I was helping a friend change his oil filter today. Got it all back together, topped up the oil, cranked her over and all of a sudden a stream of oil sprayed out from the back of the cannister from where you the bolt goes through it. The stream shot about a metre out in front of the car and there was oil spewing out for quite awhile afterwards. I guess his oil pump works well enough.

We'd run out of time, so we couldn't investigate it.

Can anybody tell us what the setup is here?

Is it bolt, then washer, then rubber seal of some description, then cannister?

I'm guessing the rubber seal has become brittle and died. Otherwise, could we have cracked the cannister?

Yep it goes
Bolt > Washer > Seal > Canister.

I would guess that it is missing the seal or the seal is split.
I doubt that you have cracked the canister.

When you buy a filter it used to come with 3 seals- the one under the bolt head, the flat one against the filter, and a big one to fit in the filter head where the canister seals.
Sadly, a well known Australian (were) filter maker now omits the 2 smaller seals.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks guys.

Apparently, the seal after the washer was shot. I just heard from my mate, he managed to pick up a NOS housing, complete with the bolt and all the seals. Problem solved!

I felt sorry for him. Oil changes for an automatic with the long cannister and an a/c compressor in the way aren't easiest. He had the filter out twice today. Not to mention all the oil he dropped. Poor bugger!