My poor Protege5 may be going to Mazda heaven.... :(

[Mike999]

Hi folks, I'm not much of a poster, but do lurk quite frequently around here!

I was driving down the major highway through Ottawa, ON today (the 417) heard a pretty loud snap/bang sound. The car stayed on, however I lost all power from the accelerator, as in, nothing would happen at all, despite still being on. I coasted off the highway onto a side street and checked under the hood, and could not see anything, nor could I see anything leaking from the car. After turning the car off, it would not turn back on again. (battery was fine...I was listening to tunes until the tow truck arrived)

The car has 128,000 km on it (which is....80-90,000 miles?). We were told the timing belt had been replaced just before we purchased it, but Ive always had this lingering feeling that it wasn't replaced. My first thought about this is that the timing belt snapped, which I suppose could be relatively affordable enough to fix news so long as the valves weren't bent and nothing else was wrecked.

I have a very bad feeling that this may be something major that I cannot justify spending the money to fix, but would love any and all insight from some of you experienced P5 owners.

Thanks for hearing me rant!

 

[MazdaSpeeder]

If it's the timing belt, you should be fine. The P5 is listed as an interference engine, but the experience on these boards is that in most cases, the timing belt breaks and there's no damage. I would get it checked out...did you hear serious knocking/rattling from the engine after the belt broke? If so, not good. If not, you probably only need your timing belt replaced. Have a mechanic check it out.

 

[tweety2300]

Only way to find out is to remove the cover that houses the timing belt. I doubt the valves came into contact with the head or you would have heard a very loud knocking. If your timing belt is broken do a compression check if a valve did somehow come into contact with a piston youd be able to tell. Would it turn over at all? If it did turn over did it do it way faster than normal?

 

[pw~mp5]

Sounds like it is axle or transmission related to me. The car was still running after the bang, if it were the timing belt the engine would have shut off after the bang. The neutral switch would prevent it from cranking.

 

[Mike999]

Well, I just heard back from my mechanic (who I fully trust). He told me that it was in fact the timing belt that went, and that it damaged a pulley when it snapped. He said it was likely cheaper for them to replace the timing belt right away and then roll the engine over by hand to find out if there's any engine damage than to take the engine apart.

So I guess I'm out about 800 bucks after timing belt and tax and the cost to tow the car, and there are no guarantees that the engine didn't survive unscathed. Worst case scenario, hopefully the car is worth that much in parts to sell.

 

[pw~mp5]

The car stayed on, however I lost all power from the accelerator, as in, nothing would happen at all, despite still being on.

If the engine was still on it was not the timing belt. Without the timing belt there is nothing to turn the cams. If the cams are not rotating in time with the crank there is no way to get fuel into the combustion camber or exhaust out, therefore it would be totally impossible for the engine to be on.

 

[thecrash91]

If the engine was still on it was not the timing belt. Without the timing belt there is nothing to turn the cams. If the cams are not rotating in time with the crank there is no way to get fuel into the combustion camber or exhaust out, therefore it would be totally impossible for the engine to be on.

false, the car can turn over and start, it will just run like absolute balls and like he said hell have no acceleration. he already stated it was the timing belt so what are you trying to prove?

 

[MazdaSpeeder]

Damaged a pulley? That seems a little odd...which pulley? Maybe he meant the tensioner?

 

[Lewis7789]

I'm confused too. If the timing belt snapped then the cams wouldn't turn, so the valves wouldn't move and the pistons wouldn't move. The motor should've just died as there wouldn't be any fuel getting into the combustion chambers?

But if your trusted mechanic says it's the timing belt, then okay. And by pulley he's probably referring to a timing belt pulley. If you feel comfortable replacing the belt yourself, you could save a lot of money. A new belt is about $40 or so.

 

[pw~mp5]

false, the car can turn over and start, it will just run like absolute balls and like he said hell have no acceleration. he already stated it was the timing belt so what are you trying to prove?

Please explain to me how the fuel air mixture gets into the engine if the valves are closed and there is no timing belt. I fully under stand that the engine can turn over without a timing belt, but it cannot run.

 

[tweety2300]

How would the pistons not move? The tires would still be in motion and so would the trans which would make the engine in motion its the same thing as push starting it accept at a higher speed. It wouldn't have stayed runing but as long as it was moving it would be forced to and if it did run it would like total crap.

If a valve hit a piston it would have done it more than once and sound like it threw a rod so I doubt you have any major issues

 

[thecrash91]

because there is going to be at least one cylinder that has open intake valves, so you could be running on 1-2 cylinders, and it doesnt have anywhere to exhaust but it will still run, granted youll probably **** s*** up even worse it can still be done, hence why it ran but he had no acceleration

 

[pw~mp5]

How would the pistons not move? The tires would still be in motion and so would the trans which would make the engine in motion its the same thing as push starting it accept at a higher speed. It wouldn't have stayed runing but as long as it was moving it would be forced to and if it did run it would like total crap.

If a valve hit a piston it would have done it more than once and sound like it threw a rod so I doubt you have any major issues

Pistons would move just fine, they are connected to the crank via the connecting rods along with the flywheel/flexplate that the starter drives. The crank is connected to the cams via the timing belt. If the timing belt breaks the crank is no longer connected to the cams and therefore cannot turn the cams. If the cams are not turning the valves do not open to allow fuel/air in or close to seal the combustion chamber to build compression or open again to evacuate the burnt fuel/air mixture into the exhaust.

because there is going to be at least one cylinder that has open intake valves, so you could be running on 1-2 cylinders, and it doesnt have anywhere to exhaust but it will still run, granted youll probably **** s*** up even worse it can still be done, hence why it ran but he had no acceleration

Yes, there will probably be a couple of open valves, but open valves don't allow the cylinder to build compression. No compression, cylinder does not run. If the intake valves do not close once the fuel air mixture has entered the combustion chamber, the piston will push it back out through the intake port. Then you have the ECU which uses a cam position sensor to determine the proper time to fire the fuel injectors. Cam pulleys not turning, no signal to fire the fuel injectors, no fuel to burn. Even if one cylinder were fully functioning it would not be enough power to make the engine run with three other dead cylinders with the valves closed.

 

[pw~mp5]

If the timing belt broke while driving down the road, the engine would stop running. The engine may continue to rotate while the car is in gear using the car's momentum to turn the engine over via the transmission but the compression/drag from the non running engine would be like slamming on the brakes until the clutch was pressed in or transmission was shifted to neutral. Then the engine would quit rotating and there would be no power steering, the dash lights would all light up the same way the do when you first put the key in to start the car. If none of this happened, then the problem is not the timing belt.

On the other hand if a drive axle popped out, there would be a big bang, the engine would continue to run, the car would start decelerating (assuming it was not going down hill) and pressing the accelerator would cause the engine to rev but not move the car. Dash lights would be normal. Power steering would be normal.

 

[thecrash91]

i understand that, but i was just throwing out a suggestion, somehow it worked and ive heard of it working before. im no going to bother dissecting it happens though, just like the pyramids, nobody knows how they happened they just know they did. its also possible the engine filled with so much fuel it was able to run for a little while with open valaves

 

[Mike999]

Hey all, yes I meant tensioner previously.

Just got the call back with the new belt put on. Apparently compression tests went terribly so they took the head off, and cylinder 1 & 2 have bent valves, 3 has a bent valve AND cracked something (I want to say piston...at that point in the conversation I was a lil out of it...what with just finding out my car is dead), but cylinder 4 is a-okay!

So yeah....... worst case scenario.

Also, reading above had me thinking that perhaps the car was not on, as I keep the radio on fairly loudly to drown out the sound of the heater fan (had it on full blast on the way home...its dang cold up here right now!) and the sounds I heard were just road noise that I confused as the car running. Thinking back I don't remember actually shutting the car off, just hopping out as soon as I was rolling slow enough and starting to push it.

Anyways, Im looking at a bill higher than the car is worth to a non-mechanic, so I guess my new task is to find a good car-guy who can deal with this and wants a nice car....

It's really sad because this car has been perfect. I can't believe in 5 seconds it went from perfect, to burnt toast.

 

[pw~mp5]

You can get a low mileage used engine for about $550 in Ontario.
http://cgi.ebay.com/ebaymotors/JDM-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories
If you call them and arrange to pick it up yourself you may get it for less.

 

[drgnzadiel101]

i remember this happened to me in my accord lol. was driving, belt snapped, car stopped lol. interesting moment in time since i was taking it to the mechanic to get it replaced LOL. i sold the car to a friend since i didnt want the headache of well, head work. hope everything turns out well for you!

 

[Lewis7789]

So do the bent valves mean the FS-DE is an interference motor? Interesting.

Sorry to hear about your motor though, mate. If you do end up buying a new car, you could part your P5 out and learn a lot about cars while disassembling yours and make some good money on selling the parts. Or like posted about, you can always put a new (used or rebuilt) motor in it. Best of luck.

 

[MazdaSpeeder]

Sucks man, sorry to hear that. Lewis, the FSDE is listed as interference...there's whole thread on it. The consensus there was many guys have had their timing belts break with no damage, but with higher RPMs (like on the interstate) it can happen.