borland

I just completed my second replacement of the oil pan gasket on my 90’ S4.

The aftermarket cork gasket I installed in 2003 was starting to weep oil, so I replaced it with the silicone rubber gasket by RealGaskets.

RealGaskets recommends tightening the pan gasket bolts to between 20 and 30 inch-pounds. That’s not much torque that the bolts won’t work loose rather quickly without using a thread locker compound or by using one of the stud kits with lock nuts.

As an alternative to studs or locking compound, I made and installed a set of tabbed lock washers that were easy to fabricate.

Here's some photos of the the tabbed lock washers layed out on the new gasket and after being installed....

borland

The engine cross brace interferes with installing the new gasket, so the cross brace must be removed while supporting the engine. Engine support can be done from above or below. I supported the engine from below as I have done in the past.

I used two jack stands under the clutch housing, while the body was supported by another two jack stands at the front side lift points. On each stand, I used two 2”x2”x1/4” shims for precise positioning. Installing these engine support stands requires jacking the body, already on two jack stands, higher on one side (jacking at the side rear lift point).



The shims I used are common structural washers from Home Depot.

borland

Instead of applying a torque wrench to the pan bolts, I tightened them by counting the number of fractional turns. I used a grease pencil to mark the bolt heads where tightened at the finger tight position, then tightened all bolts to ½ turn, in 1/8 turn increments, working my way around the pan.

Because of some irregularities of the washers being seated against the pan, finger tightness is not that precise. During final run of tightening, I maintained bolt torque by feel, which kept some bolt positions slightly less than full ½ turn. I didn’t consider the non-uniform bolt spacing on the oil pan as a significant factor.

Just for comparison, I tried to measure the torque on the bolts as I tightened them in increments, but unfortunately my torque wrench scale is 40-100 inch-pounds, so I can’t say with any certainty what the maximum torque I used on the pan bolts, but it probably was about 30 inch-pounds (My ¼” Snap-on wrench can be turned down about 10 inch-pound below the scale, but may not be accurate there).

I found that bending the tabbed washers over the bolt head flats was easy. After bending the tabs up slightly for starters, a pair of needle nose pliers finishes the job. I used either a paint lid opener or flat screwdriver to initiate bending for each tab. Locating each M6 flat washer below the tabbed washer makes bending the tab much easier.

The factory bolts (30) can’t be reused with the tabbed washers due to the bolt’s captive washers. So the tabbed lock washers require standard bolts with standard flat washers. Since the silicone gasket is only 3.15mm thick compared to the factory cork gasket of 4.0mm, shorter bolts can be utilized to prevent the bolt bottoming out in the threaded cavity. I used mostly M6x1.0x25 hex head bolts, and some longer M6x1.0x30 where the bolt threads can be seen extending outside the engine block. My using a few 30mm long bolts was probably unnecessary, as using all 25mm long bolts would be just fine.

My decision to tighten the bolt to ½ turn was based on my own compression testing. I had bought two gaskets, one for testing, the other to install on the car. I did two sets of tests, one at room temperature, and the other using an oven bake for 1 hour at 300F. Here’s the test data on Excel:

borland

To make templates for all the required shapes, I used Adobe Acrobat Standard and it’s Comment and Markup Tools.

Here’s a screen capture of the finalized Acrobat file…



You can duplicate this template for your own use, by using this hyper link to the file I created: http://members.rennlist.org/glenmac/tabbed_washers3.pdf Thanks to fellow RENNLISTer Glen McCartney for making this link possible.

With the templates designed, it was a simple matter of printing the template with a laser printer, gluing the templates to a piece of sheet metal with rubber cement, then cutting them out with sheet metal sheers, sheet metal nibbler tool, and then punching the bolt holes with a sheet metal hole punch (1/4” hole). For all shapes, I used a 12”x24” sheet of 26ga galvanized sheet metal.

Marine Blue

That is a great idea.

I also needed to install lock washers on each bolt to stop the bolts from loosening.

karl ruiter

Wow. Very Nice.

928mac

Borland, That is one of the better Ideas I have seen someone come up with.

Hmmm how long till it turns into a vender product.

Brad

ROG100

Borland,
Nice job - do you feel this is better than the stud kit from any other point of view other than cost?
Roger

Landseer

Very nicely done. Thank you for that solution.
Your work is spotless, too. Man.

928mac

Roger, The biggest plus that I see is that no lock tight has to be used on this none replaceable block.

It will only be a matter of time before the chemical reaction softens the metal. IMO

The tab lock is a nondestructive repair that is a very cheep alternative.

Some may like it some may not. I can not see a neg.

SeanR

Looks like a hell of a lot of work, when a dab of red loctite on studs in the block, followed up by nylock nuts, would solve the issue.

blown 87

These gaskets NEED some type of spacer made in the gasket so you can torque the bolts down and not crush the gasket, like so many other silicone gaskets do.

928mac

Yes, you are right Sean, so if you got the studs then it would be redundant over kill. Lock tight on the studs hurts nothing.

Thats the thing that makes guys take it to the track, to see who can make it to the end, or who has the better idea.
Personally I think this is that 6 of 1 or 1/2 dozen of another.

I may put the studs in when I have the engine out, but who knows.

borland

The stud kit is a good solution, but I've never used it. Never liked the idea of not being able to remove the studs at some point in the future.

I spent lots more time in preparation than doing the install. The tabbed washers can be made ahead of time, thus not affecting any down time for the car.

I'd say not counting the time to fabricate the tabbed washers, the tabbed washer may be a faster install than the stud kit.

Mike LaBranche

Brilliant.