yj giving me headaches.

[bails85]

the jeep was running a little warm after replacing the entire cooling system minus the radiator so i bought a new one. i installed it today and decided while i was at it to replace the temp sender. well after running for less than a couple minutes the jeep started to run at 260. not sure why. im wondering if the tstat is sticking and not opening. is there an easy way to check this or do i have to take it completely out? its new but its an autozoner so i dont know how well i trust it. before the new radiator it would bounce between 190 and 230 on the guage. i saw chunks when i popped the radiator cap which led me to believe it was partially clogged. new all aluminum radiator and a temp sender and now it wants to run hot. i jammed the water hose in the lower rad hose and started the jeep to flush out any remaining fluid before hooking up the hoses to the new radiator. could i have jammed up the stat by doing this? when i filled the system with new coolant i did so by leaving the temp sender out until it pissed fluid. intstalled the filled till my flush tee on the heater hose over flowed. then topped off the radiator. fired it up and got hot on the guage after 2 min or so. any ideas? stumped and over it.

[Russ Chung]

Let the engine cool down. Make sure the coolant is full. Start the engine and feel the upper radiator hose. You should feel a distinct warming of the hose when the thermostat opens. See what the temp gauge reads when/if the thermostat opens.

[1 Bad F N Z]

Pull your thermostat to see if it is clogged, but I'd bet you have air in the system, Kevin.

[bails85]

changed the stat today and put in a new sensor. still doing the same thing. could auto zone or napa be giving methe wrong part. they seemed to have a hard time finding the sensor on their computers. and the guy from napa said that they read at different ohms. the jeep says well over 240 but its not blowing fluid into the catch tank. or popping the top. im wondering if i have the wrong sensors. does anybody have the correct part number so i can double check.

[6spdYJ]

PM sent.

[Mitch]

For what it's worth, My over heating issues on my 88YJ went away when I went with the All Aluminum Radiator (Kingman AZ) and swapped out the thermostat for a High Flow one as well as a High Flow water pump. Problem solved.

[bails85]

well i tried to reburp the system and it seem like the new radiator could be defective. the top of it gets hot but the bottom and lower hose are cool to the touch. im going to put the old one back in just to test it and see whats really going on.

[6spdYJ]

Ray, did these problems exist before you replaced the water pump? BTW, you wouldn't happen to still have the original laying around. It would be great to compare impeller direction between the two. Most of the heat in an engine is generated in the head (up high). If the water gets hot enough to open the thermostat, the hot will flow into the cool of the radiator. If the impeller direction is wrong, or the belt is spinning the pump backwards, the pump will just cavitate and cool water won't flow. It is extremely unlikely that all of the radiator tubes are clogged at the same horizontal level. I'd take the time to investigate the pump.
Straight from the Haynes manual:
"All 4.0L engines and some 2.5 and 4.2L engines have a reverse rotating water pump and viscous fan. This type of water pump can be identified by the words "REVERSE" imprinted on the viscous drive and/or inner side of the fan. On the body of the water pump "REV" is cast and an "R" is stamped into the water pump impeller> The installation of the wrong pump will cause major engine damage."
FYI, "REV" is cast into the forward side of the snout that the lower radiator tube slips onto. Look here before pulling any parts or (for crying out loud) buying any more parts.

[bails85]

ted i took your advice and checked to make sure the pump is rotating the correct way. i called autozone and the part they sold me is the pump that has rev rotation. im going to double check to make sure but at this point im going to slap the old radiator back in to see if i still have the same problem. ill pull the lower hose on the water pump and look in there with a flash light to make sure the impeller is in the correct orientation. i was only running warm before but the system was working just not efficient. once i put the new radiator and sensor in this new problem arose. so ill back up 2 steps and start over. worst case is ill have to take it to ken in hesperia but im going to stab at it till it gives. it cant be that hard. only thing im hoping is that its not a head gasket. it doesnt seem likely but i have funny luck.

[6spdYJ]

The part number on the box doesn't always match the part in the box...

[bails85]

i replaced the water pump just to be sure. the impeller had the r on it to show its a reverse pump. i checked rock auto quadratec and morris 4x4 they all call for the same pump and the same pics rotations. i cross referenced the part number on the sending unit and i have the right sensor. 2 of em. the only difference is some yjs have the sender unit " with light" or without. mine doesnt seem to take the one with light. i put the old radiator back in just to check it and im still having the same problem. the only thing i can think of now is possibly having a bad head gasket. which isnt too far fetched because the jeep has 180000 on it and it sat for 3 years.

[6spdYJ]

Mine has 196000 and gets flogged like a rented pony daily - plus sat for 4 years. Try starting it during a warm day and let it idle for a minute. See if it has an unusual amount of steam in the exhaust. If it won't confess to anything there, drive it up to about 40 in 3rd gear and let off the gas. The resulting vacuum should pull water into the cylinder and steam like crazy out the tailpipe if the head gasket is bad.

[Lumpy Grits]

When was the last time you had a rod-out done on the radiator? It's clogged, and when you refill-Don't use 'tap' water.
Use distilled with the coolant.
LG

[Lumpy Grits]

Ck your temp gauge-260* will boil coolant with a 16lb cap.
LG

[6spdYJ]

Any progress?