Fj60 1982 2F, High Flow thermostat & Thermostat Housing Bolts question, (1 Viewer)

caladin

Noob, but trying to learn
SILVER Star
Joined
May 30, 2011
Messages
508
Location
Pflugerville Tx
 
I was reading old threads about extracting the thermostat housing bolts on a 2f, as I had half a memory about those being notoriously brittle
and/or subject to Bi metallic corrosion and/or seizing.

Someone in the thread asked if the new thermostat was the "high flow" one. Could someone please point me towards where the High flow thermostat can be found?,
living in Texas, that sounds like a great idea, since I'm getting in there anyway. The one I have coming is just the standard Beck Arnley one.

As to the bolts, I can't find the thread that talked about them being brittle, though I did find ones that talked about bimetallic corrosion (in Fj40s)

If they are brittle and or Prone to bimetallic corrosion, I'd like to replace them with stainless, but all I can find in JIS flange bolt is is m8x1.25-40mm, or M8x1.25-45mm, regardless of material.

Will 40mm be ok, or should I use the 45 and add a few washers if it bottoms out??

Does anyone have a source for JIS flange m8x1.25-42mm either in stainless or Galv?

I'd have just gone for it (as I have 40s on hand), but I figured since I was going to ask about the high flow Thermostat, I might as well ask.

Thanks,
 

OSS

Joined
Jun 30, 2017
Messages
2,904
Location
Oblivion
don't use stainless steel bolts to clamp the t-stat housing together. Stainless steel and aluminum are nasty bedfellows. Corrosion between the dissimilar metals turns the aluminum threads to chalk and the bolt seizes. Stainless steel bolts will make things worse.
The best bolts to use are the plated steel bolts from Toyota for that housing. If they're installed with anti seize grease and replaced every 8 years or so they'll be fine.
They aren't brittle when they're 30 years old and attempted to be removed for the first time, they're rusted up and fused to the aluminum housing threads.

There's only one good thermostat to use in your engine: the original 190 degree t-stat from Toyota. Its by far the best for every driving condition
 
Joined
Nov 25, 2014
Messages
486
Location
Western victoria Australia
 
being notoriously brittle
They sure are. I have had 2 snap. However 2 bolts diagonally is sufficient to bolt the housing down without leaking if you get stuck. Don't skimp on the RTV though.
As for the high flow t-stat. With a 3f, personally I find the hotter factory 190 t-stat to work best in hot and cold weather.

Adding to OSS suggestion. I often wondered if high tensile black bolts would be a better option?
 
Last edited:

DrRock

SILVER Star
Joined
May 27, 2020
Messages
87
Location
Kent, CT
Timely topic as I just pulled mine out and snapped three. They are a bugger and this was exacerbated by a PO who caked everything in RTV. Mine were stuck so badly I just found a used lower housing as I ended up snapping an EZ Out trying to attempt removal. I will bring this to work once we are allowed back in our building and go at it on the milling machine so I don't damage the lower housing.

One question for everyone, when I go to re-assemble this, do I need to use any gasket adhesive etc?

A jar of anti seize is your friend. I never reassemble anything on this truck without putting some on, especially around fasteners that are near coolant and are dissimilar in material.


On the fastener topic @ToyotaMatt carries the steel fasteners for this.

Cheers, James
 

DrRock

SILVER Star
Joined
May 27, 2020
Messages
87
Location
Kent, CT
I usually do especially if the alloy is pitted/corroded, then it's a must.
Do you have a preference? I was able to get the top ousting sealing surface nice and smooth and flat. The bottom is refurbished.

Cheers, James
 

Seth S

SILVER Star
Joined
Jan 4, 2011
Messages
3,656
Location
Vermont
 
I was reading old threads about extracting the thermostat housing bolts on a 2f, as I had half a memory about those being notoriously brittle
and/or subject to Bi metallic corrosion and/or seizing.

Someone in the thread asked if the new thermostat was the "high flow" one. Could someone please point me towards where the High flow thermostat can be found?,
living in Texas, that sounds like a great idea, since I'm getting in there anyway. The one I have coming is just the standard Beck Arnley one.

As to the bolts, I can't find the thread that talked about them being brittle, though I did find ones that talked about bimetallic corrosion (in Fj40s)

If they are brittle and or Prone to bimetallic corrosion, I'd like to replace them with stainless, but all I can find in JIS flange bolt is is m8x1.25-40mm, or M8x1.25-45mm, regardless of material.

Will 40mm be ok, or should I use the 45 and add a few washers if it bottoms out??

Does anyone have a source for JIS flange m8x1.25-42mm either in stainless or Galv?

I'd have just gone for it (as I have 40s on hand), but I figured since I was going to ask about the high flow Thermostat, I might as well ask.

Thanks,
you don’t need high flow in the thermostat. You actually need the restriction at the thermostat in order to achieve proper cooling. If you ran without a thermostat you run the risk of not holding coolant in the radiator for long enough so that it can shed its heat.
 

Spike Strip

Midnight Rider
SILVER Star
Joined
Nov 22, 2005
Messages
14,788
Location
Lexington
 
 
I've heard that some have replaced the bolts with studs. Anyone try this?
Yes. Works great. Red loctite the stud end into the housing bottom, then use JIS nuts with washer to secure top. Smear the stud shaft liberally with Alum antiseize and a good dollop of Alum antiseize under the nut and washer and problem gone forever!
 

DrRock

SILVER Star
Joined
May 27, 2020
Messages
87
Location
Kent, CT
Yes. Works great. Red loctite the stud end into the housing bottom, then use JIS nuts with washer to secure top. Smear the stud shaft liberally with Alum antiseize and a good dollop of Alum antiseize under the nut and washer and problem gone forever!
After having three of the bolts on mine snap due to galvanic corrosion, this is definitely a nice alternative. The only potential downside is when you need to remove the upper housing in the future with studs in there can be a bit difficult. When my bolts snapped it definitely makes it challenging as the upper housing can hang up if there is corrosion or sealant in the hole.

That said, by following Spike’s Directions on covering the stud with anti seize then all should be fine.

Cheers, James
 

Spike Strip

Midnight Rider
SILVER Star
Joined
Nov 22, 2005
Messages
14,788
Location
Lexington
 
 
If you use studs and cover the FULL LENGTH of the stud with good-quality Alum antiseize, like Bostik or Loc Tite, you'll be good prolly for as long as you own truck.

Although, if you use the bolts above, that @ToyotaMatt shows, with liberal amounts of the correct anti-seize for Alum/Steel, you'll get the same result. Trick is to coat the ENTIRE bolt, and under the hex head, not just the threads, to prevent the corrosion of the shaft.

Tip -- If your housing is old and never separated before, best is to remove whole housing from the head, first, then torch the bolts til red hot, spray with penentrant to cool, torch again (do this a few times) and I've never had a bolt break that way or snap off in the housing.
 

ToyotaMatt

Factory Focus-Point Mind-Set Aproach
Supporting Vendor
Joined
Aug 12, 2007
Messages
12,237
Location
EAST COAST
 
 
If you use studs and cover the FULL LENGTH of the stud with good-quality Alum antiseize, like Bostik or Loc Tite, you'll be good prolly for as long as you own truck.

Although, if you use the bolts above, that @ToyotaMatt shows, with liberal amounts of the correct anti-seize for Alum/Steel, you'll get the same result. Trick is to coat the ENTIRE bolt, and under the hex head, not just the threads, to prevent the corrosion of the shaft.

Tip -- If your housing is old and never separated before, best is to remove whole housing from the head, first, then torch the bolts til red hot, spray with penentrant to cool, torch again (do this a few times) and I've never had a bolt break that way or snap off in the housing.

I offer The correct FULL length Studs and Yellow Zinc Serated Flange Nuts for @Spike Strip 's excellent alternative OEM approach

my kit contains ALL 100% OEM Toyota genuine parts

and is be a excellent approach if your follow his anti sieze prescription too , he is the TECH and TEq outside the Box man !
 

ToyotaMatt

Factory Focus-Point Mind-Set Aproach
Supporting Vendor
Joined
Aug 12, 2007
Messages
12,237
Location
EAST COAST
 
 
Those Torx Studs are PERFECT ! Wish I had those!

i mailed you out a 10 Pack bag today Alf ..........

also 10pack of the serrated gold zinc flange nuts

was going to be a TEq mystery gift surprize .......... 🤔

thanks for spoiling it brother .,,.,🤣
 

ToyotaMatt

Factory Focus-Point Mind-Set Aproach
Supporting Vendor
Joined
Aug 12, 2007
Messages
12,237
Location
EAST COAST
 
 
Those Torx Studs are PERFECT ! Wish I had those!
Alf ,

I will pm you tracking # shipping lable info

here is some NipponDenso swag too and a new promo made in japan 🇯🇵 PILOT brand stainless ateel
Roller ball rising sun mechanical logo ink pen too

I personally would think to use copper anti seize in this application ?

wouls this be a good or bad idea alf ?
Maybe our phriend @OSS knows , he is wiser then most in this skool of thought for sure ...

294735A3-0FC7-447A-983F-CE7A03B32B4C.jpeg
C75DBA57-398F-40FE-9427-DD61A94287E8.jpeg
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom