When the radiator starts spitting on you.

[scoutpilot]

Old Blue. 1948 CJ2A. My testing vehicle for WOs and M38 YSs. The radiator had a small pressure leak in the top tank. Not a big problem, add coolant when necessary. Then some small leaks appeared at the bottom. Then a small pressure leak developed at the top of the Water Pump gasket. No big problem, add coolant when necessary. Then suddenly the radiator began spitting on me when I was throttling up restored carbs. Hmmm. The spitting got worse.

Okay. I gotta do it. Total overhaul of the very old cooling system. I flushed and cleaned the system. I ordered a new, reproduction CJ2A radiator. Pete didn't have any NOS units and told me the last one sold for $1K. PHEW! I bought the Horsehair panels with the Burlap substructure. The old pieces had a Nylon mesh substructure. I bought new upper and lower radiator hoses with the correct clamps. More on them later. I had already pulled the water pump and discovered the problem was simply a gasket failure. No pump purchase is necessary pending inspection. I bought a new 160º thermostat.
I had three gallons of 50/50 from NAPA, along with a few NAPA Gold 1010 oil filters. What the heck? Do it all at once. I already had the 30W Rotella on the shelf also.
As noted earlier I had already pulled the pump and old hoses and found the failed gasket so I cleaned and inspected the pump. No play in the shaft so let's reuse it. The block water jacket was clean so I scraped and cleaned the mounting surfaces on the block. I cleaned, scaled, prepped, primed, and painted the pump with Zinc Phosphate. I already had a fresh gasket for it so I brushed some Permatex Indian Head Shellac on the mounting face and the gasket, waited until just past tacky, placed the gasket, and installed it.
The Thermostat housing needed a thorough cleaning and scale removal and was treated to the same process as the water pump. I had to punch/cut a new gasket for it. I applied Permatex Indian Head to the mounting surface and the housing face side of the gasket, waited and placed the Thermostat, then the retainer, and installed it.
All of the bolts penetrating the water jacket were treated with Permatex #2.

For the new guys, I did not apply any Indian Head to the gasket surface that mated with the head and block. Properly tightened, it seals very well and makes removal for any future work so much easier and cleaner.

The radiator went in without a problem. Hose connections were made. The new clamps disappointed me. They didn't seal the hoses properly and the hoses leaked at the ends. The slots in the screw heads are very shallow and don't allow the proper tightening torque. They appear to be either aluminum or very soft steel so I think they stretched when tightened. I had to reuse the old worm gear clamps.

The grille. Without the proper tool, installing the Horsehair was a tedious task. I had to remove the old staples and drill the holes to clean them up. Three different types of pliers to install the new staples, mostly blind, and then fold the ends over. But I got it done and that includes the lower brush guard at the bottom of the radiator.
A half-dozen or so bandaids later it's all back together with some new hardware and going to sit overnight to see if there are any more cold leaks.

Back to carbs tomorrow.
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[athawk11]

Nice write-up Rick.  A job well done...as always.

[SteveKfl]

Always a thorough job from you and your write ups.  Thanks.  I was surprised to see you use 160 degree therm and not 180.  May I ask you of the advantage?  If it would make a difference for my "L-head", note I live in very south Florida, where it is "warm" all year, to say the least.  Thanks for more of your teachings!

[scoutpilot]

Thanks for the kind words guys!  Testing and adjusting carbs requires quite a bit of idle time. The sooner I can get coolant flow the better.

[SteveKfl]

So, is the 160 degree thrm just for "testing" vs running street use?  What temp therm have you found to work best for general use for best combustion temps?  I thought I based my 180 degree one on "recommendations" years ago.  I was wondering if that might have changed now. 
 
I tried to balance my cylinder temps better by a "bypass tube" from back cylinder to pump intake, and also using the "hottest point" where the temp-sensor was located, to route my heater and the "return" to the block's "drain location" trying to put more heat under the therm between 2/3 cylinder location where test showed around 173 degrees (assisted with Colin Peabody's Surry using a 180 therm) while the cylinder head temps tested 1/2 at 173. 2/3 at 183, 2/3 at 203, and 3/4 at 192 before the "balance attempt". 
 
Unfortunately, my project took a "medical standstill" in 2016 and has yet to be tested for "results".  My theory was to tap into the hotter locations and route some of the heat to cooler temp locations to "balance the overall cylinder temps" to what I thought would be ideal around running temps 185-190 degrees with "flow" throughout all four cylinders for "even combustion".
 
Any input, thoughts, or even criticisms would be appreciated.  Thanks.  Temp pics attached...

[scoutpilot]

95% of my road test route is rolling hills. Some are somewhat steep but short. Throughout the year this part of North Carolina sees temperature range from -0ºF to 100º+F. Humidity can become oppressive at 100%. Free air temperature and humidity variations influence the engine’s burn rate characteristics. An increase in humidity reduces the burn rate and increases the combustion duration. This increase in combustion duration has the same effect as retarding the time of ignition. Thus the thermal efficiency is reduced. Additionally, the engine will overheat and is more likely to misfire as humidity increases. The cylinder temperature affects the engine fuel efficiency, knocking, exhaust gas temperature, and particularly the NOx emission. It is my theory that coolant, moving sooner through the system extends the time before an overheating condition can appear. As a reminder, a 200º temperature is not bad. Don't worry about it, but do keep an eye on it. Again, it all depends on tuning, terrain, outside air temperature, relative humidity, and driver technique.

[Ron D]

So, is the 160 degree thrm just for "testing" vs running street use?

Paragraph H-7 on page 116 of the Willys Universal Jeep Service Manual calls out the standard thermostat for the CJ-2A and CJ-3A as 160-degrees (starts opening at 150* and fully open at 170*).