Loud cracking noise - rotational with rev's

Howdy!

300TDI sounds like death! I've got a cracking noise rather than a clicking noise. The cracking is louder than the engine if that makes any sense so can be heard when stood well away from the engine.

The cracking sounds metallic, like a crushed bearing rotating and I'm hoping its something like the aux belt tensioner or something along those lines. Having done some reading and hearing more about 'clicking' than a belting loud cracking noise has me wanting to post up here. I'm now aware of the timing belt and its odds and sods behind the aux belt which echo's out but it seems too loud to be in there?

I'm not sure when or what has been changed but the tensioner pully is manky so I'm going to write that off and say its been on there with the belt too long and go ahead and change that for peace of mind, seems i'll be needing to 'touch it' to fix whatever this is so i'll get one on hand to replace it with.

Had a look on GSF for a new belt while I was at it as its got a little bit of a squeak to it, they're cheap enough and important enough I'd like to change that, however it lists 3 types? How do I go about choosing the correct one?

The cracking noise is a pulsed cracking with the rev's and gets quieter but faster as the revs build up. I guess the vibration or whatever of whats failing reduces down with speed thus making it not as bad.

It's been left long enough by its previous owner to the point its all you hear and I need to get to the bottom of it.

I have no idea how to test my way through this or what the common failures are which is why I'm posting up, I appreciate its very limited detail at this point but i'll try and give further details as asked to get to the bottom of it. I also appreciate you can't hear it at this point so I'm giving you no help what so ever but I appreciate any responses.

I was thinking about going out and spraying the living crap out of everything I see one by one in some GT85 or similar to see if I can at least reduce volume somewhere to get half an idea where its coming from - yet as a complete newbie I actually don't know what this belt is actually powering per say and wether that's actually a really stupid idea for XYZ reasons. Removing the fan on a temp basis will probably help me keep digits attatched.

So guys/gals any help to track down this or a proper procedure etc is most welcome.

Regards,

Mark.

remove auxillary belt and prove its an auxillary or not

So engine is OK to start temporary with the belt off? Forgot to ask that in the first post as that'll make it easier to tell.

Cheers,

Mark.

it is,if it goes quiet then you know its a pulley and you can feel and spin each in turn

Exactly what I needed, I'd once again be scratching my head without this forum

I'll attempt this over next coming few days because of work I'm not around the truck - I don't use it to go to work though so i'm not just driving it anyway.

While that happens, can you advise on the correct belt? GSF had 3 to choose from which (finds details) consists of;

AUXILLARY DRIVE POLY V BELT 4PK1325 -
Engine Code 23L
Driven Units Driven unit: aircon compressor

AUXILLARY DRIVE POLY V BELT 7PK1575
Engine Code 11L/16L
Driven Units Driven unit: alternator

AUXILLARY DRIVE POLY V BELT 7PK1595
Engine Code 16L
Driven Units Driven unit: water pump

EDIT: Is there some form of a workshop manual floating around somewhere?

Thanks again in advance.

Mark

Coffee Addict said:

Exactly what I needed, I'd once again be scratching my head without this forum

I'll attempt this over next coming few days because of work I'm not around the truck - I don't use it to go to work though so i'm not just driving it anyway.

While that happens, can you advise on the correct belt? GSF had 3 to choose from which (finds details) consists of;

AUXILLARY DRIVE POLY V BELT 4PK1325 -
Engine Code 23L
Driven Units Driven unit: aircon compressor

AUXILLARY DRIVE POLY V BELT 7PK1575
Engine Code 11L/16L
Driven Units Driven unit: alternator

AUXILLARY DRIVE POLY V BELT 7PK1595
Engine Code 16L
Driven Units Driven unit: water pump

EDIT: Is there some form of a workshop manual floating around somewhere?

Thanks again in advance.

Mark

Click to expand...

with tdi you have a choice of 2 err3287 or err5911 ,err5911 is slightly shorter as alt pulley on later models eng no16l25165 onwards was made slightly smaller diameter to up alt speed, if you get wrong belt it will either go on a little too easy or just possible to get on, you pull back anti clockwise on tensioner pulley bolt 15mm spanner or socket and bar to release tension to swap belt

How much force should i be putting on this tensioner? Im giving it some serious beans and its not moving at all.. my thoughts at present is she's seized up real good. There is no way i could for example get my hand in to remove belt with the force applied at present.

Edit:
Resulted to the spray the literal **** out of it.. during spraying on tensioner bearing the noise appears to quieten down and then returns the nano second the spray stops. I'll buy another and return to this thread after fitting.

Coffee Addict said:

How much force should i be putting on this tensioner? Im giving it some serious beans and its not moving at all.. my thoughts at present is she's seized up real good. There is no way i could for example get my hand in to remove belt with the force applied at present.

Edit:
Resulted to the spray the literal **** out of it.. during spraying on tensioner bearing the noise appears to quieten down and then returns the nano second the spray stops. I'll buy another and return to this thread after fitting.

Click to expand...

seems like its that

jamesmartin said:

seems like its that

Click to expand...

IF the tensioner has jammed so the tension is wrong and very high, could we be looking at other problems with overloaded bearings in things like the PAS pump and so forth? Might be worth checking them as well I'm thinking...

chris-the-gerbil said:

IF the tensioner has jammed so the tension is wrong and very high, could we be looking at other problems with overloaded bearings in things like the PAS pump and so forth? Might be worth checking them as well I'm thinking...

Click to expand...

anything is possible but usually theyd seize in a running position ie were it would normally sit,but its certainly worth checking all bearings /pulleys etc when belt is off

Looks like i'll have to crack off the tensioner nut and try and pop it off its stud that way and hope it doesnt do further damage when i wedge it of.. either to the block or me if it comes out fighting!

Once tension is off i'll have a feel around and see if anything has play if i can. If i cant i'll add the new tensioner and start her up and see if anything sounds a miss. I'll keep the original belt for this test so im only changing 1 peice at a time to make sure.

Coffee Addict said:

Looks like i'll have to crack off the tensioner nut and try and pop it off its stud that way and hope it doesnt do further damage when i wedge it of.. either to the block or me if it comes out fighting!

Once tension is off i'll have a feel around and see if anything has play if i can. If i cant i'll add the new tensioner and start her up and see if anything sounds a miss. I'll keep the original belt for this test so im only changing 1 peice at a time to make sure.

Click to expand...

sounds like a good plan , if the tensioner stud comes out loctite it back in and nip it up reasonably tight,they have a habit of coming loose and ruining the threads

Coffee Addict said:

Looks like i'll have to crack off the tensioner nut and try and pop it off its stud that way and hope it doesnt do further damage when i wedge it of.. either to the block or me if it comes out fighting!

Once tension is off i'll have a feel around and see if anything has play if i can. If i cant i'll add the new tensioner and start her up and see if anything sounds a miss. I'll keep the original belt for this test so im only changing 1 peice at a time to make sure.

Click to expand...

If you are going to change the belt and you suspect the tensioner is seized then just cut the belt with a hacksaw (or similar). That way you take the tension of the tensioner rather than trying to force it off the stud with the belt still under tension. My bet is that you aren't pulling on the spanner hard enough as they do take a fair bit of effort, having the spanner at the wrong angle also makes life difficult for yourself.

This is very true - I use a breaker bar to move mine back it would be quite tricky with a regular 15mm spanner...

Next effort i'll use my breaker and an additional pole on the end of that and just give it hell.. It's coming off anyway as you say and if i can release the tension off the belt so i can undo it safely that'll be the priority. I'd like to save the belt at this point as mentioned as it'll be a one thing at a time affair to make sure i am changing the correct parts rather than masking it.

Local shop got the tensioner so i'll be picking that up tomorrow along with a fresh belt (as i will change it in due course)

Cheers,

Mark.

Before you junk the old tensioner, remove the pulley wheel and bearing (remember its a wrong way thread that bolt..) The bearing inside the pulley is known to fail sometimes and a spare is always handy...

Good plan, i've a local bearing shop so i'll get it stripped and add that to the spares box if i don't butcher it too bad getting the b*stard off!

Ewwwwww

Is that oil? Wheres it coming from? And that tensioner looks too far round have you the right belt fitted?

Might be the photo angle, if im understanding you correctly. Truck was bought like this and im going to guess its been like this (belt length) for years.

I've got other angles on my thread in the members projects page under LULU. On my phone now it doesnt want to let me grab the pic links and paste across.

Oil is just absolutely everywhere and on everything! One thing at a time and we'll get there. As mentioned by another member earlier on the different belt lengths i'll be measuring my alt pully to make sure im getting the right belt.

What looks like the rubber between the tensioner is all broken up too, i guess the oil has wrecked that. Being soo caked just a quick blast with degreaser isnt going to cut it. New part will go on so one last thing to clean hey!