timing and serpentine belt - are they the same?

[jsgreen]

Dealership is telling me that the timing belt on my 04 v8 (56k miles) should be replaced every 90k or 5 years. I said the belt looks fine, the dealership said what I was looking at was the serpentine belt, and that the timing belt is "buried in the engine".

I thought the timing belt and serpentine belt were the same - am I wrong?

 

[BC4Runner]

They are not the same. The dealer is giving you sound information.

 

[Will816]

Dealership is telling me that the timing belt on my 04 v8 (56k miles) should be replaced every 90k or 5 years. I said the belt looks fine, the dealership said what I was looking at was the serpentine belt, and that the timing belt is "buried in the engine".

I thought the timing belt and serpentine belt were the same - am I wrong?

No, the serpentine belt can also be called the accessory belt, it runs all the things attached to the engine: air conditioning, alternator, power steering, etc. The timing belt spins the camshafts. There is a cover on the front of the engine and it is inside that.

And yes, 90k or 5 years. If the timing belt brakes, the camshafts will stop spinning and some of the valves will be left in an open position and when the piston comes up it will kiss the valves and cause extensive damage. Expensive fix, might even need new cylinder heads.

Don't think that cars with chains instead of belts are immune, I got an 85 4Runner for free because the chain tensioner broke and the cam gear skipped a few teeth. That needed a new cylinder head, but the car was free so so what. It was 19 years old and 250,000 miles when it happened.

The 4L V6 uses a chain, btw. I wish our V8's did

 

[Will816]

I just went out and looked at mine to reference; the chain is inside the black plastic covers on the fronts of the cylinder heads. If you're standing in front of the car looking at it, the radiator hose comes out of the radiator to your right, makes a turn and passes over the top of one of these covers before it makes another turn and goes into the engine. Once you see the shape of the cover it should make sense of what is inside

 

[peter78]

Well, this might be the first time, but your dealer is absolutely correct. The serpentine belt powers the fan, alternator, power steering and air conditioner. Years ago, you might of called it the fan belt or alternaotr belt. Basically the serpentine belt is one long belt that does the work of 1 or 2 belts.

The timing chain is inside the front cover of the engine. The belt does run the water pump, but the main reason for the timing belt is turning the cams that control the valves.

Also, when you replace the timing belt, you have to remove the serpentine belt, since the cost of replacing the serpentine belt is labor, it usually makes sense to replace that when you take it off.

Also, you can look at the timing belt by taking off the cover, even if it looks fine, you don't want to risk the potential cost of it breaking as it may bend your valves. The V8 is an interference engine meaning, $$$ if it breaks.

I kind of sound like a dealer, sorry about that.

 

[jsgreen]

Thank you for the fast response! Is the timing belt a DIY replacement?

 

[peter78]

Thank you for the fast response! Is the timing belt a DIY replacement?

I would say it is fast, I wrote my response and 3 came in before me. Replacing a timing belt is somewhat hard to do. I can replace starters, alternators, but a timing belt is a little over my head. You have to have some special tools and special skills, skills I don't have, but you might have.

 

[Will816]

I would say it is fast, I wrote my response and 3 came in before me. Replacing a timing belt is somewhat hard to do. I can replace starters, alternators, but a timing belt is a little over my head. You have to have some special tools and special skills, skills I don't have, but you might have.

Have you tried replacing the starter on the V8? Not fun, it is in between the cylinder banks and UNDER the intake manifold.... Everything on top of the engine has to come off. That's my only gripe about the 4.7L

 

[Will816]

Thank you for the fast response! Is the timing belt a DIY replacement?

If you tried it yourself, just remember that if the timing is off you could cause extensive mechanical damage to the engine

 

[Nuke]

No offense, but if you don't know the difference between the timing belt and serpentine belt, it's definately not a DIY. I've done a good amount of work on all the Toyotas in my sig and have had quite a few timing belts replaced BY THE DEALER.

And it's probably a good idea to replace the waterpump at 90k instead of waiting until the next belt replacement at 180k. It's easier to get to the water pump when the timing belt is replaced (at least it was on my 2nd and 3rd gens).

 

[paraordnance]

Dealership is telling me that the timing belt on my 04 v8 (56k miles) should be replaced every 90k or 5 years. I said the belt looks fine, the dealership said what I was looking at was the serpentine belt, and that the timing belt is "buried in the engine".

I thought the timing belt and serpentine belt were the same - am I wrong?

90k or 5 years? I think my service bulletin says 90k and 7 years. I had replaced TB on my 97 Audi A8 at 100k and it was a MAJOR piece of work. Belt looked like it could go for another 50k. 23 hours later it was done and everything worked perfect. I would not attempt this again unless you have access to shop full of tools and have dedicated weekend for it.

 

[paraordnance]

Re: Re: timing and serpentine belt - are they the same?

90k or 5 years? I think my service bulletin says 90k and 7 years. I had replaced TB on my 97 Audi A8 at 100k and it was a MAJOR piece of work. Belt looked like it could go for another 50k. 23 hours later it was done and everything worked perfect. I would not attempt this again unless you have access to shop full of tools and have dedicated weekend for it.

just to give you idea what you will be up to if you attempt this yourself. By the way, 23 hours its a total manpower (2 people working relaxed, not to counting beers). This is TB replacement on 4.2 V8 Audi A8

 

[Mike07SE]

Yeah, doing the water pump during a TB service is pretty much a must. Crazy not to do it, plus it's cheap insurance at that point.

 

[peter78]

Have you tried replacing the starter on the V8? Not fun, it is in between the cylinder banks and UNDER the intake manifold.... Everything on top of the engine has to come off. That's my only gripe about the 4.7L

No, I haven't, also I haven't tried it on the 01 V6 either, I have put starters on smaller front wheel drive cars, but I did put one on a Fiat 124 once, (RWD) the starter was probably worth more than the car.

I tried to replace the timing belt on a 1980 Honda Civic and though it was a small 1.5 liter engine, I was a bit out of my leaque. I took it to a dealer. After that I haven't even tried or attempted to change one.

 

[EH007]

Hey, if any of you 4th gen V6 owners want to get a glance at your timing chain, just pop open the oil filler cap and shine a flashlight into it. The chain is easily seen because it lines up perfectly with the filler opening.

 

[jsgreen]

No offense, but if you don't know the difference between the timing belt and serpentine belt, it's definately not a DIY. I've done a good amount of work on all the Toyotas in my sig and have had quite a few timing belts replaced BY THE DEALER.

And it's probably a good idea to replace the waterpump at 90k instead of waiting until the next belt replacement at 180k. It's easier to get to the water pump when the timing belt is replaced (at least it was on my 2nd and 3rd gens).

No offense taken, you are probably right and I appreciate the advice - thanks for taking the time to respond.

The dealer said the recommended replacement was 5 years or 90k miles - any idea how frequently timing belts fail around the 5 year mark?

 

[zimm]

The dealer said the recommended replacement was 5 years or 90k miles - any idea how frequently timing belts fail around the 5 year mark?

No, but if you wait, you risk totalling your entire engine. Just for fun, ask what a replacement engine costs...installed.

And yes, do the water pump at the same time, they usually don't charge you any more for labor since it comes off anyway.

 

[Nuke]

...The dealer said the recommended replacement was 5 years or 90k miles - any idea how frequently timing belts fail around the 5 year mark?

The 90k miles is a bit conservative IMO and I typically put on 90k miles in about 3-4 years. If you were at 5 years and doing a lot of stop-and-go driving I might consider the change based on time. Otherwise, just start thinking about it at 90k but don't sweat going a few k or so beyond.

 

[paraordnance]

The 90k miles is a bit conservative IMO and I typically put on 90k miles in about 3-4 years. If you were at 5 years and doing a lot of stop-and-go driving I might consider the change based on time. Otherwise, just start thinking about it at 90k but don't sweat going a few k or so beyond.

Agree, there is 4Rs with over 120k on market without TB service so I assume you can go little past that mark. My service bulettin says 72 months = 6 years, not sure where you came up with 5 years here

 

[EH007]

No, but if you wait, you risk totalling your entire engine. Just for fun, ask what a replacement engine costs...installed.

And yes, do the water pump at the same time, they usually don't charge you any more for labor since it comes off anyway.

Not to be argumentative, but you won't typically destroy your engine if your timing belt breaks on an interference engine. Usually what happens is one or more of the valves comes into contact with the pistons. This will bend the valves for sure, resulting in a rebuilt head or heads. Usually that's the extent of the damage. Very rarely is any other damage done, although it is possible (but very rare) for one of the valves to puncture the top of the piston. Even then, the damage doesn't make an engine trashed.

But I agree, it's a good idea to prevent that possibility in the first place because nobody wants to spend money on a problem that could easily be avoided in the first place by simply following recommended maintenance intervals.

Also, as far as the water pump, it is true that many people take the opportunity to change it during a timing belt change. This has been common practice for many years. However, the new 4Runners that use 100,000 mile coolant are very unlikely to experience water pump failures that were common on older vehicles. This is due to the new coolant being far less abrasive because they no loner contain sacrificial silicates. And it's the abrasiveness of the coolant that ususally causes the water pump seals to fail and eventually start leaking. So I don't think it's necessarily a good idea to change out a water pump during a timing belt change for any vehicle with the newer low-abrasive coolants.