Overheating?

[short72]

Some background...(Forgive me, I am not very mechanical)

1972 C10 402 W/AC
Truck had not been on driven since 1996
Put in a "new" 402 that had about 60,000 miles burning propane.
New gaskets, seals, wires, plugs, etc.

Engine seems to be running hot. Put in a new 195 thermostat and new temp gauge. The old gauge was not working.
Thermo IR gun was showing 210-215 degrees. Did not have the new gauge in at the time of the thermo gun reading.

Now the gauge is showing nearly pegged out at hot after about 10 minutes of idleing.

Took a meter to the gauge while it was running.
Right post read 15 volts throughout.
Left post started at 10-12 (engine cold)
Left post ended at about 7-8 volts (gauge at red)

Any advice would be great.
I will try to give more info if needed.

Thanks a lot.

Eric

[bigdogboxers]

The next check would be your water pump...

[piecesparts]

What does the temp gun show when the temp gauge is maxed out? Also is the temp gauge a quality item or a Shiney part store special? Most temp gauges work off of a variable ground circuit, the sender changes ground capability with the amount of heat applied. Did you use the sender that came with the gauge?

Look at the cooling fan, fan clutch if there is one, fan shroud---do you have one---if not you should have one, radiator condition---need cleaning

[short72]

Bought the gauge through LMC. Did not come with a sender, but had a new one put in when the motor was done.
I did flush the radiator.
Fan is direct drive with shroud.
Plan to IR it tonight with gauge hot.

thanks.

[71swb4x4]

Is this something that happened after you installed the motor? If so I would check for a water bubble first. If you get an air pocket it can actually prevent the coolant from circulating. When the truck is cool remove the radiator cap and start it up. Watch in the hole and when the thermostat opens you should see water circulating.
If you think it may be an air pocket I would drain the coolant, and then remove the thermostat housing, and refill the radiator with that housing off. When the coolant gets to the top of the block put the thermostat housing back on and finish filling.
I would hate to see you replace a bunch of parts if it's something easy like an air pocket.

Another trick is to drill a small hole in the thermostat toward the edge near where it seats. This allows air to pass through when you are filling the truck with coolant.

[short72]

Forgot to mention that I do not have the A/C system on the motor. I am looking for a working compressor right now.

I will try all these suggestions tonight. Thanks, guys.

[bigdogboxers]

I have actually found thermostats be bad right out of the box...

[stich626]

whats the timing at

[short72]

OK guys...
IR temp reading at the top of the thermostat housing did not get any higher than 197 degrees. The top rad hose started warming up right at about that time. The hottest that the thermostat housing (where the heater hose exits) got was 205.
This was after idleing for 15-20 minutes.
Gauge was showing hot. Took the truck for a spin (about 45 degrees outside) for a few miles and the gauge came down just outside the "red" area.

So....do you think that there is something wrong with the sender? Does it have to be a specific sender, or can it be a generic one?

But it seems as though the gauge is not a true representation of the engine temp.

Any more ideas? Thanks.

I did test the thermostat in water on the stove and it opened @ 195.
I have no idea what the timing is. What should it be?

Thanks. Eric

[piecesparts]

YES many temp gauges are sender specific, so it is possible that the sender is giving a false ground circuit. The T/stat opening at around 195 degrees is good, you know that it is working--have you thought about a 180 degree T/stat. If you change get what is called a Superstat. The Superstat line regulates the temp more evenly than a standard T/stat and allows for a more even engine warm up.

The timing is also good thing to check. IF timing is too slow, you will run hot on your engine. Timing should be set at factory specs or just a little advanced for performance enhancement. I take it, you just bolted this in and started it up, without checking the basic timing and calibration. Are you still running it on propane or is it now running on pump gas?

[short72]

Frank,

I have thought about a cooler stat, as I plan to drive this truck mainly in the non-winter months.
Should I call LMC to see if they carry a sender specific to their gauges? I did not see one in the catalog or online.
As far as the engine, my friend cleaned it up and dropped it in. It was running in another truck prior to me getting it into mine. I assume that the timing was checked, but will email him to see for sure. It is currently running pump gas.

thanks

ek

[piecesparts]

I would check with LMC or if nothing else go to the local parts store and get a sending unit for your truck. Do you still have the old engine, that would be another source.

I live in Kansas and I run 180 degree stats all year around in my trucks. There are cold days and I have yet to have a problem with heating in my vehicles. Remember the other vehicle may have had a totally different setup than what you have now. Try to make it all line up and then if problems exist modify from there.

[my67c20]

First off i would buy a mechanincal guage and hook it up to verify if the engine really is getting that hot. Odds are the sending unit and the guage are just not working together. My truck the cluster guage says its too hot but the mechanical guage is steady at 180. Understand that by having a pressurized system that it allows for the boiling point to be higher and therefore some of your IR measurements are not what is actually happening to the cooling system.

[JJanzen]

I have the same problem you are experiencing in my recent rebuild. I am convinced, after trying several different "correct model" sending units, that my gauge is the culprit. Next time I pull the gauge cluster, I am going to try a new or different gauge to see if that corrects the problem.