yep Brewski has a good point, a sticking relief valve could very well be the cause. I wasn't going to qualify myself with my years in this field of work because i don't feel that is necessary, but I've been in lifttruck business since 1977 so like him i've seen alot and learned alot also ;o)

but all of the mentioned possibilities are most certainly things to check

sticking relief valve, clogged return filter, customer abuse situations, and just plain old sub-par aftermarket parts.
If they have other units and they run fine the parts scenario is just a slim possibility though, based on that there has to me some other scenario causing it to blow out the end housing.


As for your question about the sprocket and chain and bearing alignment where it mounts?
i think you would hear abnormal noise or see damage to the shaft end of the pump, or see broken chains or gears before it would blow the outer end housing like that.

Like brewski says, over pressure being created from somewhere is the problem, and the weak spot is that end housing on that pump.
The fun part is just figuring out what is causing it.
what mrfixit said is a big possibility, is why i mentioned the accumulator part, checking that, but even if it is working good an abusive situation like he describes would still create havok on the systems tolerances. Somethings gotta give ;o)