Water pump, timing belt

[rain406]

Non-interference engine? What does that mean? The reason I'd replace these, is because I thought if the timing belt (or water pump) goes, your engine is practically shot. Is that true, or only on other cars?

[jglutz]

Good question...A non interference engine is the type that when any particular piston is at the top of the stoke...the valves associated with that cylinder can be compressed and they will not contact the piston. Their are very few engines on the market like this...the Festiva 1.3L will interfere if the timing skips 2 or more teeth on the cam shaft. But if the timing belt breaks, the cam can obtain a neutral position so that the pistons and valves will not crash.

Water pump failure....like any part of the cooling system...if it fails (or the driver ignores the gages)...you're not going to last long...but in the festiva the water pump is not operated by the timing belt

[FB71]

huh?^^ No, the B3 and B6 sohc are completely freewheeling. No interference at all. I can (and have) fully opened both intake and exhaust valves with the piston at TDC. That's one check I make during my builds.

Ford has a standing engineering order. Any belt-driven cam engine (Zetec) must be free-wheeling if possible. The only Ford/Mazda belt-driven engine that is interference is the now out-of-production SVT Focus 2.0L HO. The Standard 2.0L Zetec is fully free-wheeling. This standing directive stems from the 1981-1983 1/2 Escort 1.6L with the blue valve cover. They were interference engines (we called them 'crash' motors). A poorly engineered timing belt resulted in breakage around 20k miles at first, destroying losts of warranted engines. Ford quickly redesigned the head and pistons to make the engine free-wheeling, identified by a gray valve cover, starting mid 1983. The valve cover changed to black when the displacement changed to 1.9L.

Chain-driven cam engines (Duratec) are interference, and, as jg said, more than 2 teeth off will result in bent valves.

Other manufacturers do not necessarily follow those guidelines, specifically Mitsubishi, Hyundai, new Kia (since Hyundai takeover), and Chrysler MMC cars. Honda also has this issue.

[jglutz]

^^On my first timing belt change. I experienced the cam pully timing mark problem most owners do...I had the to turn the distributor full swing to get the timing in. When I adjusted the cam by one tooth (before i relaized i went the wrong way-now 2 teeth out) I could hear the valves tap the pistons.
Also, when I lay the head on the bench and turn the cam. the head will lift as the valve opens..and i think when the pistons are at TDC, they are flush or almost flush with the deck.
I will check my ford manual for my 1.9L SOHC...if i remember correctly...ford is explicit about not moving the crank or cam while the belt is off and if puting a head on they have a tool to hold the cam in postion to prevent 1 tooth out problems.

[FB71]

if you could hear valves tapping pistons, you were putting new valves in right after. Valves will not survive a contact event. More than likely, you heard lifter tap, which can occur when the valve timing is incorrect.

Valves will extend below the head deck, but pistons have releifs to allow full opening of the valve.

Those instructions for the 1.9L are left over from the 1.6 crash motor. Helm did a very poor job revising their publications. I know, I was responsible for identifying and correcting their errors. All Service Training Instructors were required to review and correct service publications as part of our ongoing assignments. I rewrote the timing procedure for the 2.5L Duratec. I also rewrote the diagnostic procedures for the Explorer transfer case electric shift. Anyway...

[gdawgs]

Good question...A non interference engine is the type that when any particular piston is at the top of the stoke...the valves associated with that cylinder can be compressed and they will not contact the piston. Their are very few engines on the market like this...the Festiva 1.3L will interfere if the timing skips 2 or more teeth on the cam shaft. But if the timing belt breaks, the cam can obtain a neutral position so that the pistons and valves will not crash.

Water pump failure....like any part of the cooling system...if it fails (or the driver ignores the gages)...you're not going to last long...but in the festiva the water pump is not operated by the timing belt

I believe every vehicle I've ever owned has been non-interference.
1) Chevettes - I broke a couple of timing belts.
2) Festiva
3) Neon(Worthless piece of crap!)
4) 99 Escort 2.0L-About 3 inches of teeth were stripped off the belt while I was driving, so the belt was off by about 3 inches. It actually still ran like that. Not well, but enough to get me home.
5) 01 Toyota Sienna 3.0L

[Safety Guy]

I had an '85 Civic "S" (in case ya didnt' know, the S stood for "slow") that I was careful to have a new timing belt put on after 60K miles. I think I had about 65K at the time.

A week or two later, my engine just up and quit. I took it into a shop and they found that the crank nose had broken. All my care was for naught! Different breakage, same result: oil burner. I had it fixed to the tune of around $400, but that was only a partial fix: it still burnt oil.

Karl

[jglutz]

What lifters? the tap I heard was the valve hitting the piston. The damage was prevented because the the HLA's took the shock. If it was true non interference...the only oud sound would have been coughing or misfire.

Two things I said prevuiously: their is a big difference between skipped timing and a broken belt.....don't kid yourself that a broken belt is the only way a timing system fails. And some manufactures consider the ability of the valve trian to acheive a non interference postion when the belt breaks that the engine be carefull.

In some engines the valves may not push the cam. Here's the example. A valve is X degrees past max lobe, another valve is at max lobe and a third vlave is X degrees before max lobe. The first and third valve in this example lock the cam and hold the middel valve down.