About this top chain guide ..?.....

[k100dennis]

So this is a guide that bolts onto some lugs on the head and is there to prevent the chain from curving upwards on the run across the 2 cam drive sprockets, correct ? Does the steel body fail from fatigue and the overhung part fall into the space between the vertical chain runs ?
Mine has 220,000 kms on it with all receipts and history. No reference to it ever being replaced. Should I do it asap ?

[GHendo]

Hi mate,

Yes, that is the infamous part. There are numerous horror stories on the forum to do with this part and it appears to be capable of several scenarios. Usually, the plastic bit that is attached to the steel bracket, comes adrift and falls down into the bowels of the motor but there are cases where part of the steel bracket itself has come off. In either case, when this happens it can dislodge the chain completely or make it jump one of the sprockets – not good !!

My advice would be to replace the guide – when I pulled mine out around 200,000km. it looked fine then while I was turning it over in my hand to examine it, the plastic bit fell off the bracket – think I dodged a bullet that time. The part is about $25 and it is an easy job to do the replacement. If you still have the original in your motor, you will find the new one is a slightly different design.

Cheers

Geoff

[Aussie_Dan]

From what I have seen it appears that the plastic rub strip that is attached to the guide can go brittle over time and eventually cracks and falls off. As this is plastic, it isn't going to do much damage on its journey down into the sump. But when this happens the chain will then rub on the metal part of the guide where the plastic was supposed to be. Over time the chain will essentially 'saw' through the metal. When this piece of metal comes loose you are in trouble - if it gets caught in any area of the timing gear, prepare to sell a kidney and empty your bank account!
Cheers, Dan.

[Lance]

Yep,
out with the old, in with the new
about an hour
cold tinnie

win/win