blasting on South Padre Island National Sea Shore ie. deep sand. I turned the A/C off and all was well. Now I "know" what the modified temp guage reads at where Toyota decided the engine is getting too hot.

I started running a brand new blue fan clutch with 10k at the same time as the guage mod. About 18k miles.

Elhombre, thanks for posting! I'm not using my A/C at all this time of year. But, maybe you're right. Modifing the gauge just gives us more info and increases the pucker factor the heavier the engine load. Probably why the stock gauge is center biased - only this is info I'd want to know.

 

[80t0ylc]

Probably a dumb question...but where can I buy a Blue hub kit?

It's the only OEM fan clutch you get now, from Toyota. Since you're in Phoenix, hook up with the Copper State Cruisers. They'll set you straight. Might even be able to set you up with a used OEM that perform better than the new blue hubbed clutches. Cruiserdan or Beno at American Toyota, a vendor here on mud gives discounts to mud members.

 

[landtank]

Probably a dumb question...but where can I buy a Blue hub kit?

if you want a new factory blue hub clutch that has already been modified you can follow the Ajik link in my sig line and get one there. It's however more that a new stock clutch from the sources mentioned above.

 

[LandCruiserPhil]

if you want a new factory blue hub clutch that has already been modified you can follow the Ajik link in my sig line and get one there. It's however more that a new stock clutch from the sources mentioned above.

IIRC you set your modded clutches temp @ 95°. Being from AZ with daytime temps rarely dropping below 95° for several months would that mean your modded clutches are open before you start your engine?

 

[FastCarGuy]

It's the only OEM fan clutch you get now, from Toyota. Since you're in Phoenix, hook up with the Copper State Cruisers. They'll set you straight. Might even be able to set you up with a used OEM that perform better than the new blue hubbed clutches. Cruiserdan or Beno at American Toyota, a vendor here on mud gives discounts to mud members.

Thanks!!

 

[80t0ylc]

After studying the fan clutch threads for several days ;p (lot of reading), and considering the plans that I have for my 80 as a tow rig with a RTT, I'm going to drain the 10K fluid out and replace it with 30K. Picked up some OFNA 30K in Boise at an RC hobby store in the last day or 2. Being that it has 10K in it now, it all won't drain out and I might thin it with some new 10K that I had left over. So it'll be slightly under 30K when finished. Probably be a few weeks before I get this done, but I'll report back with results.