Warning! (Bit long)

Hi,
This all started when my 93 XJ 4.0 ltr auto started running hot in summer 2007, I also noticed the water pump had started to leak. I fitted a new water pump, my first suspect for overheating was the fan clutch not doing it's job. I had heard of people bolting the fan solid and I thought "I'll do that", BIG MISTAKE! It did not fix the problem. Next thing I fitted was a new radiator, that fixed the overheating problem, runs cool now. I now noticed a slight rattle from the front of the engine (2008), well it's not the water pump I thought, I've only just fitted that, (5,000 miles). Harmonic balancer I thought, so I changed that, it still rattled. The noise was getting so bad that people stopped and stared! I took the serpentine belt off again and tested all the pulleys for play (I had done this about a month earlier, all seemed OK) this time I noticed play in the water pump pulley! I have just fitted another new water pump and the noise has gone!

Bolting the fan solid must have put additional stress on the water pump, I have now taken the fan clutch off all together and it still runs cool, I will fit an extra electric fan just to be safe. The moral is don't lock up your fan clutch unless you like fitting water pumps!

I'm confused. The fan isn't mounted on the water pump pulley.

Ditto on the fan not being mounted to the h2o pump. Could have been a bad new pump or did you overtighten the tension on the serp. Kind of hard to do on these but I suppose it's possible.

Hi,
I don't seem to have made it clear what I did exactly, you're right that the fan is not mounted on the pump. What I did was lock the fan clutch solid with a couple of bolts so that it could not slip, it was still mounted on it's original pulley. This seems to have put a lot of strain on the water pump. In fact on the box for the new pump it says "Always replace your fan clutch when replacing your water pump. A bad fan clutch will always damage a water pump" If I had know this in the first place I could have saved myself a lot of work! All part of living and learning I suppose.

Jeepcreep said:

Hi,
I don't seem to have made it clear what I did exactly, you're right that the fan is not mounted on the pump. What I did was lock the fan clutch solid with a couple of bolts so that it could not slip, it was still mounted on it's original pulley. This seems to have put a lot of strain on the water pump. In fact on the box for the new pump it says "Always replace your fan clutch when replacing your water pump. A bad fan clutch will always damage a water pump" If I had know this in the first place I could have saved myself a lot of work! All part of living and learning I suppose.

Click to expand...

what you did had no ill effects on the water pump, those instructions come with every water pump made by that manufacturer. The damage that can occur is overheating. A bad fan clutch will not engage properly, causing overheating and damaged everything, including water pump.

A bad fan clutch will not always damage a water pump. If the fan clutch was water pump mounted...maybe, but on these they are not.
I still think you may have got a bad water pump, sure wouldn't be the first time a bad part has been turned out.

You unbalanced the fan assembly by using only two bolts to lock it, four would have probably been OK. maybe even three but not two on opposite sides. Also was the replacement water pump new or a rebuilt, I've always had terrible luck with rebuilts so I stopped buying them about 15 years ago.
You also don't have the temp extremes over there we have here, vehicles in the North East have to function from -5 to 103, some other areas out west it's even a bigger spread. As for electrics, most here that have gone dual electrics switch back, the electrics just dont move as much air as the mechanical. You might get away with it over there.
Hey, anybody know the RPM the mechanical fan runs as at 2500rpm, I'm too lazy to do the math based on the rpm and pulley diameters vs serp belt speed.