Honeybandit

Tried using the search function to find a similar post but I found very little so hoping to get some help with this over heating issue. I have a 1990 Xj 4.0 automatic when I found the Jeep it was in a field and hasn't been ran in over 14 years so I'm slowly bringing it back to life. I've completely replaced everything in the cooling system and did the open system conversion but the xj is still running super hot I've gotten it down to where at idle it will stay a needle width away from the white light before the red no go zone(with heater on full blast) but once i put it in drive or reverse it adds just enough heat to throw it at the beginning of the the red so i shut it off. In my opinion it's running to hot in the first place before I even put it in gear and from my understanding 210° is normal operating temp so looking for advice on how what I'm missing to even get it down to that 210° in the first place. With the conversion included I've replaced
waterpump, radiator 92+, thermostat housing 92+, 195° thermostat, all coolant lines, fan clutch, coolant overflow tank 92+, and hard wired the electric fan to a switch (it blows like hell) deleted the hcv during the conversion and I've done a compression test to make sure the head and gasket are good. So what am I missing that would be causing this problem?

Turbo X_J

Verified?

Honeybandit

Lower and upper radiator hoses are within 30° of each other the head near the thermostat housing shows 195°ish and near the sensor on the back of the head 245°ish. Wasn't sure where to shoot for temp readings so just checked a few places

Turbo X_J

Does the cooling system hold with a pressure test?
Did the original coolant resemble mud or show any metallic stop leak jazz?

Honeybandit

All that nasty stuff was in the bottom radiator hose before I replaced everything and I made sure to thoroughly rinse out the heater core best I could and haven't pressure tested it since I did the open conversion

Turbo X_J

It's a safe bet that a portion of the cooling jacket in the head or block is plugged with that stuff.

Honeybandit

Thank you for the quick response and help I'm gonna try and do a few flushes today and see if that helps

dzywicki

What the heck is that stuff? Never seen anything like that come out in a flush.

tech

With stuff like that in your cooling system it looks like you will need a flush gun . a flush gun hooks up to a water hose ans a air hose . flush guns will blow out a lot of out of your cooling system has in it . doing 2 or 3 flushes with a flush gun will get your cooling system clean .

Honeybandit

That stuff was in the bottom radiator hose when I converting from the closed renix system to an open system I hadn't even done a flush yet at that point

Honeybandit

Where would I get one of those flush guns?

Honeybandit

Really dumb question but I picked up a fan clutch Napa#272310 cross referenced it with O'Reilly's because the closet Napa store is almost 2 hours away but picked up the one that O'Reilly's had for that number. Wasn't worried about it running to cool I live in South Alabama but most of what I've read everyone said it sounds like a plane taking off under the hood I haven't noticed any louder sound on top of that the fan feels like it's pushing air forward more than pulling back like the tornado I've read. I'm fairly mechanically inclined but part of me wonders if I put the fan on wrong there was a sticker on the fan blades that said front so naturally I put that facing away from the engine facing...well forward

tech

I got mine from ebay it's made by OTC and here is a link to one that looks the same https://www.ebay.com/itm/Cooling-Sys...ry!91350!US!-1 , this is one I found real fast maybe you can find one cheaper one some where .

dave1123

Okay, here's something. Water pumps made for serpentine belts run the opposite direction than the ones for v-belts. The fan blade pitch also is reversed for those. It sounds like you have a mismatch with something there. Stand in front of the radiator and see if the air is blowing out the front. If you have the wrong pump, they don't pump so well! Actually if the fan is spinning the wrong direction for the blade pitch, it will sound like a tornado but not move much air. I don't trust the counterboys at most auto parts houses to know the difference anyhow.

You need a strong chemical flush to break up that trash in the block into small enough pieces to come out. Don't forget to backflush the radiator and heater core too. I would even pull the block drain plug(s) and probe the hole with a screwdriver to get it to drain. IDK if there are 1 or 2 plugs on the side of the block. It sounds like the jeep sat for years with just water in it and that's where all that rust came from. Lucky it doesn't get too cold in south Alabama!