Tex-J

New, here. I posted in the Introductions area a couple of weeks ago. (https://www.cherokeeforum.com/f8/xj-noob-tx-204664/ )

Question: I know TUPY heads, like any head, CAN crack, but is it uncommon for them to?

Little backstory - I had the XJ at a mechanic shop shortly after I bought it (long story) to diagnose an overheating problem. The mechanic diagnosed it as a cracked cylinder head. I paid the diag fee and brought it home, where it sat for several months without me so much as looking in it's direction (way overpaid, long story, remember).

Well, I started checking it over last week and again today and I can't find evidence to support the mechanic's diagnosis.

Last weekend I checked the oil - it was coolant free. I cranked it over several times with the radiator cap off - I didn't get any bubbling. Then, today, I did a compression test - all of the compression #'s are consistent.

So I decided to let it run for awhile with the thought of checking under the oil filler cap for evidence of coolant or a crack after it got up to temp. Well, I did that.

I was half expecting some evidence of a problem, but I was NOT expecting to see TUPY cast into the head! Someone in the XJ's previous life had already replaced the head...yes!

At this point I'm thinking the overheating problem isn't related to the head at all but thought I would ask about the TUPY heads.

It's got to be something else but the only thing suspect about the entire cooling system is the coolant itself...it's brown/dark green and there is roughly a quarter inch of dark sludge in the bottom of the overflow bottle. Doing several good flushes and changing the coolant is next on my list.

Tex-J

Here are a few pics of the coolant.

randomguy310

the tupy heads are not prone to cracking. your cooling system looks a bit nasty, might try a cool flush and c.l.r. the radiator and see what happens

djb383

If u go to the CLR website, u will see that they (Jelmar) say "do not use CLR in an automotive radiator/cooling system". I would heed their advice despite what u read on the Internet/in forums.

My way to flush the cooling system........

Remove the heater hose and rad hose from the t-stat cover. Remove the bottom rad hose from the water pump. In this order......stick a garden hose in the heater hose and flush. Stick the garden hose in the heater hose nipple on the stat cover and flush. Stick the garden hose in the top rad hose and flush. Remove the recovery bottle and get all that crud out. If u decide to replace the cooling system all at once, stick the garden hose in the head (t-stat hole) and flush. The loose crud will come out of the block (water pump hole).

Your cooling system has been severely neglected........that's why it looks the way it does and that does not happen overnight. A bunch of that crap is sitting in both the heater core and radiator and can be next to impossible to flush out. If u don't replace the entire cooling system, then once u refill the old cooling system with new coolant, it is likely to turn rusty brown again very quickly. Remove the rad cap frequently (motor COLD) and check the color of the coolant. At the 1st sign of going from green/clean to rusty/dirty, do the flush again and refill with new coolant.

Turbo X_J

Any cylinder head or engine block can crack. If the cooling system is in that bad of shape you may be $$$$ ahead to just get something else.

salad

I'm guessing that after the head was replaced the owner just ran water in it. That ain't coolant!

md21722

The more common causes of poor cooling system performance are failed thermostat, bad radiator cap, bad fan clutch, clogged radiator (coolant passages), clogged radiator or condenser (air flow), bad water pump (impeller blades rusted off), inoperative electric fan, and missing fan shroud.

Overheating could also be caused by some type of head or block crack or a blown head gasket.

Since the cooling system is in pretty poor shape, it may be cheaper and quicker to simply replace all the components including the hoses which tend to degrade from the inside out. The condenser is for the A/C but if its all clogged up with bugs, dirt, or sand the radiator will not get all the air it needs.

Bustedback

If that was my rig I would replace the radiator, water pump, thermostat, all of the hoses, and the coolant bottle. I would also flush the block and heater core before installing the fresh, new parts. Don't forget the radiator cap too, it's the most overlooked part of the cooling system.

Tex-J

That's my plan. I'm kinda worried about plugged water passages in the block, though. #fingerscrossed.

djb383

Be sure to flush, flush, flush the heater core and motor after removing old parts and before installing new parts. Crud will probably continue to sluff off internally so keep close tabs on the new coolant changing color. Flush and refill again.

Bustedback

Don't be surprised if a couple of core plugs start to leak after a good flushing. Sometimes the sludge is the only thing that keeps them from leaking.

md21722

In my experience the radiator acts as a sponge for all that crap and the head and block behind the water pump looked just fine. Don't forget to change the rubber line from the radiator to the expansion jug. The expansion jug may come clean pretty easily with hot water and powdered dishwasher soap. If it doesn't, go for a new expansion jug.

Tex-J

Ok. Things just got interesting, and not in a good way. Was going to follow your flush method today. I removed the heater hose and upper radiator hose at the thermostat housing and disconnected the lower hose at the water pump. I was just about to start flushing the heater core when I thought to myself, "Just to be safe, it might be a good idea to take the heater hoses completely out and flush them separately so I'm not pushing any junk already in them into the heater core". So I did.

Both the upper and lower heater hoses each had a roughly 3" section that was COMPLETELY blocked by rusty/muddy sludge. Flushing the hoses with water had no effect on the blockages so I had to use a clothes hanger to help break the mud up.

This is what came out of ONE hose...





After getting both hoses clean, I checked the heater core by carefully inserting a screw driver as far into the heater core nipples as possible. I didn't feel any resistance in the upper nipple and the screwdriver came out relatively clean. The lower nipple was a different story.

I felt some resistance when I inserted the screw driver and this is what I pulled out:



So...at a minimum, the heater core will likely need to be replaced. I had a difficult time just getting the hoses flushed...it would be next to impossible to flush the core clean (in the vehicle, anyway).

My biggest concern, however, is the coolant passages in the block. If that rusty, muddy sludge got into the block there's no way in Hades I can flush it out completely. So the worst case scenario is a complete engine rebuild or replacement. Might have to punt this one down the road if that's the case. I already way overpaid for it due to the seller forging some documents.

On the bright side, if there is one...I did do a coolant/combustion gas test before getting started with the flush this morning...it was negative for combustion gasses.

Larry's XJ

Holy crud Batman.

Could get cooling system cleaner, might find two part that is acid and neutralizer. I have used muratic acid with baking soda run/flush. Also saw mention here of some kind of soap for cleaning, forgot which tho.

Turbo X_J

That's a wrap, Craigslist it.