The Stovebolt Site Forums The Shop Area Engine Shop 216 engine running hot

Hi i recently replaced the head gasket and have fitted a bigger radiator. Fitted a 180 deg thermostat but after the 2-3 mile run the water comes out of the overflow tube and the motors really hot.
I know the water pumps working Ok. Any one got any ideas?

Hey AdamK one time I put my thermostat in upside down! like a idiot it was the last thing I checked after pulling all my hair out,as I was sure I could'nt be that dumb! another time I did'nt have it centered in it's groove so it would'nt open. so check the easy stuff first. is the timing set right? another thought some times thermostats just go bad, so checking in a pot of boiling water with a thermometer is a easy way of elimateing that part of the equation. yes if the timing is to far advanced it will over heat.

Hi:

Currently having the same problem, 216 engine is overheating with water coming out the overflow. The last thing we did before this problem started is time the engine, and adjusted the valves. Can either of these cause these engine to suddenly run hot? Just prior to doing these two things the engine temp was fine. Please, if you have any insight on these issues I am very interested in your comments.

Dave

First you should check to see if the thermostat is opening. If the temperature goes above the thermostat set point and the upper rad hose isn't warm, the thermostat isn't opening. If you just put it together and this is happening, you most likely have air trapped in the head. In this case, run it until it is warm, stop the motor and remove the heater hose from ther top fitting just below the thermostat. Be careful because steam and hot air wil come out. Push the hose back on as soon as fluid appears. Wait a few minutes for the thermostat to open and try again.

If you fill your rad too high, it will puke coolant out when the truck warms up.
You say its hot. How hot? Did you put a thermometer in there and see? The gauge on my truck reads 20 degrees hot. The truck says its 180, when its really 160.

Hi:

It's so hot it's pegging the gage, about 215 degrees. The radiator cap is a 4lb cap, should it be zero pounds? Fianlly, will timimg and valave adjustment affect the operating temp of the engine? because these were the last thing we did to the engine just before this temp problem started. The system was purged of air a year ago and it ran fine. Both hoses get+ equally hot, so what is now causing the engine to overheat? Thanks for the help!


Dave

Drill a 1/8" hole in the thermostat to let the air escape as you fill. It's very common to have air trapped in the system.

That temperature is not good for your motor. If it were me I would pull the thermostat, run it with the cap off and see if there is fluid movement. You mave have a blockage somewhere.

Timing can affect it but not to that extent.

Take out your thermostat and see if it opens up in a pan of boiling water.

Hi:

Thanks for the help, I am appreciating it. As to the recommendations; I drilled the hole in the thermostat a year ago and it removed the air from the system. Further, I checked the thermostat at that time in a pan of boiling water and it worked fine. Thirdly, this engine was completely overhauled and the cooling passage were roded out, thus I don't think there is a blockage but anything is possible. Finally, it was suggested that maybe the head gasket is blown or the head is cracked. Please, if you have any further ideas, I apprecaite them.

God bless,


Dave

It might be worth checking the thermostat again. I had one in my Pontiac, that after sitting for six months, failed to open. Which is strange, as I thought they were designed to fail open, not closed.

I would stick a thermometer in to see if the gauge is accurate.
If it is too hot, then I'd fire it up after removing the thermostat. With the rad cap off, you should be able to see the coolant coming into the rad. Also, the truck should run cold with the thermostat removed. You should be able to see this with the thermometer as well.

Don,

I think the shortest time to overheat an engine, from a cold start, is with no coolant circulation. That's why your getting a lot of suggestions about the thermostat not working, or vaporlock at the thermostat, etc.

IF you're confident that water/coolant is circulating properly (if the upper radiator hose gets hot, that's a pretty good sign it's at least circulating at the radiator . . .), then maybe something else is to blame.

Stupid questions first: Is the fan definitely turning and circulating a good amount of air through the radiator? Fan belt good and snug?

I agree with truckernix, that misadjusted timing would contribute to overheating, but not THAT severely. And it seems to me that if timing were an issue, you'd have other symptoms along with the overheating.

I'm not experienced enough to comment on misadjusted valves leading to overheating. Seems like too much open on the exhaust could lead to over-hot valves, but wouldn't peg the temp gage, I think. Too much closed on the intake could lead to a lean condition maybe? There again, you'd see other issues I think.

My 216 started overheating badly from a lean condition. Pulling the choke out a third cured it instantly. BUT, the choke had to be in just the right spot. So maybe you're running lean? Carb float ajusted to low? Lean condition also can be caused by vacuum leaks. Is the carb tight on the manifold? Manifold snug on the block?

Hope this helps,

-Michael

Make sure your timing IS RIGHT!!!!!!! It makes all the difference

Timing can cause the engine to run hot, but 215 or more is probably caused by something more serious. Try checking for a leaky head gasket or cracked head by removing the fan belt and the thermostat housing. Fill the cold engine with coolant up to the level of the the thermostat, start it, and goose the throttle a few times. If bubbles come up in the coolant, they are coming from a compression leak, either the head gasket or a cracked head, etc. The engine will run for 2 or 3 minutes before the coolant around the cylinder walls starts to boil due to lack of circulation.

If you don't find a compression leak, look for late ignition timing and/or a water pump impeller that's slipping on the shaft. Just because the pump shaft and fan are turning doesn't mean the coolant is circulating.
Jerry

Does your exhuast heat riser valve work?

The reason I ask is because it can allow for raw gas to make it to the cylinders without vaporizing.

Check your oil. It might be dilluted with gasolene, which will cause the engine to run hot, If the oil is dilluted, check you oil level. If the level is high start with the fuel pump to see if it is leaking into the block, if it is within range of the level marks, then smell it to see if it smells gassy. diluted oil cuts out the lubricating qualities of the oil and actually can act like a solvent. Not having lubrication in your piston rings and bearings can make an engine very hot.

in another instance
I had one of my 216's running hot. so I pulled the carb and the metering needle was a very lean needle causing the engine to run hot, but it would not boil over.

I run zero pound caps on all of my trucks without issue(after I learned not to overfill the radiator)

I got a call one time on a 216 in a 40 Chevy sedan that would run hot in just a few minutes of starting it. The timing had moved because the owner had loosened the bolt to try and time it himself.

I reset the timing and it ran fine after that.

You have mentioned two or three times that you reset the timing when you adjusted the valves. Check that timing again. Is it hard to start? Does it have any power when it's running? When warmed up does it get hard to start?

My money lies on the timing being off.

Any Luck?