Anyone's timing belt snapped and bent valves?
- Thread starter mikebontoft
- Start date
Did you personally diagnose these motors with bent valves? If so, please try to post up some pics. Otherwise, I think we have a case of some mechanics assuming the motors are interference when they actually aren't.
kudakev615
Member
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- pro5
can somebody sticky this?
I have the 2002 shop manual and haven't found any mention of the engine being non-interference. Do you have a page reference? Also have the Mazda FS engine manual and cannot find it there either.
Clifton
mikebontoft
Member
- :
- 02 Focus SE, 90 626 GT
^^ also I have the Gates timing belt book that says Interference.......
well we'll find out for sure hopefully tomorrow or next week. My boss is having me take in some subaru heads and told me to go ahead and take mine in with them to the cylinder head shop.... to "find out what's wrong with it" (so in other words, I'll be getting a head job)
ALSO ALSO ALSO....... I go to him with my newfound info... "You'll never believe what actually may be the problem. bad valve seals." He says, "Actually yeah I do believe it. It's just like the Ford Escort and those had a lot of occurrences of seals crapping out. It even took out the motor once in a while." So I'm leaning towards the seals and not valves. the engine looks fine (also I forgot to post more pics)
I know these don't help for anything, but I uploaded them so I'm putting them up dammit :B
well we'll find out for sure hopefully tomorrow or next week. My boss is having me take in some subaru heads and told me to go ahead and take mine in with them to the cylinder head shop.... to "find out what's wrong with it" (so in other words, I'll be getting a head job)
ALSO ALSO ALSO....... I go to him with my newfound info... "You'll never believe what actually may be the problem. bad valve seals." He says, "Actually yeah I do believe it. It's just like the Ford Escort and those had a lot of occurrences of seals crapping out. It even took out the motor once in a while." So I'm leaning towards the seals and not valves. the engine looks fine (also I forgot to post more pics)
I know these don't help for anything, but I uploaded them so I'm putting them up dammit :B
look I am Mazda certified and have been through plenty of training. i am an Ase auto technician I don't just turn wrenches. Like we discussed in the class last week any manufacturer can tell you that their motor is non interference. just for you to buy it and i am not saying that evertime the belt breaks that this motor bends valves it is a case by case bas-sis. just trying to start the motor really is not enough rpm to do any damage. Also you have to remember that the Mazda manual is in Japanese first then translated to English. so sometimes their meanings are not the same as ours.
I hope you marked where what cam went where and all the wafers. If you did not it can be a real pain in the butt to put it all back together after they do the machine work. Im not 100% sure but I think between the cam and wafers their is only like +/- .002 tolerence. I think its like .004 to .009 Just a heads up. Or you could be in the boat like my head was... Bent three valves..........after the head job , I had to buy 6wafers, they are $20 each from mazda, and can only be bought at mazda.
mikebontoft
Member
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- 02 Focus SE, 90 626 GT
^^ those are called the shims, right? I only had one fall out and I put that back in. cam bearing caps......... no freakin idea. I know they're numbered, but the exhaust ones just don't make sense and that's how I found them. Intake side was fine.
I don't buy this. If your motor is interference and your belt breaks, you will always bend valves due to the inertia of the motor. Unless you've got some retarded high compression ratios that stop your engine in 1/4 of a camshaft turn or less, I don't think you can say that an interference engine will only sometimes bend valves.
If you can provide a specific example of an FS-DE engine with bent valves (with pics), great. Otherwise I maintain that our motors are non-interference, and that the Gates belt company is wrong.
Im with him. Interference basically means that the piston and the valve occupy the same space (hopefully at different times) Non interference means that they never enter each other's space.
If its non-interference, then unless something is terribly wrong, it can't bend valves.
If its interference, then it IS going to hurt valves, inevitably.. Once those valves quit spinning, its a extremely small fraction of a second before the piston is going to enter that valve's space. I don't see how mph or rpm is going to change that any. They either occupy the same space or they do not. Speed isn't going to change the space they occupy.
"But all evidence points to non."
Please explain why Burchett's head bent valves when the wrong shims were installed in the cam followers? That shouldn't happen in a non-interference engine.
I have seen some posts where people said their valves were bent after the timing belt broke. Why?
In a recent spark plug thread why did some people say the pistons closed the gap on extended tip plugs? One poster said he measured the extended tip plugs and they were .25" longer than stock plugs. That shouldn't happen with a non-intereference engine. Surely the valves extend more than .25" when fully open.
"Speed isn't going to change the space they occupy"
True, but speed will change the length of time it takes to reach that space. Slower speed takes longer. I don't know if that's enough difference to matter but it may?
Clifton
Please explain why Burchett's head bent valves when the wrong shims were installed in the cam followers? That shouldn't happen in a non-interference engine.
I have seen some posts where people said their valves were bent after the timing belt broke. Why?
In a recent spark plug thread why did some people say the pistons closed the gap on extended tip plugs? One poster said he measured the extended tip plugs and they were .25" longer than stock plugs. That shouldn't happen with a non-intereference engine. Surely the valves extend more than .25" when fully open.
"Speed isn't going to change the space they occupy"
True, but speed will change the length of time it takes to reach that space. Slower speed takes longer. I don't know if that's enough difference to matter but it may?
Clifton
mikebontoft
Member
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- 02 Focus SE, 90 626 GT
^^ If I read this right, this would be OTHER than stock specification......and quite possibly interference
racerx43269
Member
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- 2002 mazda protege 5
his motor would have to be something BESIDES stock, and this is why... ( when i find out where it said non interference ill post it i just cant find it but i know it says it some where.
if you look at the piston design, there are domes where the valves have clearance, first off... secondly our piston comes to the top of the block, and stocks.. it does not extend past the deck portion, there is a .16mm gap that is allowed for expansion of the pistons, ( that is from wiseco when i spoke with them earlier today
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- -- 03 P5 / 23 CX-5 --
Will somebody just put a long block together to STOCK spec without putting a timing belt on and video turning the cams and crank in opposite directions by hand and see what hits or NOT and end this decade old argument already?
The long reach plug comments are baseless without exact plug numbers. I've run NGK ZFR5F-11s for years without any bent electrodes. Thickness of an aftermarket head gasket could cause issue if the tolerances are that close. So many vague references being made about different possibilities here.
The long reach plug comments are baseless without exact plug numbers. I've run NGK ZFR5F-11s for years without any bent electrodes. Thickness of an aftermarket head gasket could cause issue if the tolerances are that close. So many vague references being made about different possibilities here.
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mikebontoft
Member
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- 02 Focus SE, 90 626 GT
Bigway that's what I was expecting to see with mine......
head shop closed early today lol. it's going in monday now. Sounds like it's gonna be around twice the cost I paid for the car! LOL
head shop closed early today lol. it's going in monday now. Sounds like it's gonna be around twice the cost I paid for the car! LOL
mikebontoft
Member
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- 02 Focus SE, 90 626 GT
lol that would suck
