Bill Ball

When doing the TB on my 89 I decided to replace the oil pump gear. The original oil pump gear is anodized aluminum at least through 89. The replacement gear from Porsche is steel. I popped on the new gear and was buttoning things up when I noticed a cryptic note on page 17-5 of the WSM associated with a diagram of the area stating "22x16x1 shim - use only together with light alloy gear".

So, I pop off the new steel gear which looks to be located OK and sure enough there is a shim behind it, trapped by the woodruff key. and comparing the steel and aluminum gears, it is clear that the steel one has a boss on the inside that is 1MM higher than the original.

A silly MM. It doesn't look like the gear will hit the cover or that the belt won't be fully on the gear.

Is there an easy way to get a stuck woodruff key off?

How many people have put the steel gear on and never knew about this?

SharkSkin

Liquid Wrench. Let it sit for a bit, then, backing the shaft on an anvil or the anvil plate behind the jaw on a vise, tap gently on either end to see if you can get it to rock. Be gentle, you don't want it to mushroom and wedge in there even tighter! You just want to see if you can get it moving with the gentlest of persuasion. Failing that, try to get a small sharp cold chisel up under its edge, on the circumference, to lift it out. Failing that, get a thin dremel cutoff wheel of a similar radius to the woodruff key(resize a wheel using a rock if necessary) and just cut right down the length of the key, leaving the sides stuck to the shaft. Once you get the center part out you should be able to use a small drift on the edges of the key to pop the halves toward the center of the groove.

Float the new one in there on a nice thick glob of anti-seize.

Or, get the 1mm boss milled off the gear

Jim R.

Bill,
I recently replaced mine, but I am not sure/can't remember if my replacement was steel of aluminum. I don't recall the new gear being heavier than what I took off. The part number was 928.105.125.12. The crank gear I replaced was definitely steel and much heavier. My new belt rode just fine on all the gears- centered and no wobble. I left the shim in place and have no clearance issues.

Jim R.

Bill Ball

Hi Jim:

The PN you listed above is the crank gear.

My original oil pump gear is stamped 928.107.107.11. The replacement is stamped 928.107.107.13

According to the PET, 928.107.107.11 was dropped and replaced by ...13, so everyone is getting the steel oil pump gear now. I bought the gear over a year ago. So, if you did this recently, you have the same dilemma as I am facing.

Bill Ball

No vise or anvil can be used in this case as the shaft is on the car. If the key does not come out with a few taps on the leading edge, I'll just put the old gear back on for now, I guess.

So, I guess Porsche went to the steel gear for later cars to get better durability, determined the shim was not needed, eliminated it and created a bit of a maintenance problem for earlier cars.

SharkSkin

I guess you're not very determined to get it out... the oil pump is held in by what, 3 screws?

PorKen

The 78-79's had steel cam gears too!

Engine weights, lbs:
78-79 573
80-82 540
83-84 575
85-91 582
92-95 586

Bill Ball

Dave:

I wasn't planning on taking out the pump. Seals are fine, etc. Glad to hear it is easy - not done it before.

The key came out easily after all and the new steel gear is in place without the shim. I can't see how that one MM makes any difference if left in. I can see that it is not needed with the steel gear, but, so what?

So, is this oil pump gear trivia?

SharkSkin

Oil pump seals, from what I've heard, are a big WYAIT item. Glad to hear yours are OK. Also glad the key came out OK. Sometimes they act like they are going to be stubborn, then wimp out right away when you show up with the "proper"(BFH) tool...

Bill Ball

I have the seals to do the oil pump and agree it is a clear WYAIT candidate. I wimped out because I am running out of time and I need to button this up. Might botch a seal and be stuck for another day. I messed up my right arm in a wrench accident last Sunday when I started this (wrench slipped, metal fan shroud mounting tab on top of radiator went deep into arm- still hurts a week later), so this has been going slowly. Should be done tonight despite all the time taken nursing my arm.

SharkSkin

Ouch! That really sucks. It takes real determination to forge ahead when you're hurting like that. Funny how you end up forgetting about it till you bump it again, eh? I understand too about not wanting to dig into something that may strand you. So what's the rush? Driving event next weekend?

Bill Ball

No driving event next weekend. Just gott clear out the garage (I have stuff all over) so we can put my wife's car back in.

We will have a drive down the coast in September. News about that soon.

Jim R.

Hey Bill,
Hope you got it all back together without further injury. Sorry about the wrong part #, I was feeding my 11 month old at the time. I must have gotten old stock for my gear, because it was anodized like the cam gears, and weighed the same as the old part so I am not too worried about the fitment. Thanks for the correction and good luck with your project.

Jim R.

SharkSkin

I hope that drive isn't the first weekend of Sept. or I won't be able to make it...

Nicole

Hi Bill:

I'm sorry to hear about yoru injury! Hope it is healing well!!!

Don't forget that we are here when you need help!