Thermostat replacement

[cruiser]

I'll be replacing the thermostat in my 1974 Duster 225. I've been running a Stant super stat 195 degree, which seems to be failing now. What 195 thermostat worked for you? And just to be sure, the pointy end goes toward the radiator, the squared bottom end toward the cylinder head, right? Thanks.

 

[toolmanmike]

Yes on the pointy end. Stant used to be good. May be not any more. Take a look at Robert Shaw if they are still around. Test any one you buy in a pan of water on the stove with a thermometer before installing it.

 

[RustyRatRod]

It's funny that Chrysler had a recommended thermostat style, but they won't fit in the slant 6 unless the thermostat hole is opened up a little bit. lol This is the style I run, but as mentioned, they will not fit without enlarging the hole. It doesn't take much at all, but it won't fit otherwise. I prefer the 160, but that's the 195 in the link, since that's what you mentioned.

High Performance 195 Degree 306 Thermostat - Stewart Components

Manufactured by Robert Shaw and modified by Stewart, these custom thermostats feature a balanced sleeve design and are designed for high flow, high RPM applications. Strongly recommended for any performance application. Refer to our Tech Tips page for information on which thermostat is right for...

www.stewartcomponents.com

 

[Dana67Dart]

For the record...

I recently replaced my run of the mill Stant thermostat with a "High" flow thermostat same temp. Made no difference to my temp at speed where I was having concerns.


I was typing when RRR posted, that is the high flow T stat I used.



BTW MotoRad owns Stant and I think a few other companies

 

[RustyRatRod]

For the record...

I recently replaced my run of the mill Stant thermostat with a "High" flow thermostat same temp. Made no difference to my temp at speed where I was having concerns.


I was typing when RRR posted, that is the high flow T stat I used.



BTW MotoRad owns Stant and I think a few other companies

Did you have to enlarge the hole? I have probably ten slant 6 heads and none of them would fit that type thermostat. It's real close. I could probably pound it in with a hammer. But then of course, the sides would be bound against the head and it would not open. lol

 

[Dana67Dart]

id you have to enlarge the hole? I have probably ten slant 6 heads and none of them would fit that type thermostat

273 fit like a glove, Just not OJ's glove. OH crap I went there!

 

[RustyRatRod]

273 fit like a glove, Just not OJ's glove. OH crap I went there!

Oh ok. This was about a slant 6. OJ was guilty as sin. I went there. lol

 

[Murray]

I only use Mr Gasket high flow stats.

 

[Dana67Dart]

This was about a slant 6.

Agreed but mostly.. a thermostat is a thermostat. Mostly engine independent.

 

[Darter6]

Rusty is right, there is a difference between the slant and V8 outside diameter size.
Why ? Ma Mopar only has the answer.
Quality of parts now a days....

 

[RustyRatRod]

Rusty is right, there is a difference between the slant and V8 outside diameter size.
Why ? Ma Mopar only has the answer.
Quality of parts now a days....

Yeah and it's strange. Why they did that is anyone's guess. I'd say the difference is only "around" .010". It only takes a minute or two with a dull, purple and black burnt up grinding burr to open up the hole enough.

 

[halifaxhops]

la and slant are the same B/RB are a bit larger. I have some older NORS ones if needed.

 

[RustyRatRod]

la and slant are the same B/RB are a bit larger. I have some older NORS ones if needed.

Not with the thermostats we're discussing. The LA high flow type will not fit the slant 6. It's a skosh too big. Look at post #3. That's they type thermostat. I have a feeling it's "supposed" to fit the slant 6, but it doesn't. Only takes a minute or so with a grinder and you're there.

 

[slantsixdan]

It's funny that Chrysler had a recommended thermostat style, but they won't fit in the slant 6 unless the thermostat hole is opened up a little bit. lol

Donno where you got the idea that kind of thermostat (an old design called "balanced sleeve") was recommended or used as original equipment by Chrysler for Slant-6s, but…nope. It wasn't. It's not a good idea, either; you can embiggen the thermostat hole in the head, but pretty good odds the head casting on the inside of that hole will still wind up blocking that kind of thermostat's sleeve from fully opening.

Anyhow, the OP's problem isn't being caused by having used a reverse-poppet type thermostat instead of this balanced-sleeve type.

If you want a high-flow thermostat for a Slant-6, and you don't like the Stant Super-Stat (maybe they're no good any more? Donno, haven't needed one in years), Tridon makes nice ones in Australia—the TT2000 series, available in 160°, 170°, 180°, 190°, and 192°F ratings. Thiz 2025 and we have the internet, so they can be bought from afar.

 

[RustyRatRod]

Donno where you got the idea that kind of thermostat (an old design called "balanced sleeve") was recommended or used as original equipment by Chrysler for Slant-6s, but…nope. It wasn't. It's not a good idea, either; you can embiggen the thermostat hole in the head, but pretty good odds the head casting on the inside of that hole will still wind up blocking that kind of thermostat's sleeve from fully opening.

Anyhow, the OP's problem isn't being caused by having used a reverse-poppet type thermostat instead of this balanced-sleeve type.

It doesn't. I've tried it. I wouldn't run it otherwise. I'm dumb, not stupid.
(....and that's actually debatable. LOL)

 

[slantsixdan]

Okeh, it doesn't hit your particular head, very fine. I've seen 'em hit enough heads (one was enough) to not pursue the idea of needlessly enlarging the hole to fit a not-the-right-kind of thermostat.

So…what's got you thinking that design is superior (it's not) or recommended for the Slant-6 (it's not)?

 

[RustyRatRod]

Okeh, it doesn't hit your particular head, very fine. I've seen 'em hit enough heads (one was enough) to not pursue the idea of needlessly enlarging the hole to fit a not-the-right-kind of thermostat.

So…what's got you thinking that design is superior (it's not) or recommended for the Slant-6 (it's not)?

It is in terms of flow.

 

[slantsixdan]

It is in terms of flow.

1. No, sir, it is not. For one thing, flow through the thermostat is not necessarily a more-is-always-better deal. For another, a regular ol' normal ol' boring ol' plain ol' stock thermostat flows plenty of coolant. The main benefit of a high-flow one is you get a warm fuzzy knowing you put in a high-flow one.

2. Still waiting for you to cough up that nonexistent "recommendation by Chrysler" for people to use a kind of thermostat that's not built to the correct dimensions for a Slant-6 engine, in a Slant-6 engine.

Sorry, RRR, but you're FOS on this one.

 

[RustyRatRod]

1. No, sir, it is not. For one thing, flow through the thermostat is not necessarily a more-is-always-better deal. For another, a regular ol' normal ol' boring ol' plain ol' stock thermostat flows plenty of coolant. The main benefit of a high-flow one is you get a warm fuzzy knowing you put in a high-flow one.

2. Still waiting for you to cough up that nonexistent "recommendation by Chrysler" for people to use a kind of thermostat that's not built to the correct dimensions for a Slant-6 engine, in a Slant-6 engine.

Sorry, RRR, but you're FOS on this one.

Ifin you say so.

 

[slantsixdan]

Yeah, I'm not done. How'd you check to make sure your oversize thermostat can open all the way in your head? I know how I did it, and I'm curious if you did it the same or differently.

 

[RustyRatRod]

Yeah, I'm not done. How'd you check to make sure your oversize thermostat can open all the way in your head? I know how I did it, and I'm curious if you did it the same or differently.

I took a measurement from a fully opened thermostat and measured the clearance from the thermostat flange area to the inside of the head.

 

[RustyRatRod]

But you're right....as usual. The literature where "I thought" Chrysler recommended this type for the slant was actually for one of the LA engines.

 

[slantsixdan]

Check yer timing, dude; you're spozeda wait til _after_ I post this (from the '73 FSM) to post that!


(I took apart one of those V8 thermostats and rigged it locked-fully-open, then tried to insert it in the enlarged head hole. Nope, it fouled on a small part of the casting inside.)

 

[RustyRatRod]

Check yer timing, dude; you're spozeda wait til _after_ I post this (from the '73 FSM) to post that!


(I took apart one of those V8 thermostats and rigged it locked-fully-open, then tried to insert it in the enlarged head hole. Nope, it fouled on a small part of the casting inside.)

View attachment 1716353601

That's it! I was trying to find it. Thanks.

 

[RustyRatRod]

There's actually another that shows that style thermostat....but it's an under hood sticker.

Spozeda?