Fj60 thermostats swap. Uhoh

[60TOY]

Just wanted to share my joy during the holiday season. With a clatter I started my thermostat swap, then with snap and another and another till there were four. I was left with four broken bolts on my housing.

Awesome, no Christmas shopping today. Bah humbug.

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[Output Shaft]

Major bummer
Had you replaced the thermostat some time ago in the distant past?
Or is it original?

I believe that the four long bolts should be replaced whenever the T-stat is replaced. The cadmium plating corrodes off over the years and bolts rust and gall in the aluminum.

Also the bolt threads should always be coated with antisieze grease prior to assembly.

 

[gregnash]

Bummer... yeah those bolts going into that soft metal housing are a b#$%@. Check local yard to see if there is a 60 you can salvage from if it completely screwed the housing. Invest in a decent bolt extractor set to get them out.

 

[Cruzerman]

Common issue. What Output Shaft said. Replace bolts whenever doing this job and coat in antisieze.

 

[Spike Strip]

You can salvage the lower housing by removing it from the head and heating each broken corner until cherry red, then douse with wax or penetrating spray. Do this a couple of times, then remove with an appropriate extractor. I've done this about 10 times now and each time works perfectly.

Don't use bolts when reassembling, use threaded studs 8mm x 1.25 x 60mm with nuts and you'll never have the issue again.

Use red loctite to hold in the lower housing.

S8X56E - Metric Stud [S8X56E] - $1.77 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair

 

[Elbert]

you might find a used lower housing in good shape.....yea some of these OEM setups suck when the bolts snap....Seems like the expectation is that you'll have that problem with removing the thermostat housing...

 

[60TOY]

Well what started as a disaster, ended on a great note. Didn't even curse all that much as I worked through this unexpected gotcha.

Ended up pulling the whole unit off the head and took a chance that my local machine shop was open at 2pm on a sat. Luck was on my side. Took longer to split the halves then it did to heat the bolts to work them out. Everything worked out and I didn't have to tap new threads!! I loaded anti seize on the new (stainless) bolts and slapped everything together with gasket and red stuff.

Wish I had seen the earlier post about the studs...great idea. I did clean everything up really well and used plenty of anti seize.

Thermostat looked to be the original and it was shot(stuck open, very stuck). Pretty sure the housing was original 30 year old time capsule.

Thanks for all ideas on this one. Lesson learned..



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[gregnash]

Looks like I might have to invest in those. Not sure if I am going to replace my t-stat with the head work or not.


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[Output Shaft]

Good show.

.... but the best bolts to use from a corrosion standpoint in the t-stat housing are new cadmium plated Toyota bolts.

PN: 91611-60845

The corrosion potential between cadmium and aluminum is much lower than between stainless steel and aluminum....although antisieze may save your bacon.

If you want to use stainless steel, I'd follow @Spike Strip s advice and use studs, so you never have to deal with this again.

The reason your old bolts seized wasn't because of rusted steel, it was from galling caused by the corroded aluminum. Stainless steel will not protect you from that, and will actually accelerate it.

 

[lovetoski]

Damn, that's good info there. Thankyou.

 

[doug720]

Output offers good and wise advice, don't use SS in contact with aluminum. Especially with liquids and heat.

 

[Spike Strip]

x4 billion. Or, you will need to use lots of Nickel-based anti-seize, not the cheap copper-alum stuff.

FWIW, you can get reg cad metric bolts that will work, most places, they'll just have 13mm heads instead of the JIS 12mm. Lots of antiseize under flat washer helps, too.

 

[OGBeno]

91611-B0845 is the new part number for the bolts.

 

[DoubleNickels]

Don't use bolts when reassembling, use threaded studs 8mm x 1.25 x 60mm with nuts and you'll never have the issue again.

Use red loctite to hold in the lower housing.

S8X56E - Metric Stud [S8X56E] - $1.77 : Bel-Metric, Metric Hardware, Metric Fasteners, Metric Bolts, Metric Nuts & Time-Sert Thread Repair

AWESOME. Great idea!