Has anyone ever broken a timing belt on an FS engine?

YoGeorge

Member
:
2003 P5
Hi all:
I'm new to the forum, bought an '03 Protege5 last October; I'm an old guy who has owned a bunch of cars going way back. (Still have a "toy" '91 BMW 318is)

In any case, I bought my car with 52,600 miles on it, now has 57,500 or something. Maintenance schedule says to inspect the timing belt at 60k, replace at 105k.

Previous timing belt experience--I just sold an Acura 2.5TL (great car but I needed a hatch) with 132k miles, owned it from 37k. Factory interval on that belt was 105k, had it changed w/water pump around 100k. BUT, way back when, we had an '86 Escort GT (bought new for my wife) which had a recommended change interval of 60k or so--and lucky me, it broke at 57k while I was driving, left lane of a busy freeway.

The Escort was NOT an interference engine, so no big problem, but if I pop the belt on the Mazda, I have a problem (as I would have had on the Acura).

Has anyone ever heard of a belt breaking on one of these FS motors before 100k? My gut is maybe to just change it at 90k (at the same time as a plug and coolant change is needed) or if I'm broke (have a kid in college), maybe push to 105k. Makes more sense to push past 60k as well, since the water pump is still pretty new now, but at 90-100k will make a lot more sense to have that replaced. Should I pull the valve cover at 60k when I change the plugs and look at the belt? (I'll probably take it in for the belt change--have done big work like this, but have a bad back....)

I asked my Ford service writer (for my E150 van) what he'd suggest, as this was the same motor that they used in Probes, and he said I'm good to 100k...

But if anyone tells me about a busted belt, I may revise my plans. ps--car is an auto trans, so it probably hasn't been revved to death (my BMW is a 5-speed so I can get my ya ya's out)

Thanks,
George
 
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Since we are on ths subject...Is the FS motor an Interference motor?
I have never seen any info around here pertaining to this.
 
Since we are on ths subject...Is the FS motor an Interference motor?
I have never seen any info around here pertaining to this.

When I was researching changing my timing belt (which I did at ~97xxx miles), I came across many threads about interference/noninterference. From all of the threads I read it said the FS motor is NON-interference. There were some people that were over 120,000 miles and said they wont change there belt until it breaks (not that I would consider doing that (drunk)).
 
I wonder if Me changing out my rod/Piston setup creates a interference situation.

I went with long rods which slows down the piston in the upper area of the cylider..I wonder if this would cause interference if I broke a belt?
 
I wonder if Me changing out my rod/Piston setup creates a interference situation.

I went with long rods which slows down the piston in the upper area of the cylider..I wonder if this would cause interference if I broke a belt?

[OFFTOPIC for Force]
Does it move the piston any further up in the cylinder? if so, you should check it. This is easily done, and quickly done.

Get some Play-Doh, sit in on you piston when it's at the top of it's travel, and put a really really light spring in place of one valve spring. Install head, and push valve to the lowest point in it's travel. Remove head, inspect play-doh.
[/OFFTOPIC] :)
 
[OFFTOPIC for Force]
Does it move the piston any further up in the cylinder? if so, you should check it. This is easily done, and quickly done.

Get some Play-Doh, sit in on you piston when it's at the top of it's travel, and put a really really light spring in place of one valve spring. Install head, and push valve to the lowest point in it's travel. Remove head, inspect play-doh.
[/OFFTOPIC] :)

isnt the piston usually shorter to compensate for the longer rod?
 
typically, but it can vary by setup. There are just way too many piston, rod combinations out there. See: Chevy small block.
 
Piston heighth isnt any different I dont beleive..And by this..I mean center of Crank journal to Piston Face heighth.

....but the time it sits at TDC is different and how long in the rotation it takes for the piston to make its way downward is also slower as it starts to travel if I understand the Theory correctly.
I just wondered if this extra "Dwell" time at the top, would cause interference if I did happen to break a timing belt?
 
If you guys want to see some CRAZY s***, I'm going to make a thread in OT about my stroker Chevy build. Want to know about clearances in an engine? Try adding 18 cubic inches, solely with stroke.
 
Piston heighth isnt any different I dont beleive..but the tme it sits at TDC is different and how long in th rotation it takes for the piston to make its way downward is also slower as it starts to travel if I understand the Theor correctly...I just wondered if this extra "Dwell" time at the top, would cause interference if I did happen to break a tming belt?

If it doesn't touch with the piston at TDC and the valve all the way open, it will never touch, regardless of how long it is dwelling. Take 5 minutes and do the play-doh thing just to be on the safe side
 
Oh..and to answer this guys question...

Since its confirmed that its a Non-interference motor..I would say you are safe to wait until 90K or longer if you deem it neccessary.
 
Piston heighth isnt any different I dont beleive..And by this..I mean center of Crank journal to Piston Face heighth.

....but the time it sits at TDC is different and how long in the rotation it takes for the piston to make its way downward is also slower as it starts to travel if I understand the Theory correctly.
I just wondered if this extra "Dwell" time at the top, would cause interference if I did happen to break a timing belt?

the dwell doesnt really matter if the belt lets go, its if the piston will touch the valves or not
 
I guess your right..once the belt breaks..Its free rev independantly for the crank and the valvetrain...

If its gonna hit..Its gonna hit.
 
Oh..and to answer this guys question...

Since its confirmed that its a Non-interference motor..I would say you are safe to wait until 90K or longer if you deem it neccessary.

Thanks, guys....here is a paste from the Dayco timing belt catalog...which says the FS motor IS an interference motor. You all seem pretty assured that it's non-interference--have any of you actually confirmed non-interference on your own? (I'm in "trust but verify" mode, and am not quite sure who to trust....) I have seen conflicting info...

2003 MAZDA PROTEGE5 - L4 2.0L 1975cc GAS FI N
Belts / Tensioners / Pulleys
Part Number Description
5040362 Alt. & W.P.
New Specification
5040365 Alt. & W.P.
5050460 Comp. & P.S.
95228 Timing Belt (Camshaft)
Interference Engine
 
I have, ive been through a motor (not my own), plus xelderx has done about 5 built motors and confirmed it. its not interference despite how its documented.


Thanks, guys....here is a paste from the Dayco timing belt catalog...which says the FS motor IS an interference motor. You all seem pretty assured that it's non-interference--have any of you actually confirmed non-interference on your own? (I'm in "trust but verify" mode, and am not quite sure who to trust....) I have seen conflicting info...

2003 MAZDA PROTEGE5 - L4 2.0L 1975cc GAS FI N
Belts / Tensioners / Pulleys
Part Number Description
5040362 Alt. & W.P.
New Specification
5040365 Alt. & W.P.
5050460 Comp. & P.S.
95228 Timing Belt (Camshaft)
Interference Engine
 
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