Cambelt Eating itself to pieces

[nismovzr2003]

Hey guys,

As anyone ever had any issues with their cambelt eating itself to pieces?

Recently been running in new bottom end, approximately after 750-800km I started to hear a real concerning noise which at the time I thought may have been a bearing related issue within the block. Sounded like a whirring heart beat, however, only happened when engine was cold and not once the engine was warm.

Had some guys listen to it, however, they were not concerned that it was a bearing related problem. Anyway the engine needed to come out to have some head work done and the clutch inspecting and god what a mess I found!

I first noticed a whole lot of black dust sitting inside the crank pulling, once removed saw a whole lot more black dust and what appeared to be damage to the cambelt. Once the front covers were off, holey crap what a mess, black rubber dust everywhere!!

For some reason the cambelt has been wearing on the front edge, not the top just very front edge, it looks as if the belt has been riding forward an rubbing on the rear of the crank pulley, where it mates with the crank sprocket, well thats what I\'m assuming anyway.

Have taken a whole load of photos but have no idea of how to upload them on hear, if someone could talk me through it I\'ll upload them for all to see.

Any help or guidance greatly appreciated.

Cheers

http://s850.photobucket.com/user/Aaron_McLean/story/37479

[Rosssub]

Pics: ;D

http://www.clubsub.org.nz/forum/index.php/topic,147.0.html

[DRFVDR]

looks to me like there is a guide missing from the crankshaft ( well all the subaru ones i have done there is a wee washer on the outside of the crank gear)

also check that the adjuster bolt is not cross threaded and the idler is not on an angle

[nismovzr2003]

 We are borg said:

looks to me like there is a guide missing from the crankshaft ( well all the subaru ones i have done there is a wee washer on the outside of the crank gear)

also check that the adjuster bolt is not cross threaded and the idler is not on an angle

Whats the adjuster bolt ur referring to? Where can I get hold of this washer/guide u have referred to?

Cheers.

[nismovzr2003]

Ive never had any issues with it before, weird.

[lachlan]

was the crank bolt done up tight enough and puched both pulleys all the way onto the crank ?

[nismovzr2003]

 lachlan said:

was the crank bolt done up tight enough and puched both pulleys all the way onto the crank ?

Yep was done up to the right torque setting an everything

[Subirex Automotive]

 We are borg said:

( well all the subaru ones i have done there is a wee washer on the outside of the crank gear)

washer?? there are no washers in front of crank sprocket. as per picture it looks like there is two wear points. 1 from the outside edges which indicates the belt might be wider compared to oe ( there are two different widths on these models) causing it to rub hard against the cam pulley guides. 2 check the aftermarket belt guide on the crank sprocket, remove and see if it is rubbing against the top part of the belt, if it is than the clearance is too tight.

also check your alloy crank pulley for wear marks

[nismovzr2003]

 subirex']

[quote name='We are borg said:

( well all the subaru ones i have done there is a wee washer on the outside of the crank gear)

/quote]

washer?? there are no washers in front of crank sprocket. as per picture it looks like there is two wear points. 1 from the outside edges which indicates the belt might be wider compared to oe ( there are two different widths on these models) causing it to rub hard against the cam pulley guides. 2 check the aftermarket belt guide on the crank sprocket, remove and see if it is rubbing against the top part of the belt, if it is than the clearance is too tight.

also check your alloy crank pulley for wear marks

Cheers buddy,

Is there any difference going from an open deck ej20 to a closed deck stroker using a 2.5L rear thrust crank with corresponding crank sprocket with v3 sti heads?

Cambelt worked fine on the old block, belt guide doesnt seem to be an issue, no wear marks on the top of the belt at all and looks to have good clearance.

Cheers for the help

[Subirex Automotive]

closed deck shouldnt matter

[nismovzr2003]

 subirex said:

closed deck shouldnt matter

As mentioned, was the same belt that I had on the ODB, had no problems with it. Whats the differences in thickness?

Cheers

[marc]

 nismovzr2003']

[quote name='subirex said:

closed deck shouldnt matter

/quote]

As mentioned, was the same belt that I had on the ODB, had no problems with it. Whats the differences in thickness?

Cheers

Hmm It took me a little while to find my fisrt one of these haha and yep was fixing som1 elses fark up... but ill share my knowledge with you (dont usually bother on here :-\ )

I almost garentee u when som1 (whoever built your block or similar) seperated the halves etc hit your cambelt idler mount to the left of your crank pully in your picture and thus causes the belt to "run off" as the idler is not square andy more. With the engine like it is (apart no crank pully/covers on etc) put a spacer of some form on your crank pully bolt and put it in the crank pully so you can rotate the engine over clockwise. Then rotate and see if it wants to "walk" the belt off your centre crank sprocket. If so pull off all your idlers and check their block half seating surfaces..

[nismovzr2003]

 marc']

[quote name='subirex said:

closed deck shouldnt matter

/quote]

As mentioned, was the same belt that I had on the ODB, had no problems with it. Whats the differences in thickness?

Cheers

Hmm It took me a little while to find my fisrt one of these haha and yep was fixing som1 elses fark up... but ill share my knowledge with you (dont usually bother on here :-\ )

I almost garentee u when som1 (whoever built your block or similar) seperated the halves etc hit your cambelt idler mount to the left of your crank pully in your picture and thus causes the belt to "run off" as the idler is not square andy more. With the engine like it is (apart no crank pully/covers on etc) put a spacer of some form on your crank pully bolt and put it in the crank pully so you can rotate the engine over clockwise. Then rotate and see if it wants to "walk" the belt off your centre crank sprocket. If so pull off all your idlers and check their block half seating surfaces..

Cheers marc,

When u said the cambelt idler mount in the photo to the left of the crank sprocket, are you meaning the one prior to the tensioner, the small one that bolts onto the removalable plate that attaches to the block?

Cheers for the help

[nismovzr2003]

Cambelt definitely wanting to walk off of the crank sprocket, with only a couple of rotations the belt had moved 3-4mm off of the crank sprocket and left inlet cam gear.

Will be checking all idlers and replacing if necessary.

Cheers for all the help guys, much appreciated.

[marc]

The one opposite the tensioner on the other side of the crank pully is usually the culprit. Look closly too as it only takes a small burr on the block surface to create a pain in the ass. But check all while your there

[nismovzr2003]

 marc said:

The one opposite the tensioner on the other side of the crank pully is usually the culprit. Look closly too as it only takes a small burr on the block surface to create a pain in the ass. But check all while your there

Cheers buddy, awesome work!

[nismovzr2003]

Have removed idler\'s, there doesn\'t appear to be any issues with the idler\'s or there mating surfaces except for the idler that bolts onto the block at the top left hand side of the crank sprocket, appears to be some old caked on thread locker or something of that nature, its not on the whole surface.

Would this really be enough though to be making the belt want to walk off of the crank sprocket??

Check out the pic\'s

http://s850.photobucket.com/user/Aaron_McLean/story/37609

[marc]

 nismovzr2003 said:

Have removed idler\'s, there doesn\'t appear to be any issues with the idler\'s or there mating surfaces except for the idler that bolts onto the block at the top left hand side of the crank sprocket, appears to be some old caked on thread locker or something of that nature, its not on the whole surface.

Would this really be enough though to be making the belt want to walk off of the crank sprocket??

Check out the pic\'s

http://s850.photobucket.com/user/Aaron_McLean/story/37609

Ither your camera wouldn\'t focus or my eyes/computer are bugged as I can\'t see much in that last photo lol. The one that I\'m thinking has red lock tight or similar all over it?! Definitely not a help and can\'t really see the tensioner one. Post up some better close ups of all the mounts? Bit hard to tell over the internet without feeling them etc but yeah can\'t help much more from here otherwise . If u really get stuck and live in auckland not to far from mt Wellington I might be able to have a quick 2 second look

[nismovzr2003]

Righto, have checked all mating surfaces and there doesnt appear to be anything wrong with these and all the idlers appear to be spinning true, have put on a new belt....but it still wants to walk off of the crank sprocket, what else is there to do/check?

[boon]

Is the crank sprocket on straight?

[nismovzr2003]

 boon said:

Is the crank sprocket on straight?

Im assuming its straight, as it slides onto a spline and then is held in place with a key, how would it not be straight?

Cheers

[kamineko]

with the belt off, can you push/pull on the crank itself? (excessive endfloat?)

[nismovzr2003]

 kamineko said:

with the belt off, can you push/pull on the crank itself? (excessive endfloat?)

You meaning with the crank pulley and bolt in also? I havent check yet however the crank sprocket and crank pulley both mate with each other so I dont see how the crank sprocket could float?

[marc]

 nismovzr2003']

[quote name='kamineko said:

with the belt off, can you push/pull on the crank itself? (excessive endfloat?)

/quote]

You meaning with the crank pulley and bolt in also? I havent check yet however the crank sprocket and crank pulley both mate with each other so I dont see how the crank sprocket could float?

Hes meanin aka farked thrust washers/crank thrust surface, u need to push the clutch in and out then grab the crank pully and pull it forwards towards the radiatior and see if it goes clunk forward. A little movemnt is ok like sweet fark all to the human hand.

Im not saying its not that but ive seen a few subarus (pretty damn rare) with like 2mm of movent from extreamly worn thrust washers and the belt has still suprizingly been fine.

All it can really be is one of your idlers/cam sprockets etc isant true. (common sense) or the belt would run true. It could be somthing really out there (too stupid to bother mentioning really lol - like head machined on the wack of wack angles or somthing rediculas) but I still say more then likly what I first said. Get som1 properly experenced to take a look for you just to double check..

Or wait for others to start bouncing ideas cus its a pain over the net without being infront of the car...

[nismovzr2003]

 marc']

[quote name='kamineko said:

with the belt off, can you push/pull on the crank itself? (excessive endfloat?)

/quote]

You meaning with the crank pulley and bolt in also? I havent check yet however the crank sprocket and crank pulley both mate with each other so I dont see how the crank sprocket could float?

Hes meanin aka farked thrust washers/crank thrust surface, u need to push the clutch in and out then grab the crank pully and pull it forwards towards the radiatior and see if it goes clunk forward. A little movemnt is ok like sweet fark all to the human hand.

Im not saying its not that but ive seen a few subarus (pretty damn rare) with like 2mm of movent from extreamly worn thrust washers and the belt has still suprizingly been fine.

All it can really be is one of your idlers/cam sprockets etc isant true. (common sense) or the belt would run true. It could be somthing really out there (too stupid to bother mentioning really lol - like head machined on the wack of wack angles or somthing rediculas) but I still say more then likly what I first said. Get som1 properly experenced to take a look for you just to double check..

Or wait for others to start bouncing ideas cus its a pain over the net without being infront of the car...

Hopefully its not the thrust washers, engines only done 800k\'s! Can u check for the clunk with the engine out or can u only do it with the engine in utilising the clutch?