Timing belt failure log MTBF

Post by **kallekula** » 17 Jul 2014, 08:51

Bought my car which had 220k on it by then. No service record.
Water pump had seized and caused the belt to come off. Is that more common than the belt itself snaps?

Post by **abscate** » 17 Jul 2014, 08:57

Still accumulating data in this thread only. Will discuss in separate thread.

Post by **shaker_chi** » 17 Jul 2014, 21:13

On my 1994 n/a 850 with 203,000 miles I am on my 3rd belt. Replaced the tensioner at 135,000 miles. Will throw on a fresh belt in the next 30 days. I also have the original water pump with zero leaks.

Post by **chestermo** » 18 Jul 2014, 06:10

2001 S60 T-5. Bought in 2007 with 73,000 miles. Timing belt with tensioner and roller changed in 2010 at 96,000 miles. Water pump was not changed.

Post by **cn90** » 18 Jul 2014, 07:45

This is what I gather from my own experience and other forums.

From an engineering stand point: belts, whether it is serpentine or TB, are made by the same material. The difference is the TB has teeth.

Pulleys are pulleys, whether they are serp belt pulleys or TB pulleys, the design is very similar.

1. Most serpentine belts break around 140K-150K or so. You can deduce the same thing for TB.
This is why Honda Odyssey owners manual say change the TB and SB at 105K or so.
Safe practice.

2. Pulleys: we call them pulleys but they are basically bearings. My serpentine belt bearings were replaced at 145K, they made noise and the grease dried out.
In BMW forums, the idler pulleys break apart at 170K or so: these are probably from people who turn on the stereo too loud and fail to hear the noise from their belt pulleys; in one word "neglect".
- If you are a "crazy" person, then I guess you can remove the pulley seals and re-grease the pulleys to prolong its life. But nobody does it.

3. WP can fail in 3 ways:
- Bearings falling apart
- Seal leaking
- Impeller falling apart (not a problem with Aisin WP)
The Aisin WP typically last until 180K, after that it is unreliable.

The bottom line: different components have different lifespans, but the TB job involves not only a lot of labor, but the consequence of broken TB/pulleys is disastrous (new cylinder head etc.), this is why Volvo says replace the TB at 100K-110K or so.

The SB: you can push it a bit if you are short of budget, but I'd replace the SB and pulleys every 120K or so, better than getting stuck in the middle of nowhere.

Last but not least: throw the old SB in the trunk as spare!

Post by **cn90** » 18 Jul 2014, 07:48

hansenjg wrote:If you are still looking for data, here is mine for my 2000 C70 Ragtop. Bought in 2005 with only 20K on it. Changed OE belt at 125K miles in 2010. Also replaced tensioner and water pump at that time. Should not have replaced pump I think. 65,000 miles later (after a fairly long time of losing just a little coolant constantly) the water pump seized up and took the timing belt off. Engine destroyed. When I opened it up to see what I could do with it, the timing belt was still in pretty good condition except for the cuts and scrapes from when it got thrown off. Don't use cheap water pumps and don't replace them unless necessary!

Replacing WP at 125K is fine, good practice.
The problem is: you used a bad brand.

Most people here use Aisin (highly recommended because it is OEM), many are happy with HEPU too. Nothing else matters!

Post by **kallekula** » 18 Jul 2014, 10:05

cn90 wrote:
hansenjg wrote:If you are still looking for data, here is mine for my 2000 C70 Ragtop. Bought in 2005 with only 20K on it. Changed OE belt at 125K miles in 2010. Also replaced tensioner and water pump at that time. Should not have replaced pump I think. 65,000 miles later (after a fairly long time of losing just a little coolant constantly) the water pump seized up and took the timing belt off. Engine destroyed. When I opened it up to see what I could do with it, the timing belt was still in pretty good condition except for the cuts and scrapes from when it got thrown off. Don't use cheap water pumps and don't replace them unless necessary!
Replacing WP at 125K is fine, good practice.
The problem is: you used a bad brand.

Most people here use Aisin (highly recommended because it is OEM), many are happy with HEPU too. Nothing else matters!

The pump that seized on my car was HEPU. New pump is Aisin.

Post by **cn90** » 18 Jul 2014, 10:59

How many miles on the HEPU before it seized?

Post by **precopster** » 18 Jul 2014, 16:20

For the record JDSR60 reported a higher incidence of Hepu WP failures a couple of months ago so he is sticking to Aisin WP.

Phil Zimmerman · Post by **Phil Zimmerman** » 02 Aug 2015, 18:38

Re: Timing belt failure log
by PZ

Our l997 850 non turbo, bought new, was about due for its second timing belt change two years ago at 135,000 miles. I bought new idler, tensioner, water pump,and belt from Rockauto. New coolant was installed with the parts. The pump was Chinese.
The water pump seized and threw the timing belt 10,000 miles and two years later.

I just looked at Rockauto's water pump choices on offer for this car.There are at least a half dozen. Aisin is not an option.Which is to say, all its water pump options probably come from the same place, "over there." Talk about playing against a stacked deck!

Each year my outrage grows at the having to buy anything at all from the Chinese, it is made so poorly.
Would that I had known that I had a choice! Now that they own Volvo, I would guess that they will load the new cars and replacement parts stream with as many of their manufactures as possible.

I now own my last Volvo.