Hi,
I have a knocking sound in the engine similar to piston pin knocking but when I remove serpentine belt the sound disappears.

The sound is located near water pump. If I use stethoscope then I can locate it on top of thermostat tower and at the housing of LH engine valve cover (black). RH side is silent.

I tried to replace water pump with a new one (cheap Airtex) but the sound is still present. I also replaced water pump with a good one from my second daily car but the sound is still present there therefore I doubt the water pump to be deffective.

I am suspecting power steering pump but stethoscope transmits only high frequency continuous buzz without any knocking. When I remove serpentine belt again and pull PAS pump pulley radially I think there is faint knocking similar to the knocking I am hearing when the engine is running.

Any suggestions or similar experience? Could it be anything else "connected" to water pump or its circuit?

Thank you for any help!

 

The three 13mm bolts are not uncommon to come loose on the power steering pump pulley. Tighten them up while the drive belt is still in place.

 

Info from Jaguar. (several decades ago)

 

Thank you for feedback! I already tried to tighten it to 24Nm (and slightly above) and it didn't solve the issue

I also tried to swap belt and belt tensioner from my daily car without any improvement.

 

Do any of the pulleys look wobbly while the engine is running? Maybe tighten up the mounting bolts for the compressor, alternator and power steering pump.

 

If the probe fails to locate the sound adequately, you may be in for
a long haul. Water pumps usually do not produce a knocking sound.

 

None of them is wobbly. I checked all bolts and they were tight. Also removed PAS pump pulley and put it back again. Nothing improved.

 

I can also locate this sound at the eingine's oill pan and AC compressor. Wondering if it could be the source but there is not any difference in the sound no matter if AC is on or off.

 

Probably NOT your issue but Jaguar issued info about engine noise a few decades ago.
Check your VIN or engine number if it has been replaced?

 

I would suggest you pull the oil pan down and look to see if you have anything at the bottom and throughly inspect the oil pickup with a flashlight and small mirror.

If you can upload a sound clip for us to listen to, that would be of help also.

Lastly, when you have a drive belt off there is a lot less load on the engine and it probably idles a couple hundred (?) RPM’s higher and the noise is gone because of those two things. Just an idea. I’d pull the pan first though.

 

Shame on me!

I went to make a video and knocking sound is present even with serpentine belt removed and is located at thermostat turet and around LH VVT solenoid. It wasn't there when the ambient temperature was lower or I simply did something wrong at that time. Video enclosed.

Regarding oil pump I did not find engine serial number as it is located somewhere at the rear of the block but I need to find it later. SN is not present where NIKASIL engines have it as this is steel lined engine.

 

I've known VVT fail on other cars & make awful noises, I'd assume yours would do the same if it failed as they all seem to work off oil pressure.

 

Is the engine number for steel lined engines onwards marked with yellow print on the rear of RH black cam cover?

 

The engine number is either on the left side of the thermostat tower area OR on the left side of the engine block aft of the engine mount.

 

Today I removed LH cam cover. Secondary tensioner (updated red plastic with spring) looks in a good shape and there is not any crack visible. Primary tensioners look also fine as far as I can see.

Secondary chain is tight and I am unable to press tensiner against the spring. Is that normal? I assume it is pressurized with oil.

When rotating the engine manually I do not see snything wrong or loose.

Is there a way how to inspect vvt condition? It is newer version with grooves around its outer diameter.

Any other ideas?

 

That there is an original plastic secondary timing chain tensioner. You need to remove the other valve cover and see if the flats of all 4 cams line up. The crack isn’t always visible while they’re installed.

 

Just curious, but what weight oil are you using? I've heard but have no direct knowledge that the VVT in the non-supercharged engines can be problematic with too heavy an oil.

Those are old tensioners, as mentioned above. I would at least change out the uppers as they're more likely to go and can destroy your valvetrain when they do, a full timing job and update is preferred of course, but you gotta do what you gotta do and $$ dictates.

Updated tensioners will look more like the attached photos.


Angle from the front of the car looking back.

 

I am not sure if I get meaning? Do you mean RH cover and check if both primary and secondary chain wheels are in the same plane? What is the purpose of this check and what is the tolerance?

 

I am using Shell Helix HX8 5W-40. I bought the car with unknown oil in it and replaced it. Knocking sound was present there when inspecting the car.

First I need to identify source of knocking and then I can have fun with with timing upgrade.

 

Just because one side looks ok doesn’t mean the other side is. Another thing to consider is to drop the oil pan and see if there’s any plastic in the pan and/or pickup screen.