Plugged radiator?

[wsucougarx]

Hello gentlemen. A couple weeks ago I took my M109A3 out on the road. I was a mere 3 miles from the house and noticed the temp gauge was pegged (240 degrees +). I drove her home and cooled her down. The temp was hovering around 160 after 2 hours of cooling. I was thinking it was a closed thermostat so I went to NAPA and bought a 180 degree thermostat. I decided to flush the system, replaced all the 2 inch coolant hoses, and the upper/lower radiator hoses.
Today I went out to do the final flush with the thermostat in. I filled the system up with distilled water only. I noticed the temp gauge climbed upto 220 and looks like it would keep going. I shut her off. I decided to drain off the final flush water. The initial water coming out the radiator petcock was cold (same temp as what I put in initially). The top of the radiator was warm, but the lower portion was the same as the outside temp. I continued to drain off about 2 gallons and then the water started to get warm and then hot. So, is this a good indicator of a plugged radiator? It appears the radiator is what came with the truck. It is the old green painted radiator rather than the newer all black ones. Please advise. Is there anything else I've missed? The water pump turns freely.

Yes I did do a search

 

[crasheej]

Have you tried to just flush the radiator, to me i would almost think it is the pump.

 

[bratpackdad]

I had a similar problem with a small diesel engine. It turned out to be an air pocket. I had to flush the entire system under pressure.

 

[wsucougarx]

Have you tried to just flush the radiator, to me i would almost think it is the pump.

I actually put 3 bottles of super flush in the system w/out thermostat. I ran it for about an hour or so. Didn't notice any globs of crap coming out when I rinsed the system out. The wierd thing is the intial cold water that came out of the radiator when the engine water temp gauge read about 220. Now I know it probably doesn't take much to plug a coolant system but this truck only has 1200 miles on it total.

 

[zout]

upon a refill and bleeding air totally from the system without the t stat in there did it still overheat.

It sounded like you had already refilled w/50/50 mix - new stat and it still overheats ?? Is all the air bled from the tubing ?

 

[Blood_of_Tyrants]

The water pump is not circulating properly.

 

[G-Force]

Air pocket in the block.

 

[doghead]

Is your overflow tube(on the side of the filler neck) plugged?

Did you allow it to run and warm up with the radiator cap off or loose to relieve any air after the T-stat opened?

Do you have a heater? Did you bleed it?

Have you confirmed (IR gun or by touch) that you actually are reaching 200F or more?

 

[WillWagner]

The multi is tough to get all the air out. Another thing, verify the dash gauge with a known good gauge. You could be chasing your tail!

 

[runk]

Heater is hooked up correctly ?

 

[Heavysteven]

I would replace the temp sending unit. Verify the pump is working. If that fails you need to take the radiator to a repair shop.

 

[wsucougarx]

When I had the hoses and belts off, the water pump turns freely. In fact I did verify everything was turning by looking down one of the holes. I'm thinking it could be an air pocket, faulty thermostat, or a plugged radiator. Tonight, I'll pull the thermostat and run the system again to see what happens.
Hmm, now that I'm thinking about it. I was getting full circulation during the flush. Hmm, got to be the thermostat or air pocket. Will advise.

 

[wsucougarx]

Is your overflow tube(on the side of the filler neck) plugged?

Did you allow it to run and warm up with the radiator cap off or loose to relieve any air after the T-stat opened?

Do you have a heater? Did you bleed it?

Have you confirmed (IR gun or by touch) that you actually are reaching 200F or more?

Hey Eric, yes I found out that the overflow tube is indeed plugged. In fact I tried stuffing a pipecleaner in the tube. It only made it in 1/2 inch. What was one the of the pipecleaner was some black crud.

Tonight I did another test run.

I put the garden hose in the radiator with the thermostat in then put the radiator cover on.
Results: The temperature again rose up above 220 degrees.

I then removed the thermostat and put the garden hose in the radiator and ran it for over an hour
Results: Temp stayed an even 155 and didn't rise or fall during this time. This is when the plugged overflow tube came to my mind. I did make an observation in regard to the valve that goes to the heater hose out (heater hose removed). When the radiator cap is on, no water comes out of the valve when open. As soon as I opened the radiator cap, water began to flow out of the heater valve. Hmmmm, so is the plugged radiator overflow pipe causing the coolant to stop flowing in the system?
I have ruled out a plugged radiator because during the No thermostat Open radiator cap I got warm water out of the radiator drain plug and the entire radiator was warm.
The water pump appears to be flowing great when the radiator cap is removed because water flowed out of the heater out valve.

Does this all sound right or is there something else I should be looking at?

 

[wsucougarx]

anyone?

 

[gimpyrobb]

Kinda sounds to me like you didn't drive the truck with the radiator cap on, and the thermostat out. You said that with the T-stat out, it didn't get over 155. That sounds to me like the T-stat is at fault. How do you test those, by putting it in a pot on the stove and heating up the water? Sounds like that might be the next test you need to do.

 

[wsucougarx]

Hi Gimpy, I did the test during idling only. I didn't take the truck out on the road. But yes the temp stayed at 155 with the thermostat out and the radiator cap off using just plain water. Any input on the plugged radiator overflow tube? Does that make a difference? I'm headed outside right now to see what I can do to unplug it and do the test again. I'm going to keep a dialogue on this so others may benefit

I did just do a stove test. I noticed the "old" thermostat opened around 190 and the new NAPA one opened around 195-200.

 

[bratpackdad]

Air pocket

 

[gimpyrobb]

I had an overflow tube clogged and the radiator shop that cleaned the radiator cut the tube, reamed it and soldered it back together. I have had another that was cut and then they added a rubber hose to it. The cap is "supposed" to open to bleed off the pressure when your colant system gets too hot. If it can't do its job, I would think it would help cause an over-heat situation, kind of like a pressure cooker. Make sense?

 

[gimpyrobb]

Have many of you had trouble with air pockets? I have had alot of bad radiators in my trucks and taken them out to get fixed. When I come home I install the radiator, fill it up, run the truck with the cap off till the system gets to operating temp, then put the cap on. Never had a lick of trouble. I don't have a heater in my trucks, but I would think an air pocket there wouldn't effect the engine temp much.

 

[WillWagner]

Yeah, these are hard to fill and bleed, even with a fresh radiator. Another thing, DO NOT run the engine without a stat. These have two cooling loops, block and radiator. When the stat is closed, the stat shunts the coolant through the block loop. When the stat opens, it covers the hole in the housing for the block loop and forces the coolant through the radiator...the radiator loop. If you run w/o a stat, the coolant takes the path of least resistance...the block loop. It will not fully go through the radiator and will overheat.