CheapCherokee

heres the details:
1987 203k miles
stock except for the following:
converted the cooling system to this to eliminate the coolant bottle:


even has a over flow tank:


and its got a 3 row radiator.

so ive been running this system for a while now, with no problems at all.
so for a while ive been hearing a slight noise which sounded like a water pump going out. well recently the sound got louder, and my dad agreed that it sounded like a water pump so yesterday we decided to replace it. so it take everything apart, drain the system, go get the new water pump, then put it all back together. so i fill it back up with coolant, then started it up. it was immediately noticed that the sound was still there, so apparently it wasnt the water pump....weird....while idling we were going around checking for leaks, and could not find any. well we happened to look at the temp gauge and noticed that it was warming up quite quickly. soon enough it got about 210 degrees so we shut it off. so we let it cool off for a little bit and decided to drive it a little to see if things changed. so i took a quick drive around the block, and when i pulled in the driveway it was about to hit 260* so i quickly shut it off. saw steam so we popped the hood and found coolant coming out of the cap as seen in picture 1, and the overflow tank almost full of what looked like plain water...as opposed to coolant. What the hell? we replace a water pump and now it over heats? its got recently replaced hoses and a recent flush, so that shouldnt be the problem, and while we had the rad out we flushed it out, so that shouldnt be a problem either. one thing i did notice was that the aux electric fan did NOT come on at all. the sensor was recently replaced and it worked before the water pump replacement. and yes we made sure both the fan and sensor were plugged in.

So my dad and i are stumped. it over heats after replacing a water pump and now the noise we thought was a water pump is actually something else. what could this be? we took a stethoscope and listened to all the pulleys on the serpentine belt and none sounded bad.

any ideas????

TrekkerJmm

OK dumb but a serious question, is the belt on the right way? it is easy to overlook the simple things...Tj

CheapCherokee

ya know we actually never checked that. we kinda just put it on the way that it seemed to go and it fit perfectly... im gonna go get the manual out and double check to make sure its on properly.

thanks

mike albo

did you get the right water pump?

CheapCherokee

my dad took the old one with him to Napa when he got the new one. so im pretty sure we did. here's what a guy on NAXJA said: so im going to check the PN to make sure we were given the right pump.

Rageinferior

X2,

When I bought my XJ the guy had just replaced the water pump and couldnt get it to stop overheating. He had the belt on it wrong. The Chiltons manual didnt even have a diagram for the 4.0 that worked. It said "typical" 4.0 and only had 4 pullys on it. I have seven. I have a diagram of the correct routing for mine (1990) if you want I can send it to you.

E

XJeepWerks

There's your first problem. The belts on these 4.0's NEVER fit perfectly. Lol, I put mine on wrong the first time I did it and it fit perfectly. Got a routing diagram and did it the right way and couldn't get it on to save my life. Took me a good hour and a half just to get the belt on the way it was supposed to go.

CheapCherokee

haha i see what you mean. i actually looked online today to double check the belt routing and it all checked out.... i guess my definition of a "perfect" fit is a tight fit, which is what it was. but it didnt take me THAT long to get it on

CheapCherokee

oh yea and just an update:
the guys at NAXJA helped me figure out that Napa gave me the wrong pump! they gave me the standard rotation pump when what i needed was the reverse rotation pump. i wish i would've learned of this standard/reverse rotation difference a little sooner! Napa screws me over once again!

mike albo

glad you got it figured out

XJeepWerks

Haha, their better than Autozone! Their hours are just unreasonable.

superj

wow, i would've never figured that one out

CheapCherokee

well its back to square 1!!!!
pulled the "new" water pump to compare with the old....they look exactly the same!!!!





the old water pump does have R stamped on it, its just too hard to see in the picture. the new water pump does not, yet they both look identical. what the hell? part # suggest i need the 42002 pump... but the 42004 pump is exactly the same as the old one.... am i missing something here?

mark's91-XJ

hows the fan clutch?

CheapCherokee

works fine. figured out what my weird noise was.....timing chain! its loose and was rubbing on a wear pad. putting in a new one tomorrow.