Oil Pump Gear
I know that I should replace this if you can feel any groves with your finger nail. Should it be smooth from green arrow to green arrow or red to green arrow? On mine I can feel a grove right around the red arrow. From the records I have I don't see where that gear was ever changed at any of the previous timing belt changes so I believe this gear has 134k miles on it.
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Tom
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One of my better-honed skills is encouraging other people to spend money, so it should come as no surprise that's I'd second the suggestion to replace that gear. 
So I got the replacement gear yesterday and I can't get it to slide on like I could get the original to slide off. The original one slides on and off with a little wiggling back and forth where the new one pretty much gets stuck in the first half inch.
Am I correct in guessing that the original one has just been worn down just enough to allow it to slide on and off which is the difference in the tolerances?
I'm guessing the best way to get the gear on is to put it in the oven and let it expand? I've never done that before so the question is what temp should I set it to and how long? How hot is enough to get expansion to go on? I've got a thermal camera to monitor the part as it heats up. Is it safe to use our regular toaster oven or spent $100 to buy an oven just for that kind of use?
Am I correct in guessing that the original one has just been worn down just enough to allow it to slide on and off which is the difference in the tolerances?
I'm guessing the best way to get the gear on is to put it in the oven and let it expand? I've never done that before so the question is what temp should I set it to and how long? How hot is enough to get expansion to go on? I've got a thermal camera to monitor the part as it heats up. Is it safe to use our regular toaster oven or spent $100 to buy an oven just for that kind of use?
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Tom
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Hmmm.... I don't remember needing to heat it to install. Is the end of your crank rusty or dirty by any chance? Maybe polish it a bit with some fine emery cloth, and dress any nicks in the woodruff groove? Also make sure the inside of the new gear is cleaned and oiled. Sometimes they ship with stick Cosmoline-like coatings...Richey wrote: Mon Jan 12, 2026 6:36 pm So I got the replacement gear yesterday and I can't get it to slide on like I could get the original to slide off. The original one slides on and off with a little wiggling back and forth where the new one pretty much gets stuck in the first half inch.
Am I correct in guessing that the original one has just been worn down just enough to allow it to slide on and off which is the difference in the tolerances?
I'm guessing the best way to get the gear on is to put it in the oven and let it expand? I've never done that before so the question is what temp should I set it to and how long? How hot is enough to get expansion to go on? I've got a thermal camera to monitor the part as it heats up. Is it safe to use our regular toaster oven or spent $100 to buy an oven just for that kind of use?
The old gear is 27.97mm the new gear is 27.88mm. The shaft it's self look clean with no burrs and no visible rust plus it feels smooth to the touch.
When I first tried this I used some fresh oil to lube the inside of the gear and the shaft. I went back and cleaned both surfaces with some break parts cleaner and refilled and tried again. I can get it started and could with very little ease tap it on a bit but then I have to use a gear puller to slide it back off. My concern is I can't rotate it on the shaft and being this tight once it's on it will be on and difficult to remove.
When I first tried this I used some fresh oil to lube the inside of the gear and the shaft. I went back and cleaned both surfaces with some break parts cleaner and refilled and tried again. I can get it started and could with very little ease tap it on a bit but then I have to use a gear puller to slide it back off. My concern is I can't rotate it on the shaft and being this tight once it's on it will be on and difficult to remove.
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Tom
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Factory part? I'm sure you could heat it up a bit with a torch or heat gun to get it on if needed, but I'd almost be inclined to try a different source for the gear just to see if they are all that tight. Or maybe I'm mis-remembering -- I thought they slid on (tight) without heat. Maybe Porsche added a bit more interference to rely less on the front bolt torque to turn the pump?Richey wrote: Mon Jan 12, 2026 7:32 pm The old gear is 27.97mm the new gear is 27.88mm. The shaft it's self look clean with no burrs and no visible rust plus it feels smooth to the touch.
When I first tried this I used some fresh oil to lube the inside of the gear and the shaft. I went back and cleaned both surfaces with some break parts cleaner and refilled and tried again. I can get it started and could with very little ease tap it on a bit but then I have to use a gear puller to slide it back off. My concern is I can't rotate it on the shaft and being this tight once it's on it will be on and difficult to remove.
the metal flanges / races for my balance shafts were incredibly tight. my oil pump pickup gear was not difficult to get on though.
Id try Tom's suggestion of emery polishing the crank - the smallest burr can cause a lot of grief.
Id try Tom's suggestion of emery polishing the crank - the smallest burr can cause a lot of grief.