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Brains trust...

What are the general thoughts on replacing the timing belt and water pump on an NB8B 01 model with 38,000km and full service history (annual service)

It's likely due by 'age' but wondering what the urgency would be for this repair.

My 2 cents worth is zero urgency, but I might not be part of the 'brains trust' !

Mazda don't list a time schedule for timing belt replacement, & they don't list any schedule for water pump replacement.

First & foremost I totally agree with RS2000

I think the belt would be fine unless there is a major oil leak on the main front bearing which is highly unlikely.
oil tends to deteriorate these belts

If you really want piece of mind. change the belt & runners. But that means you have to open the crank bolt. I would there fore also replace the key & crank bolt.

The waterpump?....nahhhh unless the internals have rusted off.

Similarly no urgency, but for some peace of mind, perhaps remove the cam cover & spark-plugs & inspect the length of the belt for any visible deterioration.

Yes, maybe have a look at it to gauge condition.

bruce wrote:Yes, maybe have a look at it to gauge condition.

X2. Inspect the belt and pump first. If the belt is perished then change it. If the pump is leaking then change it.

I am not sure if you can determine if the belt is faulty by just looking at it and if the water pump is leaking that is likely to be apparent. However Mazda do recommend renewal at 100.000 klm intervals though time is not mentioned.

There is no kilometre recommendation by Mazda for water pumps, only for the timing belt.
Water pumps have an external leak passage which allows any coolant that gets past the mechanical seal to escape, instead of contaminating bearings. If this leak (under pump, front of engine) is more than the odd drip, then it's probably time to replace the pump.

Thanks all for your input on this.

I'll knock it down the priority list.

Mr Morlock wrote:I am not sure if you can determine if the belt is faulty by just looking at it and if the water pump is leaking that is likely to be apparent. However Mazda do recommend renewal at 100.000 klm intervals though time is not mentioned.

Very easy to tell if a belt is near its end of life. Copper in colour on the edges. Fraying on the edges. Cracks between the teeth. Belt should be back only in colour with no fraying or cracks.

Water pump - nothing you can do about that until you have no water pumping.

Having sold Gates belts in the past and knowing that they at one stage had a recommended shelf life of the belts to be 5 years I would think that over time the belt would degrade to some level and without being used may look like it is fine but could very well fail at anytime due to potentially more work....ie being dríven more all of a sudden. If it is that old I would replace it....you have found a great car why risk it for the sake of not replacing the belt. I replaced my wifes Impreza timing belt at 70k not because it was due but because the car was 10 years old.
Not sure on waterpump sorry but again if it has not been turned over for many years it could be that water has seeped into the bearing and could have rusted the raceways......I sell bearings as well......a working bearing would keep water away a sitting bearing would allow water to penetrate wherever it can.....

i would take the valve cover off and inspect the belt as a minimum as rubber does degrade and harden.

Age factor... Replace Cam/Crank seals/Water /Timing Belt Kit shouldn't need to replace key on Crank.
Spark plugs/leads tune - full service with Brake pads replacement if necessary, change all your fluids. Check age of tyres replace if necessary.
I'd disregard your service book
Piece of Mind as others have stated-
Sounds like a lot of money at the end of the day money well spent for reliability!!
You should enjoy trouble free driving .


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Importantly also, I would recommend the replacement of your coolant hoses, specially the little ones (heater, oil cooler. bypass) I had to replace a cylinder head after the car overheated due to a blown heater hose. The waterpump, should it fail, would potentially cause the same result, and if you were replacing the waterpump it would be foolish to not change the timing belt.

I love all the maintenance suggestions - probably all true but its also likely that many cars rarely get any service. You can even look at the service recommendations in the owners manual.