Make Your Own Rubber Oil Pan Gasket?

[smokuspollutus]

Hi guys, I've completed my first engine build. Currently, engine (Cadillac 4.1 liter) is on the stand awaiting install. Everything went according to plan, but I have one point of trepidation. This engine was only ever available with a cork oil pan gasket, and as such that is all the aftermarket supplies. I hate cork gaskets and in the past have never really gotten a good, lasting seal out of them. I have the pan on now with the cork gasket, but before installing in the car, I want to make sure this is the best I can do. It is extremely difficult to change the gasket with the engine in the car (1984 Cadillac Eldorado)

 

Question: does anyone know if it is possible to purchase a sheet of rubber-like material, of the same composition you would find in an OE rubber gasket specific to that application? Though process here is; buy a sheet of material that the magical rubber gaskets that don't seem to leak, cut to match the oil pan, and install. 

 

Please excuse my ignorance, I know nothing of the difference between rubber, nitrile, neoprene, silicone, et. all.  I failed chemistry in high school so if I'm using the wrong verbiage, accept my apologies. I'm just looking for something that will seal the best for the longest amount of time. As the engine is on a rotisserie right now, ease of installation is not a concern. 

 

Anyone been down this road and can offer guidance? 

 

Thanks so much,

 

Anthony

Edited September 14, 2021 by smokuspollutus (see edit history)

[Bhigdog]

McMaster-Carr............Bob

[Frank DuVal]

How do you install the cork gaskets that have a leak issue? What type sealers?

[smokuspollutus]

Thanks for the tip for McMaster. I’ll check them out. Anyone have an idea of what material types I’d be looking for in this application?

 

re: installation: I’ve tried before mainly on valve covers but at best only ended up with something that leaked less than it did before. Always tried to do the right thing, straighten the holes if bent, used orange RTV/ black RTV, the right stuff, totally dry, but just never really worked out. 
 

I’d like to rid the engine totally of cork if possible since the valve covers are already cast aluminum with rubber gaskets. 
 

Thanks guys.

[Rusty_OToole]

What's wrong with using silicone.

[trini]

Rubber gasket is the way to go. Check with U A P. If no luck go online and look for company that manufacture rubber mats. They will probably have smooth rubber sheets. Also check with Steele Rubber for gasket material.

[trini]

Amazon has oil pan gasket made by "feltpro" . Perhaps you might want to give them a call and inquire. Otherwise go to the manufacturer and plead your case.

[Frank DuVal]

If using RTV, just use the slightest amount, applied with fingers to thin it to almost nothing. I found any build at all and the cork gasket slips out of position as soon as the oil hits it. True for rubber gaskets also! Heck, if you want to use RTV, just use RTV, NO gasket! That's what lots of OEM engines used since the early 80s.

 

I like High Tack by Permatex and only apply it to the valve cover side, leave the head side of the cork bare. Stringy stuff to apply, but works. Also good for paper gaskets, there on both sides.

 

You will get 100 different opinions!

Edited September 15, 2021 by Frank DuVal (see edit history)

[bryankazmer]

The OP asks the right question.  "Rubber" is a class of materials, like "wood" or "metal," with many varieties.  Not all are oil-resistant.  Nitrile rubber has very good oil and gas resistance (it's why the flexible connection from the gas filler neck to the tank is usually nitrile).

The other issue is hardness, measured by durometer.  The wrong hardness could impact the sealing behavior.

Sorry I can't give a specific grade recommendation - use a material intended for the application.

[Mark Gregush]

Aren't the modern "rubber" gaskets a type of injection molded silicon?

[bryankazmer]

I believe some are silicone rubber injection molded on a carrier, some are nitrile.  Don't use RTV with a silicone gasket - they are chemically too similar and the RTV can weaken the silicone rubber.

[Akstraw]

Olson’s Gaskets might be able to produce what you are looking for.  They have lots of patterns on file, and are set up to do custom work.

[smokuspollutus]

Thanks so much guys. I've been reviewing the McMaster stuff and they seem to have something that I think will work. The good point about this application is that it is a deep skirt block so the sealing surface is completely flat (no bends to be made over the main caps) So I'm pretty hopeful that I can just buy a sheet of this stuff and cut appropriately with an Xacto knife. 

 

https://www.mcmaster.com/nitrile-rubber-sheets/oil-resistant-high-temperature-buna-n-rubber-sheets/

 

It seems to check all the boxes of temperature resistance, of course oil/gas safe being made of Nitrile, and is the right size at a price I can justify. The sealing surface is 23" long so one of those 12"x24" sheets should be exactly what I need. Now its just a question of the appropriate thickness. Anyone have any pointers? Thicker/thinner/same as the existing cork? 

 

 

[trini]

3/16 thick should be adequate. Use a sharp punch/hole cutter. Try a sample hole and make sure the bolt moves through easily. Cut some threaded bolts heads off and use as dowels in the block to guide the oil pan without fouling or slipping /moving the gasket out of line. 

[Oldtech]

I would go with 1/8 myself.

[smokuspollutus]

Thanks guys. Measured the existing cork and came in at 3/16, so I went with that thickness. 

 

Heres another question, the cork gasket I put on had metal washers in the bolt holes, I assume to prevent crushing to the extent possible. Is it worth it to transfer these things to the new rubber gasket? 

 

 

[bryankazmer]

If the washers are thinner than the cork, and the rubber sheet is thicker than the washers, then they will act as "stops."  The compression behavior of cork and nitrile are not the same, but it will help get an even compression around the perimeter.

[m-mman]

On 9/16/2021 at 2:23 PM, smokuspollutus said:

Now its just a question of the appropriate thickness.

 

Modern cars and modern control systems. 

This may not be applicable to your car but there was information put out about the pan gasket on the Geo Metro 1.0L 3 cylinder engine. "DO NOT USE A GASKET!"  The factory used sealer without a gasket. They make pan gaskets and include them in an overhaul set. 

 

The problem is that if you use a gasket (whatever thickness) it will move the oil pan down and separate the crank position sensor from the front pulley. Not close enough to pickup a signal, so no spark. 

 

The complaint is an engine that will not start and run after a pan gasket replacement.

No spark because you used a gasket instead of sealer. . . . . I am glad I read about this and didn't have to figure it out on my own. 

[Bloo]

9 hours ago, smokuspollutus said:

Heres another question, the cork gasket I put on had metal washers in the bolt holes, I assume to prevent crushing to the extent possible. Is it worth it to transfer these things to the new rubber gasket? 

 

Those things are the difference between gaskets that actually work, and the gaskets on most of our antiques.

 

[Frank DuVal]

Right, the metal washers are to make the cork work well.

[Bloo]

They allow you to tighten the bolts to a useful torque without squirting the gasket out or bending the flange.

[Frank DuVal]

You will hate yourself later, but this is why Indian Head Gasket Shellac was popular back then.....🤔

 

Used it on side valve covers of Chevrolet sixes. No leaks.

[Terry Harper]

26 minutes ago, Frank DuVal said:

You will hate yourself later, but this is why Indian Head Gasket Shellac was popular back then.....🤔

 

Used it on side valve covers of Chevrolet sixes. No leaks.

Yup! and don't over tighten!👍

[Fossil]

One of the problems with cork is it tends to compress over time leaving the things almost loose. In the good old days it was a wise idea to go around with an open end wrench and snug things up on occasion using just a twist of the wrist to snug things back down. Kind of like adjusting the valve lash and adjusting the packing on the water pump. You know, the kinds of things we still do on today's cars. 

[trini]

I think those washers were installed to prevent weeping at the bolts. There are  washers with rubber " gasket " built in available. Do not over tighten.

 

My son had a Honda motor cycle years ago. He consulted me about  changing the motor oil. So he used 30 body oil from an outlet. The result was oil fumes all over the engine so he went to the Honda dealer and asked the salesman for a set of engine gasket. After a short conversation with the salesman "you do not need gaskets, you are using the incorrect oil. Here, buy this motor oil which is designed for Honda." No more messy engine .

What do you think about trying different oils till you find one that is satisfactory. May be worth a try

 

[bryankazmer]

The right oil is the one which correctly lubricates your engine.  In your example, the gasket was designed to contain the correct oil.

 

Choosing the oil based on the gasket is completely backwards.

[smokuspollutus]

Thanks for all the advice guys. My measuring skills definitely need some work because the 3/16 is pretty thick. 1/8 would have more than done the trick. But, it worked about as well as I could have hoped. Clipped the cork gasket to the rubber sheet and spray painted to see where to cut. Cut the form out with an exacto knife. Then used a cheap set of harbor freight punches to make the holes. They fit in my drill which made the process much faster and made nice clean holes. Put on the engine and to my shock everything lined up and seems to have tightened down nicely. 
 

No report on oil tightness yet, we’ll have to wait and see if I ever get the engine in the car. But, I’ll update when I do!

 

Finished product

Edited October 1, 2021 by smokuspollutus (see edit history)

[pmhowe]

I like the idea of spray painting to make the pattern. Thanks for sharing.

Phil

[smokuspollutus]

Hi guys, figured I’d update this, I ended up making another one of these for use on my daily driver which has the same engine as listed above. I used all the same material/procedure as above, just at the 1/8” thickness. Way easier to cut and drill. Anyway, it works! I did not use any RTV, just placed the gasket on the pan, installed to the engine, and tightened until I saw it just start “squish” out. I’ve driven the car about 1200 miles in the past month and the pan is totally dry. Don’t know how it will really age, but at the very least the material resists oil and heat.