Crack in plastic radiator...

[V]

Ok, first, this is not in my camaro or trans am.
It is my '96 Dodge Ram 2500 Turbo Diesel.

On Tuesday I finally did an oil change and when I had the hood popped I noticed the coolant overflow tank was almost empty. I hadn't checked the coolant in several months so I didn't know what to think. When I was done with the oil change, I took it out for a quick test drive to see how it liked the new oil over the 10 year old oil it had been used to.
Well I was really beating on it around town and when I returned home and parked it, I noticed it dripping coolant. (leak was on opposite side of rad that the overflow tank is on) The dripping lasted maybe 2 minutes. I started it back up to see where it was coming from and it wouldn't drip anymore. I pulled the shroud back a bit and followed the wet trail of coolant up to a thin crack on the inside edge to the plastic retainer, that holds the side tank onto the aluminum. The tank itself isn't cracked really. There was some dried green residue at the top of the crack so it seems it may have been leaking for a while, and it was never enough to reach to ground or for me to notice. Anyways, It was a long day already so I just left it for then.

Today I decided to deal with it some more. I moved the truck to the other driveway and had it running only a short time. When i checked the crack, it was dry. I figured the level of coolant must have dropped below the crack line, which started about 4" down from the top and went to about 6" down. I opened the rad cap, and heard it release pressure, which I didn't expect considering I figured the crack would have let any pressure out. I took the cap off and the coolant level was maybe an inch, at most, down from the rad being completely full. I had to drop off crap metal and made a trip of about 12 miles. When I got home, I looked for any leaking coolant and saw none still. The level in the overflow tank was about the same as the other day. After it cooled off, I topped off the coolant with distilled water and filled the overflow to between full and add(since it wasn't really hot). In total I added maybe 1.5 quarts of water only.

I have a feeling that the crack doesn't really open up much or often. With that being said, I really don't feel like replacing the radiator just yet. Whats the best way to TRY to seal the hairline crack? I know epoxy tends to fall off rads due to the heat/cool cycles. What about using a soldering iron to melt it a little and then melt a black nylon ziptie into the mess and "weld" it that way? Ive heard of that in the past and actually quite a bit of mention of it online. The area that has the crack is about 1cm wide and the crack runs down the middle about 3 inches. Since there is only a little material there, the thermal expansion is limited as well. If it doesn't move much when hot, there wont be too much stress on it and the soldering "welding" may hold, at least until spring. (I drive the truck maybe 2-300 miles a month)

[redsoxsstink]

im going with RTV. if that doesnt work the melting of the zip tie sounds like a good one.

[zraffz]

I've had luck patching the end caps and sometimes I dont. I've used "Goop" successfully more than any other sealant. Or you could try your luck with Dike Stop Leak. It isn't liquid glass and it sealed up the counter bores/sleeves on my big cam cummins. It won't dry until it hits air, so it won't plug up the fins, heater core, thermostat, etc.

[V]

Today I finally swapped the radiator out for a new one. Turns out that the crack was located on a metal piece that actually connects the plastic side tank to the metal core.
Trying to patch it would have been pointless after all. Plus now the truck has new coolant too, only after 19 years, lol.

[The_Bishop]

19 years? It was just in it's prime! Hahaha

[sweetbmxrider]

All things diesel last foreverrrrrrrrrrrr

[V]

the oil change took like 10 years. Same with front brakes. rears are still original i think.

the truck does only have 75k miles. With 5k in the past 11 years.

I just ordered the 6 valve cover gaskets and a fuel filter. Eventually i have to do a trans service. That only has 45k miles on it. It was rebuilt in the late 90s when to original dodge trans died.

Overall its a great truck. Doesn't look too pretty but its a workhorse and tows anything anywhere.