Oil Pump Upgrade

I read on Renntech that there is an upgraded oil pump piston and spring that is a useful upgrade to increase low RPM oil pressure. The piston is beveled to solve a sticking issue (?) and the spring is slightly longer. Has anyone done this upgrade or have an opinion about it? Does it apply to all 996 models or do later ones already have either the newer spring or the piston?

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Here's a link to what I found: http://www.renntech.org/forums/topic...essure-solved/

It's a 997 component. It helps mostly with hot idle oil pressure. I use these in all my engines.

While you are in there- upgrade the oil pump drive shaft.

My oil pressure is OK at hot idle - just below 1 bar is lowest I have seen after a workout - but this seems like an easy and inexpensive upgrade so I plan to do it. I just wanted to check the experience base here to be sure there wasn't a downside that I was missing. Thanks Jake for the feedback. And yes, that link to Renntech is where I read about this. I will have to do a little searching on the drive shaft upgrade. Is this a LN billet piece I seem to remember?

No research required because yes, it is an LN part. It is beautifully made and so simple to fit.

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My first on- track engine failure of a reconstructed engine in 2008 prompted these to be manufactured.. I had a factory oil pump drive fail, and it cost me 25K. I halted all engine builds for 6 months while we developed and tested the billet oil pump drive key. Since then, none have failed. I had one not long ago that ate a huge chunk of debris through the oil pump, but the hex key still didn't fail. (owner had installed his own deep sump kit and removed the oil pick up tube screen. He left a bolt loose that held on an oil de- foamer and it was sucked into the oil pump) Can't fix stupid, but you can charge for it. He called himself stupid before I did!

Man, would I like to post this in my office, on some days.

OK, here is a related question. On my 2000 C4 the original oil pump has the number 996.107.012.57, which if you look it up supersedes to 996.107.012.61. Back when I had my intermix in '08 and fixed the engine in '09 I thought I had a problem with the oil pump. I bought one, that was brand new, on eBay. When I received it the number was different (can't see it with the pump/engine in the car) and the casting was slightly different. I looked the number up at that point and it was listed for a Boxster. In any case I installed it on my engine and have been running it for almost 50,000 miles (it turned out the oil pressure problem was related to installing the scavenger pumps reversed). So my question is whether there is a difference in the pumping capacity of the pumps for the 996 and the 987? When I look up the part numbers for 996 and 987's they all show 996.107.012.61 now. Maybe Jake will know as he is the expert on all these M96 engines.

So for this upgrade one will need: 1 x Piston 997.107.125.01 1 x Spring 996.107.127.53 1 x Gasket 996.107.123.50 Is this the LN's product mentioned in previous discussion? Apparently will need an engine out to replace this?

Those are the p/n I ordered for the upgrade. I can't comment on the drive shaft.

Rockhouse, How's the car? Seems like you got a good one. Did you fix the center console? I still love those wheels.

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Yes, I think I got a good one. Must have been your good advice I had the console covered in grey leather and repainted all of the plastic stuff so it all looks really great now. I had the wheels refinished and they look new. You would really like them now!

TL;DR - installed in 2003 996 @105k miles and saw no change Installed the piston & spring this weekend, and my (inaccurate) OEM dash oil pressure gauge reads exactly the same as before. Even with some serious autox/long idling/heat soak I see 1.25 BAR at hot idle. Was hoping I'd see a little bump, oh well it was very cheap and took 3 minutes. I'm slightly tempted to play around with shimming the spring with washers to see if that raises the oil pressure like you could with old SBC pumps. Expensive motor to fix what ain't broken though. Heads up - the old piston can get a little stuck up in the bore, had to stick my finger up there and work it out.

Looks like you just found another part of the equation.. If the relief valve is sticky to remove, often the housing bore has been galled by foreign object debris passing between the piston, and the bore. This can also come from extended oil service intervals. Remember, this surface is NOT protected by the oil filter. The oil filter is AFTER the oil pump. If the relief bore is galled, the relief valve will not seal, or will **** sideways in the bore. I've developed a tool and process to restore this oil valve seating, and guide surface. This is often what leads to lower oil pressure within these engines. You might pull the relief piston out again, and ipecac the inner diameter and seating surface very well. This is what those wonderful extended oil services that the factory recommends are good for.

Thanks for the extra info guys. I have the parts to do this upgrade and will do so at my next oil change. And remember to inspect the old piston and bore for galling.

Hello Guys, I am new here and I would like to confirm the Chromoly Oil Pump Hex Drive 106-11 from LN, is this correct? Thanks all for the info on the forum Jake, I try to read all your posts getting into the youtube videos also. Thanks again

I installed these upgraded parts. The spring was identical to the one I removed, but the piston did have the bevel on the end which my original did not. I am guessing that the spring was introduced earlier than the beveled piston and my 8/2003 built car already had the spring upgrade.

Great thread! I'll definitely be doing this on my winter tear down. I already had the hex drive but, I wasn't aware of the spring and piston.

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Do you have any instructions on the install? I'm considering doing it with my next oil change but hate to buy a part only to find out that I'm incapable of installing it. I don't see anything on LN's website.

Bumpity bump.

Which way does the beveled edge face? Up to the roof of the car or down to the ground?

Beveled edge goes up, toward the sky. The spring fits inside the piston, so it will only go one way.

Thanks Jake, you're always a help. I typed the question before taking the new valve out of the baggie. It was all covered up by the parts label and I didn't realize it was hollow. Doh. Who happens to know what the torque spec is on the oil control nut?

Torqued to 18ft/lbs

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👍🏻

I tested the stock oil pump drive shaft to failure torque, the stock oil pump drive shaft fails at 54ft/lbs torque. I tested several to make sure the first one wasn't faulty. I made my own drive shaft from an 8mm Mac Tools Allen wrench and tested it to failure 153ft/lbs !!! Almost 3 times as much. So I make all mine out of Mac 8mm Allen wrenches now. I have 3 cars, a 99 coupe, 99 cab, and an 02 986, plus I made a few for some friends, Quite simply you just cut to length. I have not tested the LN drive shaft, but I'm sure it is much better than stock also. If someone wants to send me one to test, I'll be happy to see what it takes to snap it into. Three stock oil pump drives all three stock oil pump drives failed at 54ft/lbs simple but effective test rig Tool steel oil pump drive made from Mac 8mm Allen tested 153ft/lbs

Sorry for the huge pictures.. they were not that big when I loaded them..lol

Nifty! I didn't know what the drive shaft looked like until I saw a picture of one on Ahsai's rebuild thread. Looked like a pretty simple short hex shaft. Your post confirms it. Maybe there are other engineering parameters beyond just torque to failure but I wouldn't think there would be with such a short piece. For example, torsional or harmonic stuff.

[/QUOTE]Maybe there are other engineering parameters beyond just torque to failure but I wouldn't think there would be with such a short piece. For example, torsional or harmonic stuff.[/QUOTE] The torsional load was considered and the observation is the stock oil pump drive is extremely hard and brittle, so brittle it would not twist at all, but rather fracture like glass at 54ft/lbs. The tool steel would twist and return to shape at 100-135ft/lbs, above 135 it would not return to original shape and at 154ft/lbs it failed.

Can you change the hex shaft by removing the oil pump cover? Six screws roughly? Car is not here just now so I can't just look. If you pull the cover, will the driven gear just pull out? will the drive hex then just pull out, or are there bits that may fall out of place? Lang G

Very interesting thread. So can you change the hex shaft with the engine still in the car?

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Yes, by removing the cover the gears will pull out and then the drive will pull out. On the 996/7 to access the cover you will need to lower the engine and remove cats and engine mounting plate, on 986/7 the engine will need to be lowered and the engine mount removed.

PorscheTech3 " I made my own drive shaft from an 8mm Mac Tools Allen wrench and tested it to failure 153ft/lbs !!! Almost 3 times as much. So I make all mine out of Mac 8mm Allen wrenches now. Thank you for sharing this in Post 27 above. Since you have this mod in 3 cars ,it is a reasonable road test of the upgrade. This leaves the oil pump drive shaft upgrade deniers no (financial) excuse for not doing it. One caution, I would be hesitant to use a "made in China" allen wrench for this. Unless the wrench has a clearly stated (reputable) country of origin . stick with SO, Mac .Proto and similar. Thank you for sharing your upgrade with us.

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Your Welcome !! One caution, I would be hesitant to use a "made in China" allen wrench for this. Unless the wrench has a clearly stated (reputable) country of origin . stick with SO, Mac .Proto and similar. Exactly !! I used the Mac Tools hex because it was the first one I had tested after the testing the factory hex drive, and was extremely please with the results. I have no idea who makes these Hex Keys for Mac or if they make them themselves, but I would not be surprized if all the top tools companys (Snap-On, Mac, Matco, Proto )do not use Bondus Hex Keys Protanium Steel http://www.bondhus.com/features/protanium/body-1.htm [url] . I will do a test on this steel to see if it the same. FWIW.. A bit of information on the 997 pressure relief piston , it was designed as a cure for an unusual noise/screeching at cold idle on the early 9x7 cars. I was involved in this factory concern in late 2004. when we first discovered that the noise was coming from the relief piston we ground the chamfer on the then 996 valve to eliminate the noise. Then the 997 valve was designed and used in production and to supersede the 996 valve, the spring has not been superseded.

Just an update on the oil pump drive shaft hardness. I tested the factory drive shaft and it measured from 32-37 Rockwell C varying at different points. then tested the one I made from a Bondhus Protanium hex key , it tested 54 Rockwell C,. So the stock drive shaft not only is more brittle, and fails at 1/3 the torque, but also is less hard too !

Very interesting and informative thread. Good to see alternatives and their characteristics as opposed to the OEM drive shaft.

Awesome!!!! Well done!

FYI- Since 2008 LN Engineering has manufactured a billet oil pump drive key. This was a development that we carried out, after experiencing our first drive key failure on track. EVERY engine I have built since that has included the billet drive key.

So what are the actual measurements of the oil pump drive hex key ? So far I've got 8mm what's the length ? It looks like it might be 2"/50mm ? Of course exact #'s are always welcome

It would be nice to know the length also.

I'll dig up mine and measure it.

Thank you IMO. That would be great because then Forum Members could try the tool suggested by Porschetech3 - the depleted uranium (whatever he found?) 8mm hex wrench cut down to your length.

i've been wondering about the piston upgrade. i make a habit of checking the PET for upgraded part numbers and then trying to determine why the change (i AM a geek) - ie, AOS has 5 or so interations, so common sense says use the latest and hope that porsche has engineered-out the earlier failure modes in the later version. of course porsche wouldn't advertise that earlier versions are problematic, so caveat emptor and up to a diligent owner to figure these things out. ditto chain tensioners, chain pads, and a few other parts. i did the piston upgrade (5 minute job at your next oil change - different story pump drive) and saw a reduction in start-up chain rattle which supports the high oil pressure at start-up due to cold oil and piston binding theory. what i am wondering is - this piston is also the oil bypass valve on the oil pump yes? ie, when the oil pump experiences high oil pressure the piston moves and oil oil bypasses back to the sump, correct? if so, one of the theories on the oil starvation issue is that the oil is pooling in the heads because of scavenge pump location in the heads - i am wondering if the pooling oil in the heads is causing a high pressure situation and the bypass valve is activating? perhaps a stonger spring would help with the problem?

Yes.And welcome to geekdom Mr. Radium! In a normal engine there are plenty of drain holes to replenish oil in the sump.In this configuration we rely on those two English scavenge pumps. If they can't "keep up" as the Brits would say, the accumulating oil in the heads will cause oil smoke in the exhaust and maybe dangerously low oil level in the sump ? Solution - a partial at least may be to have a deep sump and reduce revs when you see oil smoke ?

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thanks. i get that the pooling is reducing the amount of oil in the sump, but from other threads on the issue, a deeper sump (ie, more oil) doesn't help - check the thread on the new boxster dry sump in development. so, if it is not a lack of oil, then i was thinking perhaps the bypass is the cuplrit - the pooled oil is fighting the oil pump and forcing it to bypass back to the sump. so, perhaps making the bypass activate at a higher pressure might help? or not; if this was soln then jake or LNE would have a soln on the market by now?

Qumulus had a few recent posts on an aftermarket dry sump system his buddy was developing . I'll try to find and repost it. Basically his buddy had tested various deep sump systems and Accusump for Track and found them all wanting. After destroying several engines trying to develop a better system ,he found the answer. And all will be revealed bu Mr. Q. soon -I hope. Here it is: https://rennlist.com/forums/racing-a...mp-system.html

Oil pump drive shaft length - measured on my MY98 Boxster is 50mm.

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bump with a few photos of the presumably original 2003 C2 parts vs. the updated 997 parts. I haven't installed the updated hex drive shaft yet, but it's sitting on my desk. The bolt on mine was really cinched on there, but once loose it was easy to undo it. I just used a fat finger to plug it while I checked out the differences between the old & new. After a drive around town to get gas & drop off some old oil, the oil pressure was reading a bit over 1bar at idle. The swap only required a refill of around half a quart, not as bad as I expected. 17mm wrench did the trick, had to use my pinky and eventually a small scredriver without a bit on the end to get the piston to work past the rivest for the bolt. Once out it was easy to plug it & compare & contrast. New spring a few mm longer than the old one. New piston clearly shows the bevel on the edge. All looking good according to prior advice. new piston on top, old on bottom old spring on top, new on bottom new unit prepared for installation As always, thanks to the contributors of the thread for making this low stress & easy to replicate!