Weird Cooling Problems

[Morris]

I am so close to having my car road ready, but... I am having some crazy cooling issues. Maybe you guys can help make sense of the symptoms. BTW, it's a 1500.

First the car starts and warms to optimal temp fine. Fan comes on fine (I have an electric fan). Runs around fine. Stays at perfect temp no problem.

However, after running for awhile things get a little strange. My dash temp gauge shows I am overheating big time. This picks up temp at the factory location just below the thermostat. However, I have a second temp gauge that is placed on the manifold return line, that shows I am still at nominal temp. Also, the thermo for my fam, which is located below the rad return, never kicks on in spite of the fact that the car is clearly overheating.

Whatta ya think. Faulty thermostat? Bad water pump? Air in the system?

Ps. I have pulled the brass plug on top of the pump-o-plex at the front of the engine to see if the pump is flowing, and, at least when the thermo first opens, the pump seems to be pushing water.

 

[Billm]

I would temporarily put a different thermometer in place of the main one to verify its accuracy. By "big-time" what do you mean?
Bill

 

[mccalebr]

Another option...check with local car buffs to see if any have an infra red remote thermometer that you could use; you might even justify the cost of purchasing one for yourself. I picked up one last summer at Pepboys for $49 and it seems to work well. It has a small laser to let you know exactly where you are taking the reading. If I had a dollar for everytime someone wants to confirm their guage readings, it would have paid for itself.

There is an easy test to see whether or not it's accurate. Put a pan on the stove with a few inches of water in it and bring it to a boil; enough water to just cover an egg. Drop in the egg and give it a couple minutes to come to temperature. Take a reading with the thermometer on the top shell OF THE EGG. If you shoot the water, the target becomes the bottom of the pan, next to the burner, and it will read way high. Verify that the temperature reading is within the tolerance of the unit (usually about +-2%). The reading I took when I got mine was 210 degrees...close enough, and way more accurate than my car's temp gauge, which isn't working presently.

On the car you can shoot the input and outflow radiator hoses or where I usually point, the metal thermostat housing.

Ray

 

[Morris]

Update on this issue.

My cooling system has been dumping itself into my overflow tank to the point where my cooling system is about 1/2 a gallon low (1500 has a big overflow tank). Of course after cooling, the system sucks all that stuff back in, so whenever I would check my coolant level, it was always fine. The rubber gasket was shot on my reservoir tank cap, so I replaced with a cap from Autozone. The old cap was rated at 14 #s, the new one rated at 16#s. Everything was working fine until some idgets got in a fender bender and kept me stuck at an intersection in afternoon heat for 20 minutes. Car held to together great for the first 15 minutes, then everything fell apart. When I was able to get to a gas station to check things out and cool off, I discovered that the overflow tank was full.

Any thoughts?

 

[jlaird]

Yep, when stuck like that turn off the engine.

How is your radiator, new, new rebuilt, boiled, what ever.

 

[Morris]

Radiator is old, but was functioning great when I took the car off the road 6 mos ago. I added a drain cock soldered up some joints and flushed it out real good. I also got a real good look inside when the joint came off. It looked pretty clean. As far as I can tell, its fine.

What is perplexing to me, is the cars temp did not rise at all the first 15 minutes I was stuck. Also, it was a creeping traffic situation so I could not kill the engine.

 

[64rocksprite]

Morris,
OK so the update now makes me re-think my initial thought.
From the original post I would think removing the T-stat might be the first trouble shooting move.
If the Tstat isn't opening,...then I think the block would get hot and the return side would not as you describe.
If you remove the Tstat and temperatures equalize (somewhat anyway..it'll be hotter coming out of the block of course) then there you be. Bad stat.

I'm not familiar with 1500 system and its expansion tank..not sure if the expansion tank being full would make sense with the stuck Tstat theory. Good luck with it and let us know what you find!

Devin

 

[Morris]

Devin,

What part of Texas you in?

 

[tony barnhill]

When you took the engine apart did you have it boiled out before rebuilding?

 

[aeronca65t]

Check your lower hose. It is under suction and could be collapsing.
Also, remove the brass plug and fill the coollant to the top of this. Then "burp" it by squeezing your upper hose to make sure all the air is out.
Be sure that the timing is not too retarded..this can cause overheating.
And....your electric fan is not hooked up backwards, is it?

 

[Morris]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]And....your electric fan is not hooked up backwards, is it?
[/QUOTE]

Ha ha! It was... but that was fixed early on.

When you took the engine apart did you have it boiled out before rebuilding?/

I paid for that service... but I can't guaranty that I got it. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

 

[tony barnhill]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]

When you took the engine apart did you have it boiled out before rebuilding?/

I paid for that service... but I can't guaranty that I got it.

Then you don't know if they boiled the head or blew it out with compressed air to ensure the galleys were clear & not stopped up or partially blocked.

Oh, this is the last thing to worry about - check all the other things before.

 

[kcbugeye1275]

Those temp gauges are at Harbor Frieght on sale now at $ 9.99. Thermo check and look at the lower hose sounds right to me.

 

[64rocksprite]

Devin,

What part of Texas you in?

Morris..I'm in Houston..Katy to be exact. Not too far from Austin! I haven't been there yet..I think its like 3 hrs? We have some friends here who are from Austin..they go up quite a bit. I hear its a neat town. Perhaps a cruise is in order when I get mine finished!

 

[Morris]

Cooling problem solved. Here's what I did...

1) Replaced thermo with cooler... this helped a little but did not fix the problem.

2) Replaced water pump (bearing was making noise)... this helped a little but did not fix the problem.

3) Added Water Wetter... fuhget about it! Runs too cool now! That stuff is amazing!

 

[jlaird]

Hmm, have not had a cooling problem even with the 100+ temps but will keep the water wetter in mind.