Modifying the Omix Radiator

I have been battling overheating issues since I got my ’47 2A in 2017. The original radiator has been cleaned and repaired once and cleaned out again. I had a lot of rust in the block that required several flushes to get more of the rust out after the radiator was repaired. Even so, I still had problems after a “high speed” run. This usually entailed a few miles at 45-50+ MPH. Upon slowing down, temps would come up to 190-210+ and would have a hard time coming back down to 170-180 prolonged slow driving or sitting at idle. A hot shut down would often result in a boil over. On a recent hot Reno day, I ran her for several miles at 50+ MPH. Initially she was fine, but the temp pegged the gauge at around 250 when I came to a stop and would only come down a couple degrees after sitting at a high idle for several minutes. I thought I was going to kill the engine. Later, I figured that some more rust came loose in the block and plugged the radiator. After another flush of the block and radiator resulted in more rust coming out but there was no improvement in reducing temperatures.

Stan (Grampa’s Jeep) did a nice comparison of the Omix radiator to his original.

 Original vs Omix-ADA radiator - The CJ2A Page Forums - Page 1

After Stan’s professional review, I decided to give the Omix a try. The cost was not much more than having the old one cleaned out again. I’m lucky to have a Summit in town making returns easy if I didn’t like it.

The radiator I received did not come with a cap but I was able to use my NOS vintage one from the original radiator. The Omix radiator is aluminum with a steel shroud that bolts to the radiator.

Stan’s review covered all the issues that I observed:

1.       Straight inlet tube.

2.       Non-fixed mounting bolts.

3.       Short overflow pipe.

4.       No provision for side felt.

5.       Oblong shroud.

6.       No ability to use the shroud extension.

 

I thought I would attempt to correct some of these issues and, at the same time, make the radiator look more like the original.

First, the inlet tube would need to be cut off and a new piece, cut at an angle, in place. Not wanting to potentially void the warrantee and having limited TIG aluminum tube welding experience, I opted not to correct this. It does make the hose a little difficult to attach especially if you use the metal pipe section. (The lower fit fine.)

Second, the mounting bolts are loose. I epoxied them in place since it is impossible to get a wrench I there. When I went to mount it, the bolts would not align with the mounting holes. I had to break the bolts free with a plastic hammer. I think the remaining epoxy did help hold the bolts in place so that I could tighten them down.

Third, the overflow pipe is too short and a long section of rubber hose would not look original. I bought some ¼ soft copper tube, bent it into shape, extended it to well past the bottom of the radiator and painted it black. Since I could not weld/solder the copper to the aluminum, I used a short piece of hose with some shrink tube to hold it together.

Forth, I made side panels to allow for the use of the original felt. I cut two panels 13” x 3” and used my “Bubba approved” press break to make a 90 degree ½”tab. The panel is held in place with the bolts connecting the shroud to the radiator.

 

 

 

 

The correction of the oblong shroud opening and the inability to use a shroud extension took some work. Using a cardboard and the shroud extension, I made templates for new panels. I then TIG welded them around the perimeter of the shroud. I left the existing metal in place. The shroud extension required the relocation of a couple mounting tabs. I also TIG welded nuts and washers to the inside of the shroud to make assembly and disassembly of the extension easier.

 

 

 

Installation of the radiator was straight forward with just a little issue in connecting the upper hose.

 

 

 

 

 

A few things that I learned:

My shroud extension was a little beat up from a previous encounter with the fan. So, getting the opening correct was challenging. I ended up splitting the seam and rewelding it with a slightly larger diameter to get it to fit better. A new shroud would have made the installation better.

I did not remove the old radiator to use as a comparison as I was modifying the Omix. Unfortunately, I have the Jeep parked in the street and could not have it non-operational while I made the modifications. If you look at my comparison photos, the top round portion of the Omix shroud is mounted about 1” higher than the original. There is over and inch of fan clearance at the top but, at the bottom, there is about ¼”. If I have the radiator out again, I will redrill the six shroud mounting holes ½” lower. This should balance out the alignment.

Also, having the old radiator out might have helped me creating a template and getting the shape of the opening a little bit better.

I have only done one test drive so far. Outside air temperature was in the mid 80’s. For my short two mile “high speed” run to and from the gym, the temp remained at 160 and did not go past this on the next two miles when speeds were in the 30-40’s. When I parked after going a few blocks at 25 MPH, she was at 180 and with a fast idle, the temps started to immediately drop. So, hopefully, this radiator keeps the temps down in the hot August days ahead and no more rust breaks loose. 

Micah

I know a lot of us have distain for Omix parts. I too was reluctant in going with this radiator. I have had zero problems with it so far. It has solved a long standing irritating issue with overheating. In August, with temps in the high 90s to 100, she never got over 180. A few weeks ago, I towed my M-416 half filled with dirt and rocks up into the hills to unload. In four low with a heavy load up hills, the temperature was not an issue. 

So, I cannot think of anything bad to say about this radiator other than the issues that required modification. 

I have to admit that I made one mistake in my modification. I did not realize that the shroud has a right and left side. I thought they were equal but if you look at where the top of the shroud sides meet the rounded portion, it is different side to side. I mistakenly put mine one the wrong way. The next time I have the radiator out, I will rotate the shroud. This should correct my tight fan clearance issue on the right side and may help with the clearance at the bottom. The only bad thing is the shroud extension will be up side down with the seam at the top and the radiator cut out 180 from where it should be. Neither of these should be an issue.

Micah

I figured this might happen since I mounted the shroud 180 degrees off and the clearance was very tight n the passenger side. Maybe someday, I will reinstall a new one and get it in the right position. The radiator has kept the temps down without a problem. So, we will see if I can get through the summer without the extension. 

This is the second time this has happened. The first was with the stock radiator. I'm surprised that there is this much movement. Anyone else had a similar issue?

Micah

I'll take a look. I replaced all the mounts a couple years ago, but as you said, they may be junk. The cable was good when I replaced the clutch a couple years ago. Maybe it has loosened up. I'll check that too. 

What is the major difference with the new mounts you have? 

Micah

Micah,

Changing motor mounts is pretty easy. Undue the 3 nuts on each mount. Put a piece of wood on your floor Jack and slip it under the oil pan. Jack up the motor until the mounts will slip out. I found that if you tip them a little they come out easier. New ones go in the reverse process. Might have to watch the fan to make sure it doesn’t bind up on the radiator shroud as you’re jacking.

Less than 1/2 hour job.

This guy goes through the process and shows the Big Willy mounts. And I like listening to his accent.

Thanks for the link. I replaced the mounts a couple years ago. They may have been junk ones too. So, maybe this will keep the engine in place. Did you notice any more vibration?

Micah