I popped my radiator cap off this afternoon and noticed there is some "silt" at the bottom of the elbow as well as around the rim. It is very fine and kind of metalic looking.

What is this? I imagine it is not supposed to there.

1997, 4.0 with 198,000 miles. Radiator replaced around 170,000

That's not unusual to see, the 4.0 block is a sand cast block and you sometimes get some particles from that circulating through you cooling system, I would recommend doing a coolant flush.

It could also be that some PO used AlumASeal in it at some point. It's hard to get it all out. It won't hurt anything.

X2 on the aluminum radiator seal and heal stuff being added by last owner-
BE CAREFUL flushing that stuff out- I did, trying to be all perfect and stuff- then the heater core started dripping... that sucks-

There are a few folks who've installed a coolant filter set up that will help to eliminate a lot of the crud floating around the coolant system. I've seen them more on diesel trucks, but their are a few write ups and videos on youtube talking about this for Jeep XJs. Always hard to get all that casting sand out.

https://www.cherokeeforum.com/f67/co...ite-up-236267/

Thanks for the reply's. I put a new radiator in 20,000ish miles ago... would the alumaseal still be floating around?

I havent had any issues with other heating but may just have it flushed in the next couple months.

Means your heater core had some holes in it and needed to be replaced. Hopefully it identified itself before the winter!

"Replies." Apostrophes are not used for plurals.

Oh, yeah, easily. But if that's what it is, stop worrying about it. It will do no harm, and like BillyBoy said, it might be what's keeping your heater core together.

If it's AlumaSeal, somebody put it in there for a reason. I have known of AlumaSeal and CopperSeal to fix small leaks and last for years, right until somebody flushed their system and unplugged the leak.

Unlike the liquid goops that are sometimes used, neither AlumaSeal nor CopperSeal will cause you any problems with your cooling system. It's fine.

95XJman,


I bought my 96 XJ with 49k miles and no coolant problems that I know of (no indications that PO had ever added anything to the coolant to stop leaks). It had the silt as well. Every time I flush or fill the system, I collect as much out of the radiator fill neck as I can and move on.