Radiator blockage

[Faltura]

I have a 72 F-350 with a 360, 3 row radiator, large top tank. I have notice that the temp guage reads higher than normal. I took the rad cap off ( cold )and started it up and when the t-stat opened coolant poored out the top. When I put the cap back on, it seemed to be fine. After it warmed up, I checked the of temperature of the top tank and bottom tank. It was about 198 at top and 185 at bottom. (195 t-stat)

Would the coolant pooring out the top and the small temp diff. confirm that there is a blockage?

[fordman]

usually that is the symptom of a blown head gasket or a cracked head. but something is making it get too hot and making it spew like that. but it could be clogged up. can you look through the finds and see light? maybe the fins are plugged with bugs and dirt.

[Faltura]

It only pushes water out the top of the radiator, not gas or air. It does not get hot or boil over, the gage just runs higher than usual, Not higher than half way to hot. I would think that a blown head gasket would give you exhaust gas in the radiator.

[fordman]

when you look down into the radiator and see the tubes how do they look is there any build up what color is the water?

[Faltura]

The coolant is clean because I have changed it out but the tubes look pretty crusty. They don't look blocked but look crusty. I thought that I might take the radiator off, stick a small light in each opening and then use a small mirror and look through the other end. Maybe that will give me 3 views down the tubes to see if there are any stopped up.

The radiator looks original and like it has never been rodded.

[cmoore]

Try flushing it out first. Drain it, refill with water and about 1 gallon of vinegar...let it cook @ idle for about 20 minutes....flush again...refill. I got out a lot of gunk that way...replaced hoses while I was at it. The older hoses had a spring stiffener in them to prevent collapse, but they eventually rust-out.

Good luck...

[Faltura]

I guess that will get a lot of the garbage in the block as well.

[fordman]

yea a radiator flush wont hurt anything for sure. it will help break up whats in the system.

[cmoore]

However, with the "vinegar cook", you run a risk of dislodging any sludge that MIGHT be plugging other small leaks. Better to find out now, than on the road some place...

Regards...

[goldwing44]

I thank you might want to take it out take and have it rodded out.Also it is normal for water,coolant to come out of the top when you remove the cap.Also the Temps you have are normal
Dean Gray

[lee_ford]

I would back-flush it. Any large rust flakes clogging the tubes may not be dislodged by a vinegar cook. But a good back-flush should get them out. You can do this yourself with a garden hose. Pull the engine end of both hoses off. Wrap the outside of the garden hose fitting with a shop rag and wedge it in the lower radiator hose. Swing the top hose over to where the water and crud coming out will not cover the top of your engine. You might be surprised at the crap you see coming out the other end.

A couple of important points:

Do this with the radiator setting right side up and let it fill with water from the bottom. Otherwise if removed from truck and flat on the ground or upside down, (to keep the water off of you) there will be air pockets over some of the tubes and they will NOT get back-flushed.

Also turn the faucet on just slightly at first and let the radiator fill. Then increase water flow/pressure slowly after you see water coming out the top. This will insure no air pockets and all tubes are flushed. Be sure you have a tight grip on the radiator hose / garden hose connection.

Once you get out what you can this way you may not need or want to do the vinegar cook. The vinegar will dislodge some large pieces that might get wedged in the top of the radiator tubes. Which will mean another back-flush is needed. These large calcium flakes will not be stuck to the tube but stuck in the tube and will restrict flow unless back-flushed out.

It sounds like a lot of work, but worth it if you loose the over heating issue.

[cmoore]

I like lee_ford's idea of the back-flush too. Plan on getting wet but the results are worth it.

[fordman]

in a radiator shop if they rod out the radiator. they will cook it first in caustic soda. to break up the deposits in the radiator. but not always. i think i would try the vinegar thing first and then do all of the flushing backwards and forwards and all ways that i could. how ever after boiling them out they usually come up with a few small leaks that were there before. so those have to also be fixed when rodding one out. it really depends on how crusty it is. and old looking. if your radiator is green colored on the outside be careful and just try and flush it only with water. it may be too thin to save after any kind of chemical flush.

[Faltura]

I back flushed it. Got some junk out. I then took the hoses off and stuck a rope light in the bottom end and looked through the two top holes with a mirror and could only see a tiny bit of light through 2 of the tubes. Then reversed the light and mirror and saw nothing. I fugured that if 3 areas of tubes were that clogged, it would be worth just getting it rodded out. The crusty stuff looked like calcium and was tought to scrape off the end of the tubes.

The guy at the shop said that it looked like it had never been opened up before and it was the original equipment. He had to do some heavy soaking and roding. I'm anxious to see how it turns out. I'll pick it up today and maybe this week end see what happens.

[lee_ford]

I was going to say, take it to a good radiator shop, but thought the do-it-yourself way should be addressed. The pro will do an excellent job and you will be glad you spent the extra cash. Let us know the results.