How old is yr timing belt

[gslender]

Oh, so unless it is recommended to replace it you see no reason to replace a part that can stop dead the engine why you are travelling down a highway in heavy traffic at speed? You think fuel pumps just work forever hey? Smart you are!

[johnjasonchun]

230k 04-msm visual inspection = good condition!

JohnJasonChun.Com

[project.r.racing]

What is the recommendation to replace the fuel pump ?

When broken.

[Mr Morlock]

PRR you are right of course. Gslender- most people do not keep their cars beyond average service life- and that might be 15 years. Even with an old car most folks replace the items that they can see worn or leave other components alone if they are functioning well. People don't just replace things generally speaking just because they might fail but the subject was timing belts and there is a specific time change recommended- there is none for a petrol pump.

[gslender]

Morlock - the OP was asking how old timing belts can get, and stated that he intended driving until it failed. The OP even pointed out that as it was a non-interference engine there is no risk of damage.

The OP is correct. Me and other mechanically aware and capable people have confirmed that indeed, there is no damage expected by not replacing as per the schedule.

You've debated this point and not once provided a mechanical reason as to why it must be replaced at the scheduled time. Simply the reason is that there isn't one.

You then decided it would be dangerous to drive on the highway and have the car come to a complete stop (if the timing belt snapped). I've pointed out that plenty of parts are in the car like that, and that unless your advice is to also replace those, then the timing belt is no different. So why do the timing belt if you won't also replace fuel pump and other parts that also can bring the car to a dead stop on the highway? It just doesn't make sense and illogical.

You've now decided that Mazda said it must be replaced at a scheduled klms and that it must be followed. Again, there is no logic other than Mazda know and why would they lie or mislead - so despite there is no known reason, because Mazda wrote it in the schedule guide, it must be follow 100% without any deviation or thought - and doing anything against that would be seen as foolish and bad advice? Really? How far in the sand does your head have to be for you to think like that?

Honestly, you seem determined to be right regardless if you're presenting a reasonable or logical reason. The only reason for the fuel pump not having a schedule is that it is unlikely to fail within 100,000 km whereas the timing belt could - and the issue is simply convenience.

I genuinely feel it is a shame that someone may read your posts and think you are educated on this subject - they may even feel they should follow that advice and remain as uneducated as yourself on the mechanical reasons for timing belt maintenance.

If you don't change the timing belt, there is no damage going to occur - FACT!

If you don't change the timing belt, there is no increased risk on the road (compared to other parts that can disable a 15 year old car) - FACT!

You can jump up and down about Mazda's scheduled advice all you want, but FACT is, there is no reason to change a timing belt, other than convenience.

QED

[Aussie Stig]

Here, here, the above by GSLENDER is why this forum is essential to my motoring. Mr M is having another brainfart.

PS this week MY fuel pump (not MX-5) failed whilst driving and I have to deal with it. Whether electrics, fuel, tyres, hoses or belts a disabling event can happen to anyone, anytime.

[Mr Morlock]

Long post slender but short on basic logic- you just don't grasp it all. Read some of
the other posts also from knowledgable people.

Maybe you don't quite get what all car makers do- they recommend what needs to be serviced and at what intervals. They don't do it using a tarot pack they apply engineering principles ie guys that are professionally trained. If you can show me where they recommend changing an fuel pump unless it is shown to be faulty then please show us all.

Not changing timing belts in line with service recommendations is not clever. If people choose to do this it's their look out. No one can give stats on when belts break because if there is not enough data and most people change them every 100,000 or so.

Insofar as the daft point about fuel pumps - when would you suggest people change them 3 years - 6 - 9-25. Mine will get changed if it fails and that may never happen.

Aussie stig you are not seriously trying to tell us that things fail on cars are you. What a revelation but a tip is ignore servicing and you might find more things that fail.

[gslender]

Epic Mr M, just epic. So you're clinging to Mazda said so, so it must be true logic.

ROFL

[pezchops]

i have had 2 timing belts fail in different cars.
both failed just after starting up.
i presume the initial load on the belt is greater,and spikes when starting up.
once running the load would be less and more consistent.
odds are most failures would be soon after or during starting.
interesting to hear when others have had it happen.
i dont know how old my belt is..im probably heading for breakage number 3

[Mr Morlock]

Pezhops.. I read that start up is quite common for failure.

Gslender- if you have worked in the car industry and been involved with designers and engineers you will know the processes. I would certainly accept servicing recommendations from the people that design and build cars whether it be Mazda or Toyota etc. The component makers and engineers know the failure rates because they test products. The OE belt will have a Mazda spec which also includes tests required to get approval. The recommendations re service change will be conservative.

[gslender]

Mr M I know people who work in the car industry who are design engineers and there is no way they would blindly follow advice in a service schedule book without first having the principle knowledge and context of why it was written.

People who follow advice or read books with no clue or understanding of what they are reading are the dangerous kind of people - they act and behave with authority but have no concept of the decisions they are making.

Having trust is a noble thing - being blind is a disability.

[hejira]

Im driving a 2000 nb thats only done 60k.

My concern is that the rubber in the belt could fail when it gets to a certain age as I've read they're only supposed to be good for 5 years.

Although my shocks have only done 60k when I replaced the springs the other week I found the rubber bump stops were either crumbling away like shortbread or literally gone. I know its not the same material but..

[Mr Morlock]

slender you are getting crazier by the minute - this has to be the quote of the year from you "People who follow advice or read books with no clue or understanding of what they are reading are the dangerous kind of people - they act and behave with authority but have no concept of the decisions they are making".

That is just laughable. Reading books or taking a look at the service manual of a car or your washing machine or your motor mower does not require you to be an expert on all things mechanical and electrical. People read books so they do get some understanding. Automotive engineers are often specialists in their fields- an engineer who is an expert on plastic injection moulding and materials will rely on the transmission engineer when it comes to gearboxes.

The whole point of a service manual is to follow the guidelines- thats why there is an owners manual.

When I buy a product to use I read the directions and take that approach to repairs or most things that I don't do regularly. You don't have to be a pharmacist to read instructions on a medicine bottle.

[gslender]

Crazy like a fox.

Mr M pls don't confuse following the user guide with giving mechanical advice on what maintenance is needed. That's why you're dangerous. You read the instruction guide for a washing machine and then assume you're educated enough to challenge people who know how to service and perform repairs on a machine.

[manga_blue]

As well as that I'm not even sure that there'd be no damage if the belt broke. On my head I've found that inlet and exhaust valves touch each other when they're both at full lift. That means it's theoretically possible for it to bend or snap valves before the cams stopped turning altogether.

I'll test that and come back with it confirmed for a BP4W head.

Can you confirm that your head (where you believe this to be true) was 100% stock and not using higher lift cams? Also, you have to consider that the camshafts have zero momentum and technically would require a fair bit of inertial force to overcome a valve spring compression - so whilst maybe you are correct, the reality is that it just cannot occur as the camshafts aren't going to spin if the belt isn't driving them.

Mine's a BP05 head with standard valves and seat heights. The cams in there now have lifts of IN 9.2mm/EX 9.6mm, versus 8.6/8.6 standard. IN and EX valves interfere by quite a long way, about 2mm, if I set one pair of EX valves to full lift and rotate the IN cam independently. To install the cams I have to position both cams at their set points and not rotate them until the belt is on. I've done that a few times but I do remember that I started doing it when I had standard cams because they caught once and I almost bent the valves until I realised that I had interference at the valve rims.

I think the situation could be safer with a BP4W head because it's high-ported and the valves sit a bit more vertical.