Radiator question

[arrows]

So, my tractor overheated (the warning light bulb must be burnt out because I had no warning), and the coolant did some combination of boiling off and leaking out. Previously, the radiator cap fit snugly onto the radiator, but now after inspection it looks like the metal bent when it overheated, to vent steam I guess. So the cap no longer fit tightly. So I banged on the lip of the mouth of the radiator to get it back into position so that the cap would fit snugly again. I thought it would work, but after starting up the tractor, coolant eventually started leaking out from the cap again. And this was a new cap, so that wasn't the issue. Looking closely again, I can see that the metal lip is still very slightly deformed, and I tried prying and banging but I can't seem to get it totally uniform, picture-perfect.

Are radiators caps really that sensitive? And, the $300 question, do I really have to buy a new radiator or is there still hope for fixing this one?

 

[Phillip w]

Boy I'm confused. Do you have pics? Usually getting one hot will not mess up the neck of the radiator. And usually the is an overflow tube to handle an overflow/boil over. If you got it really hot, you may have cracked/warped the head. This could be causing you problem now, and that is a big and expensive problem. What kind of tractor is it? (Make&model) hopefully it is an all cast block. If you have aluminum heads, there is a good chance your in big trouble.

 

[Texasmark]

On running temp. One of my tractors, I bought new in 2007, has been running closer to mid temps for jobs done in the past at a lower running temp. I did the flush and new fluid thing and it was better but still higher than original. Yesterday I was looking for a fume leak into the cab from the engine compartment and accidentally turned the fan with the engine off.....oops, fan belt loose. Wink! Smoking gun. I had spare belts for engine and AC so on went a couple of new belts and a tensioning sequence. Just haven't touched the engine in all those years except for fluid changes and didn't even think about wear on the V belts.

 

[arrows]

Hopefully this attachment works...
So, it looks pretty good to me. The part that got bent is in the foreground, the metal rim that holds the cap on. But when I put the cap on, there's a little bit of wobble when I press on it, and once the engine heats up, coolant starts leaking out from the cap (and the overflow bottle, but that's a separate issue that I assume will be fixed with a new bottle). Everything's on as tight as I can get it.
It's an old Yanmar, YM2500. Definitely not aluminum. And the fan belt is in good condition, and the radiator isn't clogged up with debris either. (There may be corrosion on the inside - I don't know).

 

[Ford850]

Are you sure you are getting the cap all the way on? Most caps will turn on to a point and then need to be pressed down hard and turned another 1/4 turn to lock in place.
When removing them, that first 1/4 turn unlocks the seal but the cap is still loosely locked to the neck so it can't blow off if the radiator was hot when you removed it. Then you would press and turn more to fully release the cap.

 

[flyerdan]

The radiator cap seals pressure at the bottom, the smaller spring loaded gasket that rests in the bottom of the filler neck. The bigger concern now is why did it overheat and what is causing the over-pressurization of the cooling system to force coolant out, which unfortunately points to combustion pressure being introduced into the cooling system by a breach somewhere.

 

[TimberHole]

Sounds to me like you have a head/gasket issue. No way an overheating issue bent the neck.

 

[RobinC]

Hopefully this attachment works...
So, it looks pretty good to me. The part that got bent is in the foreground, the metal rim that holds the cap on. But when I put the cap on, there's a little bit of wobble when I press on it, and once the engine heats up, coolant starts leaking out from the cap (and the overflow bottle, but that's a separate issue that I assume will be fixed with a new bottle). Everything's on as tight as I can get it.
It's an old Yanmar, YM2500. Definitely not aluminum. And the fan belt is in good condition, and the radiator isn't clogged up with debris either. (There may be corrosion on the inside - I don't know).
View attachment 529864

A couple of things come to mind for what it's worth. 1st. very lightly draw a wide smooth file across the brass opening. This should show you the high spots where the rubber gasket is not allowing a true seal if the opening is bent. If bent up, and seal is not true, lightly file the brass to flatten the high spot after tapping down to try to flatten it without taking too much material.

2nd: Any good radiator shop (are there any left?) should be able to solder out and replace the neck and opening that is not sealing to allow for a new cap.

My two cents worth on the fly. Hope you get-r-fixed for a reasonable amount $$$. Best of luck.......Robin C.

 

[Soundguy]

Run with cap off. If its getting combustion gasses into the water, it should bubble immediately.

Clean flange, with with a coat of spray paint or primer, let dry. Put a piece of 800 paper on a piece of 2x4. Sand across it squarely a couple swipes. Same info as the file trick, but easier and safer. High spots get sanded, low doesn't. Have paper tight on the sanding block.

 

[skipmarcy]

Looks like in the picture that the "ramp" that the ears on the cap ride on is bent in towards the rad. neck just before the stop tab. I would try to gently pry that ramp back out with a flat blade screwdriver or such to get it vertical and parallel with the neck again. Then look at the two tabs on the cap and see that they are flat and will be perpendicular with the ramp. The way it looks is that the cap tabs might be missing that engagement and riding up some. I wouldn't run a file much on the top sealing surface as that is a raised ridge of metal and not very thick. Clean the contact surfaces on the radiator top and the gasket on the cap and put just a thin layer of grease on one or the other and very carefully screw the cap on and remove and see where grease is transferred. I also agree that if the engine immediately tries to push coolant out right after starting you very likely have a head/block problem.