FJ62's Overheating. Several of us don't know why.

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I'll be taking pictures later on but the initial coolant color after using the thermocure is black. It's definitely doing something. I'll be flushing the block again after work today and will fill it with distilled water and thermocure again. This time I plan to run it for several days.
 
Here's the color of the distilled water with Thermocure after driving the cruiser for about 2 hours yesterday. Looks like old motor oil! So it's definitely doing something...is it the fix? Jury is still out on that one but this has me hopeful!

You can also see my old coolant has kind of an orange tinge to it.

PXL_20210719_193604336.webp
 
Here's a Debbie Downer side note:
So it's been said that rust scaling inside a cast iron block and head can cause heat transfer from the metal to the coolant to not be as efficient.

The temperature gauge reads the temperature of the coolant, not the actual metal. If a cast iron engine was coated on the inside with rust scale, the heat transfer from the metal to the coolant would be slower - so the coolant would actually be cooler. Temperature gauge (which is coolant temperature) would show lower.

This logic may be wrong, but I'm thinking that pouring some rust remover inside the engine won't be the fix.

I had my cylinder head off after 30 years and 290,000 miles. When I peered inside it and the block, I could see a very light patina of orange in a few spots, certainly nothing that would affect cooling at all.
 
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OSS said:
Here's a Debbie Downer side note:
So it's been said that rust scaling inside a cast iron block and head can cause heat transfer from the metal to the coolant to not be as efficient.

The temperature gauge reads the temperature of the coolant, not the actual metal. If a cast iron engine was coated on the inside with rust scale, the heat transfer from the metal to the coolant would be slower - so the coolant would actually be cooler. Temperature gauge (which is coolant temperature) would show lower.

This logic may be wrong, but I'm thinking that pouring some rust remover inside the engine won't be the fix.

I had my cylinder head off after 30 years and 290,000 miles. When I peered inside it and the block, I could see a very light patina of orange in a few spots, certainly nothing that would affect cooling at all.
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I would tend to agree with this statement. Makes sense. However looking at my coolant tells me I have more than just rust scaling. The truck sat outside for a year with no water pump attached before I even got to it. My thinking is that the rust is more extensive in my case. I also believe I have sediment in the block. I currently have the drain plug in the rear of the block off and will be flushing the entire system again. Yesterday I did not have the rear plug off. I will be placing clear plastic containers underneath to catch any sediment that may fall out as the flush will be happening on a gravel driveway and who knows what come out of there.

I also noticed when I pulled the drain plug on the radiator yesterday it was only trickling out. I had the radiator cap off so it wasn't a pressure thing. This tells me I have crap in there too.

I mean I've tried everything else and this is kind of a last ditch effort and will not make things worse (I hope). I dunno... I'll continue updating as I have them.
 
OSS said:
Here's a Debbie Downer side note:
So it's been said that rust scaling inside a cast iron block and head can cause heat transfer from the metal to the coolant to not be as efficient.

The temperature gauge reads the temperature of the coolant, not the actual metal. If a cast iron engine was coated on the inside with rust scale, the heat transfer from the metal to the coolant would be slower - so the coolant would actually be cooler. Temperature gauge (which is coolant temperature) would show lower.

This logic may be wrong, but I'm thinking that pouring some rust remover inside the engine won't be the fix.

I had my cylinder head off after 30 years and 290,000 miles. When I peered inside it and the block, I could see a very light patina of orange in a few spots, certainly nothing that would affect cooling at all.
Click to expand...
I'm inclined to agree with you. I think the case where this wouldn't be the situation would be where coolant flow is being restricted at some location. My radiator is only two years old (CSF), but it's been somewhere around 15 years or so since I've flushed my system. And if one has religiously used Toyota Red coolant but may have used tap water or other than distilled, I could see a possibility of scale buildup rather than rust.
 
The manufacturer of that stuff says that it's an environmentally safe formula, but you gotta wonder what the hell its chemical composition is that can pull black ooze out of the cooling system. Or what the hell that black ooze is. Geepers
 
CruisD64 said:
A while ago there was a guy in San Carlos, CA that did chemical flushes (not harmful) through the block. He used a pump and circulated through the block in both directions with some chemical. Rinse and repeat. I'm thinking I'll do something similar.

This is the shop that does it. I'll try reaching out to them and find out the best way.

San Carlos Auto Radiator

www.sancarlosradiator.com
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They must be good at what the do because their website looks like it was made using free software from a CD that was inserted a copy of PC Computing from the early 90's! I don't even see a physical address. EDIT: I found it: 1009 El Camino Real, Millbrae, CA
 
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CruisD64 said:
I'm not counting anything out at this point. I did order one of those high pressure water and air guns.

Hopefully forcing the water in both directions loosens whatever is in there. I'll be doing that first and then a proper chemical flush.
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I have an FJ60 and I have been going through this for about ten years and never figured out what was causing the overheating issue. I did everything you've done so far, but not a professional chemical flush.
 
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cps432 said:
So anything you do at this point is an improvement
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Haha. Yes. This is still from the first Thermocure flush. The second batch went in today and I'll be running the car with it for a week or so depending on how much I drive. I might be going into Reno this week so that'll be 70 miles.

The first flush was only after driving about an hour and that's what came out. Curious to see if the next one looks similar after more driving.
 
I installed a 2F that had been sitting for 12 years (cooling system open to the air) in my FJ40. All the rust scale in the block eventually clogged the radiator. The symptom was that the truck would slowly start to overheat on the freeway, with lots of air going thru the radiator. Classic case of 'not enough radiator capacity' due to clogging.

I suspect that after you do all these flushes and potions and lotions, you will need a new radiator or a serious cleaning of the one you have.

Steve
 
Round 2 of Thermocure is currently draining. Still dark but definitely lighter than round one. I'll be doing it again and driving the car down to San Francisco next week.
 
Doesn't matter at this point. I found out my motor needs a rebuild. Or I didn't do the head gasket right. Decided since I was doing all this to try the coolant leak test and sure enough the fluid turned yellow right away. I'm going to rebuild my motor. Still deciding whether or not I wanna just convert to an H55F while I'm at it. Luckily my companies stock is doing great so moneys not really an issue but still it sucks. I doubt it's the thermocure that did it but at this point it doesn't matter. Lotsa greyhounds for me tonight....

PXL_20210723_224813423.webp
 
CruisD64 said:
pr0n pic of the overheating monster! :p

View attachment 2739334
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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?
 
Spook50 said:
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?
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Was going to say the same about the bumper its my favorite rear bumper for 60s and 80s one day I may purchase one.
 
CruisD64 said:
Doesn't matter at this point. I found out my motor needs a rebuild. Or I didn't do the head gasket right. Decided since I was doing all this to try the coolant leak test and sure enough the fluid turned yellow right away. I'm going to rebuild my motor. Still deciding whether or not I wanna just convert to an H55F while I'm at it. Luckily my companies stock is doing great so moneys not really an issue but still it sucks. I doubt it's the thermocure that did it but at this point it doesn't matter. Lotsa greyhounds for me tonight....

View attachment 2739468
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Think of this as a “design opportunity”....
 
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