Running Hot (1 Viewer)

[Malleus]

Temp gauge modded or not? Factory has a faker circuit that translates temp fluctuations into dead middle reading.

No, both of mine are OE. If I want the sensor reading, I plug in my OBDII reader. That's where I got my numbers. Which is why I haven't bothered to mod my gauge...of course, when my '94 comes home (from Dallas, BTW), that'll be on the list.

 

[iansplatinum]

I was just about to ask if you had adjusted the temp gauge. According to conventional wisdom, the US OE gauge won't move until it's too late for you to react; i.e., it'll read in the middle of the range at 176° just as well as 210°.

Yes mine is modded and seems to be fairly accurate. I like knowing what's actually going on (can rev engine to cool her off when it gets close to red)

I don't have OBD2 so don't have the ability to digitally read the temps

 

[calokie]

Is your thermostat clocked in the proper deg orientation? Their is a weep hole/ jiggle pin and it needs to be set at a specific degree. I'm not saying this is your problem its just an observation from when I installed mine, seems like a minor thing that could be easily overlooked. Also did you use Toyota thermostat and aisin or OEM components?

 

[80t0ylc]

OP's is a '93 and mine is a '94 - both a OBD1 which which won't work with a OBD2 reader. Also, OP's 1st post mentions a modified temp gauge. So is mine. Biggest and best thing OP has done is getting away from bronze/copper radiator.

 

[iansplatinum]

Is your thermostat clocked in the proper deg orientation? Their is a weep hole and it needs to be set at a specific degree. I'm not saying this is your problem its just an observation from when I installed mine, seems like a minor thing that could be easily overlooked. Also did you use Toyota thermostat and aisin or OEM components?

Thermostat in the vehicle is Toyota OE. I believe I clocked it correctly but it was 2 years ago. I've done thermostats before and am aware of the weep hole (they always go to the highest point) so I doubt I would have done it incorrectly.

 

[iansplatinum]

OP's is a '93 and mine is a '94 - both a OBD1 which which won't work with a OBD2 reader. Also, OP's 1st post mentions a modified temp gauge. So is mine. Biggest and best thing OP has done is getting away from bronze/copper radiator.

Surprisingly I haven't noticed a difference. I researched my issue and came to the conclusion that it must be the CSF brass radiator, but now my Arizona-recommended TYC acts the exact same.

 

[calokie]

Thermostat in the vehicle is Toyota OE. I believe I clocked it correctly but it was 2 years ago. I've done thermostats before and am aware of the weep hole (they always go to the highest point) so I doubt I would have done it incorrectly.

I'm not even sure what happens if its done incorrectly. Good luck man, Keep us posted

 

[Malleus]

Thermostat in the vehicle is Toyota OE. I believe I clocked it correctly but it was 2 years ago. I've done thermostats before and am aware of the weep hole (they always go to the highest point) so I doubt I would have done it incorrectly.

I doubt it would've taken this long to cause a problem if it was installed incorrectly...

 

[BILT4ME]

I'm not even sure what happens if its done incorrectly. Good luck man, Keep us posted

If it's done incorrectly, you don't get all the bubbles out until it thermally cycles a few times. The jiggle valve allows the bubbles to weep through the system and move to the top instead of one sudden rush of a bubble that can blow off a radiator cap or a sudden massive air bubble into the overflow bottle.

 

[Malleus]

I should have the (current) thermostat out soon. We can compare notes then.

 

[Malleus]

If it's done incorrectly, you don't get all the bubbles out until it thermally cycles a few times. The jiggle valve allows the bubbles to weep through the system and move to the top instead of one sudden rush of a bubble that can blow off a radiator cap or a sudden massive air bubble into the overflow bottle.

Clever, those Japanese.

 

[BILT4ME]

12 months ago, I was having some overheating issues pulling a small trailer. My first thought was a bad fan clutch because I could see a tiny bit of oil weep where the hub met the shaft. AFAIK, it was the original fan clutch at 285K miles.

So I bought a new hub from Amazon (Aisin) and installed it.

Did not solve the problem.
So, I replaced 100% of my hoses, thermostat, coolant, and went through it all because it was at the 100K miles service window. It had all been in there for 7 years.

Before installing the T-Stat, I tested both the old and new side by side in a pan of water. The old one would only open about halfway. The new one would be open fully by 180°F.

After all the new stuff, my cooling system has been working well.

Until last week. I was sitting in a drive through, chatting away with my son, griping about the customer service at this establishment, and as I accelerated to pull away, I felt a sudden rush of hot air from the vents of the AC. It took a second for my little brain to understand what just happened, when I realized the AC kicked off, which meant the engine hit 226°F. I kind of freaked out, popped it into neutral, held the engine about 2000 RPM and it came right back down.

That tells me for sure that the fan hub is NOT working. I have already been kicking it around in my head to do an oil upgrade and possibly an adjustment to the clock the spring inside it, but my truck is a DD, so I need to decide if I should just reinstall my old fan clutch while I mod the new one, or mod the old one, then install it.

Either way, now I'm upset because I DD this truck and I can't afford to have it down and inoperable for more than a day other than possibly a weekend and my wife doesn't me working on the truck every damn weekend.

So, as I type this, I think I will reinstall the old one (that apparently wasn't bad) and then mod the new one, then swap it again later.

So, I'm sharing my experience, and MOST thermostats fail completely open so that the temp never comes up. My old T-Stat started to fail by only opening part way. maybe that's the issue you are experiencing as well. Just a thought.

 

[BILT4ME]

Clever, those Japanese.

Yeah, the Japanese......


My 59 Studebaker T-Stat has a hole in it for the same purpose. So does every GM T-Stat made.

 

[iansplatinum]

My old T-Stat started to fail by only opening part way. maybe that's the issue you are experiencing as well. Just a thought.

Hate to think that this might be the problem with my 2-year old OE toyota thermostat but it certainly sounds like it.

 

[baggar11]

I would say your fan clutch is on the weak side if you're saying it takes a couple minutes to cool back down while revving at idle with the AC off. I recently moved to Arizona and have seen quite a few 110+ days. The fan clutch on my cruiser sounds like a dang semi with any revving past 2k. I only have 7k CST fluid in my fan clutch, so I'm not completely Az ready. I do see temperature creep on my rig if I'm just sitting there with the AC blasting. But I can rev at idle with the AC on and see temperature changes within about 30 seconds.

I would highly suggest modding your fan clutch with 10k+ fluid and setting the opening temperature. If you don't see any significant improvement, put another aluminum radiator in because it's not shedding heat like it should.

 

[80t0ylc]

I tend to agree with @baggar11. I was going to suggest similar actions, but have doubts that your 2 yr old OEM thermostat is the culprit. Like I said before, if your thermostat is bad, you'd see a wider range of overheating. Also, not to , but make sure your radiator is sealed so the fan has to pull air through the radiator and not around it!

 

[Malleus]

I love a good horse beating...was it running hot all through the recent heat wave? Before? Start at some point recently?

 

[iansplatinum]

I love a good horse beating...was it running hot all through the recent heat wave? Before? Start at some point recently?

It seems to have started about a year ago and seems to have slowly gotten worse. Offroading trip in March was not as hot ambient temp but did require me to go blast the engine fan to cool off the car a couple times. Then another wheeling trip saw me stuck on a rock and touching bottom of red. Took a while to cool it off when blasting fan clutch. But it is pretty audible.

Going to: replace thermostat, refill fan clutch with 30k fluid, and tape up shroud.

 

[Malleus]

UPDATE:

The JUL'95 80 is running within the acceptable temp range. The existing thermostat was open 7 -mm (of the required 10-mm) at 203°F. Although it did start to open earlier than the new one, it would not fully open at HOT.

I could have bet that it was OK, if you had put it in my hand and told me nothing about it, or the truck; 5 minutes in a pan on the stove told the story. It has been in the engine at least 5 years. I haven't installed one since we bought the truck.

The fan clutch is definitely not working and doesn't seem to matter. Of course, it's only 90°F here, too.

I'd focus on the thermostat first, and see where that gets you. I agree with @80t0ylc though, if it cools at speed, it shouldn't be the thermostat. Checking it only costs you a ew gasket and whatever coolant you spill, though. Then you have the peace of mind knowing that is, or isn't, the root cause.

 

[lumbee1]

It seems to have started about a year ago and seems to have slowly gotten worse. Offroading trip in March was not as hot ambient temp but did require me to go blast the engine fan to cool off the car a couple times. Then another wheeling trip saw me stuck on a rock and touching bottom of red. Took a while to cool it off when blasting fan clutch. But it is pretty audible.

Going to: replace thermostat, refill fan clutch with 30k fluid, and tape up shroud.

I had similar issues. Fan clutch was bad. I modded it with 12K fluid in 2017. Recently noticed that sitting in drive thru's the temp would spike. I picked up a blue hub from a friend and pulled mine off. Side by side I couldn't tell a difference but the blue hub had more fins and was known good so I installed it. While walking back to my garage, I spun my fan hub once last time and don't you know it spun like it had bearings installed in it. The hub would engage sometimes but then spin freely like it was low on fluid.