New Thermostat - doesn't fit in thermostat housing

[ckuske]

Hi Guys,

I have been suspicious that my thermostat may be sticky or only partially opening, so I bought a new Motorcraft RT-1139 (192 degree, fitment guide says it should work).

I also bought a Motorad and a Gates (which I found out is Motorad in disguise) first, but I read some bad things about them, and I am replacing a Motorad.  So, I figured I'd go OEM anyway.

Anyway, I got the new thermostat and did a fit check inside the housing.  The thermostat has one section on the top that is "out of round", meaning one side has a bump on it that prevents it from going into my thermostat housing fully.  It doesn't fully seat into the recess, there side with the "out of round" side is prevented from going into the housing fully.  I've tried rotating it, I can't find to seem any angle where it seats properly.  The Motorad and Gates sit flush.

Has anyone else encountered this?  The housing is aftermarket, but I'm not sure what it's origin is.  It needs to be a 90 degree, and have a threaded hole in the top for a temperature driven vacuum switch.

Here's a picture of the new thermostat with the area I'm wondering about circled.

I think I just bought the wrong thermostat - given my situation, is there a Motorcraft thermostat that I known to work and isn't a 40 year old NOS part?  Or is there a different housing I should be using?

[ckuske]

Correction, the new Motorad one doesn't fit either!  Same "out of round" issue. (I got the idea to try the Fail-Safe one, but decided to not use it after reading lots of reports of them failing open when the engine really didn't overheat)

[ArdWrknTrk]

I always use Stant Chris.

My 460 is different than Wheezers, in that it sits on top, not stuck on the front.
You DO Know that the sticky gasket is to hold it in place, right?  

[ckuske]

Thanks Jim.  Stant was my first thought too. Motorad owns them now also.

I’m aware of the gasket helping the install. But, the thermostat not sitting flush in the housing  will cause a problem, right?  I imagine water would find its ways past…



The jiggle pin is at 12 o’clock

Sorry for the rotation, did this from my phone for now.

[ArdWrknTrk]

Yeah, that's not good..  

Damn M&A penny pinching Is ruining America!

[ckuske]

Any opinions on if I should drill a small hole in the Gates thermostat to serve as the "jiggle pin" hole? (Oriented at 12 o'clock)

I think based on what I am seeing, I don't have much choice but to go with the Gates one, as it is the only one out of the three that I've purchased that fits in the housing properly.

[ArdWrknTrk]

3/32 at most.

You can do it if you think you need it to fill the system.

[Gary Lewis]

If the Gates fits I'd go with it.  And the only reason I know of for drilling the hole is to aid filling the system.  But I've started using Bill's recommendation of pulling a heater hose and filling until it runs out there, which seems to do a good job of getting it full.  However, you'll still probably have to top the system up after a few cycles.

Having said that, I've been reading about coolant system filling funnels, like these shown on Amazon.  Haven't used anything like that, but they look good.

[grumpin]

I would try to find an OEM housing or another aftermarket housing.

[ckuske]

I haven't found an aftermarket housing that is an oval shape at the top to accommodate the Motorcraft theromostat.

I did find some NOS housings, but they are around $150 on eBay.  

It seems like a lot to pay for a $8 thermostat. I may regret it, but I put the Gates in and will try it tomorrow morning...

[grumpin]

ckuske wrote

I haven't found an aftermarket housing that is an oval shape at the top to accommodate the Motorcraft theromostat.

I did find some NOS housings, but they are around $150 on eBay.  

It seems like a lot to pay for a $8 thermostat. I may regret it, but I put the Gates in and will try it tomorrow morning...

Yikes! Might be worth it though.

[ckuske]

You can be the first to tell me "I told you so" when I come back whining that this thermostat failed too.  

And, when I have to yell and scream at the bottom bolt of the housing after trying to get it out for an hour of fooling around with my 1/2" ratchet wrench one "click" at a time.

I should have waited and spent the money, but I want to drive my truck!

[ArdWrknTrk]

The heater loop on (these) Ford's is in bypass mode all the time.
Anyone who has trouble filling a 385 or Windsor is doing it wrong.

Bill is right, the heater hoses (where they pass into the heater box) is probably the highest point.

Stick one hose out through the passenger hood hinge, so it's higher still, and put a funnel in it.
Pour coolant until it flows out the disconnected neck of the heater core.

Done.

[ckuske]

Thanks everyone for their feedback.  I wasn't worried about filling it.  I didn't drain the radiator, I just caught what dumped out when I took the thermostat housing off.

I put the Gates thermostat in last night, and started it up this morning.  The thermostat is opening earlier, and the temperature gauge seems to be happier (right in this middle instead of between A and L)

That being said, I am going to put a new connector on the temperature gauge sender, as it wasn't reading until I jiggled it. It's on order and I'll do that in the next few days.

On to the next thing (after I scrape together some more $)!  

Maybe I try to diagnose why the speed control isn't working next... (it hasn't worked since I got the truck back - my guess is the controller next to the computer - but are the common failure modes?)

[ArdWrknTrk]

I hear you on the $!
I just paid $75 to get a 0.020" pinion shim (had to buy 10, and UPS shipping only option)

Now I have to get my races pressed on, ( $20 each = $60+ tx) and I should have everything else I need to put my differential back together.  

[ckuske]

Awesome!  The “simple” things tend to evolve into something more, don’t they?!

[ArdWrknTrk]

Blowing up my rear end has screwed me since January.
I need to make some money, but it's a catch 22.

[Gary Lewis]

Glad you got that going, Chris.  

On the speed control, go to Documentation/Electrical/Speed Control for schematics, illustrations, part numbers, and instructions from the factory shop manual as well as for the tester.  Speaking of which, Scott/Kramptocs has one and I have lots of spare parts.