longtime visitor, new member here
I have a 2000 jeep cherokee right hand drive for work, yes a mailman, that just had entire cooling system replaced(new radiator, redone heater core, lines, etc.). Keep getting rusty dirty antifreeze when running for 15 minutes. Still does it about 8 or 9 flushes. My mechanic says it might be a sign of block rusting out and maybe start looking for a new engine or be prepared for this one to die. Good news is he has a 4.0l jasper engine with 20k miles on it coming out of another jeep that will bolt right up to mine for $1000.
Question is can it be anything else i and he are missing that causes that?
any input is appreciated and thanks a ton beforehand.
A running vehicle is my livelyhood and i cant risk it shutting down suddenly.

 

What kind of flushes? Just water or extended chemical flush such as Prestone?

Blocks don't just suddenly rust out. Is the Jeep new to you? Have you had cooling problems or were the new cooling components just a preventive measure.

 

Keep draining/refilling with fresh 50/50 mix. As soon as it starts to change from clean/green, drain/refill again. Find a new mechanic, save your money, he's just trying to get it.....all iron motors rust internally when cooling system maintenance is neglected.

 

prestone chemical flushes.
I bought jeep about a year ago and previous owner put in radiator stop leak that blocked heater core. we fixed that and works great. My route has boxes so close together that it does run hot in warmer weather, stop and go driving, but on open road driving it runs fine temperature wise. Aux cooling fan on radiator keeps it from getting super hot.
We just cant nail down why there is constant rusty, dirty coolant after we flush and run it a while.

 

Jeep sat idle for about 6 months while previous owner was trying to sell it. I was guessing that is where the rusting came from.
Now we just cant stop it. I would flush it when it turns rusty but it turns from green to rust in a matter of days, maybe a week.

 

Keep draining/refilling with 50/50......it'll clear up, eventually.

 

^^^ This. If you had to swap out the motor every time the coolant gets rusty looking, there would be a heckuva market for new engines.

 

Do as djb said. And find a new mechanic that isn't trying to screw you out of $1000.

 

Aging coolant turns to acid which causes decomposition, rust=neglect. If it's that bad you should consider replacing all the block & head core plugs now before they blow out.