Anyone's timing belt snapped and bent valves?

^^ lol goddammit..... that's the exact opposite someone else told me today. The 1.6 and 1.8 might be non-interference, but the 2.0 is interference........ (braindead

the cams were NOT completely out of the head. they were totally loose though, I was able to pick them up and almost pull them out. they SHOULDN'T have been sitting on any valves.

but then again my teacher is kind of an idiot..... takes the "technical" approach to everything. I usually do everything the opposite he tells me and it works fine. lol.

OK anyway though, I thought I'd give a better in-depth idea of what I did. If I didn't mention it, I DIDN'T DO IT :)

Let me clarify just in case I didn't do what you guys think I did (or didn't)

found the engine with a snapped (right at the top between the cams) timing belt. I could rotate the cams with a wrench if I needed to.

I undid all the cam cap bolts enough to pull the cams out so they were not pushing any valves down. (so I was told to do)

Took the schrader valve out of the compression checker hose, took out ALL spark plugs, threaded in the hose, attached the compressed air line to it, and air blew out either the intake or the exhaust depending on the cylinder.

DID I DO THIS RIGHT?? I guess I'm taking the head off tomorrow morning if no one can correct me here.

I was thinking that maybe if I set the timing marks and put the new belt on, tighten everything up, and thread in a compression checker, maybe I'd get some readings on it. (considering the fuel pump is dead... otherwise I'd just see if it started)
 
^^ and I still am... I mean seriously LOL. according to the test I did it says interference, a really good book on purely engines for shop use says interference (except for Tribute), EVERYONE and EVERYTHING else says non-interference (except the shop teacher) so what the hell? LOL.
 
well i can tell you this, my valves are NOT bent and when i was replacing the timing belt i turned the engine over like 10 times without the timing belt attachted
the piston didnt hit the valves, which means, non interference lol
 
right LOL........ so WTF happened to mine?? haha. maybe I'll just mess with the cams for a bit. torque em down and see if anything gets stuck. maybe put the crank at TDC and see if any valves (on the opposite end.......considering obviously bent valves don't touch the piston anymore :B) make love with the piston

edit: SO...... here's an idea...... keep the cams all loosened up like they are (maybe even take them out) hook up the battery charger, disconnect the coil, and crank it. think that would make the valves hit?

wait I guess not, since they should be closed :| OH right ok, tighten down the cams and place them so the valves should be open when I'm cranking . YEAH.
 
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I think I'll do that tomorrow (except for the fact the fuel pump doesn't work....... I hope someone has some type of petroleum spray sitting around) it's originally what I wanted to do.... but I dunno.


I bet this is totally what was being said at first, but can I really just take the old timing belt off, keep the cams loose or remove them, and have a compression checker screwed in to one cylinder at a time, and just crank the engine to see if I have any compression?
 
welp......I decided to take the head off anyway. It's not all the way off but it's undone. can't seem to take the intake mani off either with it or separately. I got all the bolts both on the top and the two on the bottom. the head slides around a bit though now
 
I found since working at the mazda dealer that. when these 2.0 t-belt pop over the speed of about 30pmh. they bend valves we have two in the shop now. both of them only have about 80,000 on them.At school they said they were not but later was told that it cold happen if they were on the highway. I hope this helps you in your decision.
 
^that sounds about right. ALL the tech manuals say the 2.0 IS an interference motor from what i've seen, mitch, all data, clutch mauals ect. but i have personally installed a timing belt on a 2.0 protege at work with a broken belt. it broke on start up and the customer cranked on it a few times before getting it towed in. hell i even cracked it over to verify the symptom. so if it were an interference motor, valves would be bent from the bottom end turning over while cranking. i installed the new timing belt and it ran fine. but it seems that if the car is going at normal speeds of 45mph or so and the belt breaks, the pressure of the crank spinning with the valves not moving WILL bend the valves....thats my theory and i'm sticking too it(hi)
 
I LIKE that theory...... besides, usually timing belts snap on the road more often than just sitting there (yeah I made that up, it's probably about even for both for all I know. LOL)

oh yeah anyway the book I was referring to was "Timing Belts" by Gates. THAT lists all 2.0 DOHC engines as interference, except the tribute. 1.6, 1.8 sohc and diesel engines are non-interference (from what I can remember. I'm gonna scan the page but I forgot the book lol)

edit: oh and I forgot...... I couldn't take the intake mani off cause of the bracket that attaches it to the block. DUH. lol.
 
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kudakev615 said:
^that sounds about right. ALL the tech manuals say the 2.0 IS an interference motor from what i've seen, mitch, all data, clutch mauals ect. but i have personally installed a timing belt on a 2.0 protege at work with a broken belt. it broke on start up and the customer cranked on it a few times before getting it towed in. hell i even cracked it over to verify the symptom. so if it were an interference motor, valves would be bent from the bottom end turning over while cranking. i installed the new timing belt and it ran fine. but it seems that if the car is going at normal speeds of 45mph or so and the belt breaks, the pressure of the crank spinning with the valves not moving WILL bend the valves....thats my theory and i'm sticking too it(hi)
Click to expand...

So...we have a "sorta interference" motor? :)
 
^^ based on the evidence.......YES.

edit: someone should cut the timing belt (well leave the tiniest bit of a strand on there) and rev the engine and see if it will bend the valves :B
 
..

I had my timing belt replaced for the first time this past fall at 128,000 miles. My mechanic said the Tensioner was all f'd up. I'm glad I replaced it when I did.
 
Larkin W. said:
I had my timing belt replaced for the first time this past fall at 128,000 miles. My mechanic said the Tensioner was all f'd up. I'm glad I replaced it when I did.
Click to expand...

Exactly - preventative maintenance is what it's all about, and that's the key. We can sit here all day arguing about our motors being interference, non-interference, etc., but if you replace your timing belt when the manual says to, the design of our motors is a moot point.
 
^^ lol well that IS the key point...... never let this happen. BUT in my case, I dunno what happened and I just bought the car for very cheap thinking it was non interference...... come to find out it is.
 
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