Overheating issues, please help

[Old65C10]

I picked up this 65 C10 a while back. When I got it, It would over heat.
I figured this was a head gasket and I ordered the parts. I just got around to doing the head gasket and I now need the truck to run.
I replaced the head gasket, thermostat, inspected the radiator and the water pump. I can find no issues.
However, the truck runs for 15-20min and overheats. Is it likely that the block or head is cracked? I do not own a pressure tester or a CLT (Compression leak down tester)
I have found anther engine, supposed to be good, but I would like to know if this original engine is good or bad. Any way to know?
Any suggestions would be great.

[Braunschweiger]

How is the Overheating Displayed, original Display, additional Display, or with an Infrared Thermometer. My original Thermometer always showed too much, with an Infrared Thermometer it was just under 180° Fahrenheit.

[Old65C10]

Originally Posted by Braunschweiger

How is the Overheating Displayed, original Display, additional Display, or with an Infrared Thermometer. My original Thermometer always showed too much, with an Infrared Thermometer it was just under 180° Fahrenheit.

No gauge needed, violent spewing from the overflow hose. Loads of steam, noises, etc. I'm not sure if the "Hot" light comes on, I never got in the truck, this was all observed from under the hood.

[geezer#99]

How full are you filling the rad when cold?
The level should be a couple inches from top.

[61hawk]

If nothing else works pull the freeze plugs and flush the block. I've flushed out a ton of casting sand and wires out of blocks.

[Arne]

Do you have a fan shroud on it? The stock fan doesn't pull much air when just sitting without a shroud.

[Riverstory]

I installed an overflow bottle and immediately resolved the issue. Allowed me to keep the radiator completely full.

[MikeN]

Originally Posted by Riverstory

I installed an overflow bottle and immediately resolved the issue. Allowed me to keep the radiator completely full.

Do you recall where you got that overflow container? I need one, and I really like the way yours looks and fits.

[Riverstory]

Originally Posted by MikeN

Do you recall where you got that overflow container? I need one, and I really like the way yours looks and fits.

FROM EBAY
Radiator Coolant Overflow Reservoir Bottle Tank Jug w/Cap for 13-17 Suzuki Swift
(224122736579)

$20 BUCKS. Made the simple bracket and attached to side of battery box

[MikeN]

Thanks!

[Chevy nutcase]

Originally Posted by Riverstory

I installed an overflow bottle and immediately resolved the issue. Allowed me to keep the radiator completely full.

It took me a sec to realize that photo flipped 90° and I was ready to ask if it's ok if batteries are ok laying on their side lol

[Rubbertiredtramp]

Originally Posted by Chevy nutcase

It took me a sec to realize that photo flipped 90° and I was ready to ask if it's ok if batteries are ok laying on their side lol

Yeah I made that same mistake, I thought it must be a much newer truck, but now it makes sense.

[SkinnyG]

WITHOUT an overflow bottle, the rad should be filled to about 1" below the neck; this allows for expansion.

WITH a bottle, the rad should be right full.

Small block Chevy heads are notorious for cracking. A cracked head (even with a good gasket) will push combustion gasses (and temperature) into the cooling system, and no rad in the world will cool that. However - that usually shows up by overheating at speed, and cooling off fine while idling.

There is a dye you can get to test the coolant to see if combustion gasses are an issue. It's cheap, check your local auto parts store.

A plugged rad (internally or externally) can't get rid of the heat.

A faulty water pump can't get rid of the heat.

A new thermostat isn't guaranteed to work. NEW just means Never Ever Worked.

What are the specific conditions in which this thing is overheating??

[ACK]

Along with the above suggestions, is the radiator cap good? How's the timing, retarded timing can make the engine run hotter.

[Old65C10]

So, I think I need to spend a little more time playing with it before I totally condemn the engine.
I replaced the head and the T-Stat. The Radiator cap is not new, but I replaced it several years ago, but then never ran the truck. So, it is a few years old, but not really used.
I pulled the water pump and it is good. I will flush out the engine before I put it back.
The long story is this: in 2017 I found this truck behind a barn near Yakima Washington. Last on the road in 1995. I pulled it out, did all the normal stuff to get it running, new brakes, tires, fluids, etc.
I drove it a little on short runs to the store, etc. and it seemed OK. However anything more than 10 miles and it would overheat.
I assumed back then that the head gasket was shot and that was why it was left behind the barn. I ordered a new complete gasket set and it sat in the box in the shed with the truck just parked until last week.
Now I need the truck for my son, he blew the trans in his car and we need this for him to drive.
I pulled the head, replaced the head gasket, replaced the T-Stat, pulled the water pump, etc. I started it up added water and let it idle. It overheated in a very short time. I then let it cool a bit, added some more water and let it run. I keep adding water to keep it topped up, but then it overheats and spews it all out.
It has never had a fan shroud that I can see. It should be able to idle for a long period of time with out overheating.
I do have a replacement engine, but it is "assumed good", not proven good.
I may try to fill it up one more time and see what happens, but not sure it is going to be any different than the last time.

[Steeveedee]

Six-cylinder-engine powered trucks don't usually have a fan shroud unless they are air-conditioned; they only have a finger-guard. Overheating at idle is generally due to lack of airflow.

Did you do anything with the radiator? Look inside to see what the tubes (that you can see) look like. There could be enough solder bloom that make that an issue. If it sat a long time, I'd just have the radiator rodded (at a minimum) to remove it from the list of things that could be bad, (but that isn't necessarily going to fix it- it's in the assurance category).

[Riverstory]

So you stated that you added water. and then more water. If you only added water, it will boil over. You need a 50/50 coolant mixture.

[geezer#99]

Originally Posted by Riverstory

So you stated that you added water. and then more water. If you only added water, it will boil over. You need a 50/50 coolant mixture.

You can use just water.
Check the chart in here.


https://ricksfreeautorepairadvice.co...t-verus-water/

[Dead Parrot]

Is there oil in the water and/or water in the oil? Either is a common symptom of cracked head/block or bad head gasket.
Does it run smooth until it overheats?
Is there a bunch of blue smoke(oil) or white smoke(coolant)?
How do the plugs look?
Do you get a lot of heat out of the heater?

If there is no fluid in the wrong place, no smoke, smooth running until it overheats and the plugs look normal - guessing bad/plugged radiator or a block with really fouled water passages.

If you keep overheating it, you risk turning a possibly good motor into a definitely bad motor.

[vince1]

I'd change a rad before pulling an engine.

I changed my 250 to a 350 and the fan is now quite a ways back without a shroud. I put a temp gauge in to supplement the cold/overheat light and am surprised it doesn't overheat.

You said you checked the water pump so the impeller must be intact. I had a car where the plastic impeller broke apart and the engine would overheat. Also, make sure it is turning the right way. I don't know if in your case it is a possibility but on some cars that also use serpentine belts an incorrect pump could turn in the opposite direction.