'72 350 cooling system concerns

[southplainsag02]

I recently purchased a 1972 lwb stepside with a 350 and after driving for only a few miles it blew a small hole in the radiator. I took the radiator to a repair shop and they said that it was bad after pressure testing it. So, I installed a new radiator, new water pump and a new 195 degree thermostat. The only thing that I did different from what I pulled off the truck was run the top heater hose to the water pump and not to the new radiator. I have driven the truck twice since all of this and only about 10 miles at a time just to make sure there is no problems. When I pull in the garage and pop the hood it seems VERY hot in the engine compartment. My question is, is this normal or is there something wrong? I just checked the engine compartment after the truck has sat for 3 hours and I was able to pop the radiator cap of with my bare hands but it is still very hot under the hood. Maybe I am just being overly cautious. Thoughts?

[GASoline71]

That engine needs a 180 degree thermostat. The 195's weren't used until the TBI engines.

So is one hose going from the water pump to the top of the heater core, and the lower one goes to the intake manifold?

Gary

[southplainsag02]

That is right, the hose that runs to the top of the heater core is connected to the side of the water pump. The hose that runs to the bottom of the heater core is connected to the intake close to the thermostat. So do you think that if I change the thermostat to a 180 degree it would run cooler?

[Old Yeller 1970]

First of all welcome to the forum from a neighbor across the county line. It's looks like you have a solid truck there based on your introductory thread that I missed. I live a few miles southeast of Ralls. Next time Old Yeller and I are headed to Lubbock maybe we can stop by for a minute.

What is your temperature gauge reading? I have a 185 degree thermostat in Old Yeller and it stays well to the left of center. With a 195 I would think you would be close to the center or just to the left if everything is working normally.

James

[oldgold70c10]

I run a 195 stat in all my stuff and what you describe sounds normal. Just make sure that you've gotten all the air out of the cooling system & keep it filled; as long as nothing is plugged up to prevent flow you should be OK.

[southplainsag02]

Old Yeller,
Thanks for the help neighbor. I live a few miles north of Idalou so it would not be too far out of the way if your headed to Lubbock. My truck did not have all the gauges on the instrument cluster, but it has a cheap aftermarket temp gauge. It has been reading 190-195.
How do you burp a radiator...do I take the radiator cap off and let the engine run?

[Old Yeller 1970]

Originally Posted by southplainsag02

...do I take the radiator cap off and let the engine run?

That's one way to do it. You'll have to let it run till it's hot enough for the thermostat to open and then add what's needed.

My way isn't very scientific owing to my impatience, I've always poured in the coolant and run the truck wherever I was going. After returning home and letting it cool off I'll add more as needed.

Since these are closed system radiators (no reservoir) they normally end up with a coolant level that is several inches below the top. More than that and it's wasted when its forced to blow out to keep the correct pressure.

I'll PM you with my personal info.

[Longhorn Man]

sounds like nothing is wrong to me.

[Old Yeller 1970]

Originally Posted by Longhorn Man

sounds like nothing is wrong to me.

Yes, I second that too.

[PanelDeland]

Check the actual temp of the coolant by letting it run until warmed up(the thermostat opens)with the cap off.Use a known good thermometer and see what the temp is.The guage may be off enough to cause the temp to look high.I would run a 180 since it tends to get a bit warm in Lubbock.
Also,are you running a fan shroud?What type of fan?These things can push the temp up.

[southplainsag02]

Ok, I admit I am not a mechanic and I am trying to learn as much as I can...so I hope I am not asking too many stupid questions. What is the direction of flow of the water in the engine? It seems to me that the most logical is from the bottom of the radiator to the water pump, then through the motor and heater to the thermostat and then back to the radiator. I installed a 180 degree thermostat and it did seem to bring the operating temperatures down a bit. Thanks for the help!

[JCD]

Installing a lower temperature thermometer does not necessarily mean your engine will run cooler..

What a 180 thermostat means is.. that is the temperature the water and coolant reaches in the engine block, before it opens and allows it to pass into the radiator for cooling.

At that point it's up to the efficiency of your radiator to cool it down before the water in the block heats back up to 180 again.

If the radiator is plugged, or inefficient (Single core, or smaller passages) it won't cool it down enough before it's forced back into the block by the hotter fluid coming in.

On the same note, installing a 160 temp thermostat in a vehicle with an inefficient radiator would almost always run too hot, and may overheat regularly..
The thermostat opens too soon, and the coolant in the radiator doesn't have the time it needs to sufficiently cool the fluid.
That means the coolant in the radiator is at or near the 160 mark, and doesn't stay in the block..
It starts to flow constantly from the block to the radiator, and overheats.

Your 195 thermostat is keeping the coolant in the block longer, and allowing the water in the radiator to cool longer. the trade off is a hotter engine compartment.

Only if you have a larger core radiator, or a new efficient one with no plugged lines, will a lower temp thermostat work well, and keep the engine compartment cooler.

J.

[Longhorn Man]

the pump sucks from the bottom of the rad into the engine.