The Stovebolt Site Forums The Shop Area Engine Shop 235 Motor Heating Up

My truck is a 1950 3800 Series Chevy with a 1954 235 motor in it. Last couple times i started it, it runs good but if you watch the temp gauge inside, it heats up quickly after just a couple minutes and the needle is soon past the 180 degree mark and is headed for the 212 degree mark. I shut it off and do not let it get that hot. But if you then go under the hood, the hoses are still cold to the touch, both upper and lower radiator hoses and the smaller ones going to the heater. The engine block is plenty warm, but the hoses are cold. Possibly a stuck thermostat, or water pump is bad? Maybe the block does not have much coolant in it for some odd reason? Any suggestions appreciated! Tom

Hard to say, Tom but I'd suspect a stuck thermostat or at worst a water pump that has spun off the impeller. The block should have coolant in either of those cases, but I believe you're on the right track. At least the thermostat is an easy one to check and if it seems ok, the water pump might be the culprit. Good luck.

What Jon G said. I was having all kinds of problems with my inside gauge, the high temp was scaring the bajeebers out of me. Put a Mr. Gasket Thermo Cap on and 212 + turned into 160 degrees. Doc

Agreed with the water pump. I'll bet that the lower hose would at least get warm, but with no pump flow both should stay cold. With no flow through the radiator, no heat is exchanged and the engine would get plenty hot.

"Pretty warm" is not a temperature reading. Try checking the temperature of the cylinder head casting in the area of the thermostat housing with a laser thermometer as the engine is warming up. Does your thermostat have a "jiggle pin" or a small hole drilled in it to prevent an air lock from forming?
Jerry

Incorrect engine timing can also cause overheating. I found that to be the case with my newly rebuilt 54 235.
Mike

I agree with Mike and Jerry, I don't know if everyone will agree but I always use a static light then a timing light if I think it's necessary. On 216's and 235's I use the Heisenberg Theory. " After checking all possibilities one usually finds that the simplest is the problem." I find that we are all having problems with many parts from China regarding reproduction. Pretty much everything. Save your old parts guys the GM's are going to rise again. Doc

Doc, I use a somewhat streamlined version of Heisenberg- - - - -it's called the KISS principle!
LOL!
Jerry

I learned that as Occam's Razor, Doc.

Thanks everyone for your idea's and comments. This past weekend I didn't get much done on the truck, last minute yard work needed to get done before Fall turns to Winter here in Minnesota. But regarding the truck, a short time a go I had put a new tank heater in it ( I know most vehicles in states south of here doesn't need them). This electric tank heater warms the coolant and circulates it thru the motor and heater core so the truck starts easily in the cold weather. You do need to drain some of the coolant from the system in order to install the heater. After the installation I put more coolant back in, but I'm wondering if an air pocket or something like that formed and wouldn't allow me to put back enough coolant. However, looking at the crud and ugliness inside the radiator, I have decided to pull the radiator and flush it out which means draining the system again. I have new gaskets for the water pump and thermostat housing so I can look closer at the water pump to make sure it is OK or not. There was no noises coming from the pump when the engine was running, but there could still be an issue with it. I was thinking when the radiator is back in and it's time refill everything, I would take the thermostat housing and thermostat out, and pour the coolant in there, that would make sure the block and head would be filled up. Then top off the radiator as needed to hopefully fill the system as it should be (any thoughts here). Hope to work on the truck this week and get the issue corrected. I need to use the truck for some of these Fall chores yet - once the snow comes though, no more driving till Spring. Thanks again! Tom

I watched a youtube video of cleaning the crud out of the freeze plugs, something to consider.

If your going that far be sure to clean out the block. Various chemicals are available. Lots of opinions here.