interference engines
 

there is no excuse for interference engines. pistons can have grooves in the piston that allows for valve clearance. Then to make matters worse ,they run the water pump off the timing belt. This increases the chance for failure. Now they want you to not only replace the timing belt at regular intervals, but also the water pump. this is poor engineering at best, and possibly planned intimidation to force you to buy replacement parts before you actually need them.

The piston top plays a big role in the distribution of the fuel/air mix throughout the cilinder.

It's easy to see there could be a conflict of interest between having a non-interference engine, and having an economical / clean one - and as always, you can expect some manufacturers to solve it better / differently than others.

The belts have gotten better though - on my engine, it's 240.000km / 150.000 miles between replacement. I can live with that.

I think most/all Fords have non interference engines. All of my Escorts and my Contour have non interference engines. Some of the first Escorts with the 1.6L engine were interference type.

As euromodder mentioned, this is becoming a non-issue with alot of newer vehicles. 150k+ intervals means that most vehicles will only have their timing belt/belts & water pump replaced once in their lifetime. When you break down the cost of replacement parts/labor per mile the cost is pretty small compared to consumables like fluids, tires, batteries, etc.

I agree with you in principal, but there are so many other things that tick me off about the OEMs that this one is pretty minor.

mikehallbackhoe -

Agree with all of the above. I will say that if you have an interference engine, you *should* have a timing chain instead of a timing belt.

CarloSW2

on my subaru, they want you to change the belt, water pump, and all the idler pulleys, at a cost of over 1500.00, I found a mechanic that I trust, who replaced just the belt for 100.00 and I supplied the belt. I recently purchased a crx with 130,000 miles on it . the belt should be replaced at 90,000 miles. I don't know if it has been replaced or not, so I will have to replace it just in case. guess I will be calling my mechanic.

The Honda timing belt should be good for 100,000 to 120,000 miles and if you buy the timing belt from the Honda dealer the belt is $26 and $60 for a water pump or $35 for an after market water pump.
I've never heard of a Honda water pump failing but then again with the water pump only being in service for 100,000 miles it shouldn't ever fail.

I assume that a big part of the reason behind not having large pockets that the valve can fit in instead of crashing in to the pistons is that part of designing a high compression engine that doesn't ping is making the combustion chamber smooth and free of sharp edges or large pockets... so by having an interference engine you gain efficiency with a trade off of every 100,000 miles you needing to buy less then $100 worth of parts, or last time I had my civic VX timing belt and water pump changed it was $300 total, now if I didn't have an interference engine and just waited for my timing belt to brake I'd have to then pay for my car to be towed and I'd still have to pay for it to be repaired, only it would happen at a random point in time when I was on my way to work instead of when I set aside the time for the work to be done as planned.

the Isuzu 2.2L the valves are not at a angel to the piston. they have rockers that bend or push-rods that bend when the valves strike the pistons....
sorta the lesser of two evils

so even though its a interference engine, with 21 to 1 comp.
in the event of timing failure....head removal is seldom ever needed.
(i know of no one that has had too)


the engine was made bolth ways, belt and gear timing.
on road is belt, off road is gear.
and no you would not want to use a gear model on the high-way.
there de rated about 30/50% for running water pumps, gen sets, welders ECT ECT
and have much lower max rpms.

The reason for using a belt isn't because of the higher revs of the on-road application, but because of noise emissions. A gear train would work awesome on your engine but it would be noisier.

I have chain in one of my cars, water pump is run with V-belt, valves are adjusted easily with pliers and a wrench, you actually can adjust the timing, not possible with really lot of modern stuff.

Surely it needs more care and adjustments, but if that is price for car to go 20 years without anything major, then I'm happy to adjust and service it bit more.

There are points (breaker) ignition in it too, many say how bad it is, but I have found it being bullet proof, if one has taken time to service it, takes only few minutes, does not cost really anything.

Also car is so easy to work with, there are always left enough space for tools, so that all jobs are really fast to do, I think that nothing takes 1 hour, maybe all brakes might take that time if made all lubricating too. Lift spare wheel out from engine bay and after that everything is in reach right away.

I have more modern thing, it eats all sort of joints at our bad roads, also radiators and heater fans are parts that need regular replacing, many things need removing lot of parts first to get access to what you need to change, alternator belt change needs removal of front wheel and inner fender if you buy service, that adds up to labour time.