Finally getting the '51 back on the road after king pin job, and everything was going fine until I took it for a test drive around the neighborhood. Noticed the thermostat temp rising, and was waiting for it to fall when it hit 180*, but it didn't drop. I got back to the house as it was creeping toward 220*, shut it down and let it cool. I have an extra thermostat and a new water pump that I bought years ago due to the pump that came on the truck looks like it's the oldest part on the engine. Anyway, I pulled the thermostat, and it was pretty gummed up looking with rusty looking sediment. (The truck has been nearly undriven since the timing gear stripped a few summers ago. Had it replaced last summer, but didn't want to drive it until I changed out the king pins and put some new tires on it, which I've recently done.) I installed the new thermostat, took it for a 4-5 mile ride to the gas station to fill it up with fresh fuel (after pouring some octane booster in it), keeping an eye on the thermostat. When it hit 180, I was watching for it do open up and drop. It must have opened, because it never got above 180, and to get to the gas station I have to get out on the state highway for about 2 miles. I drove it back home and all was well, so I decided it would be a good time to flush the radiator and engine and put in new antifreeze. After draining it, I flushed it with the hose for about 5 minutes while it ran, then closed the petcock and filled it back up (while running, of course). I poured some cascade dishwashing powder in with it to break up any junk or rust, which i learned about on this forum. I then took it for another ride around the neighborhood and as I went down the hill and it warmed up, I started noticing that the gauge was rising and passing 180 again! I drove back up the hill to the house as it was getting close to the 220 high point. Pulled into the house just as it was starting to whine a little. Shut it down and checked under the hood. There was no water coming from the overflow tube. Nothing was leaking anywhere, including the water pump. I didn't mention, but the radiator is a "new" aluminum Champion that the PO put in before I got it 8 or so years ago.
So, I'm getting ready to go out and first open up and check the new thermostat, drain the radiator and see what's up there(still getting rusty looking water out of it after the first few flushes, hence the cascade in the last refill, before flushing it out again), then probably just go ahead and install the new water pump to be safe.
Has anyone ever installed a new thermo then had it not open after flushing it like that? Also, every water pump that's ever gone bad on me has had the tell tale weep hole leak at the bottom, but this one doesn't seem to be leaking. I will say that I had a good shop do the timing gear change, and I don't know if they pulled the water pump to get that job done, but I don't think so. Anyway, I'm on my way back out to start pulling and checking and replacing, so I wanted to ask you all what your thoughts are on this problem. The way I see it is, maybe the thermostat got clogged with something that broke loose, or maybe the pump was out/going out all along. But this wouldn't make any sense, since I drove it about 6-7 miles to the gas station after the thermo change witout it getting too hot before I flushed it out again. Thanks for any ideas or comments. Lee
