Timing Belt Replacement Questions

[fishin]

I am at 83,000 miles on my 99 100. For some reason, I am really worked up about the 90K scheduled service which includes the timing belt and water pump. I am a by the book maintenance guy, but have never owned a vehicle that had a timing belt that needed to be replaced. I have a few questions for you all.

1. Do I really need to replace it? Has anyone ever seen one break?
2. If not at 90K, how long can I go? Can I do it at 150K?
3. I drive about 30K per year. Anything else that I should be thinking about? I change my oil every 5K and rotate tires every 10K.

I just hate to spend money on stuff that I can not see or touch. The timing belt and water pump will never be seen by me.

Your advice will be very helpful.

Thanks,
Brett

 

[DMX84]

FWIW- the engine is a non interference motor. Meaning that when the belt goes you won’t bend valves.
But when it does break it’s going to leave you stranded.
DMX

 

[spressomon]

Not the best strategy...but with 92K on mine and no opportunity to do the 90K until late winter or spring '07 I am rolling the dice.

 

[Landpimp]

they will go past 90K.....but I would not want to find out how far, someone said theirs was like 180K.........nothing personal but thats stupid

my belt looked great at 90k.....but why chance it? also replace the water pump, tensioners ect

the 100's seem to need little beside the normal maintence.....but spend the $ on it.

 

[spressomon]

they will go past 90K.....but I would not want to find out how far, someone said theirs was like 180K.........nothing personal but thats stupid

my belt looked great at 90k.....but why chance it? also replace the water pump, tensioners ect

the 100's seem to need little beside the normal maintence.....but spend the $ on it.

I figure mine will be around 100K when I finally can get time to do it. And it will be the full job with w.pump, tensioner and even starter while I've got it opened up.

 

[richg]

FWIW- the engine is a non interference motor. Meaning that when the belt goes you won’t bend valves.
But when it does break it’s going to leave you stranded.
DMX

It IS interference. At least according to everything I've read including the factory shop manual. So you snap the belt, you at least are looking at bent valves.

Can the belt go longer than 90K, yes. How much longer you decide to go is up to you. I certainly wouldn't go to 150K. I bought my LC used at 108K and did the service shortly thereafter. The belt looked really good all things considered, but the water pump was weeping coolant and its bearing was loose. Prior to the removal of the pump, there was no indication of any problem whatsoever.

rich

 

[BMWSTOY]

These engines are non-interference - that is why it is not listed in the maintance menu at my local dealership.
According to the service manager: It will leave you stranded if it breaks, but will not affect the valves. The crank will spin, but the vehicle will not move because the belt is no longer spinning the cams.
The belts life depends on many factors - temps, revs, etc, etc. Knowone knows how long each one will last. The reason 90K is on the recomendation, no belt has broke less than this or its on Toyota's warranty and they don't want that.
I replaced the belt, tensioners, and w-pump on a V6 and the stealership tells me that it is easier done on a V8 - less pulleys - I will be wrenching as soon I purchase one.

Richg, exactly how would valves be bent if the belt from the crank breaks? I would be very interested in learning about this - can you provide the reading on this.

 

[hkeller]

I, too, think the V-8 IS an INTERFERENCE engine. This is simply a matter of how close the top of the combustion chamber is to the top of piston at top dead center. The piston should only top out when all of the valves are closed in the combustion chamber. In some engines, there is enough clerance that, even if the valves open, due to a t-belt break, at top dead center, the piston will not hit the valves. In other engines, there is not engough such room. As such, when the belt breaks, certain valves will be open (sticking down into the combustion chamber) when the piston hits top dead center. Hence, bent valves and damaged pistons.

If I recall, more fuel efficient engines (such as ours) are more likely to have the small (no clerance) combustion chambers.

Any body no for sure which is correct?

 

[richg]

These engines are non-interference - that is why it is not listed in the maintance menu at my local dealership.
According to the service manager: It will leave you stranded if it breaks, but will not affect the valves. The crank will spin, but the vehicle will not move because the belt is no longer spinning the cams.

Richg, exactly how would valves be bent if the belt from the crank breaks? I would be very interested in learning about this - can you provide the reading on this.

It is specifically stated in the factory service manual that valve/piston damage can occur if the crank/cams are rotated relative to one another. I don't have my shop manual here with me so I can't site the page number.

If the engine is running and the belt breaks, you are almost assured of at least valve damage. The reason this happens is because when the belt breaks, the crank is no longer "in time" with the cams. Gates has a good description up on their site if you like http://www.gates.com/brochure.cfm?brochure=2256&location_id=3487

rich

 

[fishin]

Okay, okay. You guys are like talking to a heart doctor and weighing 500 pounds...

What should I expect to pay my dealer to do the 90K service with timing belt, water pump and starter? I also thought that I may as well do my transmission and transfer case fluid and filters, as well as the front and rear end. Anything else I should look at?

My cousin is selling his 2004 GMC Denali and I am wondering if I should buy it from him and sell my Cruiser, or go ahead and do all of the 90K service stuff. I tow a boat and some ATV's on a weekly basis, as well as traveling off road two or three times per month.

Help me think this through!

Thanks,
Brett

 

[Landpimp]

I see no reason to do the starter......its not like the water pump where the labor is almost nill for the pump when doing the belt. but do have a spare starter already

think I paid $700 for my 90K, I had the tensioners already but t-belt, water pump, t-stat, serpitine belt and fluids all came from the dealer

 

[Steph23]

$700?? That sounds lower than I have heard for all that.

Can you give a list of everything you had the dealer do for that price?

 

[BMWSTOY]

That is a great explanation by Gates (thanks Rich), but I still hope that this engine is non-interference like my local dealer told me and 50-60% of the folks on this site think. Strange that it is not clear. It seems it would be free or not and the dealer should know for sure.
I have never heard of this enging as being "fuel efficient". I for one would not call 12-16mpg as efficient.
I still want one and I am still going to change everything when I get it - Insurance.

 

[hkeller]

Regarding fuel efficiency: I agree, the truck, as a whole, is not efficient, but the engine is. Remember, it is hauling about 6500 lbs, with large contact patch tires. Given its desplacement, it does OK.

 

[jp213a]

I am at 83,000 miles on my 99 100. For some reason, I am really worked up about the 90K scheduled service which includes the timing belt and water pump. If not at 90K, how long can I go? Can I do it at 150K?

This post claims 197,000 miles on the timing belt and water pump.
https://forum.ih8mud.com/showpost.php?p=444967&postcount=1
My timing belt looked almost new when changed at 112,000. Obviously, the risk of breaking a belt increases the further you push it but IMO the risk is very low up to 130,000.

 

[BMWSTOY]

Well, I just purchased one with 117K on it, so I am not going to push it. I will be wrenching very soon.

Interferrence or not, I do not want to be stranded where mine is going to go - Colorado backcountry here I come.

 

[Dandon]

(...)

I just hate to spend money on stuff that I can not see or touch. The timing belt and water pump will never be seen by me.

Your advice will be very helpful.

Thanks,
Brett

Brett, do you ever see your heart, your liver or your brain? I guess not. But this is not a reason not to do any preventive maintenance on them, is it?

You don't see your engine oil either, unless you look at it on purpose. The only difference between it and the timing belt is that the oil is a lot easier to inspect. But that doesn´t mean they (both of them) don't need to be inspected, and eventually changed. Well, you *could* probably run a surprisingly awful lot of miles without changing oil before the engine ever fails, but the risk increases steadily. Same with the t. belt.

 

[SC4Hundred]

If you drive 30k a year, it won't be that long until 120k; you should do it between now and then lol.

 

[fishin]

I change my oil every 5K and all of my other fluids every 30K. I am very good about routine maintenance. Never having dealt with a timing belt simply had me questioning whether the car needed it, or whether the dealer network needed it done to make their mortgage payment.

What do you think regarding independent mechanics versus the dealer? I have not gotten any response for an independent mechanic in St. Louis.

Thank you for all of the great advice, and keep it coming.

Brett

 

[kitkraft]

I am at 83,000 miles on my 99 100. For some reason, I am really worked up about the 90K scheduled service which includes the timing belt and water pump. I am a by the book maintenance guy, but have never owned a vehicle that had a timing belt that needed to be replaced. I have a few questions for you all.

1. Do I really need to replace it? Has anyone ever seen one break?
2. If not at 90K, how long can I go? Can I do it at 150K?
3. I drive about 30K per year. Anything else that I should be thinking about? I change my oil every 5K and rotate tires every 10K.

Realize that by being honest with you I am offering myself up to the opprobrium, scorn and contempt of the conscientious folks on this forum....
Having said that:
1. Yes and No.
2. I first did it at 215K...no, that's not a typo...that's stupid
3. My only failures have been an electric window, a broken antenna mast, that little sunroof wind deflector thingy cracked early on, and a fuel pump around 100K+.