Oil Pump Cover Chamfer -- Cont. A-65-8

[larrysmith1016]

I'm rebuilding an A-65-8 Continental. The oil pump cover plate also serves as a bearing for the pump drive. The plate's hole for the drive shaft is chamfered on one side, but not on the other side. I can't tell from the manual which way the chamfer on the oil pump plate goes -- inside or outside. New gears, rebuilt rear case, and new plate -- so I don't want to mess up.

Thanks in advance for a little help from an engine guru. The engine is for an experimental.

[NY86]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

The chamfer matches the radius where the pump gear meets the shaft.

[larrysmith1016]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

The chamfer matches the radius where the pump gear meets the shaft.

Thanks. We got the thing worked out, got good numbers on most of the clearances inside the oil pump by the Continental Service Manual. Everything was new but the pockets. We used Plastigage, eyeballs, mikes, and feeler gauges. Then for the moment of truth.

Good oil pressure until the airplane flew a while and then the pressure took a dive. Owner came in scowling. The pressure had fallen to near zero.

Looks like I'll be tearing the whole dadburn engine down again.

How about some of you Continental A-65 gurus telling me what you think it might be. I suspect we got an internal leak robbing us of oil pressure somewhere inside the bottom end.

I was thinking about pulling the rear case from my BC12-D and trying it. It is a known quantity, keeps 15 psi at idle and 35 psi at cruise, no matter how high the oil temp.

[3Dreaming]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

If the pressure drops off like that when it's hot it most likely is the case/cam bearing area. Tom

[Ragwing nut]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

Oil pressure on small Continentals is directly related to the front case cam bearing and the front journal of the cam. Those have to be perfect to have hot idle pressure. I make sure anymore to have the cases line bored to match the cam that will be used to get min new tolerance.

[Dick Huish]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

Had one like that. Turned out to be a crack in the case. Same symptoms. Dick

[larrysmith1016]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

I suspect the problem is with the front cam journal. Thanks for that. I remember measuring those clearances and advising the Flybaby owner to send the case off--- but he balked at the cost.

Thanks so much for the advice from everyone. We DID rule out a lot of the other things like a faulty oil pressure gauge, bad rear case, bad crush washer on the oil pickup, etc.

While I'm on a spending spree, I guess I'll order new BC12-D struts from Alaska. Mine still pass but one of them has a dent I never did like.

Bye for a while.

[Hank Jarrett]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

Yea, I have 4 BEAUTIFUL struts in the hangar, but the hassel just makes me want to throw in the towel and buy sealed struts. I STILL get mad when I think of that whole fiasco.
Hank

[Mark Julicher]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

I have a yellow-tagged case.
PM me if you want details.

[astjp2]

Re: Oil Pump Cover Chamfer -- Cont. A-65-8

I have seen a C-85 cover used with 2 A-65 drive gears, one being modified and cut off shorter so there are 2 pinions for the idler gear. this is used a lot on the Reno F-1 racers...Tim