Subject: Bolts On Oil Pan
From: "Larry Gunter" <firstname.lastname@example.org>
Date: Wed, 29 Aug 2001 10:17:19 -0400
I had the oil pan gasket replaced about six months ago. Ever since, the bolts have been coming loose and oil has been seeping out. I have to periodically re-tighten them (almost every 100 miles). Has anybody else experienced this problem? Is there a fix for it?
Are you sure they are getting loose or is the gasket extruding itself out of the space between the pan and the block. You may want to mark a few of them and then see if they have actually moved after a few days. Here is my BTDT for whatever it is worth.
I replaced the pan gasket 2500 miles ago and after only a couple hundred miles it was seeping a little. Well OK I said lets at least check the torque (I was using an inch/pound wrench for accuracy and the bolts WHERE to spec when I installed them). Surprise some were only finger tight so I retorqued carefully. Seeping continued and got worse, bolts were again finger tight so I YB4ed the bolts to stop the leak and make sure they didn't loosen any more. The bolts were the primary leakage site because the gasket hole is much larger than the bolt and many of the bolts penetrate into the crankcase so the end of the bolt is bathed in oil. Leaking more, bolts loose again. So I marked the bolts to see if they were turning or the gasket was compressing. They didn't turn, they did leak and were finger tight. I was always careful about the torque and tightening is increments so that all bolts were equally tight as the pan was pulled up snug. At 1000 miles the leaking was terrible, it was now coming from the edge of the gasket not just the bolts and on close inspection the gasket was now paper thin (not to mention destroyed). Some of the bolts that were in blind holes were now bottoming out. Fill in about 50 choice words then order a new pan gasket. Lots of work to get at this, but wanting to NOT make the same mistake with the new gasket I analyzed as carefully as I could. I was pretty certain about the torque values all the time and even though I obviously made it worse and eventually destroyed the gasket, still it did leak right off the bat. I had used YB4 on the gasket and bolts. The only learnings I found to give hope to the next gasket was that the first one had extruded itself, I was really expecting a repeat. I decided the YB4 on the surface of the gasket did not seem like a good idea, it shouldn't be needed and it helped to lubricate the extrusion process so I did not use any on the second gasket. I did use a gasket adhesive on ONE side (the pan side) of the gasket to hold it in place during assembly and possibly increase it's grip on the metal to resist the extrusion. It was not the hard kind, but the purple permatex that looks like contact cement. I DID use YB4 LIBERALLY on the bolts themselves because the large hole in the gasket must be sealed somehow. The YB4 trapped in the bolt holes remained liquid probably for months, it certainly was just like in the tube a week later when I checked one. Probably it's liquid state helped to push the gasket laterally and cause trouble, but to get a seal there has to be something filling the bolt cavities so I used it. Finally during installation I watched for any sign of bulging that might indicate the gasket was experiencing lateral forces. It was slight, but the bulging was there at 2 or 3 ft/lbs and the spec for normal 6mm bolts is 6 or 7 ft/lbs. So I torqued them all to 3 ft/lbs and now at 2500 miles I have a completely dry oil pan, including every bolt head and they never were retorqued. In fact I was going to retorque today just make sure they were all even, but that would be foolish (if it ain't broke.....)
RSS Ralph S Smith
From: Michael S Briggs [mailto:email@example.com]
Sent: Saturday, May 05, 2001 6:30 PM
Subject:  oil pan gasket ponderings
A while back, perhaps a year ago, there was talk about why no one had made an aftermarket oil pan gasket of another material instead of cork, so it wouldn't crack if over tightened. Has anyone considered making a copper gasket?
I'd be willing to bet that it would be better to put it together with no
gasket at all. I have had real good luck with either Permetex "Ultra
or Loctite "Gasket Maker." I'm not sure if I got the name of the
product correct. They are completely different materials as the Ultra Blue
is an oil-resistant RTV silicone product and Loctite makes an anaerobic
material. I rebuilt a Chrysler engine a while back and bought a gasket
set - all that was in it was a head gasket, Crank oil seal and a couple of
tubes of goop. The engine never leaked a drop. I use the Ultra Blue
seal the crankcase halves of my aircraft engine (applied from the outside)
and they would leak no matter what I used until I tried the RTV. The way I
do a seal like the oil pan is to put the stuff on sparingly (don't want too much to get in the oil) and tighten the bolts hardly more than finger tight - just enough to get the stuff to ooze. Then I wait about a half hour to let the stuff partially set up before I tighten it the rest of the way.
That prevents you from just squeezing all of it out of the joint and keeps the rubber in compression.
Pan casting is not rigid enough for a copper seal and the bolts wouldn't give enough clamping force to crush it. Marc Thomas had a valid comment on that cork gasket. Did you notice all those beautiful fins molded into the thing. Did you notice that it hangs out in the air stream. Well it is shedding heat. If you bolt it directly to the block it won't be thermally isolated anymore and it won't be as effective. I thought that was a real good piece of logic. That being said I know there was one lister a couple years back who went the glue in place route with success. Never got a long term report from the guy and I can't for the life of me remember who it was. Last name Greene maybe?
When I did all my gaskets last year I glued the pan gasket in with blue permatex both sides. Left it for two days with the bolts finger tight till the glue cured and then tightened it to spec. I also 242ed the bolts so they wouldn't loosen prematurely. Don't expect it to ever leak again.
79 US 5ish speed
I've been quietly working on my car this spring and summer and not doing
much talking, so I'd thought I'd put this useful tidbit of information out
It took me about two years to finally put a small oil leak to rest. It's now been dry for months, so I can finally claim victory and share the news of how I fixed it. The telltale signs of the leak were ever-present drops of oil on the oil sender wires, and a grimy coating on the belly pan. I replaced the oil sender - no change. I unscrewed the oil sender housing, replaced the crush ring, reinstalled the housing and torqued to proper specs - no change. As part of my motor mount replacement, I replaced the oil pan gasket with a new one, coating both sides of the gasket with Yamabond 4 sealant. That worked great as far as the oil pan gasket was concerned, but I still had that pesky leak in the vicinity of the oil pressure sender!
In a rare, brilliant flash of inspiration here's what I decided to do next. I removed the oil pressure sender and its housing and cleaned the threads thoroughly to remove all oil. I then coated the threads with a small, but even amount of the magic Yamabond 4 sealant. This was done for the threads on both the oil pressure sender and the housing. I let the Yamabond cure for 30 minutes or so and then reassembled everything. I reused my old crush ring, but, to be thorough, you might want to use a new one.
I left my belly pans off for a couple week and, much to my amazement, the oil pressure sender stayed dry! So, I reinstalled the belly pans and took them back off a couple of months later while performing other service. Still dry! No grime on the belly pan at all. So, there you have it. Ride on down to your nearest Yamaha bike shop and pick up a tube of YB4 and give it a try.
Oh, one more thing. As I recall, it can be a little bit difficult (OK, impossible) to get a wench onto the oil pressure sender unless the alternator has been dropped down out of the way. Maybe you can get in there with the appropriate size "stubby" wrench - I don't know, because I didn't have one. I recall wrapping the pressure sender with something to protect it (electrical tape) and then using a pair of Vice Grip pliers to get the thing off and back on. (I see you cringing, and I don't blame you! Hey, it worked for me!) Once the sender was off, removing the housing was pretty easy. It just required a 1/2-inch drive socket wrench. Be careful as you let the housing down, there is a spring that you'll need to pay attention to for proper reinstallation, as well as the crush ring. Also, you will need to catch some oil with a small catch pan, but really not very much comes out.
Remember, the 928 Frenzy is coming next month. Send in those applications to Pete, and I'll see you there.
> Good Morning.
> I am about to replace the oil pan gasket on the red '87. I have received conflicting advice about whether or not to use some type of sealant with the gasket. Any opinions would be greatly appreciated. Thanks in advance.
> Larry Gunter
> Fredericksburg, VA
I've done 4 928 OP gaskets. (and 40+ V8 AMC's)
-one w/ Yamabond, bad results
-did it over again w/ blk RTV, better, not perfect
-did 2 w/o sealant, worked the best.
AEDSYMMV (as ED says your mileage may vary)
I used Yamabond before but will not this time.
The gasket was stuck on so well that it took me hours to remove the pan, after I got all the bolts out and more hours to clean the Yamabond off the pan and block faces. Yamabond did not adhere evenly, better at the bolts than in between. Besides, I wondered, doesn't the oil leak through the gasket as the gasket dries out? If so, then the only way to truly prevent oil leaking from the gasket between the pan and the block is by replacing it.
Sorry in advance for this turning into a pan gasket diatribe.
The gasket provides three functions:
First it is a splash seal for flung oil assuming that there is basically no pressure in the pan. This also assumes that the pan is not overfilled and that the capacity of the pan is the rest capacity of the system.
Second it provides an air seal to the engine as it runs under vacuum in the crankcase normally. Some engines false idle air this way when the breather system is plugged. I know my Audi does this. I don't think that the LH or Motronics have this issue but it does happen. All depends where the fumes are dumped into the intake. This is also especially important in evacuated dry sump systems.
Last it is a thermal break between the block and the air cooled pan. This is one of those extra little design features that separates our cars from the rank and file of automotive engineering and is one example of the stuff I love about the car. It's actual contribution to overall cooling is most likely small but it is the stuff that German car engineers worry about because their task is to design something that can go down the Autobahn with the throttle mashed to the floor for hours!
On top of all that there is a torque spec for the 7mm? (10mm hex) diameter steel fastener that is in the manuals that is misleading because it is actually for a metal to metal joint. This does not apply to a 3mm? cork gasketed joint. The actual torque spec should be tighten the bolts all hand tight then rotate them all the same amount until the gasket is firmly seated. Going back to your original estimate, yes, somewhere between 20% and 30% is what the text book would say for Neoprene or equiv but cork is sort of an old school wildcard back from the days before torque wrenches clicked. There is probably a way to estimate the durometer of cork and then figure out the percentage associated with that but it is probably a crap shoot. That tells me that Porsche must have used it for a very good reason. If they didn't they should be shot. I wish I had thought to ask that question at Euro 928 2002.
So what does all that mean? The spec is basically tighten it enough to not
squash the poor thing and enough to keep the fasteners from vibrating loose
(can't be done). Or if you are me blue locktite the bolts AND blue permatex
both sides of it snug it up and forget it....That is unless you use Mobil 1.
If so it is going to leak no matter what you do :)
If you want to compute compression you can always just use the thread pitch and convert it into degrees of turn of the head of the bolt. IOW 1mm? (not sure of the actual just an example) pitch equals 1mm per 360 degrees so if you have a 3mm gasket 20% = 0.6mm of compression or .6 * 360 = 216 degrees. That won't feel like enough. Been there.
It is also expected and planned that this gasket will be snugged over its
life. That means that unless you have had your 90 from day 1 and done all
your own work and not snugged that gasket then you are correct in assuming that you can measure a new one and derive inference from it. If it has been at the dealer ever there is a good chance that it was snugged some number of times and then that theory is blown. This is once more credence that Porsche must have had a damn good reason for doing this because access is a big issue for part of this gasket.
Hope this helps to frame out what is involved in answering your tightening question. Probably not what you expected.
79 US 5ish speed (next time I am in there I am getting rid of the gasket and using the crank girdle sealer and shorter bolts on the pan with proper
torque on the bolts)
Cork gaskets have been around since Moses and might have been responsible for
the fact that we still haven't found the Ark.
Our oil pans are carefully made to be flush with the front undertray assuming your engine mounts are intact. They also have nice fins moulded into them. The entire sump capacity fits in the pan without overlap up onto the block. So do you think that Porsche might have been trying to thermally isolate the pan using that thick gasket to get that last little bit of cooling for the engine? Remember that the first 928 did not have a separate oil cooler. So that pan design is a hold over from the original design effort in say 72 or 73.
I put blue permatex on both sides of the gasket and finger tighted it upside down overnight. I then snugged it up to my spec with purple loctite on all the bolts so they wouldn't vibrate loose. Put Mobil 1 in and within 1 month of doing a complete regasket with the engine out the engine was seeping at all of the cork gaskets and most of the paper ones. Got rid of Mobil 1 and got rid of the problem. Now I use whatever synth is on sale that isn't Mobil 1. Until they reformulate I ain't gonna use Mobil 1 anymore.
If someone wanted to make a nice CAD drawing of the gasket we could easily get laser cut EPDM or Viton or Buna or Goretex something that would be the modern upgrade equiv for the cork. At this point with what we know about these cars it would seem that we could just loctite the pan on like the lower crank girdle and be fine especially if you have an external oil cooler version of the car.
Here's my installation approach:
Thin bead of high-temp RTV silicone around the outside. Torque the bolts lightly by hand and keep going around the block until they're not yielding under the light torque. No thread locker at all. This allows checking and then re-tightening as needed. The key is to not overtorque the bolts. The gasket gives a bit at first but after three or so cycles it's not giving any more. No, not squishing it out but making sure it's torqued correctly.
I was playing around with the idea of some other material for the gasket,
even thought of using Yamabond. Jim Bailey of 928 Int'l talked me out of it. He
theorized that the engineers used the thick cork, with no bonding material, for
a couple of reasons. The thickness of the cork does play a role in lubricating
the engine. The cork gasket will absorb oil, and continue to absorb oil, until
it becomes saturated. Then it will begin to leak.
Replacing it is dependent on how much oil on the floor you can tolerate.
Me, I'm rather intolerant.
'82, 5 spd
I'm not sure of "the latest" thinking but I've gone back to the stock thick gasket. I like the extra 2mm or so between crank and pan.
A thin bead of RTV around the outside and it's fine. I've taken to going around the bolts 3 or 4 times and snugging it down, not crushing it. It yields a bit and a couple extra light twists gets the bolts firm. (6 ft-lbs firm.)
I used HyLoMar on mine. This is the BMW equivalent of Yamabond from the Yamaha Motorcycle shop. Unlike silicon these sealers stay flexible, although silicon or even Permatex will probably work as well.
I applied a very thin coat of HyLoMar to the two surfaces. I started with block first then laid on the gasket and then applied a thin coat to the pan. The stuff sets quick so it is good to work fast. Don't use too much because you do not want small bits breaking off and clogging the oil screen.
Once in place I put in a couple of bolts to hold everything. Then proceeded to put in all the bolts in and snug them up a little to hold the pan in place. After 24 hours I removed the bolts, coated the threads with some blue Loctite and then torqued them to spec.
If you attempt to torque the bolts while the sealer is wet then the gasket will crush. Once the sealer is dry it holds the gasket in place.
This arrangement appears to be holding.
There is a company that makes a stud kit. It is a little expensive, but I like the idea of setting the studs with red Loctite and then using locking nuts to get the correct torque.
Dan the Pod Guy