Plugged radiator?

[WillWagner]

The last time I did a cooling system repair, I put a petcock in the intake manifold just in back of the stat. After the radiator filled, I put a pressure tester on the rad and gave it a few pumps 'till coolant came out of the vent. I then had to add about a gallon of coolant. I do not have a heater.

 

[wsucougarx]

Just got in from unclotting the radiator overflow tube. In fact I stuck a small drill bit in there and turned it by hand. Lookes like the clot took up about 3 inches of the tube. Once I freed everything up, I shot some brake cleaner in there to make sure. Sure enough she's cleared up. Will test everything out tomorrow and advise

 

[Hammer]

That is why I like stats that have the little bleeder hole in them. Air will naturally bleed itself out.
Of course it is really easy to drill a 1/16" hole to do the same thing.

 

[wsucougarx]

Well, today I went out and retested the coolant system. Seems the unplugged radiator tube didn't help. I'm really scratching my head now. When the temp gauge showed 240 degrees I took the small 3/4" plug on the thermostat housing off. Hmmm, doesn't look like it opened. Now I'm really thinking. The thermostat was tested 4 times in the house on the stove and it did open around 190 and was fully open at 200 degrees. I'm really starting to wonder if I have a faulty temp gauge or sending unit at this point. Other than a mystery air pocket the gauge and sending unit are the only real untested items. This leads me to my next question. Is the temp gauge grounded to the gauge panel via gauge hold down bracket on the rear part of the gauge? The reason I ask is, when I got the truck, there was an o-ring wrapped just under the gauge bezel to stand it off the panel. The reason they did this was the gauge hold down bracket was too short. To make it look better, I got rid of the o-ring and used a piece of rubber as a spacer b/w the panel and rear hold down bracket. In other words, no metal to metal contact in the rear of the gauge.
Now tomorrow I'm going to test the sending unit/gauge using a pan of hot water and a thermometer to see if the temps line up.

 

[x-ray]

Might be an air bubble/pocket. Had a similar problem with my M35a2 without heater, changed out T-stat, hoses, flush, etc. scratched my head for a week or so. Finally I drove it over to a friends/mechanics house. His driveway is on a good incline, got it there and let it cool. When it did, it took another 2 gallons of coolant it wouldn't take before, Drove it home- temps normal.

 

[wsucougarx]

WHEW and .......I'll explain.
I went up to Harbor Freight tools to buy one of those laser temp guns. Wow, incredible little toy. Found myself checking the temp of everything around me...anyways back to the topic. Went out to the truck, said a little prayer that the culprit would be found today. God answered my prayers. Ok, filled the system with distilled water because I knew this would be it. The problem would be revealed today. Started her up and let her run for a little bit. Noticed the gauge was reading 140, did the temp gun and it read 80. Continued on....Temp gauge read 240. Temp gun read 160. Hmmm, I thought. Somethings got to be wrong. Then I thought to myself, how is the gauge grounded. In a post earlier I asked if the gauge needed to be grounded because when I got the truck. Then Army used a 1/4 O-ring to space the bezel from the panel. I didn't think anything of it and removed the o-ring and put a rubber spacer b/w the back of the panel and the gauge hold down bracket. Thinking about this ground, I removed my NON CONDUCTING rubber spacers.....BOOOM. The gauge matched up to the temp gun. My prayers have been answered once again. We're good to go. So lessons learned. MAKE SURE YOUR GAUGE IS GROUNDED TO THE GAUGE CLUSTER!!!
One headache down, several more to go....I love a challenge but not too many in a row

 

[Heavysteven]

Great, good catch. I always love the easy fixs.

 

[gimpyrobb]

Glad to hear you got it fixed. Sucks to feel like your chasing your tail.

 

[wsucougarx]

Doh, hmm from all this idling and playing with everything....I just noticed I have fresh oil dripping on my starter. Wonder if it's coming from the turbo...probably. Verified it is indeed oil. I was hoping it was just water washing some soot and carbon down onto the starter. It appears it is coming out b/w the j-pipe/turbo joint. Anyway of telling if it's a leaky turbo seal or something else w/out tearing it apart?
The price of buying a low mileage truck. Seals are probably dried out.....

 

[gimpyrobb]

You sure its not the "slobber tube" leaking? If it doesn't have an extension on it, that could cause your issue.