ckuske Posted May 3 Share Posted May 3 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? Link to comment Share on other sites More sharing options...
ckuske Posted May 3 Author Share Posted May 3 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) Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 3 Share Posted May 3 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) 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? Link to comment Share on other sites More sharing options...
ckuske Posted May 3 Author Share Posted May 3 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? 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.  Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 3 Share Posted May 3 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. Yeah, that's not good.. Damn M&A penny pinching Is ruining America! Link to comment Share on other sites More sharing options...
ckuske Posted May 3 Author Share Posted May 3 Yeah, that's not good.. Damn M&A penny pinching Is ruining America! 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. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted May 3 Share Posted May 3 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. 3/32 at most. You can do it if you think you need it to fill the system. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 3 Share Posted May 3 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. 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. Link to comment Share on other sites More sharing options...
grumpin Posted May 3 Share Posted May 3 I would try to find an OEM housing or another aftermarket housing. Link to comment Share on other sites More sharing options...
ckuske Posted May 3 Author Share Posted May 3 I would try to find an OEM housing or another aftermarket housing. 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... Link to comment Share on other sites More sharing options...
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