Cambelt Question

[jeffreyt]

I saw reference to the cambelt on another thread and realised I do not know what the recommended cambelt change mileage/period is on the SC431 engine.

Can anyone enlighten me and let me know what the Lexus dealers charge for a cambelt change.

Many thanks

[steve2006]

For the LS430 which is basically the normally aspirated version of the same engine as the SC430 the recommended mileage is 90,000 or 9 years whichever occurs first.

[Paul_G]

For early model SC430s (2001ish) it is 10 years or 100,000 miles, I did a lot of investigation with Lexus garages to confirm this. Had mine done at Lexus Tunbridge Wells, it was around £400.

[jeffreyt]

thanks guys.

Mine is a 2001 car with 82K on the clock so its ready for a change.

[Paul_G]

Yep mine is a 2002 with 45k, and I had it done last year. Probably better safe than sorry.

[alphacat]

For the LS430 which is basically the normally aspirated version of the same engine as the SC430 the recommended mileage is 90,000 or 9 years whichever occurs first.

Both engines are normally aspirated...

[alphacat]

For early model SC430s (2001ish) it is 10 years or 100,000 miles, I did a lot of investigation with Lexus garages to confirm this. Had mine done at Lexus Tunbridge Wells, it was around £400.

I have asked around too and looked at the service information on the Lexus web site.. The interval is 100,000 miles. There is no yearly recommendation. Its true some Lexus stealers 'advise' every 10 years but they would wouldn't they? Recently there was an 02 car for sale having done only 13000 miles from new. There is absolutely no reason to do a cam belt change on such a vehicle. apart from the one which ensures income for Lexus dealers.

I hardly ever use a Lexus dealer its too far away and my car is serviced by an ex lead engineer from the Toyota World Rally team. He advises careful inspections after 10 years, change at between 80,000 and 100,000 miles to be on the safe side.

[Teeonethousand]

We bought ours a few months ago from Lexus dealer and it had 17k on it but 10 years old. The dealer changed the belt as part of the sale prep - without asking

I always thought time had an effect as well as use

[scudney]

Yes it has as rubber does perish over time even when not used hence eg(6 years or 60,000 miles)whichever comes first

[alphacat]

 

Yes it has as rubber does perish over time even when not used hence eg(6 years or 60,000 miles)whichever comes first

  The time scale for the deterioration of synthetic materials from which the can belt is manufactured (its also a reinforced belt) is measured in units that don't apply to natural rubber. We are talking more like 10 decades, not ten years.

The fact is regular inspections after a certain time are more than safe in enough and can, in the main be carried out by almost anyone who has a bit of common sense.

The scheduled interval for this item was certainly initially never measured in time, just in miles of use.

While I was looking for a 430SC 18 months ago I considered buying a 2002 430sc the fan belt had not been changed.

The owner had it confirmed by a particular Lexus Dealer that it did not need changing as the vehicle had only covered 38 000 miles the belt had been inspected and was considered as good as new.

Now while some who are not engineers and have little experience, may well think 10 years is a long time. It just isnt for most modern composite materials (The belt is a modern composite reinforced belt) . I work for an engineering consultancy that has contracts all over the world and my focus is on reliability. Changing the belt on a car that's has done less than the 'recommended' 100,000 miles and has been inspected is just giving money away. Many dealers need a kick for recommending work that doesn't need to be carried out but then that's quite common as most drivers haven't got a clue about what they are driving and its a national sport for dealers to make money from them.

Let me explain a little about the interaction between time and use. To make this point clearer.

Materials that have some tendency to degrade over times do so proportionally to temperature over time. In other words temperature speeds up any degradation. (Actually time isnt the main problem temperature and wear is) During say 10 years of use a belt will spend a particular part of that time at much higher temperatures while being used than when being still. If the car was run continually for 100,000 in a few months I would expect to see a belt that had suffered considerable wear as the times spent at high temperature's would be significant ensuring that small deviations in belt construction could produce deterioration. Of course in more demanding environments the risk is greater. 100,000 miles is a very, very conservative interval. As you would expect from a company like Lexus or in fact most companies these days. These belts will not fail suddenly without deterioration unless there is a serious flaw in manufacture of materials control. In that effect they could fail when new so its a pointless consideration. So any sensible owner would inspect the belt (you can see it by lifting the bonnet) when its done 50000 miles or so. personally I shall change mine at between 80000 miles and 100000 miles or if its show any signs of wear or damage. At present its done 62000 miles and it looks like new. The car is nearly 8 years old. Many people pay out for items they don't need to buy out of fear or ignorance or poor advice or insecurity.. That's what these forums are good for but unfortunately many individuals who don't know what they are talking about give poor advice and spoil it.

[alphacat]

Here is a picture of the 430SC timing belt. It can be inspected with the bonnet up from the top but needs the engine cover removed to see more of it. Its not that hard to keep an eye on it. Timing belts are surprisingly flimsy but immensely strong and include features that make the engine smooth an quiet. They don't need any separate guides etc like some chain driven cams have to have. compare the Lexus simple belt to a similar Audi engine (the 4.2 litre S4) shown first ??? This is chain driven and never needs changing (in theory) but the chain guides do and they are nylon (see them in white) and can cause the chain to rattle at quite low mileages (40000 miles etc)

[steve2006]

 

For the LS430 which is basically the normally aspirated version of the same engine as the SC430 the recommended mileage is 90,000 or 9 years whichever occurs first.

Both engines are normally aspirated...

 

Arr of course, I have been believing all this time that the SC stood for Supercharger when it probably stands for Sports Coupe, reason is I was once thrashed off the line by an SC430 in my LS400 :)

[steve2006]

 

Here is a picture of the 430SC timing belt. It can be inspected with the bonnet up from the top but needs the engine cover removed to see more of it. Its not that hard to keep an eye on it. Timing belts are surprisingly flimsy but immensely strong and include features that make the engine smooth an quiet. They don't need any separate guides etc like some chain driven cams have to have. compare the Lexus simple belt to a similar Audi engine (the 4.2 litre S4) shown first ??? This is chain driven and never needs changing (in theory) but the chain guides do and they are nylon (see them in white) and can cause the chain to rattle at quite low mileages (40000 miles etc)

 

I can see the timing chain on the Audi engine but all I can see on the SC430 engine is the sepentine belt?

[jeffreyt]

thanks Peter ,your post on reliability was very informative .Coming from an insurance background the subject of reliability and probability of breakdown are close to my heart.

I looked at the cambelt this morning and was surprised at how good it looked, no marks or any visible problems.Perhaps I will not be rushing to spend money and get it done .

Previous to the SC430 I had an Alfa Spider and the Alfa OC forum is full of people absolutely obsessed ( and I mean obsessed ) with cambelts.

It is regarded as an inherent weakspot ( along with all the others) and the subject is discussed endlessly.

My thanks to all for your responses.

[scudney]

As informative as it might be,not one to take chances or gamble if its due a change it gets changed,always better safe than sorry,furthermore costs alot more when it snaps/damage it causes.Peter you might as well consider putting in a disclaimer before someone in future decides to sue (eg I will not be held responsible for any damage caused,if you do not change your cambelt as and when due),simples.

[jeffreyt]

whoops,perhaps I gave the wrong impression.I don't intend to simply ignore my aging cambelt following Peter's post.

I only do about 2k a year and that's mostly summer mileage so I think its safe to leave it until next spring as it will still only be about 83K or less

by that time.

[alphacat]

As informative as it might be,not one to take chances or gamble if its due a change it gets changed,always better safe than sorry,furthermore costs alot more when it snaps/damage it causes.Peter you might as well consider putting in a disclaimer before someone in future decides to sue (eg I will not be held responsible for any damage caused,if you do not change your cambelt as and when due),simples.

PC rules but I don't play that game I am not an Lexus Garage or a Lexus employee anyone taking advice of others and trying to sue will have a hard time with me. My post was aimed at explaining the reality as compared with the information given out (to make money ) by Lexus dealers. Its based on very reasonable engineering principles and information available to anyone. People who know nothing about engineering are right to play safe and do as they are told by the manufacturer these people should never own a car out of warranty. Life is a gamble and risk is exiting .. I suggest you live a little and play the game before you die its likely to be less expensive. However I will admit the down side on cam belt issue is that the Lexus 430SC engine is an ' 'interference' engine this means that if the cam belt breaks in service it could (probably will at revs above idling) make contact with some of the valves. The result will be very expensive. However these belts are not made of rubber (as suggested by someone earlier) but a particular type of reinforced nylon and they are immensely strong. It would be very very unusual for a belt to fail in service without some sort of prior deterioration and don't forget Lexus recommend changing at 100,000 miles. That's a lot of use. It would be a great experiment to buy a belt (you can get them new from under £5) put it in a landfill site (in a waterproof bag) and dig it up in ten years time and test it.. I bet it would be fine !! But no one can guarantee anything in engineering.. Its all about statistics when looking at manufacturing reliability.

[alphacat]

Here it is wrong pic posted before !!

[dave1]

. It would be a great experiment to buy a belt (you can get them new from under £5) put it in a landfill site (in a waterproof bag) and dig it up in ten years time and test it.. I bet it would be fine !! But no one can guarantee anything in engineering.. Its all about statistics when looking at manufacturing reliability.

It may well be fine in 10 years after being sealed in a waterproof bag and buried, conditions totally different conditions to reality.....no friction (causing wear), very little temperature variation, no vibration or movement or possible contact with contaminants!

[alphacat]

. It would be a great experiment to buy a belt (you can get them new from under £5) put it in a landfill site (in a waterproof bag) and dig it up in ten years time and test it.. I bet it would be fine !! But no one can guarantee anything in engineering.. Its all about statistics when looking at manufacturing reliability.

It may well be fine in 10 years after being sealed in a waterproof bag and buried, conditions totally different conditions to reality.....no friction (causing wear), very little temperature variation, no vibration or movement or possible contact with contaminants!

Exactly and those criteria are caused by mileage not time. See what I mean ??? On the USA Lexus web site they have even bigger problems. Lexus dealers there often insist it needs changing after as little as 50,000 miles or less. I suppose my pessimism is driven by so many known occasions when Lexus dealers (or in fact any dealers) just don't have any other focus in life but making money from car owners. Days of professional pride and customer care are long gone. They would argue black was white if it made them a few extra pounds. I am still convinced the original Lexus recommendation was 100,000 miles and no time limit was advised. If that was changed it wasn't done so on failure recording from what has been recorded elsewhere online it was done on dealer appeasement grounds !! I did read some where that on a casual survey by the US Lexus club not one case of a failed cam belt was recorded. On another that deterioration usually gives some kind of audible warning before the belt ceases to drive. My own belt is now approaching 70,000 miles and the car has had one (out of 3 owners) lady owner who didn't take care of it properly so I will be probably looking to change mine early.. On my recommendation, not the dealers.

[john leeds]

Hi all

Is there any way you can tell if the belt has been replaced as there is no proof in the paper work that came with mine ,its a 52 car on 55k miles ,its mot record show it's had light use all of it's life although the records show 1st an 2nd owner's took good care of her but owners 3 and 4 only had her a year each and then when I got her my trusted garage gave her a full service plus disc and pads .I'm just wondering when if I should do it or not ,any advice appreciated many thanks john .

[Paul_G]

Have you asked Lexus? If it's been done by a main dealer they should know.

[scudney]

Hi if you can't confirm if it has been done already,then for piece of mind have it done as soon as possible,better safe than sorry,moreover your car is over eleven years old - 10 years or 100,000 whichever comes first is the interval.

[sendz]

http://www.lexus.co.uk/owners/lexus-servicing/#/FixedPricePromise should cost £295 inc vat at Lexus main dealers. Good price?

[alphacat]

Sounds too good to be true!! £295 I wonder if it include parts and VAT... Even if it is the full cost which I very much doubt, I bet they find another few things that 'need' doing...