brit4x4
New member
- 9
- 12
- 3
- Location
- Jackson, CA
TL;DR;
Summary.
NOS Water Pumps will weep for 10 to 15 minutes after installation, mount the water pump with the weep hole up so that you can see when it stops weeping. If you are worried about debris falling in the hole coat it with some grease. If the seal starts to fail the water will push past the grease and with the hole at the top it is much easier to check.
Also, with the NOS Water Pump installed and before putting the radiator back in, run the fan mounting bolts in and out of the holes a few times. The NOS pumps have paint and possibly rust in the holes that will make attaching the fan super difficult if you don't do this.
Loosen the 4 bolts holding the radiator platform to the the front of the chassis, it makes removing and re-installing the lower hose much easier.
Fill with water only initially in case disassembly is required or leaks are found.
Temperature gauges may not tell the truth ... more to come on this.
The Story.
Last year, 2021, I moved the 120 miles from Santa Clara California to Jackson California. I have a 1975 M35A2 and a 1967 M109A3 Shop Van. My son drove the Deuce and I drove the 109. The first 20 miles were fine then the 109 started spraying rusty water from under the hood. Our 4 hour journey turned into closer to an 8 hour journey. Stopping every 10 miles or so to top off the water. The temp gauge was pegged at 240. We made it despite the outside temp being over 100 degrees as we drew near to Jackson.
Dismantling and flushing
I finally had the time back in March 2022 to start dismantling the cooling system. To help the radiator removal I loosened the 4 bolts holding the platform that the radiator sits on, this gave that extra bit of wiggle room that helped get the lower hose off. The radiator overflow tube was blocked. Flushing the radiator produced some nasty muck. I purchased one of those engine flushing tools that uses compressed air to force the water through the block. I removed the thermostat and the water pump including the housing. with those off I could flush via the top port (behind where the thermostat housing connects) and via the pipe that leads to the oil cooler. A lot of nasty stuff came out and I flushed back and forth until the water was clean and flowing more quickly.
Reassembly and some interesting lessons.
In the end because the bottom mounting on the radiator had rusted badly I opted for a new one from C and C Equipment. Nice black brand new radiator, the packaging wasn't great and I let them know, luckily there was no visible damage. However, the top hose connection is offset by about 3/4" from the thermostat housing port. I have managed to get them connected by using a longer piece of 2" ID hose, we will see how well that works. Again having the radiator platform loose made it easier to fit the bottom hose that is always a pain.
Water pump revelation
the old water appeared to be ok, but I had a NOS one in the parts box, so I figured new radiator new pump. I bolted everything back together and filled the system with just water, I did not want to waste anti-freeze if it turned out that there were leaks or there was still a problem. I noticed that there was a leak, as I traced it I could see that it was the NOS Water Pump, and it looked like it was coming from the bearings. Radiator back out I took the water pump off and that is when I noticed the "Weep" hole. To verify that the water was coming from the weep hole I mounted the pump back into the housing with the weep hole at the top. I did not want to have to reinstall the radiator just to fill it with water to prove the weep hole was the source of the leak, so I purchased a shop vac step down hose adapter that fits perfectly into 2" ID pipe and then a rubber 2" rubber pipe cap. I cut off the unwanted part of adapter and inserted it into the bottom hose, with the rubber end cap. I removed the thermostat housing and filled the water pump. The weep hole, now facing up, was definitely the source of the leak. Well poop, I guess I need a new pump 
but not wanting to give up I did some research, this is what I found :
"New water pumps need at least 10 minutes of idle time before the seals settle and the weeping stops", "yeah right" I am thinking. But I gave it a go, everything reassembled, filled the radiator, with water coming out of the weep hole but kept going until the water level was at the bottom of the filler neck. Then started the engine and stood there hose ready with water coming out of the weep hole and being flung everywhere by the fan. Slowly but surely the weeping stopped, I didn't time it but probably 10 to 15 minutes. Moral of the story don't give up on your NOS pump too quickly.
When the engine was overheating spraying water on the journey from Santa Clara, I had no idea where my laser thermometer was, so no way to verify the temps of cooling system components. The temperature gauge was pegged at 240. After reassembly, including a new temperature sensor I was hopeful that temp gauge would sit vertical at about 180. Nope, it climbed on up past that to about 220 and sat there. However, my laser thermometer was giving readings of 176 max and way less when pointed at other cooling system components. The thermostat is supposed to be fully open at 180, it was definitely open because the top hose was now hot and so was the top of the radiator. I now need to test the temperature gauge . It could also be corroded connectors and/or a wiring issue. I will post more as I find the causes and solutions.
Summary.
NOS Water Pumps will weep for 10 to 15 minutes after installation, mount the water pump with the weep hole up so that you can see when it stops weeping. If you are worried about debris falling in the hole coat it with some grease. If the seal starts to fail the water will push past the grease and with the hole at the top it is much easier to check.
Also, with the NOS Water Pump installed and before putting the radiator back in, run the fan mounting bolts in and out of the holes a few times. The NOS pumps have paint and possibly rust in the holes that will make attaching the fan super difficult if you don't do this.
Loosen the 4 bolts holding the radiator platform to the the front of the chassis, it makes removing and re-installing the lower hose much easier.
Fill with water only initially in case disassembly is required or leaks are found.
Temperature gauges may not tell the truth ... more to come on this.
The Story.
Last year, 2021, I moved the 120 miles from Santa Clara California to Jackson California. I have a 1975 M35A2 and a 1967 M109A3 Shop Van. My son drove the Deuce and I drove the 109. The first 20 miles were fine then the 109 started spraying rusty water from under the hood. Our 4 hour journey turned into closer to an 8 hour journey. Stopping every 10 miles or so to top off the water. The temp gauge was pegged at 240. We made it despite the outside temp being over 100 degrees as we drew near to Jackson.
Dismantling and flushing
I finally had the time back in March 2022 to start dismantling the cooling system. To help the radiator removal I loosened the 4 bolts holding the platform that the radiator sits on, this gave that extra bit of wiggle room that helped get the lower hose off. The radiator overflow tube was blocked. Flushing the radiator produced some nasty muck. I purchased one of those engine flushing tools that uses compressed air to force the water through the block. I removed the thermostat and the water pump including the housing. with those off I could flush via the top port (behind where the thermostat housing connects) and via the pipe that leads to the oil cooler. A lot of nasty stuff came out and I flushed back and forth until the water was clean and flowing more quickly.
Reassembly and some interesting lessons.
In the end because the bottom mounting on the radiator had rusted badly I opted for a new one from C and C Equipment. Nice black brand new radiator, the packaging wasn't great and I let them know, luckily there was no visible damage. However, the top hose connection is offset by about 3/4" from the thermostat housing port. I have managed to get them connected by using a longer piece of 2" ID hose, we will see how well that works. Again having the radiator platform loose made it easier to fit the bottom hose that is always a pain.
Water pump revelation
the old water appeared to be ok, but I had a NOS one in the parts box, so I figured new radiator new pump. I bolted everything back together and filled the system with just water, I did not want to waste anti-freeze if it turned out that there were leaks or there was still a problem. I noticed that there was a leak, as I traced it I could see that it was the NOS Water Pump, and it looked like it was coming from the bearings. Radiator back out I took the water pump off and that is when I noticed the "Weep" hole. To verify that the water was coming from the weep hole I mounted the pump back into the housing with the weep hole at the top. I did not want to have to reinstall the radiator just to fill it with water to prove the weep hole was the source of the leak, so I purchased a shop vac step down hose adapter that fits perfectly into 2" ID pipe and then a rubber 2" rubber pipe cap. I cut off the unwanted part of adapter and inserted it into the bottom hose, with the rubber end cap. I removed the thermostat housing and filled the water pump. The weep hole, now facing up, was definitely the source of the leak. Well poop, I guess I need a new pump but not wanting to give up I did some research, this is what I found :"New water pumps need at least 10 minutes of idle time before the seals settle and the weeping stops", "yeah right" I am thinking. But I gave it a go, everything reassembled, filled the radiator, with water coming out of the weep hole but kept going until the water level was at the bottom of the filler neck. Then started the engine and stood there hose ready with water coming out of the weep hole and being flung everywhere by the fan. Slowly but surely the weeping stopped, I didn't time it but probably 10 to 15 minutes. Moral of the story don't give up on your NOS pump too quickly.
When the engine was overheating spraying water on the journey from Santa Clara, I had no idea where my laser thermometer was, so no way to verify the temps of cooling system components. The temperature gauge was pegged at 240. After reassembly, including a new temperature sensor I was hopeful that temp gauge would sit vertical at about 180. Nope, it climbed on up past that to about 220 and sat there. However, my laser thermometer was giving readings of 176 max and way less when pointed at other cooling system components. The thermostat is supposed to be fully open at 180, it was definitely open because the top hose was now hot and so was the top of the radiator. I now need to test the temperature gauge . It could also be corroded connectors and/or a wiring issue. I will post more as I find the causes and solutions.
