MarcDeSoto Posted May 13, 2022 Report Share Posted May 13, 2022 I bought this thermostat NOS back in the 80s, but have never tested the fit. Now that I'm buttoning up my cooling system, it seems that the thermostat does not fit. It doesn't seat snugly in the housing. I guess this is the wrong thermostat? Quote Link to comment Share on other sites More sharing options...
Bryan Posted May 14, 2022 Report Share Posted May 14, 2022 There are 2 sizes. Mine is 2 1/2 inches. The outer rim has to fit in the recessed groove. They're not expensive. 1 Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 14, 2022 Author Report Share Posted May 14, 2022 As you can see in my pic above, the thermostat doesn't seat in the housing because it's too tall. I saw that they sell them at OReillys for $8. We will see. Marc. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted May 14, 2022 Report Share Posted May 14, 2022 Mark Here are pictures of the correct thermostat for your car taken from my Autostat catalog. Rich Hartung 1 Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 14, 2022 Author Report Share Posted May 14, 2022 (edited) I got the OReillys thermostat today, but it doesn't fit my housing either! I wonder if NAPA would have it? If not, I guess i'll order it from AB. Should I buy the 160 deg. or 180 deg. thermostat? I live in a warm Southern Calif. climate if that makes a difference. Edited May 14, 2022 by MarcDeSoto Quote Link to comment Share on other sites More sharing options...
Sniper Posted May 15, 2022 Report Share Posted May 15, 2022 I run a 180 thermostat, it's 101 here right now, I don't overheat. Running too cold is part of what sludges up the oil. 1 Quote Link to comment Share on other sites More sharing options...
9 foot box Posted May 15, 2022 Report Share Posted May 15, 2022 Here are some 180 thermostat numbers, NAPA THM155, Stant 13928, Gates 33028, Carquest 30028. For 160 degree, NAPA THM55 and change the 8 to a 6 for the others. What thermostat did you just try from O’Reilly? There is a rubber seal that seats on the top of the thermostat, be sure that it is in the box. The one you bought 40 years ago, doesn’t even look right. Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 15, 2022 Author Report Share Posted May 15, 2022 https://www.oreillyauto.com/detail/c/plus/engine-cooling/thermostats/thermostat/555a1167c2f6/murray-plus-180-degree-thermostat/mcs1/3928/v/a/21216/automotive-car-1948-desoto-s-11?q=thermostat&pos=0 This is the one I ordered that would not fit. Quote Link to comment Share on other sites More sharing options...
FarmerJon Posted May 15, 2022 Report Share Posted May 15, 2022 (edited) Part number is likely right and part is wrong. I bought 15 different store brand t-stats, including Napa 155, none fit, and or were missing the rubber seal. Bought NOS Napa 155 from the 1990s, fit fine. Edited May 15, 2022 by FarmerJon Typos 1 Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 15, 2022 Author Report Share Posted May 15, 2022 NAPa told me they don't carry anything that would fit my thermostat. So I'll try AB. Quote Link to comment Share on other sites More sharing options...
Bryan Posted May 16, 2022 Report Share Posted May 16, 2022 None of these? https://www.rockauto.com/en/catalog/desoto,1948,s-11,3.9l+237cid+l6,1486774,cooling+system,thermostat,2200 Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 17, 2022 Author Report Share Posted May 17, 2022 (edited) For some reason I missed those on Rock Auto. Thanks. I already ordered one off of Ebay, NAPA 155 that Farmer John suggested. Edited May 17, 2022 by MarcDeSoto Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted May 20, 2022 Author Report Share Posted May 20, 2022 Because so many thermostats were not fitting, I ordered two more in hopes one would fit. The Rock Auto thermostats was just like the OReillys one. It was too wide to fit in the housing. Rock Auto has an unfair return policy. They make you answer about 20 questions, and then they say Is the part we sent you the part you ordered? I say Yes, but it didn't fit. Then they say OK since we didn't make a mistake, we will not refund the shipping to you. So their policy is they don't stand behind their products. Luckily, the old NAPA 155 in an old box did fit. I got it on Ebay thanks to Farmer Jon's tip. Thanks Farmer Jon! 1 1 Quote Link to comment Share on other sites More sharing options...
Sniper Posted May 20, 2022 Report Share Posted May 20, 2022 RA gives the measurements ont he thermostats. You probably could have figured out it wouldn't have fitted from that. Quote Link to comment Share on other sites More sharing options...
FarmerJon Posted May 20, 2022 Report Share Posted May 20, 2022 (edited) Iirc It isn't the outer flange that is wrong. It is the upper "bubble" that is formed wrong. It is a manufacturing defect. Edited May 20, 2022 by FarmerJon Quote Link to comment Share on other sites More sharing options...
Yukonuck Posted October 29, 2022 Report Share Posted October 29, 2022 You are very correct on making that statement about the "bubble" dimension. I received a p/n 155 stat (Balkamp) thru NAPA and it's a 2 piece arrangement. Stat is fine, o-ring would work, height is ok, but the brass flange bubble is too big to fit into the housing. Quote Link to comment Share on other sites More sharing options...
MarcDeSoto Posted October 29, 2022 Author Report Share Posted October 29, 2022 On 5/20/2022 at 12:19 AM, MarcDeSoto said: Because so many thermostats were not fitting, I ordered two more in hopes one would fit. The Rock Auto thermostats was just like the OReillys one. It was too wide to fit in the housing. Rock Auto has an unfair return policy. They make you answer about 20 questions, and then they say Is the part we sent you the part you ordered? I say Yes, but it didn't fit. Then they say OK since we didn't make a mistake, we will not refund the shipping to you. So their policy is they don't stand behind their products. Luckily, the old NAPA 155 in an old box did fit. I got it on Ebay thanks to Farmer Jon's tip. Thanks Farmer Jon! I was wrong. The thermostat I bought from Ebay, the old Napa 155, also did not fit after all! I finally had to buy one from AB and finally, it did fit. Quote Link to comment Share on other sites More sharing options...
Yukonuck Posted October 29, 2022 Report Share Posted October 29, 2022 Maybe we don't have to use that brass "bubble" piece with the new replacements? The outside diameter of the modern thermostat may well hold it in place between the head and the thermostat housing upon assembly. There is a by-pass connected at the housing too. I admit I did not try this yet. I tested my old one and as it appears to be working ok, I reinstalled it. It is 175degree so that is going to do for now. I wanted to install the 180degree as I use the vehicle year round and reside in Yukon Territory, Canada. We get some cold winters and that bit of extra heat is nice for the passengers and good for the engine. Quote Link to comment Share on other sites More sharing options...
andyd Posted October 30, 2022 Report Share Posted October 30, 2022 Don't know if this info will help but the thermostat housing on the 1941 Plymouth I had used the same bolt spacing for the 2 bolts that held it to the cylinder head as the V8 thermostat housings so I just used the later type of thermostat, ie the type that has a bolt hole on either side and is "flat" rather than squat like that shown......it was a 180 degree thermostat & worked fine...........admittedly this engine had an internal bypass.......not the external that is shown in the OP post.....................andyd Quote Link to comment Share on other sites More sharing options...
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