tab a

I'm doing the OPG while changing motor mounts and have a few questions that I didn't see answered in all the OPG threads I read through:

1. Any idea why the pan lip has 5 'cut-outs' and 5 shorter bolts? Not easier for Porsche to make the pan lip the same for all 30?
2. I've seen lots of talk about the bolts loosening with time. Why do they? Never seen that on any of my other cars.
3. Didn't see it mentioned anywhere but seems like it will be easier to put the front bolts back in before installing the oil level sensor?
4. Any sealant suggested for the oil level sensor gasket and the gasket next to it, for the blanking plate?

Thanks.
Thon
85 Auto

Mrmerlin

1 the cutouts are for clearance to the cross member and the starter.
2 Vibration and the heat cycles and low torque all combine to let a steel bolt turn out in an expanding aluminum housing.
3 I dont remove the oil level sensor, if your doing that, and it takes a gasket, use Drebond 1202, if it takes a O ring used DC111.
4 see 3

dr bob

In some there are accessories (like the starter...) that need the tiny extra bit of clearance.


The original cork gasket dries out and shrinks with heat and time. Plus, the spec torque on the bolts to get t just the right compression/squish on a NEW GASKET is tiny, leading me to think that there's a vibration component too.


Definitely. These are among the tougher bolts to get back in though, so place a few others around the sump, draw the sump up to just touching the girdle before you try and place those tight-quarters bolts.


You can but I've never needed any. The gaskets worked fine dry for me.


Happy to help! Look for hints from guru members Mrmerlin, SeanR, GregGBRD, Bill Ball, etc. for the best hints and clues. The New Visitors thread in the stick section includes links to many of the best tips sites we know so far. Always a good idea to get a bit of education from the masters of course.

GregBBRD

The original cork gasket would not allow the 6mm hardware on the oil pan to be torqued to full torque, without the cork gasket being over compressed and pushing out. 40 or 50 inch lbs was all the gasket could be tightened to. This amount of torque does not "stretch" 6mm hardware for good clamping pressure to occur.

Combine this with the cork material, which is 1960 technology, and the oil pan bolts continually came loose.

Do yourself a huge favor and order my new oil pan gasket. Technology wise, this pan gasket material is 50 years more evolved, is very resistant to compressing, and allows full torque on the oil pan's hardware (72 inch lbs.)

Roger at 928 R Us stocks them or you can order them directly from us.

Some of the best money you can spend, on your 928!

Geza

If I was doing this job again, I would make a slight modification. I'd fill in all the pockets on the oil sump gasket surface and sand flush increasing the gasket bearing surface. It was very dumb of Porsche to pocket out the gasket surface. I would also check out Greg's gasket.

For those interested, the pockets are there to maintain a relatively consistent wall thickness. Castings do not like to have thick and thin sections adjacent to one another. Since the thin sections solidify quicker, and shrink while doing so, they pull the liquid metal in the thicker section away, causing what is called shrinkage. The pockets are indeed necessary, but should have been on the outside of the sump.

dr bob

Knowing what I know now about the factory gasket durability and the finicky installation requirements of the thick silicone balloon gaskets, I'd be all over the GB gasket for this fun job. I've done mine twice in 20+ years, look forward to at least another 15 or so on the cork composite gasket I put in a few years ago now. I can change those gaskets in my sleep... er, nightmares... now in less than a a day all in. What's the NPV of a day of cleaning and wrenching a dozen years from now? Way more than the cost of a good gasket today.

GregBBRD

While there's no way I can test the gasket material I'm using for 15 years or more, the manufacturer is very confident it's a "long term" material solution.

And if it isn't...I'll be the first one to know and will use whatever other "new" modern material that is available, at that time.

Right now, this material is absolutely "state of the art" for this application!

tab a

The GB gasket sounds like a great solution, but I already had a cork one in place, ready to snug up. Maybe next time.

I understand vibration, heat cycles, low torque, gasket shrinkage etc. but I LIKE to think Porsche engineers understand/stood all those things far better. It's not like alum, steel and cork were new materials in the late 70s!

Thanks for all the suggestions!

Thon

dr bob

A spot of adhesive or threadlocker might be an idea for the bolts with the cork/composite gasket. Similar to recommendations for the silicone gasket to keep fasteners from loosening. None of this is rocket science. It's making the best use of thr trecnology and parts we have available. You can make your own from stock material as Ake does, or get one ready to go from Greg. Good news is that I "only need to put a new factory gasket in every 20-25 years if done with care. Bad news is that I need to replace the darn theng every 20-25 years even when doone with care. This was all easy to justify when motor mounts needed replacement more often.

I don't want to be hunting for other reasons to have the oil sump off to justify replacing the gasket. I work to keep everything under the car "lickin' clean" anyway, so the real solution needs to be dry forever.

As I tell my clients: It needs to work perfeectly every time, without fail. Failurei s not acceptable. It's too expensive. Some argue, but the tinkle-down costs of the failures bring them back to the table. The 928 oil sump gasket is annoying but not fatal when it fails. Tranlate "annoying" into $$, and suddenly a real solution starts looking really good.

Strosek Ultra

Anyone with a pair of scissors and a 7mm hollow punch can make his own oil pan gasket, it is a piece of cake.
I am using the AFM 37/8 gasket material from Victor Reinz. Thickness 1,0 mm or 1,5 mm. More thicknesses are available too.
Can be found on eBay. Other corresponding gasket materials can be found at Summit and others.
Åke

DonaldBuswell

So when I ordered from Roger an Oil Pan Gasket, and I said send me a good one, the one that arrived is not made of cork, chances are it's 'yours'?

Strosek Ultra

The cork material becomes compressed over time, the bolts must be retightened at regular intervals.
The AFM 37/8 gasket material from Victor Reinz will not be compressed and is best used between two machined flat surfaces such as the oil pan and the girdle of the 928.
When I worked on BMW motorcycles in the 60s, the oil sump gasket was made of cork, which is understandable since the oil sump was made of sheet metal which quickly got warped.
In 1970, BMW came out with a new line of engines with cast and machined oil sump but they continued to use cork gaskets which showed the same kind problems as we see for the 928 today. I then started to make my own oil sump gaskets of a material similar to the AFM 37/8 which do not compress which became the final solution to the problem.
Åke

GregBBRD

If it's a light green color and not red silicone or cork, it''s mine....Roger bought a bunch of them, for his clients.

Wisconsin Joe

The cork one is 'ok'.

From what I've read, the Greg Brown one is far, far superior to it.

But if you think the engineers made the best choices, think again.

The accoutants had a say in the process.

And the list of 'stupid crap that Porsche engineers did' when they designed many of the cars is pretty long.

GregBBRD

There's no huge secret about what material I'm using....you can read about it here:
http://www.thermosealinc.com/product...ngersil-c-4401

If someone out there thinks it is cost effective to make your own gasket (a half hour of labor, in my shop, costs the client more than the total cost of my pan gasket. And I'm pretty damn sure I can't cut one out and put all those holes in it in a half an hour), you are more than welcome to order a sheet of this material and make your own gasket.