FJ62 thermostat replacement quick write up

[Randy88FJ62]

Thermostat P/N 90916-03052
Gasket P/N 90430-43002
Water Gasket P/N 16341-61030
4 bolts on housing P/N 91611-B0845

You do not need to drain entire coolant from truck. About 2 liters drops out from the top radiator hose when removed.

Order the 4 bolts! I can’t stress this enough. I took a risk knowing mine had been done 12 years ago by previous owner and I was concerned at their condition when I removed them.

I used special rtv for sensors and coolant related components but others have gotten away without. I used anti-seize on all bolts installed. All bolts were brass wire wheeled completely clean before re-install.

 

[Randy88FJ62]

 

[Randy88FJ62]

 

[Randy88FJ62]

Be very careful with your connectors. One of mine was toast and needed a new crimped spade.

 

[Randy88FJ62]

Here are the tools used. I was paranoid about the bolts breaking so I used a tee wrench to evenly break them free. The picks were used to remove and install the wire lock on one connector.

Crescent wrench was used to remove OEM tensioned hose clamps. If yours are aftermarket then use corresponding sockets.

Both sockets shown are 12mm.

 

[jmstu76]

What temp thermostat did you go with? 180 0r 190?

 

[Randy88FJ62]

Not sure. Whatever the OEM Toyota P/N corresponds to

 

[Kleatus]

View attachment 1803880 Here are the tools used. I was paranoid about the bolts breaking so I used a tee wrench to evenly break them free. The picks were used to remove and install the wire lock on one connector.

Crescent wrench was used to remove OEM tensioned hose clamps. If yours are aftermarket then use corresponding sockets.

Both sockets shown are 12mm.

Where are your SAE sockets to break off the cross threaded standard bolts, ez-outs, torch, welder to weld nuts to remnants of the bolt with the broken ez-out in it, headlamp for doing this in the dark outside and hand warmers because it's 5 below zero?

Nice write up, and something everyone should do correctly before the above set of curcumstances set in.

I would add that even though it is more work initially, at the first hint of trouble with the bolts I'd recommend juat taking the lower housing off of the head and taking the whole works to a vice to finish the job with better access and control.

 

[ZGMikey]

Trying to figure out why the picture is blacked out??? But thanks for the write-up. I'm starting to think mine is stuck open because it takes a loooooong time to get warm.

View attachment 1804184

 

[Randy88FJ62]

The printer I used was upset at pictures for some odd reason. Nice to see they use a tee wrench!

 

[Randy88FJ62]

Question for those with the background on this system. My o-ring gasket was missing on top of the thermostat when I opened it up. Would that cause me to not have heat in the cab? I haven't had heat in the cab since I bought it. I've removed the heater core a few years ago and cleared it out to no avail. So my guess is this will fix or heater valve on firewall is next.

 

[Kleatus]

Question for those with the background on this system. My o-ring gasket was missing on top of the thermostat when I opened it up. Would that cause me to not have heat in the cab? I haven't had heat in the cab since I bought it. I've removed the heater core a few years ago and cleared it out to no avail. So my guess is this will fix or heater valve on firewall is next.

Without the gasket in place (or if it's bungled up on installation), coolant can bypass the thermostat, which will keep the engine from warming up in the intended manner.

Domestic stuff typically has a differently shaped thermostat and only requires a single gasket at the housing only, and no rubber gasket on top. If some shop or previous owner who never cracked open the manual or knew how it is supposed to work, but had replaced thermostats on say Chevy pickups did the job last, it probably never occurred to them that the rubber gasket is required.

 

[Randy88FJ62]

Kleatus,
Any idea on how it would affect the heater inside the cab?

 

[Kleatus]

Kleatus,
Any idea on how it would affect the heater inside the cab?

The thermostat is basically a heat sensitive valve. It serves to restrict heat loss of the cooling system by keeping engine coolant from flowing to the radiator. It helps the engine get up to operatung temperature faster, then when it reaches its opening temperature, it opens up allowing flow to the radiator. If it's missing, stuck open, or if the coolant can bypass it by a missing gasket, the radiator is constanly receiving (and taking heat away from) the engine coolant, which especially in cooler temperatures or with light engine loads means that the engine can't reach proper operating temperature. Since the heater (think of it as a little radiator inside your dash) is part of the cooling circuit, it too won't be able to get hot enough to be effective.

Conversely, if the thermostat is stuck closed or clogged up, the radiator isn't receiving flow and can't take heat out of the system and the engine will get too hot.

 

[AlabamaCruisin]

Thanks for this write up! Plan to work on this project soon!

 

[Spook50]

Stumbled on this while digging for part numbers for the bolts. I can't agree more that they should be changed when doing a thermostat job. Just not worth the risk you take when attempting to reuse them.

Honestly I'm surprised none of our Mud venders offer the whole set (thermostat, gaskets and bolts) as a "thermostat maintenance kit", as far as I know. @cruisermatt what do you think? I've got this little job on the list for springtime too

 

[AlabamaCruisin]

Stumbled on this while digging for part numbers for the bolts. I can't agree more that they should be changed when doing a thermostat job. Just not worth the risk you take when attempting to reuse them.

Honestly I'm surprised none of our Mud venders offer the whole set (thermostat, gaskets and bolts) as a "thermostat maintenance kit", as far as I know. @cruisermatt what do you think? I've got this little job on the list for springtime too

Try this one from City Racer LLC

 

[AlabamaCruisin]

Try this one from City Racer LLC

Obviously out of stock at City Racer, but bolts seem to be there.

Also, Cruiser parts has just the bolts: Bolts at Cruiser Parts

 

[AlabamaCruisin]

Stumbled on this while digging for part numbers for the bolts. I can't agree more that they should be changed when doing a thermostat job. Just not worth the risk you take when attempting to reuse them.

Honestly I'm surprised none of our Mud venders offer the whole set (thermostat, gaskets and bolts) as a "thermostat maintenance kit", as far as I know. @cruisermatt what do you think? I've got this little job on the list for springtime too

I found two options at City Racer (Kit) and Cruiser Parts (Bolts only)

 

[cruisermatt]

Stumbled on this while digging for part numbers for the bolts. I can't agree more that they should be changed when doing a thermostat job. Just not worth the risk you take when attempting to reuse them.

Honestly I'm surprised none of our Mud venders offer the whole set (thermostat, gaskets and bolts) as a "thermostat maintenance kit", as far as I know. @cruisermatt what do you think? I've got this little job on the list for springtime too

The other Matt does