Hello everybody my name is Ettore and I'm new to this forum!
I'm from Italy so forgive me if I make some mistake!

I just baught a 2003 xj x350, the 4.2 sc. When at idle there is a knocking noise coming from the front of the engine, it goes away as soon as you give gas.
I read a lot about problems with the timing chains and the tensioners but i'm pretty sure the noise does not come from the inside.
So i took of the water pump belt and the noise has gone!! I took off the belt tensioner as well because i thought he was the one making noise but i checked it and it looks alright to me. The water pump makes some noise if i turn it by hand, could that be the problem?
Does any of you guys know if it is common for the water pump to be noisy?
The car has done 120000 km by now.

Thank you in advance for your help hope i can fix it soon!
You guys know so many things it's surprising haha

 

I bought sorry haha

 

Waterpump is not suposed to be noisey ! You will need to change that . And also check the sc belt tentioner bearing for rumbles and slop along with the one you removed . Also spin the sc back and forth to check for exessive backlash in the snout coupling inside the sc .
And don't forget to give the alternator a spin to check that too for noise .

 

Hey Datsports thank you for your advice!
Haha yeah I know the water pump shouldn't be noisy, sorry I meant ' is it a common fault on that engine for the pump to be noisy? ' I didn't express myself as I wanted to
I put everything back and ran the engine again with the belt on and with a stetoscope I found that the pump is the reason of the noise. All good with alternator and bearings. I'll remove the pump on tuesday.
I did check the sc and it's ok
Thanks a lot for your reply!
I will have to check the gearbox too because on the dash it says 'gearbox fault' and the car doesn't run smooth at all.
I read I need the car to be idling to check the transmission fluid level. When the fluid temperature is around 30°c the fluid should be at the level of that plug on the passenger side right? it's an ellen key I think. Is it true that if the car is not running a huge amount of fluid will come out of the plug as soon as I remove it?
Thanks again!!!

 

Regarding the transmission oil level, look at this thread called "2004+/4.2 liter transmission dipstik" there is a video.

 

Yes most water pumps will fail after or around 100000km regardless of brand , mine went at 156000km on the Str and was original , one thing to make sure is that it has organic acid antifreeze (oats) befor you refill the coolant if does not then you'll need to do a thorough flush of both the coolant sistum and the intercooler sistum befor refilling with oats antifreeze and bleed the charge coolers ,I also disconnected the heater supply pipe to flush the heater matrix , mine had the rong stuff in it when I purchest it .
That's a helpful vidio about the zf 6hp26 ! But I noticed thay did not change the matronics sleeve Wilst doing this video , and I would highly recommend doing that , it also states on the vidio that you must use the zf pan/ filter and zf fluid . Well that's up for debate too
I used a motorgaurd steel pan and seperate filter (for the ford territory) and totul zf6 fluid witch meets the shell requirements , witch I purchased from our local zf agent and it's what thay use too ! There are other brands too mercon sp is popular .If your just topping up thou then wise to use the zf lifeguard 6 fluid as that's probly what is in there . Don't know about the xj's but the s type drive tunnal raps tightly around the fill Bung , and I just dropped the back of the trans by removing the trans cross member to acsess and relies the Bung , put it back up leval for the fill prosedure then doped it again to tighten the Bung afterwards ! Some times a tranz error is caused by the sleeve filling the matronics plug with oil so check that too !