harmony Posted February 10, 2023 Report Share Posted February 10, 2023 I'm finally getting around to seeing if I can get my 251 engine from a parts car I bought several years ago, running. I just built a run engine stand for it and I noticed something I hadn't really paid attention to before. It looks like the thermostat housing has an attachment for what looks like maybe a bypass around the thermostat. I took that flex hose off and on the top portion there is a valve like a choke valve and it looks like it was controlled by linkage to be manually opened or closed. Looking into the other section coming off the base of the thermostat housing, I can see way in there, how the opening is divided into sections in the casting. I believe that opening is below the thermostat. I haven't removed the housing yet but in the last picture you can see from looking straight down, that there is no thermostat. Has anyone seen this before? Quote Link to comment Share on other sites More sharing options...
Sniper Posted February 10, 2023 Report Share Posted February 10, 2023 Well, the T pipe is obviously home made, the brazing work tells me that. Not sure on the outlet. Is that second outlet brazed on too? I'd be inclined to call that someone's redneck engineering Quote Link to comment Share on other sites More sharing options...
harmony Posted February 10, 2023 Author Report Share Posted February 10, 2023 (edited) 53 minutes ago, Sniper said: Well, the T pipe is obviously home made, the brazing work tells me that. Not sure on the outlet. Is that second outlet brazed on too? I'd be inclined to call that someone's redneck engineering Yes I noticed the brazing as well, but I wasn't sure if it was just a repair job or if it was a redneck add on. Hopefully I'll have a better idea when I take it off today. The 1 1/2" take off on the bottom is also brazed on. I can't tell if the whole piece is brazed on or if it's just repaired. It's not easy brazing casting successfully water tight, but it can be done. I think the real mystery is,,,why? Edited February 10, 2023 by harmony Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 10, 2023 Report Share Posted February 10, 2023 The lower thermostat housing looks AG or industrial? You don't want or need it...replace it with the factory thermostat housing and a new correct thermostat. 1 Quote Link to comment Share on other sites More sharing options...
harmony Posted February 10, 2023 Author Report Share Posted February 10, 2023 1 minute ago, Dodgeb4ya said: The lower thermostat housing looks AG or industrial? You don't want or need it...replace it with the factory thermostat housing and a new correct thermostat. What is AG ? Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 10, 2023 Report Share Posted February 10, 2023 Agriculture.... 1 Quote Link to comment Share on other sites More sharing options...
harmony Posted February 11, 2023 Author Report Share Posted February 11, 2023 The only thing I really learned by taking the thermostat housing off was that the thermostat is above the what I'm calling a bypass opening in the housing. Which in itself puzzles me. I mean if it was below the thermostat, I can see how the manually operated valve would let coolant circulate even if the thermostat was closed, if the owner chose to do that. But the way it is configured, I really don't see the purpose of it. In the one photo you can see the divided sections more clearly and that part doesn't look homemade to me. The piece coming off the back of the housing, where those holes are, looks a lot like a radiator bottom tank fitting. Maybe it is, maybe it isn't, it just has that shape to it. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 11, 2023 Report Share Posted February 11, 2023 Now that the housing is off it looks like someone has brazed that lower curved part on the T-stat housing.... Get a good thermostat housing. A common part. Quote Link to comment Share on other sites More sharing options...
harmony Posted February 11, 2023 Author Report Share Posted February 11, 2023 9 minutes ago, Dodgeb4ya said: Now that the housing is off it looks like someone has brazed that lower curved part on the T-stat housing.... Get a good thermostat housing. A common part. What I'm trying to do is solve a mystery. Quote Link to comment Share on other sites More sharing options...
Dodgeb4ya Posted February 11, 2023 Report Share Posted February 11, 2023 (edited) That it is...maybe it's a anti-cavitation by pass. Edited February 11, 2023 by Dodgeb4ya Quote Link to comment Share on other sites More sharing options...
Sniper Posted February 11, 2023 Report Share Posted February 11, 2023 Someone rednecked it for some reason, not likely to ever know why. 1 1 Quote Link to comment Share on other sites More sharing options...
vintage6t Posted February 12, 2023 Report Share Posted February 12, 2023 (edited) Hard to tell from the picture but do the smaller fittings on each side of the upper Y tube actually flow coolant or are they just bosses for the inner flap valve shaft? Also even though the current configuration has a short hose from the thermostat housing base to the upper Y. I can envision a different setup where there is one hose at the thermostat base feeding some aux heater/radiator/block pre-heater and a second hose returning from the aux unit to the Y. Open the valve in the Y to feed the aux unit. Close the valve to bypass it for normal operation. Edited February 12, 2023 by vintage6t Quote Link to comment Share on other sites More sharing options...
harmony Posted February 12, 2023 Author Report Share Posted February 12, 2023 Pretty sure that they would flow coolant, since it is coming right off the top of the thermostat housing. The engine came with a 1946 Windsor and it was still mounted and wired into the car. Otherwise it's possible that the engine could have been used somewhere else previously. These 251's were used for many purposes and maybe your theory could hold water ( pun intended) if it was a bush donkey engine and it was feeding something else with coolant as well. That could still be the case and then later in life someone put the engine in the car and just ran that short flex hose as a short cut method to seal the cooling system. Just a thought. The next time I'm at my shop, I'll check my parts catalog to see if there is more than one part number for that thermostat housing. Even though there is a lot of brazing on the assembly, which would indicate a redneck invention, or possibly a repair job, it doesn't explain the grate like oval holes in the thermostat casting at about the level of where the thermostat would sit. Granted the Y piece definitely looks home made. But then again, if you're out in the bush and the original piece got damaged beyond repair, you'd use whatever you had available to create your own homemade version. Again, just a thought. Quote Link to comment Share on other sites More sharing options...
vintage6t Posted February 12, 2023 Report Share Posted February 12, 2023 A hint as to the origin of the engine will be the number stamped into the block. It's on a pad on the left side, near the front just under the head. Quote Link to comment Share on other sites More sharing options...
harmony Posted February 12, 2023 Author Report Share Posted February 12, 2023 27 minutes ago, vintage6t said: A hint as to the origin of the engine will be the number stamped into the block. It's on a pad on the left side, near the front just under the head. Do you think that will indicate if the engine was marine, industrial, automotive, etc? Quote Link to comment Share on other sites More sharing options...
vintage6t Posted February 12, 2023 Report Share Posted February 12, 2023 . 1 hour ago, harmony said: Do you think that will indicate if the engine was marine, industrial, automotive, etc? At least IND, or Auto - Chrysler or Desoto. Also year Quote Link to comment Share on other sites More sharing options...
nonstop Posted February 13, 2023 Report Share Posted February 13, 2023 Just a wild guess, but it sort of seems like someone’s attempt at a home made thermostat. The butterfly allowing them to control the heat or bypass. I could very well be wrong. Quote Link to comment Share on other sites More sharing options...
harmony Posted March 2, 2023 Author Report Share Posted March 2, 2023 (edited) I've bought what I'm thinking is an upgrade of the original thermostat. It's a NAPA #155. I went this route because I've read that guys that have bought the tall original style aftermarket ones don't open when they are supposed to. What the #155 does is it allows you to use a conventional thermostat. It comes with a thick rubber gasket that goes on the top of the thermostat and seats tight against the smaller opening inside the thermostat housing. After that rubber washer is in place the thermostat goes next, then there is a copper/brass, spacer that goes on the other end of the thermostat. That spacer should slip up inside the thermostat housing and sit in the provided lip. It's followed by the base washer and I'm sure it would be fun to get it all in place without it all falling out. Well I just got one and the copper/brass spacer is too big in diameter. By a fare amount. Somewhere between 1/16" and 1/8". It wasn't expensive and it comes with a 180 F thermostat, I won't be returning it. But there is no real way of modifying the spacer so my only choice is for me to get out the die grinder and make the inside diameter of the housing bigger until it slips in. I'll have to be very accurate because as you will see in one of the following pictures the lip is quite small. Even though the recess in the housing would have allowed for a much bigger lip, which I've shown in one of the pictures with the adapter slid over to one side. Now I know people have said to just buy a new housing and turn the one I have into a door stop. But keep in mind this project is to just see if this engine will run and if it has decent compression. Who's to say that the opening in a new housing is any different than the one I have anyways. If it passes the running & compression test, I'll probably try to get the fluid drive operational while it's on the run engine stand. Assuming the generator, regulator, and trans relay are operational. But first things first. I'm wondering if anyone has bought this NAPA 155 thermostat kit? In the last picture I flipped the spacer upside down, just to illustrate that the lip could have been a bit larger. Edited March 2, 2023 by harmony Quote Link to comment Share on other sites More sharing options...
Young Ed Posted March 2, 2023 Report Share Posted March 2, 2023 I'm running that exact one in my P15 for 15ish years now. Quote Link to comment Share on other sites More sharing options...
harmony Posted March 3, 2023 Author Report Share Posted March 3, 2023 3 hours ago, Young Ed said: I'm running that exact one in my P15 for 15ish years now. Did it fit right out of the box? Quote Link to comment Share on other sites More sharing options...
harmony Posted March 3, 2023 Author Report Share Posted March 3, 2023 (edited) Today, I used the die grinder to oversize the opening, until the copper/brass adapter portion slid in. Then the next issue arose. The thick rubber seal was about almost 1/8" too thick. So rather than trying to cut it down, which might have caused leaking issues if I didn't get a perfectly cut, I decided to bend the two protruding tabs on the adapter, down as far as I could. In the pictures below you can see the difference from when it came out of the box and how much I had to bend the tabs in order to make it all fit snugly. I had it so that adapter was just a little bit proud of the housing. That way once it was assembled and the bolts tightened, the thick rubber seal would compress slightly. Then the next challenge was assembling it. I was fighting gravity. Not only that but the housing has to be slid in so as to connect with the small short bypass hose coming off water pump assembly. I thought maybe if I used Permatex gasket maker on all the parts and both sides of the base gasket, that it would stay in place until I got the housing in place. Not a chance, and everything fell to the floor. So round two,,,,, I got all the parts in place again, rubber spacer, thermostat, copper/brass adapter, and the base gasket, by holding the thermostat housing upside down. Then I used a steel rule to hold everything in place by pressing on the bottom of the thermostat. Then I flipped the housing 180 degrees, and slid it into the bypass hose, while still keeping upwards pressure on all the parts with the steel rule. Once I got the bolts started in the holes and threaded in almost all the way, I slid out the steel rule, and I can only assume that at that point nothing shifted out of place. Wow! what a job that was. Not for someone that doesn't like challenges. Edited March 3, 2023 by harmony Quote Link to comment Share on other sites More sharing options...
FarmerJon Posted March 3, 2023 Report Share Posted March 3, 2023 Looks like you got one of the many defective ones. See how tiny the bottom flange is? look at it compared to a Old stock one: Quote Link to comment Share on other sites More sharing options...
harmony Posted March 3, 2023 Author Report Share Posted March 3, 2023 3 hours ago, FarmerJon said: Looks like you got one of the many defective ones. See how tiny the bottom flange is? look at it compared to a Old stock one: Hummm!!! Good point. Thanks for that picture. Definitely a big difference. I did take some measurements with a digital caliper and if I ever feel the need to check or replace the thermostat on my '48 Chrysler Windsor, I'll try to remember to do a comparison. Or if I ever see a thermostat housing at a swap meet, I'll be sure to buy it and see how it compares. The bonus would be if it still had a thermostat in it. Another issue, even though it might be knit picking, but the thick rubber seal is wider in the original. ( see my first picture) Mine was packaged in a way that made it oval in shape slightly, so I had an issue with it staying in place before I could get the thermostat on top of it. I even tried clamping it for an hour or so to get it back into a round shape. It they hadn't cheaped out on the width of it, I'm sure it would have stayed round. Quote Link to comment Share on other sites More sharing options...
Young Ed Posted March 3, 2023 Report Share Posted March 3, 2023 16 hours ago, harmony said: Did it fit right out of the box? Yes and my car had the same style in it that I replaced. 1 Quote Link to comment Share on other sites More sharing options...
harmony Posted March 4, 2023 Author Report Share Posted March 4, 2023 My apologies to China. According to the box, my 155 thermostat assembly was made in Israel. Quote Link to comment Share on other sites More sharing options...
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