Possible Overheating (1 Viewer)

[leonard_nemoy]

I was always told a bad fan clutch overheats at idle and gets better with speed. I am pretty sure he said it runs hotter at speed than it does at idle. This should indicate poor coolant flow soft hoses, are bubble, loss of pressure due to an old cap etc..m Fan clutch's are there to push air over the radiator at low speeds. The speed of air coming through the grill overpowers the fan clutch at speed. At least this is how multiple mechanics explained it to me....

 

[Tools R Us]

I was always told a bad fan clutch overheats at idle and gets better with speed. I am pretty sure he said it runs hotter at speed than it does at idle. This should indicate poor coolant flow soft hoses, are bubble, loss of pressure due to an old cap etc..m Fan clutch's are there to push air over the radiator at low speeds. The speed of air coming through the grill overpowers the fan clutch at speed. At least this is how multiple mechanics explained it to me....

I'm guessing, but,,, they were not knowledgeable 1FZ mechanics?

 

[doc_random]

What color is the coolant?
Original coolant was Toyota Red.
I had the Previous Owner of mine mix in Green coolant and it is reported that causes sludge. This will slow the flow through the channels within the engine and result in poor cooling. I actually had to get in a front end collision that resulted in a new radiator and the engine being flushed. My cooling improved greatly.
Green coolant vs. Red coolant
"Should use only Toyota Red. It's been reported that combining the standard green with it will cause sludging. "

 

[-Spike-]

I was always told a bad fan clutch overheats at idle and gets better with speed. I am pretty sure he said it runs hotter at speed than it does at idle. This should indicate poor coolant flow soft hoses, are bubble, loss of pressure due to an old cap etc..m Fan clutch's are there to push air over the radiator at low speeds. The speed of air coming through the grill overpowers the fan clutch at speed. At least this is how multiple mechanics explained it to me....

Some cars probably work that way, but not the 80. Motion seems to create more load on the cooling system than than the increased air flow can overcome. They are very fan-reliant.

 

[BILT4ME]

And yes, you can run green coolant. Just pick a color and go with it but DO A FLUSH with distilled water.

Green or Red, but not both.

Green is cheaper and easier to get in remote areas.

 

[iRoughNeck]

If you are indeed on the original thermostat add that to the list as well

Definitely, thanks!

 

[iRoughNeck]

Pretty much guaranteed to be your problem. Buy the Aisin FCT-004, don't get one from the dealer, save your money. Do the fluid swap yourself (you don't even have to do it now..but its a convenient time). Use 20K cst fluid (purchase on Ebay, Amazon, etc).

I am 2 hrs. North of you, so we have the same weather (sweltering heat for 4 months). Replace the Thermostat with OEM and also the radiator cap with OEM. Check your hoses to be sure they haven't become soft. Make sure your belts are tight, use OEM 'matched' only for your drive belts, anything you like for the A/C belt.

Consider adding an Aux fan for your A/C condenser (You'll be needing the A/C soon), its easy to do and helps dramatically in slow traffic, plenty of threads on it if you search. It can be set up to run a number of ways.

Let us know if you have any questions, we are here to help.

Flint.

First of all, I am very grateful for folks like you and others on this thread for the detailed responses!

Most of the hoses and belts appear to be new and tight. I think the A/C condenser fan is a great idea and it is definitely on my list next. Last year we got close to 110 F with high humidity around here. I can't imagine a 24 year old compressor doing well in that heat.

I will report back as soon as this is all complete.

 

[iRoughNeck]

And yes, you can run green coolant. Just pick a color and go with it but DO A FLUSH with distilled water.

Green or Red, but not both.

Green is cheaper and easier to get in remote areas.

Looks like I am currently on the Toyota red, and since the radiator was installed less than a few months ago it can't be super old. According to the service manual however (I found one for a 96 at a garage sale, I am hoping it is not too different), it seems as if though the shroud has to come off so I guess it needs to get drained anyways.

Thanks,

 

[wrxFTWdey]

I overheated my 80 a half hour after I bought it. I drove for 15 minutes with my ebrake on and without overdrive on at 70 mph on the freeway. I pulled over because the temp gauge spiked to the red out of nowhere. It wasn't a gradual increase, the needle literally spiked and then went back to normal. I stopped in a jack in the box parking lot and there was steam and coolant spewing out of the reservoir cap. That happened in September of 2017. Luckily the previous owner put a new head gasket in there about 500 miles before I bought it, and I haven't had any problems even after that one incident. It's possible the head gasket is partially cracked. I have a rhythmic stumble at idle, but who knows and who cares. It runs around 185-195 and the highest I've ever seen temps was 200 according to my ultra-gauge. When this motor goes, I'm gonna gank it out, and throw in a LS. Biggest complaint is that 80s are seriously slow. I've driven humvees, APCs, and IFVs that are faster than my land cruiser.

 

[iRoughNeck]

What color is the coolant?
Original coolant was Toyota Red.
I had the Previous Owner of mine mix in Green coolant and it is reported that causes sludge. This will slow the flow through the channels within the engine and result in poor cooling. I actually had to get in a front end collision that resulted in a new radiator and the engine being flushed. My cooling improved greatly.
Green coolant vs. Red coolant
"Should use only Toyota Red. It's been reported that combining the standard green with it will cause sludging. "

Toyota Red is what is in there I believe. Thanks,

 

[flintknapper]

Toyota Red is what is in there I believe. Thanks,

Possibly Zerex Asian also. Both are excellent coolants for our vehicles.

Robot or human?

 

[iRoughNeck]

Finally got to this. Here is the update:

Replaced the fan clutch, water pump, thermostat, radiator cap and both belts. All genuine Toyota parts. Flushed the system and added fresh Toyota Red.

Temperature gauge still around the 2/3 mark! Temperature reading from the TC shows a value of around 185 F, which according to my local LC specialist is within factory spec. I was under the impression that 165 F was the normal value.

He is insisting that the sender is faulty. I do agree with him to some degree, as the needle goes from 0-2/3 within 20-40 seconds of starting up the vehicle. Even with no coolant in the system, I doubt that is possible.

Here is the strange part though. Even after replacing with a brand new Toyota fan clutch, I feel as if though the fan is not properly engaging. I believe I heard the roar once with the cold start, but subsequent testing consisting of letting it sit seemed to create no appreciable change in fan speed. May be it is just a matter of perception on my part and I cannot tell when it is engaged vs. free spinning.

The parts that came off the vehicle seemed fairly new as well meaning that the previous owner had likely been taken by the faulty needle as well.

On the bright side I did get three seals taken care of while she was open, so not a total loss. I am thinking of taking her to the dealership this weekend to get some closure on that fan clutch.

Thanks to everyone for your help and kind regards!

 

[ppc]

The OEM thermostat is 185 degrees. Your engine is running perfectly. Your gauge or sender may not be accurate. The fan clutch will only roar for a short time only when completely cold. Some have tested the clutch but trying to stop it with a rolled up paper when overheating but I wouldn't try that. Given the 185 temp I think it is running properly.

 

[flintknapper]

Finally got to this. Here is the update:

Replaced the fan clutch, water pump, thermostat, radiator cap and both belts. All genuine Toyota parts. Flushed the system and added fresh Toyota Red.

Temperature gauge still around the 2/3 mark! Temperature reading from the TC shows a value of around 185 F, which according to my local LC specialist is within factory spec. I was under the impression that 165 F was the normal value.

He is insisting that the sender is faulty. I do agree with him to some degree, as the needle goes from 0-2/3 within 20-40 seconds of starting up the vehicle. Even with no coolant in the system, I doubt that is possible.

Here is the strange part though. Even after replacing with a brand new Toyota fan clutch, I feel as if though the fan is not properly engaging. I believe I heard the roar once with the cold start, but subsequent testing consisting of letting it sit seemed to create no appreciable change in fan speed. May be it is just a matter of perception on my part and I cannot tell when it is engaged vs. free spinning.

The parts that came off the vehicle seemed fairly new as well meaning that the previous owner had likely been taken by the faulty needle as well.

On the bright side I did get three seals taken care of while she was open, so not a total loss. I am thinking of taking her to the dealership this weekend to get some closure on that fan clutch.

Thanks to everyone for your help and kind regards!

185° F to 190° F is normal operating temp (for a properly operating cooling system in temps under 95° F ambient. Up to 200° in hotter climates is not be unexpected.

Your sending unit (possibly dash gauge) is likely the culprit.

If you want a more aggressive action from the your fan clutch replace the Silicone Fluid with 20K CST fluid.

 

[leonard_nemoy]

You could always try the old newspaper test. Roll up a single page or two of newspaper and stick it in the fan, the newspaper should be able to stop the fan from free spinning when it's cold but it should not stop the fan from spinning when it's hot.

 

[MaTm]

Finally got to this. Here is the update:

Replaced the fan clutch, water pump, thermostat, radiator cap and both belts. All genuine Toyota parts. Flushed the system and added fresh Toyota Red.

Temperature gauge still around the 2/3 mark! Temperature reading from the TC shows a value of around 185 F, which according to my local LC specialist is within factory spec. I was under the impression that 165 F was the normal value.

He is insisting that the sender is faulty. I do agree with him to some degree, as the needle goes from 0-2/3 within 20-40 seconds of starting up the vehicle. Even with no coolant in the system, I doubt that is possible.

Here is the strange part though. Even after replacing with a brand new Toyota fan clutch, I feel as if though the fan is not properly engaging. I believe I heard the roar once with the cold start, but subsequent testing consisting of letting it sit seemed to create no appreciable change in fan speed. May be it is just a matter of perception on my part and I cannot tell when it is engaged vs. free spinning.

The parts that came off the vehicle seemed fairly new as well meaning that the previous owner had likely been taken by the faulty needle as well.

On the bright side I did get three seals taken care of while she was open, so not a total loss. I am thinking of taking her to the dealership this weekend to get some closure on that fan clutch.

Thanks to everyone for your help and kind regards!

It sounds like your 80 is running properly. I'm not sure if it's been mentioned in this thread or not, but it's possible your gauge has been modified. The idea behind it seemed like a good one, but turned out to be more worrisome.

93-97 Coolant Temperature Gauge Modification

@bmwjnky Hey that is different! Not seen that pressure sensor before, what does it do when the engine has little or no pressure when cold? @orttauq It was a long while back so cannot remember (50/10?), but I used whatever was listed by the OP, IMO one of the best mods ever. regards Dave

forum.ih8mud.com

 

[iRoughNeck]

It sounds like your 80 is running properly. I'm not sure if it's been mentioned in this thread or not, but it's possible your gauge has been modified. The idea behind it seemed like a good one, but turned out to be more worrisome.

93-97 Coolant Temperature Gauge Modification

@bmwjnky Hey that is different! Not seen that pressure sensor before, what does it do when the engine has little or no pressure when cold? @orttauq It was a long while back so cannot remember (50/10?), but I used whatever was listed by the OP, IMO one of the best mods ever. regards Dave

forum.ih8mud.com

I wish I had seen that a few weeks and $500 ago. That is exactly where my needle hovers around. I did pyro it before the work and it came back around 186 F which I thought was high at idle. I guess I learned the hard way. On the bright side it has all Toyota components now including the red coolant.

Thanks again!