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If only the silicone gasket manufacturer wasn't cheaping out by not include crush sleeves with the gasket, life would be a lot better and so would be customer feedback.With the crush sleeves the bolts can be properly tightened and you don't have to use band aids like Loctite.
The point is you don't need a gasket here at all as they all just eventually leak, be it tomorrow or 30 years from now. However, in my limited experience, it seems the cases don't leak. I had nothing but problems with the gaskets until I ditched them all together. You don't need the gasket. Are you really ever going to take the oil pan off unless the gasket is leaking or you have a fatal catostrophe? Probably not. Clean it up real well, make sure it's all clean and flat, and get peace of mind
I followed the "snug them up and add threadlocker" protocol until....
dr. bob: I am using this method for the time being. the touch, plus half a turn, is MUCH tighter than what
I did a few months back. I was, perhaps, too careful, with tightening and went to touch, and then a tug.
I found the PO receipt for the oil pan gasket that was done <8k ago. I "want" to believe that my gasket
could, should, still be good??
I believe a new gasket will help hold the bolts in better than an old one. The old gasket has lost some of its spring, and when you snug up the bolts it gradually starts to relax and stays deformed instead of pushing back like a spring. So you lose clamping force and then the bolts back out more easily.
Decide what it's made of, as the torque/squeeze is way different between the silicone vs the composite gaskets. Use a sharp probe to test if the answer isn't already obvious. If it's a composite cork-and-neoprene gasket, follow the Porsche-recommended 5 lbs/ft recommendation with threadlocker on clean bolts and holes. This is one place where Brake Cleaner is the cleaning weapon of choice. 5 Lbs/ft is way too low for even a 3/8-drive click wrench, so you will be looking for a 1/4"-drive that plays in lbs/inch and scaling the lbs/ft number times 12 [inches per foot], or about 60 lbs/inch. This torque is small enough that getting everything even takes some care. Push the sump up by hand and tighten the bolts until they are just touching. Then go after them a couple flats at a time, until they all reach 60 lbs/inch at about the same time. Better to sneak up on the 60 lbs/inch in increments of 10 so they really do stay even. The sump is relatively stiff so snugging one too much will cause you to tighten all the ones near it by too much, even though the wrench shows the correct number. For those bolts that won't allow access with the standard torque wrench, there are a couple options. One is a crowfoot end if there's room, with a correction based on the center-to-center offset as a fraction of a foot. Otherwise use a box-end wrench and tighten to match the feel of the bolts ou can access with the torque wrench.
The silicone gasket still demands the touch-plus-turns method, as the gasket is so soft that it will squeeze and distort before you see a change in torque applied, at least using common click-type wrenches. There are some interesting strain-gauge torque meters, interesting but not really necessary for letting the gasket do its job.
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No gasket? Yes, it's readily possible with the sump and girdle fitment we have under the 928 engine. A few decades ago now, a project Jaguar six-cylinder engine had the common problem of seeping oil as the engine temp changed. Even in pre-anaerobic gasket maker products, an available Loctite silicone sealant at the time made short work of the problem. The more modern solutions allow you to disassemble without lifting the engine and cutting the silicone out. Cleanliness is absolutely critical to success with either method.
AD0911 with the studs in the block you cant swap in a new gasket without removal of the crossmember,
the studs are a PITA to install, plus the nylock nut makes it difficult to judge how much clamping force is being supplied to the fastener .
That said the stock bolts work great if you clean them and the bolt holes, add a drop of blue loctite .
Dave the OPG gasket can be installed without dropping the cross member if the motor mounts are good.
NOTE the oil pan has to be drained and filter has to be changed.
I cut a copper wire to about 4 inches remove the insulation and then you have nice strands of wire to fasten the OPG to the pan ,
about every 5 holes or so the Gasket fits around the outside of the pan you can use either cork or silicone either one can be used and will fit. ,
Hardest part is removing the starter, and cleaning the oil out of the pan sealing surface indents.
Thanks, Stan.
I agree starter R & R with anti-roll bar is a pain on jack stands. I've done it before, so I guess I can do it again.
BTW, Stan, do you have a preference between cork and silicone OPG's?
Dave
Last edited by j.kenzie@sbcglobal.net; 12-17-2017 at 12:43 PM.
If only the silicone gasket manufacturer wasn't cheaping out by not include crush sleeves with the gasket, life would be a lot better and so would be customer feedback.With the crush sleeves the bolts can be properly tightened and you don't have to use band aids like Loctite.
Absolutely!
Jim Corenman worked on retrofitting sleeves into one of the silicone gaskets. The problem was that the gasket varies in thickness by quite a bit, making one thickness sleeve too thick in one area and too thin in another.
AD0911 with the studs in the block you cant swap in a new gasket without removal of the crossmember,
the studs are a PITA to install, plus the nylock nut makes it difficult to judge how much clamping force is being supplied to the fastener .
That said the stock bolts work great if you clean them and the bolt holes, add a drop of blue loctite .
Dave the OPG gasket can be installed without dropping the cross member if the motor mounts are good.
(....)
One has an option to suspend the engine with a crossbar lift from above. Then loosen/remove the bolts that hold the upper motor mount brackets to the block. This allows you to lift the engine towards the limit of bellhousing clearance to gain some room, maybe an inch or so above stock motor mount height. Look in the motor mount threads for some DIY options for raising and supporting the engine from above. I have one of the crossbar lifts with the chains and screw jack bolts that makes short work of any overhead support needs like this. Others use lumber to build a bridge support, using threaded J hooks and chain to get similar results. Support the gearbox well when you do this, and be gentle as you lift as you are compressing the foam insulation block in the tunnel and above the torque tube.
Installing a silicone gasket can be a bit of a challenge this way, because it demands a perfectly clean surface to seal. If the old cork gasket is really crispy there's risk of leaving crumbs still stuck to the sealing faces; access for inspection is limited, so you get to use an inspection mirror from below, or maybe your endoscope/borescope inspection camera. If a previous gasket has had sealer/adhesive added, all bets are off for getting the surfaces clean with the minimal workspace available.
I want to say that I'm getting better and faster at dropping the crossmember for motor mounts, but the truth is that it still takes the better part of a retiree workday to do it all, and include all the cleaning and wheel alignment. Still, I'd rather be thorough and be darn sure that the gasket is in there correctly on clean sealing faces, vs the risk of just one little chunk of old gasket causing some seepage. I get to clean the oil sump completely in and out, with no risk of crud studs washers bolts etc in the sump before it gets refilled. OPG's are almost always replaced because there was oil leaking, so the cleaning part of the project becomes even more substantial. The bottom of the engine, the bellhousing, gearbox and the tub are coated with oil plus all the road crud that's stuck to the oil film. The crossmember and steering rack provide a handy storage cavity for the same stuff, so at least the bottom protection plate under the crossmember needs to come off even if you don't drop the crossmember. At that point I'm a dozen or so bolts away from dropping the crossmember and gaining full access to the bottom of the girdle when the sump is unbolted. Stan and SeanR do these tasks regularly and can speak better to the difference in total time spent for both methods.
Jim Corenman worked on retrofitting sleeves into one of the silicone gaskets. The problem was that the gasket varies in thickness by quite a bit, making one thickness sleeve too thick in one area and too thin in another.
It's a very crude gasket....
Here's a picture of my effort. The advantage of course is that the cap screws (or nuts) can be properly torqued and won't come loose, and the degree of compression can be accurately controlled.
Or could be, if the gasket thickness was predictable. But as Greg points out, the thickness of the silicone gasket material varies quite a bit-- from 3.10 to 3.30mm for the one I modified. I figured a minimum of 0.1mm compression would be needed to avoid leaks, so 3.00 mm spacers for this particular gasket-- custom made. The thinnest part barely compressed, while the thickest part compressed about 10%-- about as much as I was comfortable with.
The problem for any sort of production is that this particular sample was much better, thickness-wise, than could be expected from commercially-available material. Hi-temp silicone sheet is spec'ed at +/- 0.020" (0.5 mm) for 1/8" material (3.18 mm). So the spacer would have to be around 2.5 mm to guarantee no leaks, with a worst-case compression of around 30% which seemed like way too much. Add in the time to drill a couple dozen holes in rubber and then assembling without spacers going all over the shop floor... Nice idea, but...
The right way to do this would be a insert-molded rubber gasket as is commonly used for auto-tranny gaskets. All you need is a few thousand orders to pay for the tooling...
Out of curiosity, has anyone tried a locking fastener such as Stage 8, or a safety wire drilled bolt, to maintain torque of the silicone OPG?
Thanks,
Dave
Here's a picture of my effort. The advantage of course is that the cap screws (or nuts) can be properly torqued and won't come loose, and the degree of compression can be accurately controlled.
Or could be, if the gasket thickness was predictable. But as Greg points out, the thickness of the silicone gasket material varies quite a bit-- from 3.10 to 3.30mm for the one I modified. I figured a minimum of 0.1mm compression would be needed to avoid leaks, so 3.00 mm spacers for this particular gasket-- custom made. The thinnest part barely compressed, while the thickest part compressed about 10%-- about as much as I was comfortable with.
The problem for any sort of production is that this particular sample was much better, thickness-wise, than could be expected from commercially-available material. Hi-temp silicone sheet is spec'ed at +/- 0.020" (0.5 mm) for 1/8" material (3.18 mm). So the spacer would have to be around 2.5 mm to guarantee no leaks, with a worst-case compression of around 30% which seemed like way too much. Add in the time to drill a couple dozen holes in rubber and then assembling without spacers going all over the shop floor... Nice idea, but...
The right way to do this would be a insert-molded rubber gasket as is commonly used for auto-tranny gaskets. All you need is a few thousand orders to pay for the tooling...
Thanks for shining some light on this because the I don't think the manufacturer or vendor ever address this. I've installed one of these gaskets on a car and did not like the way the bolts had to be thread locked.
Very interesting information all round.
Schocki worked with "Real-Gaskets", way back when, to produce the 928 SOPG after he fitted the similar product to his 911. I remember it well as I gave him the cork gasket used as a template.
Sold thousands of SOPG's with very few if any complaints. Any issues are usually associated with over tightening of the bolts. Probably sell one cork gasket every 12 months so not many use them out of my customer base. The instructions tell you to snug up the bolts and not allow any bulging of the material. I also recommend reusing the original bolts. Thoroughly cleaning the bolts and threaded holes and applying a drop or thread locker.
Nice that we have a choice.
Another down side of the cork gasket is shipping costs - especially World Wide.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
12-16-2017, 04:47 PM
George Layton March 2014