The Stovebolt Site Forums The Shop Area Engine Shop 216 Overheating.

The engine in my 1951 4400 is over heating. Sunday, I drove it to a car show which was only about 10 minutes away with no issue, at least that I noticed. After the show, I decided to fill the tank so I drove to a station about another 10 minutes down the road. As I pulled in the station, I noticed the temp gauge was at 212 when I shut the engine off. I filled the tank and started it hoping to cool it off with added air flow from driving and the temp did drop a bit by the time I got home, another 10 minute drive. When I got home, I checked under the hood and found the tops of the tubes in the radiator were dry and the metal support under the radiator wet so I knew I had boiled away coolant. This engine was recently pulled and all gaskets and seals replaced as well as having the radiator recored by a reputable shop. The mechanic had commented on how nice the insides of the motor were indicating that it was not necessary to rebuild. He did comment on crud in the water jacket but also washed it out with a pressure washer. So now I have to figure out what the problem is. Should I remove the thermostat? Could the water pump be an issue? The mechanic thinks we should mount an electric fan in front of the radiator but I'm not to keen on that idea. Any way to tell if the water jacket has blockage in it? Any other ideas on what might be wrong? It does start and run smoothly.

A laser type temp scanner can be a big help when diagnosing cooling system problems, and they're not expensive. Check Ebay for some possibilities for that option. What degree thermostat are you running, and have you "boil-tested" it to see if it's operating properly? Suspend the thermostat in a pan of water on a stove and gently increase the temp while observing the stat. It should begin opening at or near its rated temp, and open fully at higher temps. Be sure the temp sensing part of the stat is facing toward the engine- - - -it's possible to install it upside down. Professional shops usually have something called a "block test kit" that looks for exhaust gas in the coolant from a leaky head gasket by drawing an air sample from the cooling system through a colored liquid. The blue liquid turns yellow from a small leak, and green from a big one. The check fluid sold by NAPA stores seems to work better than the similar stuff sold by O'Reilly's for some reason.

Use the laser thermometer to check areas of the block and head to see if there are any hot spots. If it's hotter near the bottom of the cylinders there's probably an accumulation of rust and crud in the bottom of the water jacket.
Jerry

Thank you HotRod for those suggestions! I do have a laser thermometer but hadn't thought to use it to diagnose this issue. If I do find a hot spot, is there a way to flush the block without pulling the engine?

People have poured various types of acid into the water jacket, followed by a strong solution of baking soda to neutralize it. Then run lots of water through the system before refilling with a 50/50 mix of antifreeze and water. Muriatic acid like the type used to clean masonry, diluted with water to about 10% concentration works to soften the deposits and the flush removes it. Be aware that rusty freeze plugs might end up leaking from pinholes the acid exposes, and some of them can involve a lot of work to replace. That's particularly true of the one at the back of the block that's partially covered by the bell housing!
Jerry