Can’t get thermostat back in housing without leaking. Edit: got tstat in, bit running at <180f

Ozark Bushwalker

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I put the or O-ring around the disc part of the tstat but couldn’t fit it snug back in the housing this way. When I started to refill it started leaking out the bottom of the housing, where part of the oring was sticking out.

Is the oring supposed to be installed this way, and/or is it really necessary at all? The old tstat didn’t have one I don’t think.

I’d appreciate any help getting this to seal.

Thanks

F19B6D2B-85C0-446A-9B40-82CF931D3247.jpeg
 
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The o-ring has a groove around the inside surface and it fits around the flange of the t-stat.
If that's what you are doing, and it still doesn't fit, are you sure you have the correct part number?
 
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I've had mine off about a million times flushing the system to get rid of the rust. Is your pic how you're inserting it? Each time I've placed the thermostat into the block side and then slid on the input piece. Make sure it doesn't get unseated and slide down where it'll pinch/leak when tightening. Also make sure the jiggle pin is oriented correctly.
If your o-ring is bad fel-pro 35445 works and is available at most stores.
 

Ozark Bushwalker

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The o-ring has a groove around the inside surface and it fits around the flange of the t-stat.
If that's what you are doing, and it still doesn't fit, are you sure you have the correct part number?
Yes I inserted it by pacing it inside the grove in the o-ring. I ended up taking it off and moving the jiggle valve up farther, but now there’s still a slow leak from the bottom of the housing, which seems to be pooling up in the location below.

47809513-C790-41FB-A31B-ACCC59AE00EE.jpeg
 

Ozark Bushwalker

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Also I have an AISIN THT-015 from Amazon
 
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Also I have an AISIN THT-015 from Amazon
Aisin thermostat or gasket? I know rockauto/amazon lists the THT-015 as the correct thermostat but it's too small in diameter. **Disregard, was sent wrong part.
 
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Ozark Bushwalker

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Also in the pic it looks like part of rev gasket is visible on the top of the housing: is this incorrect?
 
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Also in the pic it looks like part of rev gasket is visible on the top of the housing: is this incorrect?
OEM thermostat and gasket insert into the circular cutout on the block/output piece perfectly. Not supposed to see the thermostat gasket when it's buttoned up.
I'm pretty sure THT-015 is too small in diameter. **Disregard, was sent wrong part.
 
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Ozark Bushwalker

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OEM thermostat and gasket insert into the circular cutout on the block/output piece perfectly. Not supposed to see the thermostat gasket when it's buttoned up.
I'm pretty sure THT-015 is too small in diameter.
If anything it seemed too wide to fit into the housing. The O-ring keeps sticking out the edge as seen above.
 

Ozark Bushwalker

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Can anyone confirm AISIN THT-015 is identical with OEM or will it not fit properly?
 

Njck22

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can you take a better picture? one without the coolant inlet pipe attached? I don't understand how you oring is squeezing out.
 

Ozark Bushwalker

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Well I would but its in there now and the rad is full of coolant so I’d have to dump it all again.

Is there a way to drain the rad without getting coolant everywhere? It seems to catch on the crossmember and dribble all over the place.

I just place it up high this time and part of the oring stuck out as a result.
can you take a better picture? one without the coolant inlet pipe attached? I don't understand how you oring is squeezing out.
 

Ozark Bushwalker

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In this thread AISIN tht015 is stated to be the correct part. I think I might’ve torn the oring which could be causing the slow leak.


how snug is the tstat supposed to be when installed? I was having to hold it in place while I tightened the bolts, and it was hard to get the oring positioned correctly without having it stick out.
 
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In this thread AISIN tht015 is stated to be the correct part. I think I might’ve torn the oring which could be causing the slow leak.


how snug is the tstat supposed to be when installed? I was having to hold it in place while I tightened the bolts, and it was hard to get the oring positioned correctly without having it stick out.
Made me double check. Looks like they sent me the wrong part. I know when compared to my original this one was visibly smaller in diameter.
Regardless, haven't had any issues using a fel-pro 35445 gasket and OEM thermostat.
IMG_2339.JPEG
 

Ozark Bushwalker

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Made me double check. Looks like they sent me the wrong part. I know when compared to my original this one was visibly smaller in diameter.
Regardless, haven't had any issues using a fel-pro 35445 gasket and OEM thermostat.
View attachment 3050827
Were you able to get the tstat in snug with the gasket attached? As I said I'm having to hold it in place while I tighten the bolts and hope everything is lined up.

The first time it just gushed out when I filled it, now I've got it down to a slow leak. I'm dreading having to drain all the coolant again just to have another crack at getting it right. Its a PITA to try and catch it all when it's dribblinh all over the place off of various parts of the undercarriage.

MAybe I could attach a 5/8" hose to the petcock valve and direct it into a container? Has anyone done this?
 
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I use a big wide open pan to catch coolant, think I bought at the local parts store. Auto Zone or O'Riley's will carry them.
A hose into a jug is a good idea and should work fine.
might be able to buy extra room, if you pull the splash guard, but not sure, I haven't been "in there" in a year or better.
The T-stat with gasket should plug into its hole on the block, its a snug fit. Then the cover compresses the gasket. You shouldn't see any gasket, its all contained in the counter bore under the cover.
 

Ozark Bushwalker

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I use a big wide open pan to catch coolant, think I bought at the local parts store. Auto Zone or O'Riley's will carry them.
A hose into a jug is a good idea and should work fine.
might be able to buy extra room, if you pull the splash guard, but not sure, I haven't been "in there" in a year or better.
The T-stat with gasket should plug into its hole on the block, its a snug fit. Then the cover compresses the gasket. You shouldn't see any gasket, its all contained in the counter bore under the cover.
I was referring to the gasket with the groove that goes around the flange as you said. The thermostat wouldn't fit snug into the housing with that attached.

Maybe I just need to apply more force? I had a hard time getting the old one out.
 

Ozark Bushwalker

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Also anyone know if you can get a new o-ring that will work with the AISIN at a local parts store or would you have to go to a dealer?

And if one were to drain the block and rad/tstat housing, then fill up with coolant until the radiator is full, is there an estimate to how much more would have to be added once the engine is started and it circulates?

Thanks for the help.
 

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