Greetings all.

So it's my turn to be riddled by a new knocking sound underhood.

The knocking seems most pronounced on cold start but persists when the car is warm. As I've tried to let the film clip reflect, it seems to be loudest right around or under the intercooler area, possibly a bit louder on the left side.

The dipstick tells me oil level is as per spec and it's 5W-30 changed less than a year ago. I believe the spark plugs were changed on the same occasion.

The car runs just fine with no stutter but I do get the impression the engine "moves" a bit more and a bit more unevenly than I would expect when it's idling and I put my hand on it.

I've read a multitude of posts here and elsewhere and realise a knocking noise could be lots of things within or outside the engine and ranging from the trivial to the dire.

So, where to go from here for a relative mechanical ignoramus? Further diagnostic steps? Get my hands on a stethoscope?

Can anyone venture an opinion judging by the sound?

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Thanks!
/Per

 

I'm sure those more knowledgeable than I will chime in: - perhaps you could remove the drive belt to check if the noise is coming from the supercharger?

Mike

 

. . . and or the serpentine belt idler/tensioner pulleys.

 

No expert here either but it sounds a little louder near the SC. As suggested try removing the belly. Also a long screwed pressed against the parts and on you ear makes a great Troubleshooting tool.

 

Thanks guys. Got my hands on a stethoscope and will report back.

 

Hope it's not the same cause as "my" occasional tapping a few years ago. I ended up with a spun bearing and a seriously munched crankshaft. Somehow the thrust washer(s) had "left the building" as well. The cheapest solution was to put in another engine (used, but with 80K fewer miles).

I'm hoping it's just the SC gears. Mine was making some noise a year or so ago. I changed the oil and all is well since.

 

So. Day before yesterday I started the car, heard the knocking (I swear I did) and drove off to see the indy. Twenty-five minute drive, got there, car warm, no knocking to be heard. It's like going to the doctor.

Indy believes it might be something related to the exhaust manifold - at least, something that tightens up when heated.

What he *did* alert me too was the faint hissing sound in the right side of the engine... which turned out be the cracked crankcase breather pipe. So now I'm looking for one of those. More on that in another recent thread.

Thanks for listening :-)

 

Are you talking about the plastic pipe coming from the valve cover or the metal EGR pipe coming out of the exhaust manifold?

 

The ruffled, brittle plastic-covered crankcase pipe. Seems pretty hard to source too Haven't found one yet.

The EGR pipe was replaced that year - that thing made a deep, whistling, whoof-whoof sound that had me well and stymied.

 

pull the accessory belt off and see if it goes away, if not drop the oil pan and look for shavings. Search for knock knock or my name for a similar post if you haven't already. My rod knock was louder than what your sound appears to be.

 

See if you can just fabricate a pipe/hose to bridge it while you look. It might stay in there indefinitely - lol. I've had some success sealing cracked air pipes with Gorilla glue. Just make sure it gets well into the crack and is fully set before putting it back into use.

 

Thanks, guess it's going to be gaffer tape for the short term. Still searching for the part. Maybe time to think practical rather than original...

 

Check out these pictures of repairs made to the bellows of the air intake in posts #5 & #11. As far as the concern about self bonding tape being exposed to heat, I believe Harbor Freight sells a High Temperature version of this self sealing tape from post #11. Plus this post is a few years old, there may be an update to post #11 about the longevity of the self sealing tape.

https://www.jaguarforums.com/forum/x...=fixed+bellows

 

Post a pic I may have an extra.

 

Sorry I'm late to this thread, but are you talking about the full-load breather pipe? Just replaced mine. Ordered from Amazon. If you're having trouble finding one, that makes me think you're maybe talking about a different part.

EDIT: And by "Amazon" I mean "eBay". :-) Part NCA3951CB

 

I had a knocking sound which turned out to be the primary timing chain. One of the rails was disintegrated and the chain was riding on the rail frame and both the tensioners were stuck with the spring collapsed.

I am talking about the primary tensioners here in the front of the engine here, not the secondary tensioners on top under the valve covers.