interference engines

[Frank Lee]

As far as "no excuse" for interference engines- sure it'd be nicer if parts smashing into each other was never a concern, but for how often the timing drive fails it's a chance the mfgs and myself are willing to take. Hmmm, been motoring and wrenching for how many decades now and have never had a cam drive fail... came close but yet not quite in an old Dynasty I picked up and decided to inspect the belt... it came apart when I pulled on it but while it was in the car it was working!

[Ryland]

If your car only has 130,000 miles on it then it should be easy! pull the timing belt cover off and check the belt for your self, if it looks like it's been on their sense 1984 and has "Honda" stamped on the outside then there is a good chance that it's original and should be changed, if it looks new and has another brand stamped on it then it's been replaced and should be good till you have 200,000+ miles on the car, if the past owner had the timing belt replaced at the dealer then it would be another Honda part (mine was replaced with an OEM belt) but most of the time the auto part store will sell you a Gates belt and they claim that their belts will last longer then OEM.
Either way the car is new to you so you should check the timing belt for age and cracks.

[mikehallbackhoe]

thanks for the tip. it would be easy to pull the top cover and see what the belt looks like.

[jtbo]

Remember that rubber belts usually have also time limit, not only mileage, 5 years is common one.

[Frank Lee]

More like 20.

[TracerZX2]

Maybe It is just Missouri weather, but timing belt fail is extremely common here. It is one of the largest causes of death for SOHC ford engines around here. Fortunately the zetecs I run are non-interferance, even though the manufacturer says otherwise. Typical ZX2 belt fail is between 80k and 130k.

With all due respect, blanket statements about the aging of a timing belt to cause failure in the rubber is not a good idea. There are way too many environmental considerations as well as how the engine has been operated to just drop a number on it.

Also, if you are replacing belt only on an engine with 130k on it, you are setting yourself up for epic fail. You need to look at the idlers and tensioners of any belt drive system as bearing failure in these items is often the reason for timing belt fail. Additionally, since the system has worn in together, I see a lot of belts walk off if the idlers not replaced.

Respects
Tracy

[jtbo]

Originally Posted by Frank Lee

More like 20.

No, it is 5 years most cars here, some have only 4 years, there are few exceptions that are longer, but I don't know single one that would be 10 years, longest I know was 7 years in VW, but they reduced that at some point as belts were snapping like popcorn.

Good point with climate TracerZX2, I must note that here realistic temperature range is -40C to +35C, southern part of country is not quite as cold, but it might have something to do with it, maybe at extremely cold belt is under more stress with cold oils, which causes valvetrain to be bit heavier to turn?

[sendler]

Interference valve trains are better. That is why they are used. The ideal piston would be a flat top for the minimum surface area to pick up wasted heat. Squish zones and swirl patterns then deviate from that. Putting cut outs into the piston top makes it heavier, turbulent, fuel sticks to the cut outs, increases counterproductive surface area, ect. Big vaves make more power but also increase interference. Non interference engines are a trade off to be fail safe but are not technically as good.

[TracerZX2]

Originally Posted by sendler

Interference valve trains are better. That is why they are used. The ideal piston would be a flat top for the minimum surface area to pick up wasted heat. Squish zones and swirl patterns then deviate from that. Putting cut outs into the piston top makes it heavier, turbulent, fuel sticks to the cut outs, increases counterproductive surface area, ect. Big vaves make more power but also increase interference. Non interference engines are a trade off to be fail safe but are not technically as good.

I am not sure I buy that the valvetrain is better. You can have an identical valvetrain with different piston tops and one is interferance and one is not. That does not make one of the valve trains better.

I will potentially buy that the combustion chamber assembly design efficiency is better.

Respects
Tracy

[sendler]

Originally Posted by TracerZX2

I am not sure I buy that the valvetrain is better. You can have an identical valvetrain with different piston tops and one is interferance and one is not. That does not make one of the valve trains better.

I will potentially buy that the combustion chamber assembly design efficiency is better.

Respects
Tracy

OK. I should have said interference combustion chambers are better.