i bought my jeep xj 1997 not while ago and i had a leak in oil adapter but fixed but then i noticed the radiator cap have something like mud and the coolant holder was almost empty, i heard like maybe it will blow the head gasket.
so whats my next step to prevent any big problem ?

Wtf is that? Who used your radiator as a toilet? I'm no expert but flush the **** out of that system. No pun intended.

"To prevent a big problem?"
Sell it.

whats the worst scenario ?

New motor and cooling system at best but did you look under the radiator cap before you bought it? Is it overheating now?

i don't think its overheating, what do you suggest to do?
im thinking to a garage for Coolant Flush & Fill and what i should tell them to check ?

It appears to be rust. Try a cooling system flush. Drive it around afterwards to see how it performs. Don't go far, just in case. Maybe you'll get lucky, but it's likely the radiator and heater core are plugged up.

check this out.

https://www.cherokeeforum.com/f2/tem...2/#post3228367

What does the underside of your oil fill cap look like? What does your oil look like? You mentioned your coolant expansion reservoir " coolant holder" was low does coolant disappear after you fill it?

Your first diagnostic should be a block test. If it is negative you should move to a cooling system flush and maintenance.

The block test first will let you know how far you want to get into this project.

That mud is not rust. It's what's left behind when the water is boiled or evaporated out of coolant. Test for a blown head gasket, as exhaust escaping into your cooling system can cause that.

That crap coats everything and eats water pumps. Assuming you don't have a head issue (or you have one and fix it first), it's time for a cooling system overhaul and a really good flush with either Amway laundry detergent or Prestone flush. If your radiator looks like that, your thermostat is going to be gunked up and your heater core is going to be full of crud. Take it all out and replace it, and replace your viscous fan clutch while you're at it (because it will never be easier to swap than when the radiator is removed).

Edit to clarify: You don't have to replace your heater core as part of a cooling system overhaul.

Last cherokee I saw with a gunky radiator just like this had a cracked head.... But you need to get in there and flush everythinggggggg

He has a '97, which should have the 0630 which shouldn't crack. However, a blown head gasket can definitely result in the same mess.

The one I'm speaking of was a 98. The 0331's are prone to cracking, yes, but it's not impossible to crack the 0630's either.

zero maintenance?

No point in jumping to conclusions. The evidence presented thus far points toward a woefully neglected cooling system. OP should deal with that first, then keep his eyes open for signs of other potentially related issues.