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New water pump from a 2000 and up 4.0 in my 99

rav

NAXJA Forum User
Location
Albany, NY
I am planning to overhaul my whole cooling system as my original radiator in my 99 has a slight leak. I read some where that the water pump design was changed by chrysler for the 2000 and up cherokee's and apparently they also got some more HP out of it. I was wondering if any of you have looked into this, it should be a straight fit right? I see most of the pumps advertised as 87-01 any way.
 
3 HP apparently...
 
They rotate the same but the bolt pattern is different. old blocks use 4 while newer blocks use 5 bolts.
 
thanks that answers it. I guess time to look at Flowkooler now that they have fixed their impeller issues...
 
The HP increase was from the newer style intake manifold on late 99 and newer. They added the new manifold to compensate for the power lost from the pre-cats and smaller exhaust ports in the head.


You might want to re-think the flowkooler pump. Too much coolant flow is just as bad as not enough, since the coolant won't stay in the radiator long enough. I have a Stant SuperStat 195* and a CSF 3 row radiator. Everything else is newer stock stuff, and I run 195-204* consistently even on 100* summer days. My operating temps have been verified by both an IR temp gun and my Scan Gauge II. The highest temp I've seen was 208 on a long hill climb during the summer, and the coolest was 190 last week when it was 5 degrees out and I was coasting down a hill.
 
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Flowkooler flows too much for highway use. At least that is what I understand.
 
I have a Flowkooler pump installed since 2010 and 30,000 miles with no issues. I have a 2 row CSF radiator, 195 Stant stat and the 272310 Napa zj fan clutch upgrade. In the summer in stays at 195ish on the highway. In the winter in single digit temps it takes longer to warm up and runs a little cooler on the highway but still makes good heat.
 
The HP increase was from the newer style intake manifold on late 99 and newer. They added the new manifold to compensate for the power lost from the pre-cats and smaller exhaust ports in the head.
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Not sure if I agree with you on this. The new manifold was installed on 99 up 4.0's and they still made 190 HP. The 2000 onwards with the distributor less ignition and coil packs made 193 HP which was attributed to a modified impellar design of the water pump.
 
Not sure if I agree with you on this. The new manifold was installed on 99 up 4.0's and they still made 190 HP. The 2000 onwards with the distributor less ignition and coil packs made 193 HP which was attributed to a modified impellar design of the water pump.

A water pump isn't going to gain you more power on an XJ. An electric water pump like those on a BMW, maybe, but not a belt driven pump. The pump was changed to aid in cooling, since late 99+ have the added heat of the pre-cats in the engine bay.

The manifold was redesigned the same time the pre-cats were added. The new manifold was added in 1999. 1999 Cherokees didn't have the pre-cats yet, but the WJ 4.0 did. In 2000 (late '99), all vehicles equipped with the 4.0 got the pre-cats.
 
the water pump for a 1999 4.0 is the same as a 2000-2001 4.0 do some research before arguing...the 2000-2001 xj's had the extra 3 hp from the cylinder head, ignition system, and intake combined and who cares its only 3hp... and also the tj uses a different sized pulley than the xj both in diameter and center bore
 
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Whatever pump you chose, don’t over tighten the belt: less is better than more. If it squeals, just tighten slightly more. Your bearings will thank you for it in a long run.
 
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