Hey, all, I have an old Ford dump truck with a straight 6 300 (it's an
> F-500 from 1970). I got it used a few years ago and it knocked pretty
> badly and finally threw a rod yielding a viewport on the side of the
> block. I replaced the engine with a rebuilt one from a machine shop
> I've had good luck with in the past. I don't use it often, it
> probably has less than 1,000 miles on the engine but it's past the 12
> month warranty. Recently it quit running, leaving me on the side of
> the road. Today I tore into it and found the phenolic timing gear was
> stripped of all but 5 teeth. This wouldn't bother me so much except I
> had a 1986 F-150 with the 6 in it strip that gear. That was an old
> engine and I found that the oil pump pickup tube had some junk in it
> and I ASSUME that junk was sufficient to block the oil pump and strip
> the timing gear (which drives the cam which drives the vertical shaft
> which drives the oil pump and the distributor). I hate coincidences
> and this bothers me; two gears on basically the same engine, one used
> (that one in the old F-150), one new (the rebuilt engine in the
> F-500). What's worse is that I checked the pickup tube on the rebuilt
> engine just because I had that past experience.
>
> Has anybody got a, "Oh, hey, here it's this!" answer to the problem?
> Any pointers on what I should look at or for? I don't want to replace
> the gear without understanding what caused the failure because it
> could happen again all too easily.
>
> Thanks for your help and advice.
>
> --HC
That was not an uncommon problem in the 300I6. The solution is to replace with an alloy timing gear. I have one in an 82 F250, the phenolic gear lasted about 180k and was still useable but I replaced it when I rebuilt the motor.
Dave D