Water Pump Rotation - how easy to tell?

Can I check the pump-rotation without having to remove it?

My 93 XJ - which I've owned since new - has done 100k miles. For years, even in extremely hot conditions, the temp stayed rock solid just beow 210. More recently it has started to overheat (gauge gets up to the next mark above the 12 o'clock/210 figure) during high speed/high load/hot weather/highway driving. Slowing down brings the temp back to normal. Electric fan cuts in OK with a/c or when temp rises, but in hot conditions now clearly struggles to cool hard-working engine.

System has been flushed, hoses are OK (bottom one still has spring in it), and new t/stat was put in. But it still seemed to run hot, notably when heavily loaded. I suspected the fan clutch (I tried standard test: fan seemed to spin rather too freely by hand when engine was switched off while hot). So I've replaced the fan clutch.

Haven't yet been able to re-test the system under serious heat and load, but temp still seems to be creeping up above 210 in normal driving more than it used to. So now I suspect the water pump. It was replaced by a non-Jeep garage about 18 months ago because the original one was making an unhealthy noise (bearings?). I didn't see the new pump before it was fitted. Now, after browsing the forums, I'm wondering whether the garage fitted the wrong pump - one which is not reverse rotation?

Two questions: first, would the wrong pump (ie with the impeller blades the wrong way round) produce the symptoms I've noticed? In other words, would it still push or pull the water around just enough to keep the engine temp roughly normal in easy driving, but not pump enough volume to cope when things get hot? Or would the wrong pump be totally ineffective in circulating the water even in normal driving?

Second question: is it possible to tell from the outside whether the replacement pump fitted to my Jeep is the correct (reverse rotation) one or not? Or is removing the pump in order to look for an "R" on the impeller blades the only possible way to check? I just don't relish the task of having to drain down the system, and unbolt and remove various bits in order to get the pump off - just so i can look at the blades....

br1anstorm

disconnect the cps sensor and have some one start the engine. the motor will not start and you can look at the belts rotation.

Yes it would not pump enough water.

Low RPM would heat up, but high RPM would cool.

90xj06 said:

disconnect the cps sensor and have some one start the engine. the motor will not start and you can look at the belts rotation.

Click to expand...

Sorry - my original post wasn't as clear as it should have been. I can see which way the serp belt, and the water-pump pulley, rotates. My problem is in trying to identify - from the outside - whether my replacement water pump has the correct ("reverse rotation") impeller blades. I'm wondering whether the workshop fitted an older version, designed for the v-belt engine, where the pump shaft turns the other way - so the blades are angled differently.

I saw somewhere that some replacement (or OEM) water pumps have "REV" stamped on the casting as well as an "R" on the blades. Is this true? Anyone got any pics that show where to look?

br1anstorm

Your pump was changed 18 months ago, but this problem just started 'recently"?

Someone correct me if I'm wrong, but I'm pretty sure that you would have more overheating problems than you have if you had a non reverse rotation water pump on it.

Saudade said:

Your pump was changed 18 months ago, but this problem just started 'recently"?

Click to expand...

My slight lack of precision was deliberate... Fact is, it just happens that haven't used the Jeep all that much since the pump was changed.

For the first ten years after I bought it new in '93 I used my Jeep more-or-less full time (drove it across Europe, out to the Gulf, across various deserts, and back to UK). Temp never went higher than the 210 halfway mark on the gauge, even in Saudi desert with a/c on in mid summer and a loaded roofrack.

Had the pump changed, and new belt, sometime in '04. It was not leaking, but noisy and I suspected bearings were going. For the next year or so I only used the Jeep infrequently on short-distance runs (nothing stressful), because I was away from home and/or using other cars. Then in late 05 I made a couple of longish trips in Europe in the Jeep and twice noticed the tendency to run a bit hotter than I remembered. On one highway journey in peak summer, gauge stayed up near the 3/4 mark (between normal and red), despite pauses to let it cool, and running the heater. That's when I had a workshop (in France) flush the system and put in fresh coolant mix. Back in UK I had the t/stat changed when it went into the workshop for some other unrelated work on the front steering.

Jeep ran OK over the winter of 05/06 - cool weather, routine journeys. Then on a 600 mile highway trip with full load and stuff on the roof last July (couple of months ago) when the weather was really hot, I noticed engine was getting hot again at highway speeds and when hauling uphill. Slowing down (to 40 - 45 mph) seemed to get the temp down a bit (and I shut the a/c and ran the heater in bursts to help it cool...)

That's when I checked the fans. Electric one cuts in as it should (with a/c, and when temp gets above about 220). Main fan seemed not to be 'locked in' when engine was at operating temp, so assuming the fan clutch was shot, I've replaced it.

Haven't had a chance to test again uphill with full load in hot weather (it's kinda cool and rainy at present). But in normal driving the temp still creeps up higher than 210 until the fan(s) bring it down. And I'm still nagged by the fact that the symptoms I've noticed don't really quite fit with fan-clutch failure, and that the problem in effect only began after the pump was replaced. As I didn't myself replace the pump, I didn't see it before fitting, and don't know what the workshop - which was not a Jeep dealer - installed (OEM or some substitute?). So I'm wondering if they just put on "a Jeep water pump" without realising, or bothering to check, that the impeller blades needed to be angled the correct way for the serp belt/reverse rotation version - especially as the earlier (normal-rotation, vee-belt) pump casting is apparently the same shape and fits the same bolts/holes.

That's why I'm wondering if the "wrong" water pump would still work - just enough to cope in unstressed conditions, but not efficiently enough to circulate water at the volume/speed/pressure needed to stay at 210 when working hard in hot conditions?

If I've got to take it all apart just to look for an "R" on the blades, then so be it. But I was hoping I might be able to avoid all that hassle and check from the outside, so to speak - or else to have someone tell me I'm barking up the wrong tree because my running-hot symptoms indicate some other cause.

Sorry for lengthy details, but I hope this clarifies things....

br1anstorm