Water pump rotation

Rock auto is showing two water pumps with reverse rotation that have taller hub heights and a hoard of different suppliers pumps with standard rotation and shorter hub heights. From what I recall reading here on I thought all our XJ 4.0 engines used the reverse rotation water pump. Is that right or wrong? Here is a link to all the water pumps I am looking at: http://www.rockauto.com/catalog/x,carcode,1179716,parttype,2208 The guy at RA said these all fit various 1987 XJs, and do not fit the ZJ. I think he is wrong, but I am not sure!!!! Are all of the XJ 4.0s reverse rotation??? What is the correct hub height?

Just measured the 87 XJ, it is 2-3/8" hub height (apx).

Note from DJ
Two Water Pumps listed for Renix
http://www.naxja.org/forum/showthread.php?t=1004320
OP by 90BLUE_XJ
Does anyone know why there are two water pumps listed for a 90 Renix 4.0L? They are described as having different flange heights. What would need a different flange height?
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Post #3 from lawsoncl
Its 4-cyl versus 6-cyl. For grins, I looked on RockAuto and it lists two Bosch units for the 6-cyl, but that doesn't look right. www.boschautoparts.com says you need the 97082, and the 97081 is for the 4-cyl.

BOSCH 97082 2.31" Hub Height & 3 5/16" Diameter Hub => 6-cyl reverse rotation
BOSCH 97081 3.72" Hub Height & 2 5/8" Diameter Hub => 4-cyl reverse rotation
BOSCH 97080 3.72" Hub Height & 2 5/8" Diameter Hub => 4-cyl standard rotation

I just installed this one in my 90 Renix 4.0L yesterday. It was identical to my OE one and fit perfectly. Jeep's flowing coolant great and remaining at 195*. It says standard rotation, but it is indeed reverse/CCW rotation.

Napa Auto Parts: http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=TFW42004_0303846964.

Wonder how many long-term overheating problems are cause by installing the standard rotation water pump?
You know the cases where the entire cooling system has been replaced and the problem continues.

lazyxj said:

Wonder how many long-term overheating problems are cause by installing the standard rotation water pump?
You know the cases where the entire cooling system has been replaced and the problem continues.

Click to expand...

It seems that the 4.0 XJ water pump that is listed as standard rotation is reverse rotation because that is the 4.0 XJ standard rotation!!!!

I am starting to think that the whole story here of getting water pumps with the wrong rotation is simply manufacturing errors (rare ones), where the wrong impeller got installed and boxed up.

I think many of the cooling problems had multiple causes and people just kept throwing the wrong parts at it and guessing as to the cause.

I always compare the old one's fins to the new one.

FWIW the YJ and 4.0 ZJ use a different pump from the XJ, because the YJ/ZJ mechanical fan is mounted to the water pump not a special fan pulley off to the side like the XJ. Learned that while doing a 4.0 swap into an 87 YJ with a 4.2 original motor in it. We ended up using a hodgepodge of accessories and the XJ ECU, converting it from e-carbed with the Ford computer to fully MPFI, whole engine XJ parts except for the water pump which is a YJ/ZJ one, with a ZJ pulley and the YJ factory fan mounted to it. The ZJ pulley was the same exact diameter as the XJ pulley so the original XJ serpentine belt fit perfectly.

If you see a bolt pattern on the flange that appears to be different from the XJ one, you are probably looking at a miscategorized ZJ/YJ water pump, or a 2.5L one. I think the 2.5L ones are more like a 4.0 XJ one but with a different flange height while the ZJ/YJ 4.0 ones are different flange height AND bolt pattern. They also have studs rather than bolt holes in the flange, if you see that it is a dead giveaway that it is a YJ/ZJ 4.0 WP.

Anyone have photo of what the correct impeller looks like?
It would be good to have one for a reference.

lazyxj said:

Anyone have photo of what the correct impeller looks like?
It would be good to have one for a reference.

Click to expand...

Great question (LMAO), try the link in post number 4 in this thread.