And some more on the thermostat. The service manual spells it out very clear for the 160 deg thermostat.
"The standard thermostat on the CJ-2A and the CJ-3A is designed to start opening at 150 deg and be fully open at 170 deg". This is far different than a current pellet style 160. It starts opening at 160 deg and is fully open at 180 deg.
This is all making sense now.
And, when I get the Robertshaw thermostat I'm going to heat it up in a pot of water with the turkey thermometer to make sure it still works - it may be 40-years old!
Ha Ha! I had the same revelation. I just received the new "Racing" Milodon 160 deg. Thermostat https://www.summitracing.com/parts/mil-16400. Wow it is definitely a higher flow Thermostat. It was $24! I can see why. All brass and stainless. I will be testing things out soon.
Last edited by bmorgil; 09-25-2020 at 09:39 AM.
The price was right on those Robertshaw, I bought two, in case one doesn't work.
"Options are for girls"
I started poking around looking at coolant efficiencies and I found this interesting thread. It relates to a specific product, but it gave me a better idea of how little micro bubbles could form in engine cooling jackets - kind of like the little bubbles on the bottom of the pan before water boils. I can see how rough spots from the casting could be a starting point for these little pockets of water vapor.
We get smarter and smarter about less and less and pretty soon we'll know everything about nothing - kind of like a doctor today.
Water boils at 212.
50/50 ethylene glycol boils at 223.
A modern 14 PSI pressure cap raises 50/50 ethylene glycol boiling point to about 250.
With a 4 PSI cap, peeJ was getting close, (maybe 225 -230) but no burp.
https://www.evanscoolant.com/how-it-...o-overheating/
We were within 5 deg of it (Chernobyl), right at the head. The jump out and get the "LarrBeards coffee cup installed" to prop the hood, was the few degrees we needed to prevent it! A little "Air Cooling". Good call Senior Chief!
The temp gun told the tale when I got it home. It was hot 220, right at the sender, which is placed in the hottest spot of the motor. Right on top the combustion chambers. The water on the other radiator side of the housing was 190. At the radiator top it was 170. It might have steamed it right at the sender, but I think it was a ways from a spewing boil over.
I put the Milodon in last night. It runs up to about 180 then drops back to 160. Idling for about 5 min the temp creeps up to about 190 and holds. I am in a parade in a few weeks. It will be a good test. When the Robertshaw gets here, it will give me an opportunity to see how it runs as originally intended.
The Milodon will set right in the head no problem. The Thermostat housing will need to have a relief milled into it for clearance. I am going to try this also. This should help the temp gauge run closer to what the thermostat is doing. This is the way the F head is set up (and most motors).
My wife asked; “what are you doing on my stove?”
I replied; “Testing a thermostat.”
Wife; “Why?”
Me; “It’s a Jeep project.”
Wife; “Oh, I understand… .”
She’s starting to get it!
OK, I got the eBay Robertshaw thermostat today and before I drained coolant and tore off the thermostat housing, I wanted to see just what I had.
Short answer – It’s not going into my truck.
This isn’t what we hoped it would be. We were hoping for an old bellows unit that would start to open at 140 and be full open at 160. It looks a lot like a wax pellet unit – it starts to peep open a little at 160 and it’s not full open until about 190-plus.
Don’t bother!
Awsome LarrBeard! Just saved me a lot of time. The Milodon is the way to go I think. I just got back from the ice cream shop with the misses. 160 all the way there and all the way back. The low speed driving still seems to creep up but, nothing like before. Definitely a big change for the good. I am going to keep it in. I will confer the Robertshaw to the "Alter of Willys" in the shop.
Well tell the misses... "It's a Jeep Thing"!