Rubber Thermostat Housing Gasket

777Gage

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Hello All,
I was replacing most of my cooling system today on my 78 and got to the last gasket, the Thermostat housing gasket, between the upper and lower housing. I noticed the thin paper gasket wasn't going to work, I needed a thicker material. Did a quick search and cam up with this thread FJ40 Thermostat Installation How To and noticed the 2 different gaskets. I checked FJparts.com as referenced in the thread but they are out of stock. Gasket, Thermostat Housing, 58-67 FJ40 45 25, OEM

Anyone found a different source for this thick rubber gasket? (PO had used the paper gasket plus some type of rubber gasket material to fill the gap)

Borrowed a couple of pics from the mentioned thread for reference.

Thank You!

Sculptor Painting.jpg


IMG_6492.JPG
 
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777Gage

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I don't know.......I ordered all the cooling parts from Cruiser Outfitters - Water Pump and Thermostat. I put the thermostat in with the "upper" rubber gasket, and I've got a larger gap in the bottom housing than I'm comfortable with mounting for the paper gasket that was sent.

I did a Mud search and discovered others have run into the same problem.

Calling Cruiser Outfitters first thing Monday morning.
 
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65swb45

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1. The rubber gasket you are looking for is ONLY for the pre-66 cruisers. The hole spacing is different than on the newer ones.
2. Some of the replacement upper gaskets are thicker than others, and the thick ones will create a problem where none existed before. The solution is not to get something thicker for the lower application; thinner for the top. ;)
 

777Gage

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Mark,
That's exactly what I thought. In triple checking everything, as far as I know my thermostat housing is bone stock 78 (impossible not to be??) - So maybe I was sent a thermostat that's slightly too tall or the upper thermostat gasket is to thick?

If I take out the upper thermostat gasket it all fits together, but I know that's supposed to be on top of the thermostat.

I am perplexed.......it should be the easiest of what I accomplished today. I thought to check here first before applying more force than required to close the gap.
 
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Steamer

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One time I pulled out a t-stat and I found the top gasket was out of position and up on the raised edge of the t-stat’s upper part. It might be over cautious but now I have two longer bolts with the heads cut off and use them as guides, so the top housing comes straight down without bumping the stat or the top gasket. With a little down pressure, I swap out those guides for the bolts one at a time. Just a little extra step that makes me feel better.
 

777Gage

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So, 777,

Did you resolve this, and how?
I checked with Cruiser Outfitters yesterday morning, they said there shouldn't have been a gasket in the thermostat box they sent me. They sell them separately, but somehow mine slipped by with a gasket, and is thicker than an OEM apparently. (Upon checking part #'s) Also, if I take the gasket out the 2 halves of the thermostat housing fit together perfectly, so I know a thinner one will work.

They are sending me out the correct one. I'll update with pictures when I receive it.

(The gasket that was on the thermostat from the PO is also rubber and about 1/2 the thickness of the new one, but I assumed that might be due to age.)
 

65swb45

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Mark,
That's exactly what I thought. In triple checking everything, as far as I know my thermostat housing is bone stock 78 (impossible not to be??) - So maybe I was sent a thermostat that's slightly too tall or the upper thermostat gasket is to thick?

If I take out the upper thermostat gasket it all fits together, but I know that's supposed to be on top of the thermostat.

I am perplexed.......it should be the easiest of what I accomplished today. I thought to check here first before applying more force than required to close the gap.
Thats what the like button is for.;)
 

Bear

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Thank-you, 777. Please share your final results with us when your install is done.

I had been in the original discussion about this, and have wondered about the tolerances of some of the individual pieces possibly being changed over the years by a combination of different OEM suppliers along with superseded parts. Simply omitting the upper rubber gasket to allow using the thin paper joint gasket is not a wise solution, as it eliminates the purpose of the upper gasket. As this has occurred to a number of users over the years, but not the majority, there does seem to be an issue that would be nice to resolve definitively for everyone.

I am only concerned about Toyota packaged parts all fitting together correctly. Of course using anything aftermarket introduces another separate set of issues.
 

777Gage

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Thank-you, 777. Please share your final results with us when your install is done.

I had been in the original discussion about this, and have wondered about the tolerances of some of the individual pieces possibly being changed over the years by a combination of different OEM suppliers along with superseded parts. Simply omitting the upper rubber gasket to allow using the thin paper joint gasket is not a wise solution, as it eliminates the purpose of the upper gasket. As this has occurred to a number of users over the years, but not the majority, there does seem to be an issue that would be nice to resolve definitively for everyone.

I am only concerned about Toyota packaged parts all fitting together correctly. Of course using anything aftermarket introduces another separate set of issues.

So I got impatient waiting for USPS from Cruiser Outfitters, scheduled delivery tomorrow or Thurs and drove 20 min down to SOR. Called John, explained the issue, and he pulled a gasket for me. I took all the original parts and the new thick gasket for reference. The second he saw the gasket he said there's no way that's going to work, it's too thick.

I came home and put the housing all together, worked just as it should, now I'll let it set-up.
Picture below.

20200630_130521_resized.jpg
 
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777Gage

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For future reference, here is a picture of the thermostat rubber gaskets. From left to right
1. Original gasket I pulled out. (seems to be a bit spread out from age, but still pliable, could have re-used in a pinch)
2. Gasket that came in the box of the new thermostat - Aisan Part # THM-004 (thermostat part #)
3. Gasket from SOR - Part # 054-018A

The middle (#2) gasket is "almost" twice as thick and as rubber gets thicker it gets less pliable. I would have risked cracking/breaking the upper housing if I had just tried to make it work. The thinner gaskets are more elastic, if that make any sense.

Also, I'll post a pic of the Cruiser Outfitters gasket when it arrives, I think they said it was a cork gasket?

Inked20200630_122913_resized_LI numbered.jpg


20200630_122959_resized.jpg
 

Bear

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Excellent reporting--thank-you. I also have a cork joint gasket, don't remember the source. Just to repeat, you used the thinner rubber gasket from Specter on top of the thermostat, and the thin paper joint gasket, or the thicker green or blue fiber gasket in the joint between the halves? And no goobering it up with a thick bunch of silicone, right?

Specter indicates that there are two different upper gaskets, the change date being Jan. 1979. Could that be the issue here? Maybe your 1978 was at the end of the 1978 production line and received a later thermostat housing, or your previous owner changed it out with the newer piece? Additionally, I believe the two different temperature thermostats are interchangeable, but maybe there is a slight height difference between them.

Interesting that any manufacturer would include an incorrect gasket, be it OEM or aftermarket, since I believe the aluminum thermostat housing--top and bottom--only changed from 2-bolt to 4-bolt, with of course taps for sensors in some markets. Unsure if at some point in production the molds for the upper casting changed to create somewhat thicker aluminum above the thermostat. It is true that corrosion does mess with the thin ledge where the thermostat rides keeping it flush with the top surface of the lower housing, but that doesn't seem to be the problem.

Perhaps if a different replacement or substitute gasket was originally supplied by Toyota while still using the original part number, there may have been an explantation of when to use it and when not--a different application. And if there are different combinations of top and joint gaskets that need to be teamed together for certain identifiable housings, that application info would sure be nice to know. Cruiser Outfitters would know the answer to all of this, and having all the parts on hand, some dry-fits with new housings, thermostats and gaskets would provide the answers if there's any doubt.

Good you're trying to do this correctly. Obviously your previous owner recognized the same problem as you did, and tried a bush fix with a tube of silicone, something most of us would not want to repeat.
 

777Gage

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Excellent reporting--thank-you. I also have a cork joint gasket, don't remember the source. Just to repeat, you used the thinner rubber gasket from Specter on top of the thermostat, and the thin paper joint gasket, or the thicker green or blue fiber gasket in the joint between the halves? And no goobering it up with a thick bunch of silicone, right?

Specter indicates that there are two different upper gaskets, the change date being Jan. 1979. Could that be the issue here? Maybe your 1978 was at the end of the 1978 production line and received a later thermostat housing, or your previous owner changed it out with the newer piece? Additionally, I believe the two different temperature thermostats are interchangeable, but maybe there is a slight height difference between them.

Interesting that any manufacturer would include an incorrect gasket, be it OEM or aftermarket, since I believe the aluminum thermostat housing--top and bottom--only changed from 2-bolt to 4-bolt, with of course taps for sensors in some markets. Unsure if at some point in production the molds for the upper casting changed to create somewhat thicker aluminum above the thermostat. It is true that corrosion does mess with the thin ledge where the thermostat rides keeping it flush with the top surface of the lower housing, but that doesn't seem to be the problem.

Perhaps if a different replacement or substitute gasket was originally supplied by Toyota while still using the original part number, there may have been an explantation of when to use it and when not--a different application. And if there are different combinations of top and joint gaskets that need to be teamed together for certain identifiable housings, that application info would sure be nice to know. Cruiser Outfitters would know the answer to all of this, and having all the parts on hand, some dry-fits with new housings, thermostats and gaskets would provide the answers if there's any doubt.

Good you're trying to do this correctly. Obviously your previous owner recognized the same problem as you did, and tried a bush fix with a tube of silicone, something most of us would not want to repeat.
Bear,
You are spot on here and I appreciate the feedback.
My 40 happens to be a Dec 78 so I have to remember to ALWAYS tell the person getting my order what month. I did use the thin rubber gasket on top of the thermostat and a "greenish" paper/fiber gasket (SOR part # 054-020A) on the housing or joint as you reference. I did use a very thin layer of Permatex Water Pump & Thermostat Housing Gasket Maker - #22071 - on the paper/fiber gasket.

Cruiser Outfitters has been awesome in helping sort this out and I'll report again when I get their package. When I considered the postal delivery date and the additional down time to cure, I went to SOR. Very pleasantly surprised they were substantially cheaper this time around.

Can't wait to take a drive
 

777Gage

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^^^ Use that ^^^ :hillbilly:

TIP: Cut the big applicator off and use Q-tips to apply.
I had that in my hand at Autozone - remembering some Mud advice about it, and my grandfather using it forever ago. I'm not sure why I put it back and went with the water pump/thermostat gasket specific one.

If it leaks, I won't have to search! I've now got my own thread to re-install the whole thing and use the recommended Indian Head :rolleyes:
 

777Gage

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2nd Update: The mail arrived with my Cruiser Outfitters gaskets.

They have a cork gasket for the top of the thermostat - CO Part # : RADOR40058 - invoice says OEM
Paper/Fiber gasket for the housing/hinge - CO Part # : RADH60020 - invoice says OEM

Picture below if of the gaskets again now with the cork (I installed the SOR rubber gasket pictured in the post above already)
From left to right
1. Original gasket I pulled out
2. Gasket that came in the box of the new thermostat - Aisan Part # THM-004 (thermostat part #)
3. Cork Gasket from CO - Part # RADOR40058

Again, the middle (#2) gasket is "almost" twice as thick and as the cork gasket.

In some ways this adds more confusion and more clarity, rubber vs cork discussion and why the 2 options, however, thinner gasket is correct vs thicker that may come with a new thermostat.. (and SOR gasket was $1.37 and CO was $5.50)

Inked20200702_091812_resized_LI - CO.jpg


Inked20200702_092002_resized_LI - Flat.jpg
 

Onur

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There are no cork OEM thermostat gaskets.

None.

Have you thought about going to a Toyota dealership and buying the correct part? (Which happens to be 90430-40058 for your 2 bolt thermostat housing)
 
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