Took the cap off my radiator after my failed heater core flushing attempt yesterday to make sure my coolant level is good, this is what I found..



The hose that goes from the fill neck to the overflow bottle is completely blocked with calcium or whatever this crap is. Figure this is causing my low operating temperatures and no heat problem. How should I tackle this?

 

One would think that mess would cause overheating. Major neglect going on....that doesn't happen overnight.

Remove heater hose and top rad hose from the t-stat cover. Remove bottom rad hose from water pump. Stick a garden hose in the heater hose and flush, flush, flush. Stick the garden hose in the heater hose nipple on the stat cover and flush, flush, flush. Stick the garden hose in the top rad hose and flush, flush, flush. Good luck.

Read/practice my sig.

 

What is the history of routine cooling system maintenance on this engine?

I agree with djb. You've got some serious work ahead of you. This is likely going to take multiple flushes. For a cooling system in this condition, I recommend using a commercial cooling system cleaner, available at any parts store. When all is said and done and your coolant stays green, (I recommend conventional green anti-freeze for the 4.0 at a 50/50 concentration with distilled water) then report back.

While you're at this, I'd consider looking at each and every cooling system component for replacement. Especially the thermostat.

 

I'm leaning towards just replacing it all. I've only had it back from a family member for 2-3 months after years of them driving it. Its a little over 200,000 miles and I'm 95% sure there has been no maintenance done on the cooling system in the last half decade.

Radiator, hoses, tstat, tstat housing, waterpump. Anything else I should change while I'm at it? What radiator should I go with?

 

If u want a good one get a 3 core. While you have the water pump off take a garden hose and spray the block out. This will help when you start your flushes!

 

Rads only have one core.....that one core may have multiple rows.

I would strongly recommend doing radiator homework when considering a replacement rad that's different in design than the OE Factory style rad. What is the replacement rads core thickness? If the core thickness is no thicker than OE, nothing is gained regardless of how many rows it has. OE Factory rad is a 1 row 1.25" thick core. Check the core thickness of any replacement rad.....it should be at least 1.25" thick.

 

Something like this

 

The spaces between the rows does nothing to dissipate heat, heat is dissipated via the tubes that contain coolant. Subtract those spaces between the rows from the total core thickness and u get get the true/actual core thickness.....the part that is flowing coolant and dissipating heat. If either of those 3 row rads have actual core thickness significantly thicker than the OE style 1 row 1.25" thick core, then by all means, give 'em a whirl. I doubt either does.

Aftermarket marketing departments want folks to think that a 3 row rad is 3 times as thick as a 1 row rad.......not. Virtually all OE Factory style rads r of the more modern 1, very wide row, design.

 

That could be Stop Leak. Have you ever added Stop Leak to the cooling system? Is it possible a previous owner added Stop Leak?

 

A gallon or 2 of stop leak maybe, LOL.......the pic looks exactly like what a iron motor does internally when corrosion protection has dropped to zero for a while.

 

...or they got the bottle of stop leak mixed up with a can of Great Stuff expanding foam

 

I suggest a lot of flushing with a good cleaner and this isn't for the radiator either just the engine, heater core to start with be sure the heater is on and leave it on. Take most of a day to do this because the inside of the block looks that way also. After at least a half dozen times of flushing and refilling till water runs clean remove all the radiator hoses and both heater core hoses then trash them along with the t-stat housing replace it.


Aluminum radiators are great "IF" you use a really good one starting around $600 and up, the ones for $200 up to 400 aren't that good of quality and known to leak quickly or a couple of ones posted here out of the box.. One isn't needed in 95% plus of the XJ's.


My son and I both have the OEM types bought from AutoZone for under $100@. I personally would replace the water pump and fan clutch then you know the complete cooling system is in good shape in your XJ. No over heating issues at all with either XJ.


BTW my sons radiator was at least that bad if not worse and red in color, the fill/overflow tank (plastic jug) was so discolored you couldn't see in it.

 

Never heard of an XJ radiator that cost that much. What brand is that, and where would I find one?

 

Griffin Radiators makes a model for the XJ......about $600 and has two 1" or 1.25" wide rows.

I believe that is the rad that Novak sells for their XJ V8 conversion.

 

Thanks for the advice. I bought the specter oem type radiator, water pump, thermostat, housing, fan clutch and new hoses last night, so I'll be overhauling it all.