1ZZ - Interference motor?

[ShadowRuleZ]

Anyone know if the 1ZZ is an interference motor or not?I miss my old small block chevy with its 20 dollar whole afternoon timing chain replacement.

[nismo]

The Vibe has a timing chain.

[ShadowRuleZ]

Still doesn't answer if it's interference or not, which determines if it needs preventative maintanence or if I can just let it sit there until it stretches out and won't start.

[MadBill]

...Which certainly make this a less burning question, but pessimistically still worth answering.. (BTW, knowing it was a free spinning design, I got lazy on my old Pontaic Firefly (AKA Geo Metro) and skipped 3 timing belt replacements. The original finally let go without collateral damage at 348,000 km (~212,000 mi)...)

[goodvibe]

non-interference

[cohocarl]

Quote, originally posted by ShadowRuleZ »interference motorI like the term Crasher better.

[joatmon]

so what does this really mean?Is an interference motor one where if the timing of the crank and cam shafts get out of synch, you could get an open valve to contact the piston at the top of it's stroke (with bad results) ?If so, then I can see why it would be more desirable to do a preventative timing chain replacement on an interference motor.How about the 2zz with it's higher compression, is it an interference motor?

[ragingfish]

According to a mitsubishi forum:Quote » read the post about changing the timing belts and decided to make this post.Alot of people don't think about changing their belts until they pop and their car is broke down. That happened to me, but I was fortunate enough to have a non-interference motor. Some of ya'll might not know what an "interference motor" is. Think about this: Your car has about 70,000 miles on it(about the time most belts go out). You're driving down the raod and the belt pops. You figure, the belt only costs like 20 bucks, but what you don't realize is that your car has an interference motor. You go to a car shop and they mechanic tells you that your motor can't be fixed. Absolutely nothing can be done to save your motor, it's gone. How could a $20+ piece of rubber have caused your motor to die? I don't know the exact mechanics of these I-F motors, but I do know this: When your belt goes, the motor shuts off instantly. The danger is that your cylinder heads might not have closed at the right time. When you replace the belt and fire up your car, BAM!!! You hear a terrible clunk in your engine bay. Your cylinder heads have just hit each other and bent. Your engine is gone forever. That info might be off a little, but it's basically what happens. Guys, change your belts before they go.

[Jahntassa]

Well..if ours is chain driven, we shouldn't have to worry about it then, right? The only belt we have is the accessory belt..

[ragingfish]

One would think not...but a chain could fail over time too, couldn't it?

[ColonelPanic]

Although you're a lot less likely to have problems with the chain than a belt, it's still a concern...Either way, with a chain or a belt, it's still a good idea to think about what can happen should the belt/chain slip or fail....Sadly, I bet my car falls victim to something like this. LOL!

[ragingfish]

Nothing to proclude you from having the dealer check it periodically on service visits...better to be proactive than reactive!

[cohocarl]

Quote, originally posted by joatmon »so what does this really mean?Is an interference motor one where if the timing of the crank and cam shafts get out of synch, you could get an open valve to contact the piston at the top of it's stroke (with bad results) ?Exactly. The valve train stops because of the belt or chain break, usually with one or more valves open, while it takes longer for the crank to stop spinning, hopefully not because the piston hit a valve that was open.

[MadBill]

Yes, like coho says! (but ignore that garbled story from the Mitsubishi site, at least the part about "cylinder heads colliding"! A. We have only one, B. It doesn't move... ) For an engine to be non-interference or free-spinning, there must be enough valve-to-piston clearance that even with the former fully open, they will not contact the latter. This can be a challenge on a high compression engine, as that clearance contributes to the combustion chamber volume and thus lowers the maximum attainable CR, as well as possibly compromising the efficiency of the shape. I'd be very surprised if the 2ZZ was free spinning, because the high valve LIFT, high compression ratio, large cylinder bore and focus on efficient combustion all conspire to minimize piston-valve clearance. Although a nice little insurance feature, a free spinning engine is no big deal with a well designed cam drive mechanism, as the chain should be just as reliable as dozens of other engine parts whose failure would wreak similar havoc.

[ShadowRuleZ]

My 420A 2GNT 95 Eclipse has an interference motor. I beleive that timing belt vs timing chain has no basis on whether or not it's an interference motor. And interference motor is one where the valves and pistons occupy the same space at a different time. They do this because it's cheaper to manufacture. If the timing goes, it's possible for the pistons to contact the valve and ruin more or less everything in the motor. These motors require rpeventative maintance, which is to replace the timing belt/chain before it breaks, usually every 60k or 100k. With a non interference, that's not a concern since they don't occupy the same space. If the timing belt/chain breaks, it just sits there and won't start.As for chain vs belt, most belts have a 60k or 100k replacement period. They also typically use a tensioner that can also go bad, as well as several idler pulleys and bearings that can also go bad. Most of this stuff is replaced at the same time. I had $250 in parts alone for my Talon when I did the belt on it.A chain will just stretch over time. I have a caprice with the original timing chain with 180k on it. usually with a chain, you can hear it slapping against the side of the cover when it starts to get too loose. A belt on my caprice is only $20.

[Altus]

Okay - so after all that it's nice to have educated us all in the difference between an Interference motor (piston & valves occupy same space at different times) and Non-Interference (p & v never in same space).However - do we have a definitive answer as to which the 1zz & 2zz engines are?Goodvibe said in his brief & to the point message that it's Non-Interference -- does anyone have confirmation of that? Especially on the 2zz?Yo! You guys with the Service Manuals! What's the final word?

[satur9]

1zz non-interference2zz? people who mishift 2zzs heve bent or broken valves i always assumes that that was because it was interference but i couldbe wrong.

[Flip-Side]

IQuote, originally posted by satur9 »people who mishift 2zzs heve bent or broken valves i always assumes that that was because it was interference but i couldbe wrong.My brother-in-law mis-shifted his 1zz turbo-charged celica. Screwed his valves up...and some. I don't think whether it is interferance or not, has anything to do with that.

[goodvibe]

It's because the valve springs aren't strong enough to overcome the momentum of the valves at that speed. They float of the cam, travel further than normal into the cylinder and fly into the pistons. It has nothing to do with interference since the cam and crank are still timed up in this case. Again, they're non-interference.

[cohocarl]

Quote, originally posted by Flip-Side »My brother-in-law mis-shifted his 1zz turbo-charged celica. Screwed his valves up...and some. I don't think whether it is interferance or not, has anything to do with that. I had a Yamaha Seca turbo motorcycle, and I remember missing 2nd gear a couple times while it was boosting.....wow that thing would rev up so quick it wasn't funny. I'm amazed the motor held together.The valves are spring loaded, (unless you ride a Ducati ) and if the motor is turning too fast for the spring to pull the valve shut before the piston comes up....

[Stang2Vibe]

This has gotten to be quite an interesting thread. So anyone know for sure if the 2ZZ is an interference motor or not?I tend to think like MadBill on this issue, except for one thing. The 2ZZ has a full second set of cam settings that only engage the extended valve duration and lift in the high rpm range. So I suppose that it is possible for this engine to be non-interference on the regular cam, but interference on the high cam. This spec would have to be verified at both cam settings for us to know for sure.

[goodvibe]

All toyota engines are non-interference and I believe lift is included but I can't absolutely confirm. At the end of the day, If your chain breaks while in lift, you'll have some major work to do anyway. I doubt that the chain will just fall into the pan without nicking something along the way.

[Jahntassa]

Quote, originally posted by goodvibe » I dought that the chain will just fall into the pan without nicking something along the way.Lets hope if it breaks, it doesn't have enough momentum to go flying through the hood. Imagine explaining that one to insurance..

[tnpartsguy]

No, No!! Not true!!Quote, originally posted by goodvibe »All toyota engines are non-interference and I believe lift is included but I can't absolutely confirm. At the end of the day, If your chain breaks while in lift, you'll have some major work to do anyway. I doubt that the chain will just fall into the pan without nicking something along the way.Tercel & Starlet Motors, as well as 1st & 2nd Gen MR2's & late 80's early 90's Corolla LSI were interference motors!! Basic rule of thumb on Toyota motors, Timing Belt cars, scissor cam; NON-Interference Motor......Timing Belt, seperate Cam drive = Interference Motor!

[sylvainber]

this may not be the final answer but there is an informative page on the 1zz:http://www.corollaperformance.....htmland another on the 2ZZ:http://www.corollaperformance.....htmlanother article on the 1zz and it's evolution:http://www.corolland.com/engines.htmlan explanation of how lift works on teh 2zz:http://www.corollaperformance.....htmlthis one is on the development of the 1ZZ-FE: (no mention of interference either way)http://www.spyderchat.com/1zzfe.pdfi came across several mentions of the 1ZZ-FE being non-interference and some mentions of the 2ZZ also being non-interference (but it didn't seem as authoritative in the case of the 2ZZ)sylvain

[goodvibe]

Quote, originally posted by tnpartsguy »No, No!! Not true!!Tercel & Starlet Motors, as well as 1st & 2nd Gen MR2's & late 80's early 90's Corolla LSI were interference motors!! Basic rule of thumb on Toyota motors, Timing Belt cars, scissor cam; NON-Interference Motor......Timing Belt, seperate Cam drive = Interference Motor!I didn't know that we were discussing discontinued designs. Just pointing out their current philosophy.

[Faultline]

These discussions always worry me..........I feel like the referee is going to throw out a penalty flagg over this..."10 yards , for passers interference...or was that non-interference.." hmm..... I hope the eagles win today!

[ou.grizzly]

I would like to revisit this question.I have been doing some research and from my understanding, an interference engine can have a belt or timing chain.So, the 1.8L in a Base Vibe is?

[prathman]

Quote, originally posted by ou.grizzly »I would like to revisit this question.I have been doing some research and from my understanding, an interference engine can have a belt or timing chain.So, the 1.8L in a Base Vibe is? Don't know about the '09s, but for the earlier models the answer is that they are definitely interference-type.Unfortunately this has been experimentally confirmed by at least one person here who had the Woodruff key come loose resulting in destruction of the engine. OTOH, chain failures are pretty rare, so having an interference type engine isn't as bad with a timing chain as it is with a belt.

[4azdmunky]

the 1zz's are interference. I lost an engine to the crank pulley walking off after not torquing it down and not using loc tight. Cost me 5K to get a used engine installed. Kicking myself now, for about $500 more I could have had a MWR engine.And the 1zz uses a chain, it should last as long as the rest of your engine.

[ned23]

Quote, originally posted by joatmon »If so, then I can see why it would be more desirable to do a preventative timing chain replacement on an interference motor.I've never actually owned a car where a timing chain broke. Have broken at least 2 belts, however.