FJ62's Overheating. Several of us don't know why. (5 Viewers)

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4x4Labs rear bumper? Gawd I wanna get one.

Bummer on the rebuild. Definitely good that you have the funding for it right now. Have you considered a Vortec or Toyota diesel swap?
It is a 4x4 labs. This exact one is one of Lukes first. It was originally white but I had it stripped and coated black. I found it on Craigslist for $1200 in San Francisco and jumped on it. Cost me 500 to have it stripped and coated so 1700 all in. Deal if you ask me.
 
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Soooo....I have a theory. It's a longshot but it might just be right. It's possible the Thermocure itself is what caused the liquid to turn yellow. There is no change in the behavior of the motor since putting the thermocure in. It runs great. The engine oil looks fine. So I'm thinking I will continue the process as I had planned. This morning (with a pounding headache from all the greyhounds) I tried the leak test against a half used bottle of Thermocure. Literally just put it on top of the bottle and started pumping. It turned green. Not yellow like in a running motor BUT in order to get from blue to yellow you have to hit green. So it's affected by the thermocure. Fingers crossed. I figure I have nothing to lose at this point and may as well keep trying.
 
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Soooo....I have a theory. It's a longshot but it might just be right. It's possible the Thermocure itself is what caused the liquid to turn yellow. There is no change in the behavior of the motor since putting the thermocure in. It runs great. The engine oil looks fine. So I'm thinking I will continue the process as I had planned. This morning (with a pounding headache from all the greyhounds) I tried the leak test against a half used bottle of Thermocure. Literally just put it on top of the bottle and started pumping. It turned green. Not yellow like in a running motor BUT in order to get from blue to yellow you have to hit green. So it's affected by the thermocure. Fingers crossed. I figure I have nothing to lose at this point and may as well keep trying.
get a thermostat gun and measure temperature on the upper radiator pipe and then lower radiator pipe without AC running, then turn on AC and do the same, take a picture of your fan and shroud I like to see how much fan sticks out the shroud. that is the start
 
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Wohoo! Theory proven! I put a couple of drops of thermocure into the blue liquid and sure enough it turned yellow :) I think my motor is fine. Back in business baby! Turns out the greyhounds were just for fun!

PXL_20210724_143709613.jpg
 
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get a thermostat gun and measure temperature on the upper radiator pipe and then lower radiator pipe without AC running, then turn on AC and do the same, take a picture of your fan and shroud I like to see how much fan sticks out the shroud. that is the start
Temps are totally fine when the motor is idle. 180 with a 180 tstat in there (I know its supposed to be 190. I put a 180 tstat in for testing purposes) I'll take a picture later but the fan sticks out about an inch past the shroud.
 
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Temps are totally fine when the motor is idle. 180 with a 180 tstat in there (I know its supposed to be 190. I put a 180 tstat in for testing purposes) I'll take a picture later but the fan sticks out about an inch past the shroud.
measure the temp on the upper and lower radiator when you drive? I like to see if the rad is hot on the bottom
 

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Soooo....I have a theory. It's a longshot but it might just be right. It's possible the Thermocure itself is what caused the liquid to turn yellow. There is no change in the behavior of the motor since putting the thermocure in. It runs great. The engine oil looks fine. So I'm thinking I will continue the process as I had planned. This morning (with a pounding headache from all the greyhounds) I tried the leak test against a half used bottle of Thermocure. Literally just put it on top of the bottle and started pumping. It turned green. Not yellow like in a running motor BUT in order to get from blue to yellow you have to hit green. So it's affected by the thermocure. Fingers crossed. I figure I have nothing to lose at this point and may as well keep trying.
That'd be good news if it was just a false positive on the test fluid, for sure.
 
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FJ60/FJ62's came with green coolant. The first time I encountered the Toyota Red coolant was the FZJ80.
Both green/red coolant is ok provided you change the coolant on a regular basis. Coolant will go bad. Ok wait...Glycol and water will last forever. Today' coolant contains sacrificial rust/corrosion inhibitors. They coat the radiator and passages with a protective coating. Since rust and Corrosion never sleep... at some point the coolant's ability to protect the internals wears out. 2-5 years usually. This becomes more evident when the coolant changes color. With bad coolant, the nasty's start to develop inside cooling system, this in turn will clog you radiator and tiny passages raising your engine temps. This is when the flushing starts.

The Toyota cooling fan clutch has 2 features. One: viscous fluid. The fluid is what spins the fan. Direct spinning fans are very noisy, eat horse power, and are not necessary when traveling 60mph; so they are designed to slip. Two: There is a spiral thermostat wire in the front center of the clutch fan facing the radiator. The spiral wire changes shape from the hot air coming off the radiator physically reducing the amount of fan slip. When the engine starts to cool ( air through the radiator) the spiral thermostat wire releases the fan back to a slipping state. When a clutch fan goes bad, fluid leak, bad clutch it will spin freely (slip). The FSM has a temperature test for the fan clutch. All of this is balanced with the engine thermostat and radiator cap. A 190 degree engine thermostat will keep you engine around the 200-210 degree point. Assuming the engine is ok.

The cooling system needs a certain amount of pressure to prevent boil over. Each 1lb of pressure (CAP) adds about 12 degrees to the boil over point. This along with the radiator, good coolant and thermostat keeps the engine happy. The cap releases heat pressure (and coolant) into the overflow. When the pressure drops, the fluid will return back into the radiator. This is why the coolant overflow has a cold level and a hot level.

A weak engine (worn) will run hot, because it needs to work harder to move the rig. Putting more demand on the cooling system (runs hotter). A weak head gasket allows cooling pressure to escape into the cylinders, engine, or into the engine bay. Anti freeze into the cylinders will go out the exhaust (killing your converter in the process). A slightly weak head gasket will stop leaking when the engine is cool.

Knowing all the contributors to over temp conditions keeps you from shot gunning parts at your rig.
Checks:
1. Engine Compression test
2. Coolant system pressure check
3. Engine gases in the coolant (chemical test)
4. Fan clutch (engage disengage)
5. healthy cooling system (good flowing radiator, thermostat, radiator cap, good fluid, no leaks)
6. Water pump (no seeping from the weep hole, pump shaft tight)
7. Bad coolant, could/would equal blocked passages (this is when the repair shop opens the radiator and pushes a rod through the exposed passages to clear the blockage)

FYI:
A high mileage cooling system has components that wore out together. Add a new thermostat, or radiator, or radiator cap. The internal coolant pressure can change (back to stock levels). Forcing a head gasket leak, water pump leak, heater core leak, hose to leak, or radiator leak.
 
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Knowing all the contributors to over temp conditions keeps you from shot gunning parts at your rig.
Checks:
1. Engine Compression test
2. Coolant system pressure check
3. Engine gases in the coolant (chemical test)
4. Fan clutch (engage disengage)
5. healthy cooling system (good flowing radiator, thermostat, radiator cap, good fluid, no leaks)
6. Water pump (no seeping from the weep hole, pump shaft tight)
7. Bad coolant, could/would equal blocked passages (this is when the repair shop opens the radiator and pushes a rod through the exposed passages to clear the blockage)

These are great suggestions! Most of these things are good. Pretty much everything in the cooling system is brand new.

I do plan on running a pressurized reverse flush through the radiator. I'll be removing it to do that.
 
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So I'm starting to believe this thermocure stuff is magic. Tonight I ran the car for about an hour and a half and cranked the heat up all the way. I used to get maybe 105 out of it. At peak today it hit 161. That's running it full bore for about an hour. I watched it slowly climb. I didn't even turn the heat on until the engine was hot. It took a long time to get there but the heat has never blown so hot. Thermocure at work I think. I'm convinced now I have a ton of gunk in my engine and this stuff is breaking it down. Jury is out on whether or not its the ultimate fix but it's helping for sure. Unfortunately I need to drive down to the Bay for a few weeks but I will resume testing when I get back. 161 degrees. Nuts. I felt like I was in a Russian banya.
 
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Hey all. Did a valve job today and I'm hearing a ticking sound that I just wanted to confirm with you all. I THINK it's my fuel injectors but just wanted to confirm. Valves are nice and quiet now.

Try using a mechanic's stethoscope or a piece of heater hose with one side put to your ear and the other end you'll use try to pinpoint where the ticking is coming from. Be careful around moving parts!
 
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Try using a mechanic's stethoscope or a piece of heater hose with one side put to your ear and the other end you'll use try to pinpoint where the ticking is coming from. Be careful around moving parts!
Yeah, I think I'm going to pick one up today. Good call. It MIGHT be an exhaust leak but I'm seriously doubting it's the valves.
 
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Try using a mechanic's stethoscope or a piece of heater hose with one side put to your ear and the other end you'll use try to pinpoint where the ticking is coming from. Be careful around moving parts!
Got the stethoscope. It's the injectors. I can actually feel a knock through the stethoscope as it happens. I'm wondering if I should replace them.
 
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Next round of Thermocure (abbreviated TC from now on because I'm tired of typing it out) is drained! Original on the right and current on the left. It looks a lot better (you can actually see light through it!!!) but it appears there is still more to go. I'm going to fill the car up with 50/50 coolant this time around since I'll be gone tomorrow for a couple of weeks and resume in August. The plan is to drive it around a while without the TC to see if it's helped any. Unfortunately my forced water/air flush gun hasn't arrived yet. No idea where it is. Oh well. More to come in a few weeks.

PXL_20210728_202930128.jpg
 

Spook50

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Next round of Thermocure (abbreviated TC from now on because I'm tired of typing it out) is drained! Original on the right and current on the left. It looks a lot better (you can actually see light through it!!!) but it appears there is still more to go. I'm going to fill the car up with 50/50 coolant this time around since I'll be gone tomorrow for a couple of weeks and resume in August. The plan is to drive it around a while without the TC to see if it's helped any. Unfortunately my forced water/air flush gun hasn't arrived yet. No idea where it is. Oh well. More to come in a few weeks.

View attachment 2743977
I gotta say I'm impressed with your results so far.
 
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Hey all! Been a while. I ended up being in SF a lot longer than I anticipated and when I got back I didn't feel like working on the cruiser much :p

Anyway, I'm back at it but gotta say that the Thermocure did not resolve the issue. It might be a LITTLE better but was definitely not the issue.

Tomorrow I will be replacing the radiator with a Mishimoto since my current one has a pinhole leak and needs to be warrantied. That one will be kept as a spare or put into my dads 62.

I plan on using an air compressor water pressure gun with the thermostart out in both directions to try and get any extra crap out of the block. Not sure how the water pump being in the way will affect it but we'll find out. Also, I plan to use the same gun on the old radiator to see how much crap comes out of it.

This has become comical at this point. Never have I been so stumped by overheating issues before. 🤷‍♂️

EDIT: Oh, and I reran the vapor test after having regular coolant in the truck and it stayed blue so the head gasket is good.
 
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I have a theory that might be contributing to overheating. Some viscous fans sound like a tornado, and others can barely be heard. I remember reading the early 80's 3f fans were better.
Do you mean the fan itself or the clutch? I know my clutch is working fine... The fan is actually some spare that ccfj40 had laying around as the one I bought the truck with was cracked.
 

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