Timing Belt Life

[Ldub]

So why doesn't that apply to the timing belt?

You get the timing belt changed when it's working fine as preventive maintenance, before it breaks. The same principle applies to the water pump 'cuz it's so difficult to get to. You have to dig deep to get to the water pump behind the timing belt. As long as you're right there anyway, it'll take just a few minutes and not much money to change the water pump.

If your water pump fails soon, it'll be such a waste to have to remove the timing belt again. You may say, "the water pump will probably last for years longer". You could say the same thing about the original timing belt. If you decide to do preventive maintenance on one part, why neglect the other?

A broken timing belt is rare. A water pump problem is much more common. The water pump is by far the weaker part. If you're only gonna change one of those parts and not the other, I'd change the water pump. Change 'em both and be done with it.

Mark Griffin

Think about it this way...everything around the t-belt is worn after 138K. That means the cam gears etc. So the most pliable or flexible item is the rubber belt. To break in other new metal/hard items carries an inherent risk of inbalance or noise in the whole chain of action. They run the risk of becoming minimally dissimilar components near term which causes extra pressure on the old items and are thus more prone to causing failure. Keep everything the same as much as possible...that's the best scenario.

I now understand this...

To each his own gents, IMO, if I'm already in up to my elbows...you know I'm gonna replace everything in sight...

So, by the logic given, you wouldn't put on a new tensioner with a new timing belt?

[blacksambo]

Precisely. It's a new item amongst old items. The harmony will never be the same. That said, unless you replace everything, leave well enough alone. You're just asking for trouble. And...about the incidence of water pump failures...yes, I've heard that the aftermarket GTB brand pumps have failed, prematurely. I don't know about the OEM types?

[blacksambo]

I'll add to that that my technician has done hundreds of Troopers/VX's etc with no real problems using his approach.

[Gizmo42]

The problem with that logic is that I have heard of NO t-belts breaking on a 3.2 or 3.5 even with 150k miles on them. I have, however known of MANY water pumps and tensioners failing by that time. These are the original OEMs, not replacements. So, you should be replacing the water pump and tensioner as maintenance and using the same belt.

Precisely. It's a new item amongst old items. The harmony will never be the same. That said, unless you replace everything, leave well enough alone. You're just asking for trouble.

That just makes NO sense at all. Dont do any preventative maintenance, just wait till something breaks then replace the vehicle?

[Ldub]

So, by the logic given, you wouldn't put on a new tensioner with a new timing belt?

Precisely. It's a new item amongst old items. The harmony will never be the same.

Sorry but, no sale...

The tensioner is a pressurized cylinder, applying tension to the NEW belt, by way of a roller. The new belt would be the only part in the equation that the new tensioner would touch.

Harmony?...this is mechanix we're speaking of, not mystical religion, voodoo, or feng shui...

[blacksambo]

New belt is tighter/grippier and stouter/stiffer than the old belt. It's also more angular in the teeth verus a worn belt (they're more rounded). It's also shorter. It will put new pressure against the old components which they haven't had to deal with before in the whole chain of timing and cooling. If you change the cooling gearing surface and the tensioner roller surface you've got new traction points/surfaces versus old traction at older points in the chain. This direct dissonant bias is now tranmitted to the the cam shafts drive, and their gearing and bearing surfaces, that by now have most certainly degraded. It's disharmonius at best, it' s the new choir trying to sing with the barbershop quartet of old sort of thing. This guy I work with is an ace Ferrari/ Lambo/ Porsche mechanic he wouldn't steer his customers wrong.

Regarding belts breaking or also skipping out of position. If you've just followed this web site, for even a few years, you learn of original belts breaking/skipping all over the place and the horror stories of people following the wrong procedure to get things lined up again only to have the engine fail again....you never hear any horror stories coming from a water pump failure, the belt keeps its position on the cam shafts and it's a more straight forward fix, as a result.

[Ebenezr]

While you all are on this subject I have a question. I have 128000 miles and several months ago entertained the idea of changing my timing belt. I peeled the plastic cover back and when I noticed the belt was a clear translucent nylon - I quit. I assumed that it was not a stock belt and that a previous owner had placed this belt on. Am I right? Isn't the stock belt black???

[blacksambo]

Yes, black. And the model is called an Isuzu Bando STS. Love know more about the clear belt, though?

[Ldub]

New belt is tighter/grippier and stouter/stiffer than the old belt. It's also more angular in the teeth verus a worn belt (they're more rounded). It's also shorter. It will put new pressure against the old components which they haven't had to deal with before in the whole chain of timing and cooling. If you change the cooling gearing surface and the tensioner roller surface you've got new traction points/surfaces versus old traction at older points in the chain. This direct dissonant bias is now tranmitted to the the cam shafts drive, and their gearing and bearing surfaces, that by now have most certainly degraded. It's disharmonius at best, it' s the new choir trying to sing with the barbershop quartet of old sort of thing. This guy I work with is an ace Ferrari/ Lambo/ Porsche mechanic he wouldn't steer his customers wrong.

So using that logic, if the water pump or timing belt fails, you need new cams?
Or maybe even new heads?

..

[Triathlete]

Sounds to me like instead of changing your timing belt you should just put a whole new drive train in to keep everything in harmony! Oh wait, then the axles will not be in harmony...guess I need to just get a new vehicle.

[blacksambo]

In abosolute theory you are right, but in this instance we'll have to settle on as little intervention as possible to keep things singing along as best they can given their respective ages. Less change is more when it comes to governing the longterm health of the timing function.

[circmand]

Thats why tires have a date on them. At 5 years old they break down just by sitting in the warehouse. So a belt spinning around at high RPMs and in the heat under an engine is even more likely to fail. Sure you may get 200,000 miles out of it but there are a lot of VX engines out there that failed and not all from oil. As far as not broke dont fix do you wait till a tire blows before you replace it?

[Hades]

Anybody Know if there's a way to get the plastic covers off without removing everything? I know the normal condition interval is 100,000 miles (though I thought belts were 60-75 in all other cars), I'm at 144k with no prior knowledge of it being done and still unsure of the posts that I read if this is an interference engine or not. If I could get under and feel the ribbing it would be nice to know before removing everything only to find its been done recently!

[VXCanada]

I'm about to do mine. 102k miles. Unsure if it was done before as I don't have any maintenance history so it will be done as a precaution.

Waiting until the timing belt brakes would result in a tow and depending on the engine design may cause bent valves, and other internal damage. Unsure if its an inference engine design or not. If its not then you can potentially wait until it goes but then you're stuck and getting a tow....

T.

[Triathlete]

Our engines are non interference. I changed mine at 150k. It was noticeably stretched at that point (about 1/2 an inch). So while they may not break till long after the recommended change interval it could potentially lead to timing issues eventually.