Non-interference egine??? - Toyota Nation Forum : Toyota Car and Truck Forums

Manic · 12-31-2002, 02:38 PM

Hi, I was talking to a mechanic about timing belts and he said some egines were "non-interference" and that when a timing belt broke all you had to do was replace it. I gathered from the conversation that "non-interference" means that it won't drop the valves when the timing belt breaks. Is this a correct assumption and if so is the new 2003 Corolla a non-interference egine?

TigerSilhouette · 12-31-2002, 04:21 PM

Well, the 2003 Corolla has a timing chain, which never needs to be replaced unless somehow damaged. I don't know whether or not the engine is interference or non-interference though......
Hope that helps

Voodoo.Priest · 12-31-2002, 05:20 PM

The guy I bought my first AE86 off of said that the 4A-GE was that I think. All he said it does is if somthing breaks (like a belt) the engine will stop or somthing and it prevents the damaged parts debrie from damaging others.

TigerSilhouette · 12-31-2002, 05:47 PM

A interference engine is one which doesn't have enough clearance between the piston and the valves, thus when the timing belt breaks, the piston goes and hits the valve because of incorrect timing.....non-interference means there is enough clearance between the piston and the valves so that even when the valve is fully open and the piston is at TDC, there is still room in between both, averting the cause for major repairs.......whew that was lengthy, have a great new years everybody!

goodcookiedrift · 01-01-2003, 02:55 PM

yeah thats pretty much it. however, non interference engines usually have the combustion chamber in the cylinder head where as interference have it in the actual cylinder.

in 4age's, the valves will never drop bellow the deck line therfore never interfeering with the piston head.

ncik

VZV21 · 01-02-2003, 06:42 AM

1ZZ-Fe is non-interference

cdnsupra · 01-02-2003, 11:07 AM

Quote:

Originally Posted by VZV21

1ZZ-Fe is non-interference

I have heard several times that all toyota engines are of the non-interference type. It is definitely a smarter way to design things. Who would design an engine to have a complete meltdown because of a small dollar amount item like a timing belt??[you don't havfta answer that]

the only semi-acceptable reason to me for having a non-interference engine would be for torque or power gains, but they would have to be really substantial gains.

Would you really want to rebuild your complete engine because your timing belt broke, and subsequently a valve bent itself as it pushed through your piston? I think not.

VZV21 · 01-02-2003, 11:19 AM

I've heard that GE heads tend to be interference though.

wunderboy · 01-02-2003, 12:00 PM

My friend broke the timing belt in his prelude, and had to rebuild the head. Not great, but still fun. I think an engine with the valves on top of the head, or with interference, would have a higher compression tho, that would be a reason to make them with interference. But I could be wrong.

goodcookiedrift · 01-02-2003, 12:53 PM

ge heads are not interference.

and you can bend valves on interference heads from not only breaking timing belts, but by impropper timing!

nick

drivinsideways9 · 08-24-2003, 04:40 PM

I am working on a 99 corolla right now, and if you have the cam positioned where a valve is open & rotate the crankshaft, when the piston for that cylinder reaches about 10 deg before tdc, it hits the valve. Therfore, if the timing chain broke, and the cam stopped turning w/a valve open, the piston would hit it & bend the valve