[hb09]

Hi,
I've noticed while researching some problems with my i30 CRDi 1.6 (build date Sep 2008) that some people are suffering early serpentine belt failure, and I think I have correctly traced the cause, at least in my case, to a missing pin from the belt tensioner.  I wonder if this has affected other people without them realising it.

To explain I need to go back in time a bit - for the period 2009 when I bought the car, until the serpentine belt was replaced by a mechanic in 2017, there were no major problems with the car.  So in 2017, with 161,000km on the odometer, I was in far north Queensland in Cooktown and decided to get the car checked over by a mechanic.

The mechanic said the serpentine belt needed to be replaced, so I said go ahead, and they managed it, even though I doubt they have ever seen an i30 up there.  I definitely didn't spot one in a whole week.   I did notice though, that there was one change after the service.  Normally, when switching the engine off, you could hear things still spinning etc for about a second or two and then the engine was completely stopped.  Now, with the new serpentine belt, the engine would spin down "instantly" after switching off the ignition, not sure of how long but definitely much quicker than it used to.  I've been puzzling over this for two years, until a few days ago...

So the other day, with 196,000km on the clock, my 35,000km-old serpentine belt was ripped to shreds.  I had checked its length previously, thinking I might have had a too short belt, and it was 1815mm -- I see that there are 1800mm and 1815mm sizes commonly put on this car, and if memory serves the original is 1811mm (?).  I had to remove the tensioner assembly because I couldn't remove its damaged pulley, and you can see a picture of it below:



And here is a picture of the same model tensioner (model no. 25281-2A100) in new condition from koraps.com:



Note the shorter fatter black pin on the left, which restricts the range of motion of the tensioner arm, and thus puts a limit on the tension in the belt.  My tensioner is missing this pin... why? I don't know, maybe the mechanic removed it to try to give more slack to the get the belt on or off.  It would explain the near-instant engine spin down I mentioned above.  And after I put in a new 1815mm belt a few days ago, the engine still behaved in the same way, as if something somewhere is just too tight.   So I guess we have our culprit, a missing tensioner pin leading to an overly-tensioned belt leading to belt failure long before it normally would.

I was going to post this is a definitive warning for forum users to check their tensioners, but wanted to get some feedback from others who know better first.  My plan is to put a bolt in the missing pin's hole and cut the head off, and see if that helps things.  But first I have to finish the job of removing a belt fragment which managed to get past the crankshaft seal and caused the new belt to spray dirty engine oil all over the place - I will go over this in another post as I really don't know what I'm doing.

Belt fragment peeking out from behind seal:



Hopefully this post will save someone a bunch of time and money!

[tw2005]

I have my suspicions about this. How does a missing pin cause over tension if the tension is determined by the spring.? The pin is merely an end stop.  When you get this back together watch the tensioner. If it's not steady and wildly jumping then the alternator clutch pulley has seized. You may as well check tyhst with the belt off.  I've had one go an that tensioner was hammering .

[hb09]

Yeah I had an argument about this with someone, they thought the same thing as you, that the tension is determined by the spring.  Think of it this way: as the spring rotates the tensioner arm, the belt is placed under increasing tension.  Now if there is a pin there to limit the arm's rotation, the increase in tension halts when it hits the pin.  If there is no pin, then the arm can rotate even further, and increase the tension even more.  So in a sense the tension is also determined by this pin, right?  Or maybe wrong, my high school physics classes were decades ago.

When I put the new belt on, the tensioner was quite steady from memory, or at least not wildly jumping.  Also I had checked that all pulleys except crankshaft could be easily rotated by hand. 
 I guess by "alternator clutch pulley" you mean the one external to the engine case, which the serpentine belt runs over?  If so, it's definitely not seized.

Thanks for your input!

[sundiz]

Im with tw2005. If the tensioner hit the pin with belt on, then you have too long belt. Or you had broken clutch pulley in the alternator causing the tensioner to wobble.

Most likely you lost the pin, when the belt failed. After that the tensioner hit the pin with max spring tension causing it to brake down. When you change the belt and let the tensioner rest agains the pin smoothly, it will hold. When belt is broken, the tensioner is going to bang agains the pin with such a force I would not wonder if the pin would get smashed.

[tw2005]

Yeah I had an argument about this with someone, they thought the same thing as you, that the tension is determined by the spring.  Think of it this way: as the spring rotates the tensioner arm, the belt is placed under increasing tension.  Now if there is a pin there to limit the arm's rotation, the increase in tension halts when it hits the pin.  If there is no pin, then the arm can rotate even further, and increase the tension even more.  So in a sense the tension is also determined by this pin, right?  Or maybe wrong, my high school physics classes were decades ago.

When I put the new belt on, the tensioner was quite steady from memory, or at least not wildly jumping.  Also I had checked that all pulleys except crankshaft could be easily rotated by hand. 
 I guess by "alternator clutch pulley" you mean the one external to the engine case, which the serpentine belt runs over?  If so, it's definitely not seized.

Thanks for your input!

The clutch pulley is on the alternator, it locks in one direction, free spins on deceleration and also smooths out the p[ulses of the diesel motor. The tension on the belt will be constant based upon the tension in the spring. The spring tension can only reduce on the belt as it is stored energy based upon the pre-tension of the spring. As it unloads the  tension can only reduce . The limiting factor here is the belt length. The tensioner is designed to keep a fairly constant tension.  It definitely does not increase as a spring unloads or the belt stretches

[hb09]

Alright, the removed pin leading to belt failure theory goes out the window then!  It still leaves the nagging feeling about the motor spinning down so quickly on shutoff. I wonder why it is.

The clutch pulley is on the alternator, it locks in one direction, free spins on deceleration and also smooths out the p[ulses of the diesel motor.

I checked out the alternator clutch pulley by locking the alternator internals in place with a bit of wood, and then rotating the pulley, as in the below photo. With internals locked, the pulley is locked in one direction as expected. In the other direction, it can easily be rotated by hand, but does not stay spinning like say a wheel from a skateboard or roller blades.



Also I notice in the pic you can see some greasy muck on the copper windings in the alternator.  Do you reckon it needs cleaning?

[tw2005]

Clutch pulley is ok then. I  can't offer an explanation on the belt failure.

[nzenigma]

Lots to read, short on time, so question? do you have the correct belt???? Diesel and petrol are a different set up re. alt and  AC. Different length belt.

[hb09]

Lots to read, short on time, so question? do you have the correct belt???? Diesel and petrol are a different set up re. alt and  AC. Different length belt.

I believe the failed belt was 4mm longer than the original.  Shredded belt was 1815mm, probably a Dayco.
Current belt is Dayco 5050715 5PK1815S, bought from the same store.  It got some dirty engine oil on it though so I guess I have to throw it out.

I just found on ebay.com.au someone selling an apparently genuine Hyundai belt part no. 25212-2A310
here, for $40 delivered.  To trust them or not?

[tw2005]

can't see why not. Is there an oil leak issue? Is that seal being replaced? Just appears to me that there's plenty of oil residue on the alternator and timing case and not just because the belt broke I'm thinking? Oil could have caused premature failure of the belt.

What's the surfaces on the crank pulley like where that seal sits?

[tw2005]

also, what do you mean by the motor spinning down so quickly? All mine shutdown immediately and there's an anti-shudder valve in the throttle body that cuts the air intake so they do shutdown without run on.

[hb09]

can't see why not. Is there an oil leak issue? Is that seal being replaced? Just appears to me that there's plenty of oil residue on the alternator and timing case and not just because the belt broke I'm thinking? Oil could have caused premature failure of the belt.

What's the surfaces on the crank pulley like where that seal sits?

There's definitely a big oil leak issue since the belt broke.  Before this big oil leak, and while replacing the broken belt, I did notice black greasy muck in the pan under the belt and pulleys.  Didn't think anything of it at the time.  Hopefully you are right and a smaller unnoticed oil leak has led to this mess.

I've got a new crankshaft seal to replace it with.  Just busy ferreting through a newly downloaded GDS VM trying to find the proper procedure to put it all back together.

Crank pulley surface where the seal sits looks good to my eyes. There is a part which looks a bit rusted and feels rough, but I think this must be the part just outside where the seal sits. See pic below.



And here is the little gremlin I just pulled out from behind the seal:

[tw2005]

What's the gremlin? It's way out of focus. Is it belt material or other? Doing the seal should be straight forward since you've got the pulley off. Just needs to go back in nice and square, all the way home, and that crank bolt needs to be tight.

[hb09]

also, what do you mean by the motor spinning down so quickly? All mine shutdown immediately and there's an anti-shudder valve in the throttle body that cuts the air intake so they do shutdown without run on.

Not sure how to explain it better than in the third paragraph of my post up the top of the thread.  There was definitely a change after the mechanic worked on it at 161,000km.  I just got them to check everything over, and to replace the belt.  First time I switched the engine off after that, there was a very clear difference.  The sounds coming from the motor used to cease let's say 1 second (very hard to say now, 2 years later) after turning off the ignition. And then after the mechanic, it took much less time to cease, let's say 0.2 seconds -- in other words, an immediate halt.

I believe you about the air intake valve. Not sure if we have the exact same engine, mine is built Sep 2008 but the GDS software says it's 2009 when you put the VIN in.

The gremlin looks like a fragment of serpentine belt. 

[tw2005]

also, what do you mean by the motor spinning down so quickly? All mine shutdown immediately and there's an anti-shudder valve in the throttle body that cuts the air intake so they do shutdown without run on.

Not sure how to explain it better than in the third paragraph of my post up the top of the thread.  There was definitely a change after the mechanic worked on it at 161,000km.  I just got them to check everything over, and to replace the belt.  First time I switched the engine off after that, there was a very clear difference.  The sounds coming from the motor used to cease let's say 1 second (very hard to say now, 2 years later) after turning off the ignition. And then after the mechanic, it took much less time to cease, let's say 0.2 seconds -- in other words, an immediate halt.

I believe you about the air intake valve. Not sure if we have the exact same engine, mine is built Sep 2008 but the GDS software says it's 2009 when you put the VIN in.

The gremlin looks like a fragment of serpentine belt.

Now that I know we're talking about 8 tenths of a sec, I've lot interest Fairly confident mine is the same, I've had early 08, yours and the U2 update. The only one that shuts down weird and runs on a bit is my early 08 with close to 400000K.

What I was worried about was whether  that piece is belt or a disintegrating chain guide. What if it's been in there all along and caused a leak? Seems freaky that when the belt broke it squeezed past the pulley .

[hb09]

Now that I know we're talking about 8 tenths of a sec, I've lot interest Fairly confident mine is the same, I've had early 08, yours and the U2 update. The only one that shuts down weird and runs on a bit is my early 08 with close to 400000K.

What I was worried about was whether  that piece is belt or a disintegrating chain guide. What if it's been in there all along and caused a leak? Seems freaky that when the belt broke it squeezed past the pulley .

I'll have a closer look at it tomorrow, try to get a good photo.  I talked to a mechanic about the oil leak, he was familiar with what's going on, and straight away he said it's caused by a bit of belt.  The belt was really ripped to shreds and all over the place, I thought I had cleaned it all out then went for a drive and found more bits.

I should also mention what happened while taking the crankshaft pulley off.  Rattle gun didn't work so I resorted to using a breaker bar braced against the engine mount and kicking it over for a split second.  But - and I cannot believe I did this - I turned the engine fully on and let it run for a second or so.  The bolt came out so far that the breaker bar was impossible to move, I had to cut its head off to get it out.  Damage to the thread feels minimal - I can get the bolt all the way in and out using only fingers around the head of the ratchet, but the torque required varies as you go - it's easier then harder then easier and so on.  God knows what happened inside the engine.

[tw2005]

Now that I know we're talking about 8 tenths of a sec, I've lot interest Fairly confident mine is the same, I've had early 08, yours and the U2 update. The only one that shuts down weird and runs on a bit is my early 08 with close to 400000K.

What I was worried about was whether  that piece is belt or a disintegrating chain guide. What if it's been in there all along and caused a leak? Seems freaky that when the belt broke it squeezed past the pulley .

I'll have a closer look at it tomorrow, try to get a good photo.  I talked to a mechanic about the oil leak, he was familiar with what's going on, and straight away he said it's caused by a bit of belt.  The belt was really ripped to shreds and all over the place, I thought I had cleaned it all out then went for a drive and found more bits.

I should also mention what happened while taking the crankshaft pulley off.  Rattle gun didn't work so I resorted to using a breaker bar braced against the engine mount and kicking it over for a split second.  But - and I cannot believe I did this - I turned the engine fully on and let it run for a second or so.  The bolt came out so far that the breaker bar was impossible to move, I had to cut its head off to get it out.  Damage to the thread feels minimal - I can get the bolt all the way in and out using only fingers around the head of the ratchet, but the torque required varies as you go - it's easier then harder then easier and so on.  God knows what happened inside the engine.

Right. I just had a good few weeks myself with a D4EA. yes , you just bump the starter.  You must have been fatigued, I have those dumb moments too every now and then. I don't know what to suggest but could be some thread damage or the bolt . May pay to get new bolt and see if the thread can be chased just to be sure it's ok in the crank, otherwise I've never been in that situation, how to thread repair a crank bolt hole.

@nzenigma

[nzenigma]

Jeeeez , thanks, just read the whole script. Faulty Tours. 

If I read this correctly, it was the head of the breaker bar that was cut off. 

If you are using the old bolt, the thread is probably  stretched or bolt slightly bent.

 Therefore,  wind in tension varies.

 1. Get a new one.

2. use it to repair the shaft thread.

3.Use oil and wind it back and forth as you would with a thread tap.

4. Dont leave home without adult escorting you. 

[hb09]

Yeah I can't put my finger on it, but for some reason I don't quite feel like the sharpest tool in the shed. 

Ordered a new bolt from the dealership, they want $28 for it.  The thread on the old bolt looks quite good, I've put some photos of it here.

I don't know anything about restoring threads, but would it be better to use a chaser tap instead of the bolt to chase it?  I just worry that using the bolt to chase it will unavoidably leave some debris in the female thread, whereas a fluted tap will bring the debris out with it, right?

Breaker bar mid-decapitation:

[tw2005]

Yeah I can't put my finger on it, but for some reason I don't quite feel like the sharpest tool in the shed. 

Ordered a new bolt from the dealership, they want $28 for it.  The thread on the old bolt looks quite good, I've put some photos of it here.

I don't know anything about restoring threads, but would it be better to use a chaser tap instead of the bolt to chase it?  I just worry that using the bolt to chase it will unavoidably leave some debris in the female thread, whereas a fluted tap will bring the debris out with it, right?

Breaker bar mid-decapitation:

I was thinking a chaser tap but was hoping gary @nzenigma  had some input, anyway can't hurt I would'nt think

[sundiz]

If you use thread chaser to clean the threads, it might be good idea to have air compressor, or canned air and use that to clean the hole from the small metal shavings.

[nzenigma]

lovely shot of the bar.
can you get a photo of the female thread. That may give a hint as to the damage if any.
The crank usually seems to be harder steel than the bolt. It may be ok.

[tw2005]

Jeeeez , thanks, just read the whole script. Faulty Tours. 

If I read this correctly, it was the head of the breaker bar that was cut off. 

If you are using the old bolt, the thread is probably  stretched or bolt slightly bent.

 Therefore,  wind in tension varies.

 1. Get a new one.

2. use it to repair the shaft thread.

3.Use oil and wind it back and forth as you would with a thread tap.

4. Dont leave home without adult escorting you. 

Don't know how I missed this ripper script....you're still a mean and nasty bastard

[hb09]

Crankshaft female thread shots:

[Dazzler]

Good idea for Gary to ask for that. Looks pretty good to me. Can't see a problem getting the new bolt to go in there!

[nzenigma]

Yes Dazz, looks good. To make sure, you could wash it out with a long spray of WD40. Then use a new bolt.

Its a bit hard to measure the old one without a vernier caliper. Just suspicious given your description. 

[mickd]

Agree with the 2 above,
 a little vaso and screw in till finger tight ( take your mind out of the gutter  )
A new bolt is cheap insurance.

[hb09]

Thanks for the tips so far, it's much appreciated. 

Picked up a new bolt from Hyundai, now a couple more things to figure out -

I was thinking about how to tighten the crank bolt.  Crank bolt torque from the manual is 226 - 245 N.m or 23 - 25 kgf.m or 166 - 181 lb-ft.   I don't trust the crappy old rattle gun to get anywhere near this though, so I thought to put it in 5th gear and put the handbrake on to lock the crankshaft, then tighten it properly with a torque wrench.

In the manual somewhere, Hyundai says if the threads are oiled, the torque should be reduced by 15%, which brings the required torque down to 20.4 kgf.m.  With the 42cm torque wrench, this is about 54kg force (20.4 kgf.m / 0.38m) perpendicular to the wrench handle. With the wrench in place at 30 degrees from the vertical, and body weight on it straight down, it's 20.4 kgf.m / 0.38m / sin 30 = 20.4/0.38/0.5 = 107kgf.  Body weight is 80kg so with some acrobatics I might get 75% of the required torque.  Enough?


The 2nd thing is Burson sold me a seal replacement which is thinner, 5.7mm wide vs 7.0mm for the old seal.  Packaging on new seal says 461682V SEAL    41-53-6 HTCR VITON  17-06-2019.  I'm tempted to use it but then wonder if width doesn't match, then what else doesn't match? The temperature rating?

[tw2005]

Thanks for the tips so far, it's much appreciated. 

Picked up a new bolt from Hyundai, now a couple more things to figure out -

I was thinking about how to tighten the crank bolt.  Crank bolt torque from the manual is 226 - 245 N.m or 23 - 25 kgf.m or 166 - 181 lb-ft.   I don't trust the crappy old rattle gun to get anywhere near this though, so I thought to put it in 5th gear and put the handbrake on to lock the crankshaft, then tighten it properly with a torque wrench.

In the manual somewhere, Hyundai says if the threads are oiled, the torque should be reduced by 15%, which brings the required torque down to 20.4 kgf.m.  With the 42cm torque wrench, this is about 54kg force (20.4 kgf.m / 0.38m) perpendicular to the wrench handle. With the wrench in place at 30 degrees from the vertical, and body weight on it straight down, it's 20.4 kgf.m / 0.38m / sin 30 = 20.4/0.38/0.5 = 107kgf.  Body weight is 80kg so with some acrobatics I might get 75% of the required torque.  Enough?


The 2nd thing is Burson sold me a seal replacement which is thinner, 5.7mm wide vs 7.0mm for the old seal.  Packaging on new seal says 461682V SEAL    41-53-6 HTCR VITON  17-06-2019.  I'm tempted to use it but then wonder if width doesn't match, then what else doesn't match? The temperature rating?

I'm seeing 41-53-7 as the spec. See if I can find an image of OEM.

[tw2005]

Ity will just sit in a little deeper but innner and outer diameter should b ok, it's the correct material