I have a 300tdi on a R plate with around 117,000 miles on . I fitted a k&n air filter on the other day to see if it needed more air ( another story )

I ran it for a few days and it has developed a knocking noise from which two mechanics have determined that its is the alternator . Its been replaced as it was only 6 months old under warrenty But the noise is still there .

It sounds to me as the knocking is coming from the turbo or something on the right hand side of the engine . Could it be the turbo failing ?? Or something in the bottom end .

The noise sounds like a bearing has collapsed , a kind of scraping and intermitantly quietens down for only a second or two the gets loud again .

Any help would be a great help

Also why is there a oil feed in the turbo inlet pipe ???

To oil the turbo ??? What part of the alternator did they say was responsible ? Are you able torev the engine while you are looking into the engine bay ? Are you sure it is not exhaust related,physical contact or loose manifold or other bolts ?

What sort of K&N ? The proper flat element in the original air box,or a cone type ? If not the original box,what have you done with the vacuum pipes ?

remove auxillary belt and try engine while belt off try all pulleys and tensioner

Yes there is the pipe joining the air box to the turbo and it has a oily inlet pipe half way between the turbo and airbox . Is it run off the oil pump ??

Could a blocked oil filter be the problem causing the turbo to run dry ??

The alternator had a load of mud in and a loose bearing so its gone and been replaced .

Im running a staright through pipe too with only a silencer at the rear and no flexi pipe if that would make a difference ??

shocker said:

What sort of K&N ? The proper flat element in the original air box,or a cone type ? If not the original box,what have you done with the vacuum pipes ?

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Cone type , tucked the pipe (singular) at the side of the filter . What should i havce done with it ?

jamesmartin said:

remove auxillary belt and try engine while belt off try all pulleys and tensioner

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Only run it for a few seconds though am i right because it wont be turning the water pump ??

Depends,what have you done with the EGR ?

it last a bit longer than that

Go for the obvious,basic stuff first...do what JM says,then check all fastenings are done up...dont go wringing their necks,just see they are done up,then look to see if anything is visibly moving

Dont fret about the water pump just yet, I have run them with NO water in after doing cyl head repairs.....dont do it for ever though! You have got time to have a good look around while running it WITH WATER IN but no pump !

Right this is good info guys cheers ,

EGR has been blanked did that when i got the jeep nearly 2 years ago .

Looked around the engine with it running and there is no visable sign of thing moving as they shouldnt , being loose either . As i revved the engine whilst under the bonnet the noise increased and started to sound more of a squeal than a knock .

I am going to drop the oil and filter tomorrow to be on the safe side and then also try taking the belt off the eliminate that part of the equasion .

Anything else i should try ??

whats dropping oil going to prove

The pipe that goes between the air box and turbo does not have an oil feed but it does have a breather connected to the cyclone oil separator on the off side of the engine. Do you get the noise or vibration if you disconnect the pipe between the intercooler and the plenum chamber, it's worth running the engine with no boost to see if the symptoms change.

NOTE : I wrote the below before saw the OPs comment that the noise was turning into a squeal without the knocking,but since I spent ages typing it Im bloody well going to post it,relevant or not.So there !!!

I dont think that the oil change will cure this.It never hurts to change the oil (broad generalisation that someone will pick me up on!) and filter but I think your problem lies elsewhere.
The serpentine belt VERY often squeals,more so with revs.The bearing on the spring tensioner can too.It can also bang about a bit if not fixed home. Then theres water pump and everything else that runs off the serpentine that can make noise increasing with revs.

I think you would be better served doing as JM and others have said.Run it without the serpentine belt on and see if the noise is still there. Without the belts tension,check the stability of the alternator,the water pump and its pully,the power steering pump,the idler,the tensioner....they can all appear to be held on when its really the tension of the belt doing so. Its normally something simple,so dont go thinking its the turbo or something expensive yet. Check all the exhuast and manifold fixings while cold....dd you say you took the flexi section out ? If so,check the length of the exhaust for possible contact points and the mounts too.All that can sound like an engine bay noise.

With the engine running you can use a long screwdriver or socket extension bar as a sort of stethoscope,press it againt your ear and have a listen to various bits.

If anything has been on and off the front aluminium section that the alternator et al bolt to,well,there is a favourite.There are steel bolts running into an ally thread and people rarely set them to torque and use a threadlock as per the book - they tend to wring them tight. And then they come loose as the thread is damaged.This has happened more times than I can count.

Let us know what you encounter,please !

all the best mate

shocks

PS, with a cone type filter,you will hear a lot more of the turbo and exhuast than you used to. Remember that all that was going out under the wing before. When I first fitted a cone inside the engine bay I was quite surprised at the amount of noise.

Oh !! Rather than change your oil,make a good measurement before you start,put a tape measure up against the dipstick (no,not me ! The other dipstick!) then note if any has been lost once its cold again.Look in the top air hose and 'cooler for excess oil,check the rubber hoses to the turbo havent rotted,check the oil feed unions.
And if all the above doesnt do anything for you,as a FINAL,last resort,take the main air hose off the turbo (with the engine stopped,please) and carefullygrip the end of the shaft (ooh!) and check for any side or backwards/forwards play.But this is a last resort for after you have tried everything else everyone has suggested,step by step, as a process of elimination. Write it down and tick it off,easier that way.

Right , sorry about the wait the mechanic was away until today . Did as said i put the old airbox back on (wasnt told to but i paniced ) had the engine running and used a proper mechanics stethoscope (spelling might not be right ) to fault find .

Couldnt pinpoint where exactly the noise was coming from though , it sounded a dry bearing so stopped the engine and loosened the fan belt tensioner just a bit and started up again .

The noise disspeared So , engine off again and loosened the belt fully and span the alternator , was fine so moved on to the water pump , Fooked !! Just spinning it by hand the noise sounded worse than with the engine running !!

So the jeeps booked in first thing wednesday to have it sorted luckily it wasnt anything major like i had thought although i had only had the water pump done last year after at spat its bearing when i put 235/85 colways on it !!

Get a decent waterpump or you will be doing the job again in a few months,dont go cheap.If the garage are supplying it specify NO BRITPART or other budget unit.Dont take any bollocks about "this is what we always fit" its your motor.If necessary,get the pump yourself and present it for fitting.

So....the old process of elimination worked and you got a much better,cheaper result than you were expecting ! Well done,mate !

swampy177 said:

Right , sorry about the wait the mechanic was away until today . Did as said i put the old airbox back on (wasnt told to but i paniced ) had the engine running and used a proper mechanics stethoscope (spelling might not be right ) to fault find .

Couldnt pinpoint where exactly the noise was coming from though , it sounded a dry bearing so stopped the engine and loosened the fan belt tensioner just a bit and started up again .

The noise disspeared So , engine off again and loosened the belt fully and span the alternator , was fine so moved on to the water pump , Fooked !! Just spinning it by hand the noise sounded worse than with the engine running !!

So the jeeps booked in first thing wednesday to have it sorted luckily it wasnt anything major like i had thought although i had only had the water pump done last year after at spat its bearing when i put 235/85 colways on it !!

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Thats one hell of a connection, :hysterically_laughi

I think ANY water pump would spit at the very least bearings if you attach wheels and tyres to it

:doh: My bad !! Never was any good at english Thanks for all the help (appart from the ridiculing) haha