Topic: Timing Belts

[weebl]

The owners manuals on both my car and my dad's van recommend a timing belt change very 168,000 kms with an inspection done at 96,000 kms.  The longer than 100,000 km interval doesn't sit well with me, in part because this is longer than they used to be in the past, and also because both engines are interference.

My questions are:

1 - If an inspection is being done, is that not the same labour required for a belt change?  Or can a cover usually be slipped off and on easily for a visual check?

2 - Can the newer belts really go that long if the manufacturer says so?  What about once it's been replaced with an aftermarket belt?  Should I drop down to about a 100,000 km interval then?

3 - Water pumps - conventional wisdom has these replaced at the same time the belt is.  But is this only on an engine where the water pump is timing belt driven, or do most engines regardless of how the pump is driven, have the pump located in the same general area?

Things would be a lot better in my opinion if manufacturers stuck to timing chains.

[johngenx]

The visual check thing I don't get.  It's really tough to see wear on a timing belt.  To me, that sounds like a made-up service item.  What if they inspect it and 25K later it breaks?  Warranty?  Doubtful.

One thing I do know is that timing belts do actually last longer.  Changes in belt design have helped greatly.  Our Subarus interval is also 168K and I won't have them changed until 160K or so.

Something that really bugs me is the coolant pump being driven by the belt.  If the pump leaks, it wrecks the belt.  This has been done for decades and is stupid.  Why should I change a coolant pump that isn't broken?  Dumb.  Give me a timing chain that runs the cams.  Drive the coolant pump and other accessories off an easily changed belt.  And coolant pumps on most cars really only last 160K-km's?  Junk.

I agree about chains.  Of course, a poorly designed chain is not a good thing, either.  I have noticed that Honda and Toyota are now installing chains on some engines.  It's the "wave of the future."  Funny, that engineers are going back...

Of course, some never joined in.

[Roadrunner]

To error on the safe side I'd be tempted to change both the timing belt and the water pump at the same time as both are accessible at the same time. Thus saving labor costs. I'd change both at 100k kms for that reason alone.
I don't have any idea what the average life expectantcy is on a water pump. I believe it varies in accordance with irregular coolant changes, perhaps also the odd stuck thermostat causing an overheating condition.
Sometimes the fins on the back of the impeller can corrode away until the pump is no longer effective.
The water pump impeller shaft bearing can also prematurely wear out. When the bearing wears out, it emits a high-pitched squeeling sound. If you suspect it may be the pump, spray a little water on the serpentine belt (if this belt drives your water pump) and if the noise continues, replace the pump.
To identify excessive bearing wear, grasp the water pump pulley and try to force it up and down and from side to side. If the pulley can be moved in either direction there is wear on the bearing and it is wise to replace the water pump.
The above I have described is on the GM 3.4l V6 (chain drive).
Belt driven water pumps aren't accessible this way. The timing cover must be removed to access each.

[johngenx]

Allright, I understand the need to change the coolant pump and the timing belt at the same time, to save labour and the potential for the pump to leak and ruin the new belt.

However, I'm not sure why you would do them at 100,000kms instead of 168,000kms as per the manufacturer's prescribed interval?  There's no labour saving in that.  I've found that the manufacturer's intervals are quite conservative when it comes to timing belts.

Of course, you could be "better safe than sorry" on the issue, but at barely 60% of the prescribed interval, that might be a little overkill.

[Roadrunner]

Alright, let me ask you this: do you have irrefutable proof those water pumps and timing belts do in fact last until 168k kms?
If you do, then I won't comment further on this subject.
As far as the 'overkill' goes, I still change out my engine oil/filter every 5k kms/3mo. even though the owner's manual says I can wait until the idiot light and the message center on the dash tells me it's time. (that's past time in my book)

(Message edited by roadrunner on May 13, 2005)

[johngenx]

Well, with cars that have 90-100K intervals, do you change the timing belt and coolant pump at 50K?  40K?  60K?

[slybry]

You might want to check you manual. They might have are different interval for what called severe service. It might be 100,000 Kms. Driving in Canada counts as severe service due to cold winters.

One thing that worries me is what if you have a low mileage car where it takes you over 10 years to rack up 160,000 kms.

I let dealer talk me into changing timing belt on my Acura 1.6 at 65,000 Kms just because car was 6 years old. I think I got taken on than one.

[safristi]

Definitely ONE BELOW THE BELT there Sly...have ta change yer moniker!!!!

[articsteve]

I let dealer talk me into changing timing belt on my Acura 1.6 at 65,000 Kms just because car was 6 years old. I think I got taken on than one.

NO; you did not get taken.  The TIME interval on the belt is 7 years I believe; 7 years from the date the motor was first cranked over which can be a good 1/2 year or more before the car is sold.

My mother has a 2001 EL with 10K on it. In 3 more years it will probably have 14K on it.  It's parked in a heated garage so I would think that the belt would last 15 years at that rate of mileage, but I will change it at the 7 year interval regardless.

Further, I have this 900 Saab that GM says the belt is only good for 58K or 5 years.  They have paid for the last 3 belts.  The last interval had about 100K on it before they swapped it (which was outstanding on their part).  At that time, I got a new tensioner and one main roller.  Since I can't do the belt on this car without the Saab locking tool I will drive it until the belt breaks and then scrap the car.  The water pump doesn't run off the timing belt in this car fortunately.

(Message edited by Articsteve on May 13, 2005)

[slybry]

Articsteve... thanks for info about time limit. It makes me feel better.

Hey Saf !!! This is already by 41st post. Better watch it I might catch up to you some day.

[articsteve]

However, I'm not sure why you would do them at 100,000kms instead of 168,000kms as per the manufacturer's prescribed interval?

Agreed.  So at that point (168K), bite the bullet and swap the tensioner and the rollers as well as the water pump (if applicable).  Folks forget about the tensioner and rollers.  Not to many tensioners last over 300km.

[weebl]

Definitely answers my questions.  I'm waiting until 168k.

[articsteve]

And to answer you inspection question; yes they slip off the top cover.  But there is not much to see unless the belt was rubbing on something and it had major evidence of being shaved or something like that, but I think one would hear something of that nature first.  Besides if it was that bad it would just let go in short order.

[tpl]

Artic, when did SAAB change over to belts?  When GM bought them? I have friends with 88 and 89 900s with chains

[Roadrunner]

John, answer my last question. I don't answer questions with questions.
If your last question was intended for me the answer is no. I wouldn't change the timing belt and water pump until the 100k km.
I wouldn't want my name on the ownership when the water pump seizes and the belt breaks. Interference ? No thank you.
Obviously this is just my opinion, but if a manufacturer tells me the timing belt and/or water pump is good until 168k kms (Way past warranty) and it breaks thousands of kms before that limit, you can bet I'll be kickin' my butt for listening to them.
If that belt breaks in an interference engine it's going to cost one hell of a lot more than it would had the belt been changed prior.
The saying "if it ain't broke, don't fix it" doesn't hold true for everything.

[articsteve]

Artic, when did SAAB change over to belts? When GM bought them?

The chain remains on the 4 cylinder/turbo.  When Saab introduced the 900S in 1994 the morons in Detroit said the unit would not sell in the US if it did not have a 6 banger so out came a 6 cylinder with a belt.  A design so flawed that eventually GM guaranteed that all 900S 6 bangers would get 3 free timing belts with no time limit.  However, it was later determined that the original tensioner was crap and that was updated 3 times.  Meanwhile quite a high number of these motors were losing their valves particularily in 94 and 95.  Now discontinued  Basically a disaster by GM and blamed on Saab.

Must have cost a fortune.  No wonder GM is broke.

(Message edited by Articsteve on May 13, 2005)