Timing Belt, Question For The Mechanically Minded

[haleja]

Hey guys,

Looking around, ive noticed that when members replace there timing belt, they replace there tensioner bearings and water pump as well.

i can sorta understand the bearings, as if they f%out then the car will to be blunt blow up.

but i dont get why it seems to be common to replace the water pump as well.

i was talking to a few other mechanics at work and they agree with me, saying that if it aint broke, dont touch it.

- and with the bearings. should they be changed regardless as good practice, or if they show signs or wear?

[Birds]

You replace all these items because none of them show external, visual signs of wear. You cannot see when a bearing is about to collapse or when it has dried up of grease. The same goes with the timing belt...a week old timing belt looks much the same as a 70,000km old timing belt in terms of wear, they don't fray they just snap. The water pump is done at the same time to save labour in doing it down the track (you need to remove the timing belt to change it). As far as damage goes, the pump bearing can seize and the impeller blades can wear down over time resulting in shitty flow of engine coolant.

[2LV8ETR]

Because while you're there with the front of the engine off, it's easier to spend the money on a water pump and replace it then.

For the cost of the water pump, it justifies replacing it while you're doing the belt.

The last thing you want to do is kick your own arse if in 10,000km your pump shits itself and you have to rip the front off again.

It may last 200,000km, but some (me included) would rather not risk it.

It's up to what you decide in the end man.

Good luck.

[Birds]

P.S. any mechanic who says if it ain't broke don't touch it about regular service interval items is a f***ing idiot and should consider another job.

[vidospace]

Agreed. Think of it like a tyre. You never know when your going to get a flat, so keep your spare inflated.

[EJD001]

When i get close to 100k on my skyline im going to town on the engine..

Timing belt

tensioner and idlers

water pump

thermostat and gasket

rocker cover gasket

cam, crank seals

and while im there im going to get a set of cams and gears installed..

Its kinda like doing a clutch.. gearbox out and not doing the rear main seal.. realy pointless..

May i ask what u do for a job?

[PIOTREK]

might as add to the above post- TRUST BEARING also, most people seem to forget that

[Duncan]

I'd add an H to that and make it a thrust bearing but normally only do that when you are replacing the clutch...and if you are in a preventative maintenance kind of mood check the rear main seal at the same time.

[89CAL]

Do a timing belt in an RB then u will relise why u do the water pump at the same time......

It is a big job just to do something you could have done as part of a 100000km service anyway.

and if using the 'if it aint broke dont fix it' attitude with the timing belt? well I dont know about you but i like my pistons to be valve free. Timing belt can gradually fail or instantaneously fail. Replace it, it doesnt cost that much and its a whole lot cheaper then a new engine/rebuild

Thats how i see it anyway

[haleja]

the mech at work was using the dont touch it if it aint broke theory on the waterpump, which is generally the way one would look at it. BUT, as its an RB engine, and its behind the timing belt, i see your reasoning to do it (and im sure he would as well).

im an apprentice mechanic, (9 months. not 3 years) thus asking for advice. the bearings will get done with the belt, and so will the waterpump.

i just bought the skyline, its done 140000ks, im heavily considering changing it, as i have no idea of the cars history.

[mad082]

with the water pump it is also the fact that as they get older they do start to wear the impellor. so while it may seem to be working, it might only be working at 60% efficiency, which might be enough to keep temps low enough, but once it gets a little bit more worn it might not pump any water.

the "if it ain't broke don't touch it" mentality could be taken to every part of the car. why change the oil if it is still full? why change your tyres even though they are bald but still hold air?

[haleja]

if it aint broke dont touch it.

why change the oil if its still full - not the point. point is. why change the oil if it still holds all qualities of oil ie. removes hear, cleans, protects. etc. etc.

why change your tires if there still hold air. not the point. point is. why change the tire if it still grips under all driving conditions.

you can twist the "if it aint broke dont touch it" thing quite alot, but it has to be used with discression.

seriously, if a mechanic said you dont need new tires because they are still inflated they need a giant, blunt object inserted into their anus.

owell. om only asking because the RB has 140k k's on it so i was told, and i want to change the timing belt as a precaution as i dont know its history.

i dont know how far i should take it and what stuff i should replace.

[Moodles2]

On the subject, a friend's R31 Skyline. His waterpump seized, taking the waterpump/alternator belt with it. For all we know, that was the factory fitted pump, engine now has 200,000+ km

[89CAL]

140000ks with unknown history... thats the problem aye.... mine came with 78000kms on the clock (wether that was the tru milage or not is another thing) but i did all my stuff before it hit 100000ks

if you dont know the history and you can afford to do it, i would

the peace of mind is just amazing knowing youve done it

[Dorifta]

The water pump and bearings will last 2 timing belts, If follow basic guidilines, Replacing your timing belt at intervals of 100K or 7 years, which I do. If you live in warm climates maybe change every 6 years. Some manufacturers reccommend replacing timing belts at a 4yr period, I am a mechanic and know that its completely absurd..

Belts, will last longer than 100K or 7yrs, You can stretch the intervals out longer if you like. In my opinion its not worth the risk

[Dorifta]

The water pump and bearings will last 2 timing belts, If follow basic guidilines, Replacing your timing belt at intervals of 100K or 7 years, which I do. If you live in warm climates maybe change every 6 years. Some manufacturers reccommend replacing timing belts at a 4yr period, I am a mechanic and know that its completely absurd..

Belts, will last longer than 100K or 7yrs, You can stretch the intervals out longer if you like. In my opinion its not worth the risk

[Binofski]

Amen to doing it while you're in there... I did my full belt change put it all back together and turned her on n went for a drive and behold i had overtensioned the timing belt slightly and it was making a noise.... But hey im pretty bloody fast at it now

[Binofski]

Edited September 19, 2009 by Binofski

[PUDZ 32R]

i cahnged my water pump and timing belt on my RB20 and it took me about 2 hours max. piss easy on these engines.. water pump cost me $80 from supercheap (yes it was japanese, no it was not the genuine $290 pump) belt cost me $100. new rad concentrate etc another $50. piss easy and cheap if you compare the cost of valves smashed thru pistons etc etc if the belt breaks. or the emotional f**k up if the pump goes at the worst time. fix it while you can..

[Dorifta]

2hrs, you must of done a slap up job, or u spent 30mins gettiing every tool within a foot of you, not to mention packing up, bleeding coolant up and test drive, 2.5 hrs if ur shit hot, nothing personal................thermostat replacement is very unneccesary, Ive had brand new thermostats not open.