Plastic guide rails

[BenzBoy]

During this week I had a look at a Peugeot 308 engine that is dismantled for a top end rebuild. The water jackets are beautifully designed to cool the cylinder walls and some real thought has gone into ensuring there are no hot spots in that area. Not so much though has gone into the plastic guide rails for the timing chain though - they are so flimsy that they broke, letting the timing chain run wild and requiring a head rebuild. Mileage? Around 40,000K. Jaguar also used flimsy plastic guide rails with many 4 litre engines requiring a head rebuild at very low mileage - and the repair kit comprises metal guides, not plastic.
Is there some moronic engineer working his way through various companies advising them to use plastic guide rails? Arguably plastic is quieter but I doubt that the difference is discernible - cheaper I guess. I'm sure Sean will have a view on this.
Regards,
Brian

 

[sean sherry]

Well now Brain, my understanding is that " Plastic " comes in many forms. Everything is brought down to a price. The Cost Accountants have a big say on what the Engineers use. Quality Plastic is what Mercedes used for the Seat Runners in my 1980 107 S.L. Tough as old boots as the saying goes.

P.S. I have a couple laying round if anybody wants them for the asking.

 

[Michel]

Quality Plastic is what Mercedes used for the Seat Runners in my 1980 107 S.L. Tough as old boots as the saying goes.

P.S. I have a couple laying round if anybody wants them for the asking.

I'd love to have them

 

[sean sherry]

I did reply Michel, but it looks like it did not get through. How do I get them to you ? I.e., 4 off. I was thinking about Plastic composition and I guess Plastic guides have a tough life inside an engine compared to Plastic Seat Runners.
Perhaps we are to meet if Bryce can be persuaded to step up to the Plate.
He will immediately know that expression.

 

[c107]

I
Perhaps we are to meet if Bryce can be persuaded to step up to the Plate.
He will immediately know that expression.

I guess I will need to knock it out of the park!