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MG MGF Technical - Cam Belt Revisited

I just inspected the cam belt on my 1996 MGF; the belt is due for renewal on the ‘5 year rule’, although it has only done about 15k miles. The belt looks like new.
I have two questions:-
1.What is the most common mode of failure of cam belts?
2.What is the frequency of cam belt failures with respect to cam belt tensioner system? (Mine is the old style spring tensioner)
Nev

TBH Nev for what it costs, compared to the risk of wrecking your engine not to mention the worry of driving it beyond the recommended service life and hoping it dosn't fail (there is enough paranoia about HGF without adding to it !). I'd defo get it changed at the manufacturers specified time. You will also have a record confirming the change should you decide to sell your car at some point in the future. Also how will you know when it is the right time to change it ?

Just my 2p worth :)
Steve P

+ 2P
Did somebody dislike driving a 96 F so much they only managed 15k in 5 years? Why bother to service it at all then you can just throw it away when something inconveniently breaks. There is no great added value in a 'full service history' for an 11 year old car.
PS please let me have it - I struggle to do less than 22k/pa in my 11 year old and love every minute of them. :o)
Charles
C.R.B. Simeon

In all the years I have been active within club events,building and re-building sportcars etc.etc. I have yet NOT seen one single cambelt that have broken or snapped ! Cam -chains and balancer-chains -Yes,but the structure of the belts just make them either loose their cogs OR end up as a rats nest all over the seized engine.
If a failure happends to the cambelt area ,it is due to a failure of a component such as tensioner,waterpump,generator belt gets into the cambelt etc. So IMHO it is much more important to release the cambelt and check those components driven by the belt than the belt itself. Oil contamination or creaks in the belt of course needs immediate change of the belt itself. But - keep a close eye on the surrounding components. They will make the cambelt fail ! / Carl.
Carl Blom

Carl, Thanks for that, you have confirmed my thoughts. The problem is more likely to be the associated components and it the symptom rather than the cause which is observed. This supports the need to replace any suspect items at the can belt change interval.
Do you have any experience of the two types of cam belt tensioner used on MGFs; and their respective reliability records?
Nev

Sorry Carl, but that is not true in my experience.

I have seen a large number of failed belts which have not been attributed to other factors, just simple belt failures. And I have seen a *lot* of K series engines.

I would go no longer than 3 years or 25,000 miles on a K series without a belt change. the consequences of failure are too dire to contemplate for the extra expense involved.

Sure it is important to check all componentry in the belt run regularly, particularly the tensioner and also check the belt tension.

Dave
Dave Andrews

The belt problem is not distance related but the fact that it is rubber and rubber deteriorates with time. Lack of use is just as detrimental as a high mileage.
Tensioner failures have been due to high mileage or after a belt has been refitted too tight. With a mileage less than 25K, the tensioner may well be good and not need replacing however I am a firm believer in replacing the associated hardware viz. tensioner, water pump and alternator belt as they are relative cheap compared with the labour.
G. Farthing

Does the construction of the belt in any way differ from the ones used in VAG-engines ? Usually the belt is made from reinforcing wire (approx 80 turns) as a closed loop. This is then moulded in hard rubber (neoprene type ) with yet more of the same wires (but at 90 deg. angle) to the loop.
This gives the cog re-inforcement. Finally it is cut to correct width.
If the belt is treated without any sharp bends it should be indestructable and certainly not snap with something like a clear cut over its width ?
If the belt is made "the cheap way" from reinforced plain sheet that is moulded to a loop ,then I can see how it could snap at the weakest point!
At least the Piper belts I have used on my F are made as a continous belt with a magnitude of wires..
If something goes wrong (as sometimes in the Golf Diesel engine !) the wires might leave the belt and end up as a "rats nest" inside the cover. But there are always a few wires intact and still form a closed belt when the engine finally cogs over and comes to a final stop.
So, might it be that the OEM belt is NOT of the continous wire type, but the cheaper one ?
Carl Blom

I have had my cam belt break !

But being extreemly stupid, I didn't realise at the time. I was driving normally down the road for a short journey to Bangor Tech when the car cut out.

Oh bum! I thought its stalled, and put the clutch in and coasted to to the side of the road, where I tried to crank the engine over to start. After repeated attempts it wouldn't start and I called the mechanic.

Of course the engine was stuffed, pistons colliding with valves, so mechanic said

"your cam belts broken, funnily enough I thought I could perhaps get by with out a replacement.

I ended up trying to have valves replaced but spent money in vain.

Don't learn the lesson the hard way, like I did.

Brian
Brian

I have just had a look at the replacement Unipart Drive Belt, which I intend to fit to my MGF. If, as I have read on other MGF threads, cam belts deteriorate with age (irrespective if mileage covered), why is there no ‘sell by date’ or ‘use by date’ on the box or belt?
I have tried to find the wired ‘Piper belts', mentioned by Carl, but without any luck. Could these be the resilient cam belts we have all been longing for?
Carl, can you please let me know where you get the Piper belts from?
Nev.
Nev

With the greatest respect Nev, for the sake of around £30 every 5 years for a new cam belt, is it really worth taking any chances ?
Steve P

Hi Steve, I would gladly pay £60 every five years if it gave me the peace of mind that the belt would not ‘snap!’
Nev
Nev

I replaced my cambelt at 17000km when my 1.8mpi F turned five. It was like new but peace of mind was far more important. Today I inspected a 2004 TF160 with 44000 gentle km whose cambelt had snapped breaking most of the valves and damaging the pistons. Be safe and replace early, on my every day VVC F which is also used on track the belts have been replaced along with the tensioner at 80000km [which is only 48000miles] and will be replaced in 6 months when it reachs 160000km.
Andrew W Regens

Andrew, is it possible to show a photo of the snapped OEM belt ? Would be interesting to see how the broken area looks like. BR/ Carl.
Carl Blom

Hi Carl, Where did you get the wired ‘Piper belts' from?
Thanks, Nev
Nev

Sorry Carl, did not have a cammera with me and the engine is now completly striped and the owner who lives interstate has the belt with him.
Andrew W Regens

This thread was discussed between 27/01/2007 and 01/02/2007

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