FJZ Thermostat Leak (1 Viewer)

[SuperCliff]

Hey there,

I recently did a whole bunch of cooling maintenance on my '94 JDM 80, to include the PHH, water pump, heater hose lines, etc. Included in that was a new thermostat. The initial reason for me opening all of this up was because I had a small leak from a heater hose on the T-fitting. That has been addressed.

Since replacing the thermostat, I seem to have a worse leak than the heater hose I had before. When idling, it's fine, but under throttle there is a fair bit of coolant surging from the top of the thermostat, specifically where housing bolts to the block. I torqued it to spec and took forever to get the thermostat and new o-ring in place. This may sound dumb, but I'm hoping it'll seal itself with a few heat cycles. If not I'll have to pull it back apart.

Does anyone have any experience with this issue? Maybe use some RTV on the thermostat housing? Thanks in advance.

 

[Irish Reiver]

Where exactly is it leaking from? There 3 or 4 potential hoses in that area. Is it coming from the hard line that holds the thermosat or possibly the gasket between the thermosat housing and the block? There is also the 3 o rings in the same vicinity that can let go if not replaced.

 

[SuperCliff]

Good question. It's leaking from the arrow in the picture. From what I can tell, it's seeping up from there and then pooling where I circled. It doesn't seem to actually be leaking from the circle despite how it looks. I replaced all of the o-rings in that vicinity with new OEM Toyota o-rings.

I will say, it took me forever to get the thermostat/gasket to stay in place when trying to bolt the housing back on, but it seemed good when I put it back together.

 

[SuperCliff]

Any thoughts?

 

[MickeyB]

Did you replace with all new seals and gaskets? Hard to tell what gasket or seal is leaking since we can’t see it. I would get all new seals\gaskets break it down again and replace them all in that area and torque to spec. Should be good after.

 

[SuperCliff]

Did you replace with all new seals and gaskets? Hard to tell what gasket or seal is leaking since we can’t see it. I would get all new seals\gaskets break it down again and replace them all in that area and torque to spec. Should be good after.

I did. Swapped in all new OEM Toyota seals-o-rings when I changed everything over. That's the frustrating part; it doesn't make sense as to why it's still leaking. I was considering tearing it down and using RTV on the thermostat hosing just to be sure..

 

[MickeyB]

I did. Swapped in all new OEM Toyota seals-o-rings when I changed everything over. That's the frustrating part; it doesn't make sense as to why it's still leaking. I was considering tearing it down and using RTV on the thermostat hosing just to be sure..

That’s really odd. My only other thought is one of the parts is damaged and is not sealing properly. I would avoid the RTV unless you find a spot that’s damaged.

 

[lp2k]

@McSlides did you fix this?

 

[SuperCliff]

@McSlides did you fix this?

Yep. I was trying to avoid exposing myself as a dumbass. I didn't put the seal around the thermostat on properly... you would think after all these years of pulling engines and installing turbos that I would have known how to install a thermostat lol

 

[BILT4ME]

Yep. I was trying to avoid exposing myself as a dumbass. I didn't put the seal around the thermostat on properly... you would think after all these years of pulling engines and installing turbos that I would have known how to install a thermostat lol

I was going to suggest that, but I just saw this a couple days ago.......

Don't worry, others have done that too.