3FE Water Temperature Switch leak (1 Viewer)

[leucadiacruiser]

I replaced the upper thermostat housing in my FJ62 with an aftermarket housing and now am having an issue with the stock water temp switch leaking when engine gets up to temp. I read a few threads saying teflon tape is a no no, as the switch is grounded through the threads. Searching the stock part number 89428-14070 online shows many aftermarket versions have an o-ring/gasket. I'm wondering if that could be the fix. Anyone have experience with this and recommend a fix? Thanks in advance!

 

[Prairie Swamp]

Going strictly from memory I think that sensor had a copper gasket between the brass hex on the sensor and the housing. You can actually see it in the picture you posted. Auto parts stores sell a little assortment in a bubble pack that may or may not have the size you need. If not it's a trip to the dealer or online somewhere.

 

[leucadiacruiser]

Thanks @Prairie Swamp - that gasket is on the cold start timer switch. My other 62 doesn't have a washer or gasket on the water temp switch either. Wondering if maybe threads in the aftermarket housing are buggered. Everything else sits nice and tight.

 

[3_puppies]

why'd you go aftermarket?
there should be plenty of good used ones available, as most have issues with the lower half not the upper.

 

[leucadiacruiser]

why'd you go aftermarket?
there should be plenty of good used ones available, as most have issues with the lower half not the upper.

Initially was going that route. I looked at a few and most were pretty pitted. Hoping this one will work.

 

[Prairie Swamp]

This might be the style like a couple on the lower that seal metal to metal at the bottom. I know the sender for the temp gage in the dash is like this. So are aftermarket gage senders.

Those are straight threads no sealant. Depends on the quality of the two metal surfaces that seal off. This could be the failing of the aftermarket housing.

 

[Prairie Swamp]

The hole in the top of the pic is the type I'm talking about. The other open hole is the type that seals at the top with a copper washer. The third boss is a hole ready to be drilled and tapped for the aftermarket gage (metal to metal seal at the bottom.)

M16 x 1.5 if you need to chase the threads in yours.

 

[leucadiacruiser]

The hole in the top of the pic is the type I'm talking about. The other open hole is the type that seals at the top with a copper washer. The third boss is a hole ready to be drilled and tapped for the aftermarket gage (metal to metal seal at the bottom.)

View attachment 1854273

M16 x 1.5 if you need to chase the threads in yours.

View attachment 1854275

Perfect. Thanks @Prairie Swamp And really appreciate the pictures, too.

 

[bentonrover]

Going strictly from memory I think that sensor had a copper gasket between the brass hex on the sensor and the housing. You can actually see it in the picture you posted. Auto parts stores sell a little assortment in a bubble pack that may or may not have the size you need. If not it's a trip to the dealer or online somewhere.

Just ordered one from rockauto. It came with a cooper gasket

 

[leucadiacruiser]

Just ordered one from rockauto. It came with a cooper gasket

Nice @bentonrover Do you have a part number for that? Thanks!

 

[bentonrover]

This exact one. See the gasket

 

[bentonrover]

Sorry just realized we were talking about different parts. My bad. Cant answer on that switch

 

[Prairie Swamp]

@bentonrover as a side note that's the one I had to replace on my 62. It was open circuit making the ECU think it was -40 degrees out. Cold idle about 1700 rpm.

So many damn sensors on that assembly...

 

[leucadiacruiser]

Update and wrap up on this one: took the Parts Geek upper thermostat housing off and took a close look. The water temp switch port was messed up on the last couple threads. Rather than play with trying to chase it, I took a look at my old housing and decided to see how clean I could get it. Ground off a bunch of deposit crud as best I could. Put it all back together and not a drop and running perfectly. So no gasket or oring on the stock switch, anyway. I ended up going with the Mishimoto radiator. Fit perfectly and includes trans cooler ports. I already head an external trans cooler installed so not going to use them.

 

[Prairie Swamp]

Thanks for reporting out. I also have a Mishi ready to go in when I go through the whole system.

 

[NearJetties]

Old thread bump

Just replaced the water temp sensor (for ECU) and know what the cold start injector switch and water temp sender (for gauge) do. What’s the water temp switch and BSV valve on the right for?