Doug,

I know you have been tracking oil pump drive gear failures on 6 cams and I would like your opinion on a similar failure on my 2.2l (4) turbo motor.

This past weekend the drive gear on my oil pump stripped a number of teeth off. Since the distributor is driven by the oil pump the engine stopped.

The mating gear is not on the cam but on a seperate intermediate shaft that is driven by the cam belt. The teeth on the intermediate shaft has chipping along the leading edge of the teeth (no more than 0.020" down onto the face of the teeth) but are other wise not showing excessive wear (no knifedging or excess wear on the face of the teeth.

I have no idea what caused this. The car has had a steady diet of synthetic oil since it's second oil change and I have not had any oiling problems in the 175,000 miles I have put on it. At least from prying on the intermediate shaft through the distributor hole I do not feel any play in the intermediate shaft bushings.

I would like your opinion of what I can expect for a life expectancy of a new oil pump if I replace it without replacing the intermediate shaft (I can get access to the shaft gear from underneath and will use a stone to smooth off any burrs from the chipping).

Am I likely to burn out a new oil pump gear in 10's of miles, 1000's of miles or 10,000's of miles?

It's interesting to note that oil pumps, oil pump rebuild kits (with and without the drive gear) are readily availble but the intermidiate shaft is a special order from the dealer.

Thanks,

Dave



dave.clement@motorola.com

You are lucky, most Slants keep running and burn-up the bottom end.
:
: The mating gear is not on the cam but on a
: seperate intermediate shaft that is driven
: by the cam belt. The teeth on the
: intermediate shaft has chipping along the
: leading edge of the teeth (no more than
: 0.020" down onto the face of the teeth)
: but are other wise not showing excessive
: wear (no knifedging or excess wear on the
: face of the teeth.
:
: I have no idea what caused this. The car has
: had a steady diet of synthetic oil since
: it's second oil change and I have not had
: any oiling problems in the 175,000 miles I
: have put on it.
: I would like your opinion of what I can expect
: for a life expectancy of a new oil pump if I
: replace it without replacing the
: intermediate shaft (I can get access to the
: shaft gear from underneath and will use a
: stone to smooth off any burrs from the
: chipping).
:
: Am I likely to burn out a new oil pump gear in
: 10's of miles, 1000's of miles or 10,000's
: of miles?
:
: It's interesting to note that oil pumps, oil
: pump rebuild kits (with and without the
: drive gear) are readily availble but the
: intermidiate shaft is a special order from
: the dealer.

In our research into SL6 oil pump gear failures we found the same problem in other engines.
It is a complex problem with many possible causes, it is hard to say why yours failed.
One thing that we found is that the cam (drive) gear is bigger / harder then the oil pump gear. One test we are doing is to lap smooth the oil pump gear teeth and heat treating the surface (case) harder.
Time will tell if this helps solves the SL6 failure problem.
(If you send me your failed 2.2 gear, I can check the Rockwell hardness (Rc)
As for your repair, give it a try, do "stone" the rough edges as smooth as possible. If your drive gear is damaged like the one below, it will chew-up the new oil pump gear fast.
DD

That's likely the reason for driving the distributor of the oil pump.
:
: In our research into SL6 oil pump gear failures
: we found the same problem in other engines.
: It is a complex problem with many possible
: causes, it is hard to say why yours failed.
: One thing that we found is that the cam (drive)
: gear is bigger / harder then the oil pump
: gear. One test we are doing is to lap smooth
: the oil pump gear teeth and heat treating
: the surface (case) harder.
: Time will tell if this helps solves the SL6
: failure problem.
: (If you send me your failed 2.2 gear, I can
: check the Rockwell hardness (Rc)
: As for your repair, give it a try, do
: "stone" the rough edges as smooth
: as possible. If your drive gear is damaged
: like the one below, it will chew-up the new
: oil pump gear fast.

Doug, thanks for the input, I will send you the oil pump gear.

The teeth on the drive gear on the intermediate shaft do not look as bad as the cam gear in your photo but that is the type of damage though. The middle teeth on the lower left gear are more similar to the damage I have.

Since I have two other vehicles that I can be driving I think I will just take the extra time and do it right by swapping out the intermediate shaft too.

Thanks again,

Dave Clement


dave.clement@motorola.com