FJ40 Thermostat Installation How To (1 Viewer)

[Nolacajun75]

I’m not sure if this is even possible …but I’m going to ask…is it possible that you have the fan on backwards. Thus the fan is not pulling air thru the radiator.

Any chance you can post up some pictures of your situation? I’d like to see the condition of your fan.

I will post pictures. I'm at home right now. The fan is definitely not backwards. I can feel a lot of pressure blowing toward the engine and enough air moving through the radiator to suck several sheets of paper to it while at idle. The fan is in great condition. No cracks, no brakes, no nothing.

I talked to Toyota Matt. I finally got it figured out. I think with no thermostat it's looking good. So I'm going to try to take everything apart one more time. Put the OEM Toyota thermostat 190 back in and try it one more time with a thermostat

 

[John McVicker]

Sounds good…BUT…I believe it would still be beneficial for us to see pictures.

EDIT: Again, what you’re doing sounds fine, put the 190* OEM T Stat & see what happens. Just one thing tho, if running w/o your T Stat solves the issue, that’s NOT a fix, it’s a band aid.

 

[Nolacajun75]

Sounds good…BUT…I believe it would still be beneficial for us to see pictures.

Yes sir, will do

 

[Nolacajun75]

I will post pictures. I'm at home right now. The fan is definitely not backwards. I can feel a lot of pressure blowing toward the engine and enough air moving through the radiator to suck several sheets of paper to it while at idle. The fan is in great condition. No cracks, no brakes, no nothing.

I talked to Toyota Matt. I finally got it figured out. I think with no thermostat it's looking good. So I'm going to try to take everything apart one more time. Put the OEM Toyota thermostat 190 back in and try it one more time with a thermostat

Here's a picture of my fan installed. I'm like 99.99% it's not backwards, but if it is please tell me. I've been an idiot before. Won't be the last time. Thanks brother

 

[Nolacajun75]

Sounds good…BUT…I believe it would still be beneficial for us to see pictures.

EDIT: Again, what you’re doing sounds fine, put the 190* OEM T Stat & see what happens. Just one thing tho, if running w/o your T Stat solves the issue, that’s NOT a fix, it’s a band aid.

I ran it for about an hour today. It sat Island for about 30 minutes. Got about Midway on my stop temperature gauge. Everything felt normal. I drove it for about an hour and it got to the mark right before the h so it was running hot and normal but don't think it was quiteating and it was running decent but not quite sure and that's without the thermostat so I'm kind of curious if it's a either still overheating with no thermostat so I do still have a problem or b. It's working normal and I just have a air bubble in there still. So I'm going to keep trying to burp it and keep riding with no antifreeze. Just distilled water and water weather until I am 100% sure the problem is fixed and then I will put the thermostat in. What do you think?

 

[John McVicker]

Sounds to me as if you still have an issue. That is you do with 3 important ‘if’s’.

1) IF…your T Stat is good.
2) IF…your dash gage is good.
3) IF…your IR gun is good/accurate.

In the mean time I would continue burping. One question…do you have a loose driver side motor mount?

Some minor marks on your radiator fins that appear to be from the fan.

 

[Nolacajun75]

Sounds to me as if you still have an issue. That is you do with 3 important ‘if’s’.

1) IF…your T Stat is good.
2) IF…your dash gage is good.
3) IF…your IR gun is good/accurate.

In the mean time I would continue burping. One question…do you have a loose driver side motor mount?

Some minor marks on your radiator fins that appear to be from the fan.

Thank you
I don't think the motor mount is loose. Everything seems tight. I did not check it. I'm not even sure where it's at to be honest with you. The motor mount that is. The fins that are moved around a little bit on the radiator that you see next to the fan is when I was installing the fan my arm was rubbing on it.

The thermostat is not installed currently but the two thermostats that I did put in did operate correctly as I checked them before and after in boiling water.

The laser thermostat is brand new and it seems pretty accurate. I did check it. It gets boiling water and different things. I knew the temperature was and it was pretty damn close.

The gauge seems to be working as it has been in the past with no problem so I wouldn't see why it would be bad now. I did check it against ground and it did ground out Max and stay there until I turn the key off. Turned it back on and it reset itself once I move the ground. I did order another OEM sending unit just for the hell of it so I'll change that out when I get it from Toyota.

 

[Nolacajun75]

Thank you
I don't think the motor mount is loose. Everything seems tight. I did not check it. I'm not even sure where it's at to be honest with you. The motor mount that is. The fins that are moved around a little bit on the radiator that you see next to the fan is when I was installing the fan my arm was rubbing on it.

The thermostat is not installed currently but the two thermostats that I did put in did operate correctly as I checked them before and after in boiling water.

The laser thermostat is brand new and it seems pretty accurate. I did check it. It gets boiling water and different things. I knew the temperature was and it was pretty damn close.

The gauge seems to be working as it has been in the past with no problem so I wouldn't see why it would be bad now. I did check it against ground and it did ground out Max and stay there until I turn the key off. Turned it back on and it reset itself once I move the ground. I did order another OEM sending unit just for the hell of it so I'll change that out when I get it from Toyota.

Is it normal to run a little hot with no thermostat? Still not sure if I have a problem. I'm going to put the OEM 180 thermostat back on and see what happens next. This time using a vacuum setup to put antifreeze in so hope no burpin

 

[John McVicker]

No it is not normal to ‘run a little hot’ once you remove your T Stat. It is not a good idea to run your engine w/o a T Stat long term. If it runs hot w/o a T Stat it will also run hot once you put it in. It’s fine to do it while you’re testing etc. but not long term.

A T Stat is designed to help your engine get UP to proper working temperature, it’s not good to run below a certain temperature.

I’ve never used a Vacuum set up to add anti freeze and/or water. But if you do it correctly the vacuum set up is prob easier.

In your case…use your IR Gun to make decisions on what your real temps are.

 

[Nolacajun75]

Okay so for troubleshooting purposes, I am going to install this commercial grade flow meter on the top radiator hose and run it to verify the water pump is pushing water properly.

I then plan to remove that hose and keep it for troubleshooting and install a second hose with the secondary thermostat installed and run that into the cabin where I can verify exact temperature coming out of the thermostat into the radiator.

I think once I do both of these things it will tell me everything I need to know and if there is still an issue and everything works fine. I guess it either has to be a head gasket failure or something blocked up in the cylinder wall somewhere????

I'll post again once I get everything done and installed. It's going to be a week or two before I get the parts but I'll be back

 

[sleepycruiser]

Does anyone know the studs used in the earlier thermostat housings?? 1964 FJ40. I bought the bolts for it before I realized it actually has studs.

Note: They are wet bc I’m spraying PB Blaster on them to hopefully make the job easier. It’s going to suck since they are studs, I imagine.

 

[RevISK]

Does anyone know the studs used in the earlier thermostat housings?? 1964 FJ40. I bought the bolts for it before I realized it actually has studs.

Note: They are wet bc I’m spraying PB Blaster on them to hopefully make the job easier. It’s going to suck since they are studs, I imagine.

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I imagine it’s going to be better with studs.
Less chance of galvanic corrosion ruining your day.

 

[sleepycruiser]

I imagine it’s going to be better with studs.
Less chance of galvanic corrosion ruining your day.

I’m hoping. I want to replace them so I guess when I get to that point I’ll get the length/threads.

 

[RevISK]

I’m hoping. I want to replace them so I guess when I get to that point I’ll get the length/threads.

Trying to replace them is where you’re likely going to run into galvanic corrosion. If they were mine and I got the nuts off without snapping a stud, I’d bow a thank you towards Japan and run them for another million miles.

 

[sleepycruiser]

Trying to replace them is where you’re likely going to run into galvanic corrosion. If they were mine and I got the nuts off without snapping a stud, I’d bow a thank you towards Japan and run them for another million miles.

Makes sense. I might just do that and clean up the threads. Breaking them would suck.

 

[RevISK]

Makes sense. I might just do that and clean up the threads. Breaking them would suck.

Many folks swap to studs after going on a bolt snapping adventure. I’ve got a thermostat to replace on my 62 and I am dreading it. Snapped the bolts on the one in my 40.

 

[Franklin]

11. After everything is all buttoned up and back to the way you found it. Take a hose and wash down everything that the coolant could have dripped on. If you own any pets keep them away while you are washing the residual coolant away. They have a tendency to like the taste/smell of coolant.

12. Open up your radiator cap and set it to the side. Place a funnel over the radiator and fill it. Keeping the radiator cap off, start your truck and move the interior heat setting to high but keep the fan to off or low depending on your vehicle’s controls. Monitor the coolant level in your radiator it will take a little while for your engine to heat up. Once it does the thermostat will open and the coolant lever in the radiator will drop. Top it off once it does and monitor for a few more minutes to make sure all the air bubbles are out of your coolant system. Turn off the engine and install your radiator cap. Then top off your coolant over flow bottle (if it needs it) and you are done.

Check again in 50 miles. Top off if needed.

Thanks to this thread in the 100s area for allowing me to copy some of these steps.

Thank you for the detailed instructions. Waiting on a new thermostat and appreciate the help.

 

[sleepycruiser]

Credit to @S.CarolinaFZJ80 on here for recommending the use of carb studs and nuts instead of bolts for the upper housing. Pretty clever idea as you’ll never need to worry about removing the bolt. His pics.

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@letterman52
I cant take credit for the idea. Another mud member & vendor @ToyotaMatt mentioned using a stud in place of a bolt. I just stumbled across a proper length stud.

Do you recall the torque for the nuts if you have studs? I did 12 ft lbs as that is what the bolt version calls for and that felt pretty snug. Just wanted to check.

 

[S.CarolinaFZJ80]

Do you recall the torque for the nuts if you have studs? I did 12 ft lbs as that is what the bolt version calls for and that felt pretty snug. Just wanted to check.

I think I used 13ft lbs