I've fixed the ARB, and it should be as good as new. I started the wiring change to be sure the computer was feed clean full voltage and install the solid state relays. Well, I found a couple of issues that I believe were causing my problems.
The system ground wire connection at the engine intake had come loose. Also the ignition feed wire to the power relay had a bad crimp (not one I made). So what I first thought was a bad relay (I'd swapped it out before the trip) and the computer shut downs at the Bad Lands turns out to be both a ground and power connection issue!
Now I need to put the dash back together and then move to the engine bay and install the new high volume water pump to address the high rpm overheating issue. However the small radiator leak will likely be a more difficult problem to fix as the good radiator shop here in Decatur went out of business. - March 2016
This issue has been going on for a while and back in March of 2014 I had a small radiator leak and pulled it to have it fixed and cleaned as I thought that was the issue. Well it wasn't.
So I figured it must be the water pump. I ordered a High-Performance GMB Short Snout Water Pump to replace and upgrade the M. Well the old pump is just fine. The new pump has an improved water channel path design, but has a slightly smaller impeller (4-3/8" Old & 4-1/16" New) so I hope the new pump isn't a down grade.
I knew it wasn't a lower hose issue as it had a good hose and internal spring. The issue was at highway speeds, or high RPM's off roading so I was looking for a coolant flow or capacity issue. The radiator has developed another small leak, so it came out again and will get re-cleaned to be sure it has good flow.
Back after I built the engine in 2005 and got the M on the road in 2007 I had a thermostat leak. I pulled the thermostat out and found the aftermarket aluminum housing was not flat, so I filled it flat and cleaned everything up and resealed it with no leaks.
The thermostat looked good and was new in 2005. The thermostat was a Robertshaw 180º part number 370-180. This type of thermostat has a lower cup that opens downward opening up around the outer edge between the thermostat and the intake.
As the thermostat was the only thing left, I pulled it out again. I found two issues: Some of the sealant had oozed into the space between the side of the thermostat lower cup and the intake. Also when I placed the thermostat in water, it only started opening up at 190º and at boiling it was only open about 1/8".
So between a poorly operating thermostat and a partially obstructed path, I think (hope) that is my cooling issue. It was just not able to push enough coolant across the radiator under high heat loads. So I have a new Napa Premium Thermostat on order.
So I'm keeping my fingers crossed that this cures the issue, and will get it back together as soon as I get the radiator repaired. - April 2016
Had the leaks (17 of them) fixed in the Radiator (A to Z Radiator in Springfield IL) and installed a couple of side shields before re-installing it, the new water pump and thermostat.
I poured in the coolant in and nothing ran back out, however when I started the engine, the thermostat housing was spitting coolant out both sides frown emoticon .
Originally I when I built the engine the new aluminum housing would not seal, and I found it wasn't smooth and flat. So back then I pulled it out and filed it smooth and flat, but added plenty of sealant. The sealant stopped the leak, but excess was likely causing part of my overheating problem as it was interfering with the Robershaw thermostat. So even though I properly cleaned and re-filled the housing, I only applied a light amount of sealant, thus the leak. So off it came another cleaning and a more liberal application of sealant.
Thankfully no more leaks, but the engine still runs about 210º at 3,000 RPM at 60 MPH down the road. Cooler than before but still not as cool as I'd like. I'm running a 180º thermostat.
I'm guessing the engine just generates more heat then the radiator (new core in 2005) can handle. Could be a gauge issue, I did check the engine with an IR unit and it looked to be 10º cooler than the gauge read. - April 2016
