Thermostat Housing Install

[kvanoort]

I'm ready to install the thermostat housings and thermostat onto my '75 2F rebuild project and I was hoping to find some install tips here on MUD. The FSM doesn't provide any detail. If someone has a link to this procedure, that would be great.

Tips I've found and remaining questions:
- Use anti-seize on the bolts that go into the lower thermostat housing. Torque bolts to ___ f/lb?
- There are three gaskets for the thermostat? (Not including the housing to block gasket.) One large rubber, another large but thin and one that goes on top of the actual thermostat. Of the two large gaskets, which one goes where? Both gaskets came with an OEM engine gasket kit.

- I've leveled out the mating surfaces of both the upper and lower thermostat housings -- should I still use high-temp sealant on the gaskets?

- Torque for the housing to block bolts are between 13-18 f/lb? Should I use a little blue thread lock on the bolts?
- Should I use gasket sealant on the gasket between the lower housing to block?

If anyone is interested, I'll take pictures of the assembly process and post them as I put things together. Thanks for your help.

 

[rus1980]

I just did this on my 78. It's pretty easy and trust me I don't know anything about this kinda of stuff.

The only advice I could give is to replace the old bolts out of the casing with brand new ones. The old ones could be and are likely very rotten. I broke the ones on mine while trying to tighten them back on.

Also, Make sure you scrap all the old gasket and crap off the surfaces prior to replacing the gasket with the new one. You'll also want to use some gasket sealant to ensure no leakage.

Trust me on the new bolts. I can't remember the size. But it's so cheap and such a good idea.

These points seem very obvious... I wish I would have thought of them before I had to take my thermostat casing to a machine shop to have my work fixed!

 

[kvanoort]

From Coolerman's Website:

Lay the top housing on its back and place the round top gasket into it's recessed area. Apply a VERY THIN film of silicone sealant to both sides of the oval paper housing gasket and place it over the thermostat. then place the thermostat on top of the round gasket. Note: If you don't put the round gasket on top of the thermostat, coolant will be allowed to bypass the thermostat and the engine will not heat up properly. This will also result in your heater not working very well.

Coat the entire length of the two cover bolts with anti-seize. This will help prevent the cover from oxidizing to the bolts. Bolt the top cover back on. Don't over tighten!

 

[Trollhole]

Never seen two gaskets used just one paper one. Anti sieze and selant is a good idea.

I'm sure someone smarter than me will chime in.

 

[ibejamie]

I just did mine. Mine is a different version (the four bolt flange) but identical otherwise (from what I can tell).

The process is very simple- VERY important to properly install the circular gasket (on top of your thermostat in the picture) I would use the thinner of the other two gaskets with a good bead of RTV. Also- x2 on the new bolts (I see you have them in the picture) I snapped one of mine on reinstall- hasn't leaked yet, but I think the fact that I have four bolts it sort of helps out. I plan to change it out as soon as I see some leakage.

Good Luck (coming from a guy that has only just begun figuring out what tools do what...)

 

[cleanpool2]

huh???

Once you are doing this will you take pictures of how you do it.
I am not understanding which round gasket and which side up the thermostat goes.
And lets us know the out come.
both of my top bolts are broken by PO.
Any clues how to get them out.???
Pictures sure will help this thread.
Thanks

 

[Trollhole]

Once you are doing this will you take pictures of how you do it.
I am not understanding which round gasket and which side up the thermostat goes.
And lets us know the out come.
both of my top bolts are broken by PO.
Any clues how to get them out.???
Pictures sure will help this thread.
Thanks

The pic above is pretty good. The round gasket is already on the thremostat. And it is in the right position.

 

[kvanoort]

Once you are doing this will you take pictures of how you do it.
I am not understanding which round gasket and which side up the thermostat goes.
And lets us know the out come.
both of my top bolts are broken by PO.
Any clues how to get them out.???
Pictures sure will help this thread.
Thanks

This link should help you get the broken bolts out of the housing:
https://forum.ih8mud.com/40-55-series-tech/181667-thermostat-housing-question.html

I'll post pictures of my thermostat and housing install process soon . I'm still searching for information on the subject.

 

[Fast Eddy]

both of my top bolts are broken by PO.
Any clues how to get them out.???

They broke because the previous install was done without anti-sieze and they are completely corroded. You will save yourself a lot of headache by posting on the wanted parts forum and getting a good used one. The thread above has good advice if you must save it for some reason.

 

[kvanoort]

Found a link about using High-Temp RTV to seal the thermostat gasket:

https://forum.ih8mud.com/40-55-series-tech/75525-thermostat-gaskets-question.html

Gaskets for the water pump and water inlet (thermostat housing) which mount to the block, should I use any sealant in addition to new gaskets?

From Poser - Re: Thermostat Replacement
I use a light coat of silicone on both sides of the housing gasket.

Do you have the seal for the top of the stat to the housing? Should be a black rubber(hard now) ring.

I also use anti-seeze on the bolts to prevent them from corroding and becoming one with the housing through dissimilar metal corrosion, and I usually put in new bolts too, but if yours are in good condition and not detierorated, you should be fine.

From Cruiserdrew - Re: Thermostat Replacement
Those bolts are the crappiest bolts Toyota makes-I have snapped 2, and I am very careful about stuff like that.. I do what Poser does-a very thin layer of RTV-gray-on the housing gasket and antiseize the bolts. If you like having heat- make sure you install that upper gasket on the top of the thermostat. One other thing-Use Toyota gaskets-NAPA sells a set, but the housing gasket is too thick to work properly.

 

[bsevans]

I replaced my bolts with stainless steel bolts and used anti-sieze. I also ran a tap in both threaded holes in the lower housing. I found that using high temp RTV has eliminated any leaks past the gasket.

 

[kvanoort]

Thermostat Install - continued

Just thought I would share some additional work I've done to the thermostat housing for my '75 2F. After I leveled out the matting surfaces on the two housing pieces, I took my trusty old dremel with a multipurpose cutting attachment and ground down the inside edge on the lower housing -- the area where the thermostat sits. I didn't take much material off, just enough so that the thermostat is recessed into the lower housing and even with the surface. Here are a few pics.

I also picked up some water pump & thermostat housing RTV silicone to insure that there will be no leaks in the near future.

I've benefited from MUD so much that I hope someone else finds this information useful.

 

[calixto]

So are there 2 gaskets or 3? I only have a thin paper one and the oval one that goes on top of the therm....I don't have the thicker looking one in the picture at the top of the thread. Weird because I haven't busted into my housing yet to replace but it looks like I also have a thicker one like the one I am missing in my replacement set sandwiched betwen my two housing halves...it is sticking out the sides a little of the two halves. I looked at the SOR diagram and it looks like there are only two? Should I wait and get the third to do the job? Is the thicker (maybe rubber) gasket re-usable?

 

[antFJ]

from a post i read the rubber one doesn't work very well - just use the paper one and the one on top of the thermostat.

 

[motoloco]

This is an interesting post to me, I just bought a new gasket and thermostat for my march 79' there were some changes around this time to the housing I think, anyway I got the paper gasket and the round upper rubber thermostat gasket, WONT work, it is too tall with the paper gasket and wont clamp shut tight enough to keep it from leaking. I removed the upper gasket and it will seal but sure enough, it does not warm up properly and the heater sucks. I am going to try the thicker rubber gasket instead of the paper, I believe the thicker rubber gasket was for the F engines but I dont have a choice.

 

[motoloco]

Anyone know about there being two slightly different heigth thermostats between 78'/79'?

 

[mikealeus]

X2 on the rubber one not working!

 

[FJ40Jim]

Motoloco, all the t-stats are the same size AFAIK. The 79-80 t-stat housing is slightly differnet from others. Try the thick rubber gasket between halves, instead of the usual paper gasket. It's the one on the right in picture post #1.

 

[motoloco]

FJ40JIM, that was/is my next plan of attack, or, a little of the thermostat sealant on the paper gasket. Thanks

 

[redbone]

I got my '77-2F thermostat from Advance Auto Parts and it was too tall to fit with what I call the "doughnut" or rubber gasket inside the housing.