Mysterious overheating still after major parts swaps

[Peyoteboy]

I am suffereing from a heating problem that just about has my wife demanding the sale of my truck. A rundown of the heating fix attempts is as follows:

Truck overheated about 3 years ago and blew a head gasket. Had the head surfaced, gasket replaced and remounted. Still had heating issues, so i replaced the T-stat, radiator and cap. Seemed to work ok for a while, but then summer hit bad (central Texas, 100+ temps). Replaced the fan clutch with an aftermarket from autozone that only says "Torqflo" on the unit. This seemed to do ok, but fall also came along about this time. So i nurse the truck around for a year with no issues but also no AC. I get the AC going again, and temps rise now whenever i am using it, or when i run for more than 5-7 mins at speeds below 45 mph. I replace the water pump to no effect. I take it to a mechanic and they say i have a bad fan clutch and replace it. This also does not fix the issue so they replace the t-stat free, because i had an autozone one of those also.

Now i have 3 fan clutches, 1 in the truck and two in the garage. Two of them toyota parts. I have a OEM tstat. I have a new water pump. I have a 2 year old radiator and cap, and i have a truck that still overheats. I do have 223k on the motor, but the mechanic, who works mostly on cruisers, says the engine seems to run solid.

I have read about rebuilding Fan clutches, replacing O2 sensors, several other things concerning mysterious overheating. Where would be the right place to start?

BTW, i do not know about this blue core fan clutch that people mention. Is this that much better than a direct factory replacement that is all metal looking?

 

[Jason Andrews]

The new threads about this issue talk about hood louvers to dissapate extra engine heat through the hood AND electric pusher fans mounted either in front of the A/C condensor or in front of the radiator to help out the belt driven fan. If you install an aux. electric fan I doubt you will have this trouble.

 

[landtank]

if one of those OEM clutches has a Blue base I'd be happy to check it out and tweek it as I have mine for you. A small tweek to mine solved the over temps immediately.

I live in MA so you would have to plan on shipping costs here and back and probably some oil as I've also added some to mine.

Let me know.

 

[cary]

Have you checked for airflow obstructions, i.e. mud in the condensor, or similar items? How are you measuring the overheating? Have you checked the gauge to make sure the sensor isn't bad? What coolant mixture are you running? Is the radiator OEM or aftermarket?

 

[Peyoteboy]

Radiator and condensor are clean. As far as measuring the heat, the mechanic i took it to measured it with one of those laser baser heat measuring devices. He said when i was in the red, i was measuring 217 on the front of the block and 233 on the back.

I have not checked the sensor, but if i stop the truck when it gets too hot, i have had it bubble into the overflow, though i do not recall it happening recently. I was using 50/50 prestone, but i keep seeing folks mention the red toyota antifreeze, so i may try that for good measure. The radiator is a toyota factory replacement for this truck.

My clutches do not have a blue base Are only the blue ones capable of being fixed? I might be inclined to make it 4 fan clutches if this will fix the issue. If the only limitation is that noone has TRIED it with the all metal looking fan clutch, i may reread the fan clutch tread and try it myself, as i am not loosing anything.

I also just saw the thread on moving the trans cooler. If i can find out more about that i may even try that. Basically, ill try anything at this point, just so that i can justify to my wife that all hope is not lost

Also, is a pusher fan a legitimate potential resolution? I have never really thought about adding more fan capacity before via a extra fan. I have thought about looking for a bigger fan

 

[Jason Andrews]

Peyoteboy, bubbles in the coolant reservoir? IIRC, I thought that was a sure sign of a failing HG. Did your mechanic check it out since it HAS been replaced.?

 

[Rookie2]

If you're using 50/50 Prestone, that's not your problem. How do you know the Radiator is clean? You sure there's no way you've got leftover casting sands clogging the bottom of it up?

It'd help if you did the temp. gauge mod to have a better idea of exactly where you're temps are running.

Rookie2

 

[landtank]

the blue ones are the only ones that you can tweak, the older style are what they are. Usually they loose their ability do to low fluid level from what I've read.

There is no reason that your truck shouldn't run at the proper temp as is, meaning no pusher fan or other devices should be needed.

When your truck is running hot pull over and stop the engine and see how much resistance there is in moving the fan.

When my truck was running like this the fan moved quite easilly and would coast to a stop after a rotation or so. A working clutch would stop the fan after maybe 3 or 4 blades had past by.

 

[Darwood]

So you say it overheats at low speed. How is it over 45mph?

 

[Peyoteboy]

Ends up the brand new toyota fan clutch does have a blue painted base. For some reason i was thinking something crazy like a blue anodized hub in the center of the main part of the fan clutch. I couldnt for the life of me figure out why someone would do that. Guess thats what i get for being niave

Landtank, I wouldnt want to waste your time on my truck. Is it something a mechanically inclined non-pro mechanic can do easily enough? I read the thread and it didnt seem too bad, but you did alot of trail and error on it that i am not sure i got the complete gist of. However, If it is more of a "feel" and "practice" kinda thing, i would be willing to pay all the shipping and time to boot.

I did a little bit more driving around today, paying attention to the temp guage. It heats up after being stopped for 5 hours in about 2 min. It ran with the temp guage just below parallel ot the ground for about 20 min. this included several stop lights. I then hit about 3 miles of 40 mph roads and started to see the temp climb. I ran it to about 65 again and the temp slowly stabilized. Hit another stop light and the temp popped up pretty quick though. This sounds obvious, but the thing seems to get hot more easily after its been running for a bit, even if the starting temperature before the "heat up" was the same in both situations. This makes me start thinking about the thread i read about the transmission and the VC going.

All in all, after driving for at least 20 min, driving under 45 with the ac on will always overheat the engine. Above 60 but not overtaking anyone it seems to run all day. If i climb a hill or overtake someone, the needle will raise a little, but as long and i stabilize my speed on a level section of road afterward, i seem to be ok and the temp goes back down. With the ac off, everything happens alot slower, and the engine seem to have substantially more power. I am going to get it checked for being overcharged, but i will still heat up the truck in extended 40 mph zones even with the AC off

I have not yet read the thread and background on the acurrate temp guage, but will do so asap.

As far a bubbles in the overflow, this is after the engine is stopped, and ive seen it from almost every car i have ever seen overheat, so i dont think its a head gasket. I could see if the engine were running and the compression and firing in the cylinder blew back in to the colling system that this would be a problem, but i would assume this would be alot more dramatic than "bubbles". Of course, im a total neophyte, so anything is possible.

I would like to try and find the source for the issue more than a way to mitigate it, though from what i have been reading, that may be easier said than done.

 

[semlin]

first comment is that your h/g will not last long if your temp gauge is moving. i would try to minimize further driving experiments if I were you.

my first questions are coolant system related 1. does your coolant look green or does it look brown? If you used to have toyota red and someone switched to green without a very thorough flush then you can get sludge blockages from the mixture. your new rad could be blocked. 2. if you pull the rad cap is the rad full? 3. have you checked your rad cap seal for tears or wear?

after that I'll switch course, next two questions -- 4. does the temp gauge move when the AC is off? If so how much? 5. if you turn the AC off at idle just as the needle starts to move does it stop it from overheating?

Here is our best data on a 93 stock temp gauge

Pegged hot 269
Top of red 253
Bottom of red 242
Top of dead band 220
Bottom of dead band 168
Cold line 129
https://forum.ih8mud.com/showpost.php?p=998658&postcount=313

AC shut off is 226. back on at 216

normally, AC will add maybe 5 degrees to operating temp. the only way it will add more is if it takes the engine past a temp where the cooling system can handle the temp and even then it should not be a cascade problem.

If the temp gauge doesn't move without AC then I think there is something wrong with your AC. From the loss of power I'd suspect that the pulley is binding for some reason and generating a ton of heat.

even if the temp gauge does still move somewhat without AC just not as much I think I'd still try disconnecting the AC belt as my first test given how much else you have eliminated. My second test would be to turn off the AC just as the temp gauge moves at idle and see if that stops the overheating.

BTW, i could be wrong but I don't think the transfer case oil is cooled through the tranny cooler so I don't think the viscous coupling would be it. An overheating tranny could be it but to be that bad I'd think you would throw a TCM code (flashing OD light) or notice something. What does your tranny fluid look like?

 

[cary]

I'm going to start out by saying, this is going to be hard to diagnose unless you mod your gauge or throw an aftermarket gauge on there, even temperarly (you could wire one up, and just run the wires throught the edge of the hood and into the drivers door for a few days.

In addition to Semlin's suggestions, you need to double check the fan clutch, for startup roar, when it is hot, is it locking up?

Does you truck have the factory radiator shroud and fan?

What is the outside temp when you are testing this?

 

[landtank]

When your truck is running hot pull over and stop the engine and see how much resistance there is in moving the fan.

When my truck was running like this the fan moved quite easily and would coast to a stop after a rotation or so. A working clutch would stop the fan after maybe 3 or 4 blades had past by.

You must have missed this part, it's a very simple test and if the fan spins easily and coasts as I said it's in the clutch.


FWIW, you're describing exactly the situation I had. I'm not saying it's definitely the clutch but it would be my first stop in the investigation process.

 

[Peyoteboy]

Semlin -
The coolant looks greenish. I requested the complete flush job when the Radiator was replaced. I will have to talk to my buddy who i bought the truck from whether he used the red stuff before.

The Coolant level is just below the filler, prob 1/2 in.

And the radiator cap looks good.

If i drive for at least 20 min, then have to slow down to below 45 for an extended period of time, the temp will start to climb, even if the AC is off.

Idle with AC on, as long as it isnt in gear, seems ok for now. I dont know if i have tried this after driving for an extended period of time though, i will try this when i get home.

Cary-
I am going to try this weekend on the new temp guage per the acurate temp gage post.

The current fan clutch does "roar" when i start up. It lasts 5-10 secs then quiets down. Befor ereading the posts on this, i always wondered what the heck that sound was.

I will check the lock up.

Landtank -
I will try to get it hot but not too hot and check the fan clutch. This is the second brand new clutch though, so this would be real bad luck if its out



Thanks for all the posts guys. getting lots of info, and gonna try to implement some this weekend

 

[semlin]

ok, on to questions 4 and 5 then...

 

[Peyoteboy]

ok, on to questions 4 and 5 then...

HAHA, i had someone want to talk at my desk mid reply, so i wanted to make sure i saved it and didnt time out. I was getting to it

 

[semlin]

ok, here are some ideas

1. run it with the ac belt off. I am still intrigued by the "no ac" you talk about and the power loss you mention with AC on. it might just be the higher running temp.

2. did you install the t-stat? if they didn't put the jiggle valve at 12 o'clock you might have some issues

3. remove the rad cap cold and start it, look into the open rad with it running to make sure you see coolant flowing from one side to the other (water pump test). Also double check the rad cap for small tears. with a very minor tear mine held zero pressure

4. check your fan belts are not incredibly loose

5. maybe they put the rad or the fan shrowd in wrong and you are not getting proper circulation. Can you post photos of the rad from a couple of angles or compare it side by side to another cruiser? Do you have the skidplate under the truck right behind the steering damper?

6. ditto for the cooling hoses. I can't imagine how but if your truck was torn down to the h/g maybe they put something back wrong. Can you post some shots of your engine bay that show all the hoses?

7. maybe it is running very lean? any pinging? Have you checked the timing?

8. bubble test. It could be too late for your replacement h/g.

 

[semlin]

Also, some folks have installed and ac condensor fan that might help you a little? A factory AC condensor fan was available for the 80 in other markets and CruiserDan used to stock it and may still (he has one on his truck). Here are some threads on using aftermarket fans

https://forum.ih8mud.com/showpost.php?p=596415&postcount=48

https://forum.ih8mud.com/showthread.php?t=58188&highlight=condensor+fan

https://forum.ih8mud.com/showthread.php?t=98359&highlight=condensor+fan

https://forum.ih8mud.com/showthread.php?t=94653&highlight=condensor+fan

 

[Peyoteboy]

Semlin, All,
I will take pics tomorrow and get them up there. I will dbl-check the t-stat. I have done the "check the water flow" thing and i can see that it is flowing, but its not as obvious as my old 350 in my nova did.

also, maybe im confused ont he bubble check thing. I will search on the forum for a complete discussion and test that out. By bubbles i meant that after i stopped, water from the radiator started to bubble into the overflow. This happened a couple times, but i have not noticed it since the recent rash of issues. the recent issues started since the ambient temps of austin started climbing about 95 degrees again

BTW, if i run at night, i have never noticed a heating issue. This is not to say that i cant force it to happen, i just indicates that ambient temp plays a role.

thanks again and ill post pics hopefuly tonight

 

[semlin]

yup the water flow is pretty subtle on mine too but there.

bubble test is the best test to see if your h/g is blown. It involves popping the lid on your rad overflow bottle but keeping the "straw" in the coolant and watching for any bubbles. You should have someone rev the motor as high as you feel comfy (robbie, the mechanic who invented this suggested 4000 rpm) and you need to watch for about 30 seconds to be clear. Bubbles = doom.