Timing Belt Longevity

[andymoraitis]

I was wondering f some of you could tell me how long you've run on a timing belt before replacement on your 420A's. My car has 126K miles on it and I did the first change at 65K and was thinking that this thing was likely about to go in the next 5 or 6K miles, but after ripping off the safety cover and inspecting the belt, there are no frays, wear marks or other evidence of immediate problems.

Any feedback would certainly be appreciated and a definite answer as to whether breakage leads to valve train destruction would help as well. It seems that even Mitsu mechanics aren't sure since sometimes breakage creates damage and sometimes it doesn't.

Thanks in advance,

Andy

 

[dr1665]

The 420A is an interference motor. By design, if the timing belt breaks at just the right moment, you will have valves extended downwards and pistons coming up and saying goodnight to them. I've known one person to snap a timing belt at 70mph who got lucky enough to be at TDC when this happened and there was no damage, but more likely than not, if it goes, you're looking at some bent valves and maybe even dinged up piston faces too. Change her out at 130 imo.

 

[Defiant]

Unfortunately, timing belt health can't be seen. What most often takes them out -other than mechanical interference (other belts nearby failing, gravel in the belt, etc.)- is the crank sprocket shearing off the teeth it's engaging. And, it most often happens at idle, when the cams can exert the most resistance between the crank and each other. Years of age make a cam belt more likely to fail.

 

[andymoraitis]

Thanks for the feedback and also the advice. Guess I'll change that sucker in the next few thousand miles as I'd like to avoid unnecessary damage.

Many thanks again,

Andy