Mirro-Matic Stovetop Pressure Cooker Issue

[rp2813]

I recently picked up an older Mirro-Matic 6-quart pressure cooker, model 396M. 

 

I've used it a couple of times, and in both instances the lid was very difficult to remove.  It wouldn't budge, even though pressure had been properly reduced with a cold water bath.   It took about ten minutes to remove the lid the second time, including wait time when I got so disgusted I walked away from it.

 

Both times, once the lid cooperated, the gasket was sitting on top of the pan instead of tucked inside the lid.  It sort of peeled off the rim when I removed it.

 

I tried the suggested vegetable oil lubrication on the gasket the second time and that only made things worse than the first time.

 

Is it time for a new gasket?  It has definitely seen some use and is likely the original.  I have a  couple of smaller Mirro-Matic cookers of similar vintage that have their original gaskets and they work fine.

 

If it does need a gasket, it appears Mirro no longer makes them.   It's wider and perhaps thicker than later types.  I've seen aftermarket gaskets with a part number of S-9891 that are claimed to fit on the 396M, but have also seen feedback from 396M owners that claim the S-9891 isn't an exact replacement and often won't maintain pressure.

 

Is there a source for the correct gasket?  Can the current gasket be salvaged?  The latest suggestion I've read advised to use petroleum jelly instead of oil, as it has a higher heat tolerance.  It's my understanding that oil should never be used to lubricate rubber.  I don't know if that's a blanket statement or is only limited to automotive applications, but I'm not so sure I want to use anything petroleum based.

 

Any ideas out there?

 

[mattl]

New gasket time....

Mt local hardware store stocks all kinds of parts for major brands of PCs, don't know if you have a similar store by you but I'd check out a good old fashioned hardware store.

 

[norgeway]

They are

Very hard to find!! The old grey ones are much better than the black ones.

 

[rp2813]

Hans, I have the old grey gaskets on my other two Mirro-Matics and they work fine. 

 

It seems the 6-quart model is particularly difficult to find gaskets for.  There are 4-quart and 8-quart & above sizes all over the place.

 

I thought ACE might have them, but they only stock the 4-quart (394M) replacements.

 

Here's a link to the only gasket I can find on line that claims to be for a 396M.  It's hard to tell the width and thickness dimensions from just a picture, but it does look wider than the later type. 

http://www.thepartsbiz.com/Mirro-Pressure-Cooker-Compatible-Sealing-Ring-Gasket-S-9891_p_4892.html?gdftrk=gdfV25603_a_7c2027_a_7c7964_a_7c510_d_477739&gclid=CJTJ157k3cQCFczm7Aod1CQAAQ

 

[norgeway]

Im not sure...

But I think the 8 qt gasket is the same as the 6.., I use one of the 2 1/2 qt models all the time, its the same as the 4 qt,just shorter and I believe the 8 qt is just a taller version of the 6 but I may be wrong, I have one buried somewhere, I will have to look.I also have a 16 qt KFC model.

 

[whirlcool]

We have a 396M too and used the gasket found in this link. Works perfectly.

To use the quick cool down method we run cold water over the cooker until the hissing stops. Then we pop off the pressure regulator. No steam left at all and the lid just pops right off with no effort at all.

Mirro Pressure Cooker Gasket 9891

 

[rp2813]

Allen, thanks for confirming that the S-9891 replacement gasket will work.  I'm going to order one.

 

I like the Mirro-6-quart because it's wider than their 4-quart, and not so overly large like my Presto 8-quart.  Presto's 6-quart is just a taller version of their 4-quart.   I don't understand the logic behind that at all.  The Mirro 6-quart is just the right size to be my go-to pressure cooker for sure.

 

[tomturbomatic]

Have you polished the flange of the pan with a steel wool soap pad? Having that shiny and slippery will probably help prevent the ring from sticking.

 

[rp2813]

Tom, I did use a steel pad on the flange after the second incident.  I haven't tried it since, but I'm still leaning toward the gasket being the main problem.  It has some irregularities in the surface that are somewhat blister-like, and isn't anywhere near as smooth as the gaskets on my other cookers.  It has been compromised somewhere along the line.  A new gasket certainly won't hurt.

 

I bought my Presto 8-quart because Mirro parts are more difficult to find.  ACE carries Presto parts, but not Mirro.  Why, I don't know.  Since the Mirro 6-quart is IMO an ideal size for my purposes, I'm willing to go the on-line route for parts.

 

[kb0nes]

I might try a tiny bit of food-grade Silicone grease on the gasket. Apply sparingly then buff off the excess. It works great on C30 Coffeemaster.

 

[tomturbomatic]

You are right; the gasket is probably the main problem, but in the interest of leaving no stone unturned, I suggested that as a possible help since well polished aluminum does have a low coefficient of friction, unless you are trying to slide a deteriorating gasket over it.

Phil, Thanks for the suggestion. I have an aerosol can of that product sold for ice makers. I will try it on pressure cooker gaskets.

 

[rp2813]

Silicone lube, in one form or another, had crossed my mind, but now that there appears to be a new replacement gasket available, I think that's the best course of action.

 

Since the cooker works properly, I have a feeling that it was discarded because its owner couldn't locate a new gasket.  I've never come across a gasket with bumpy areas like this one has, and I've never been unable to remove the lid, so I think those two factors add up to a new gasket solving the problem.

 

[whirlcool]

I would put some cooking oil on the new gasket and then the next day wipe off any excess with a paper towel before using.

You are correct about the size. We had a Presto 4 qt before and it was just too small to do any meaningful amounts of food. It was enough for a dinner, but not enough if you want leftovers the next day, or to freeze for another day. The 8 qt will feed an army, but if there are only two of you....So the 6 qt is it.

I remember our 6qt had to get quite hot before it would seal correctly. Some steam came out around the gasket but after a few minutes it sealed itself correctly and stayed that way for the entire cooking process.

 

[rp2813]

Allen, I had the same steam escape thing happening on my '60s avocado 4-quart Mirro.  I was able to get a new Mirro brand gasket for it and it helped some, but the problem persisted.

 

A few years ago I found the same 4-quart model in unpainted aluminum at a thrift store.  The avocado one was looking beat up, and I liked the plain aluminum better, so I went for it.  It worked fine, even with the old gasket from the avocado one.  That's when I concluded that the avocado one must have gotten too hot (due to the steam escape issue) and warped.  I tossed it, and the unpainted one has been working fine ever since with the original '60s gasket from the avocado one, while the new spare is back in its original package in case I ever need it.

 

[tomturbomatic]

People striking cooking spoons and other tools on the cooker rim can create scratches and dings that can prevent a perfect seal from being formed, resulting in escaping moisture.

 

[rp2813]

Good point Tom.

 

I have never done so, but imagine there's an abundance of people who don't think about the consequences.

 

Once I discovered that the old gasket worked fine on the plain aluminum cooker, that's when I recalled an incident where steam kept escaping from the avocado one to the point where I decided to shut off the burner out of safety concerns.  I think that's what put it over the edge, so to speak.  Up to that point, I could hold the handles together until pressure was nearly reached and it would seal, but after that event where it was going to steam itself dry even with a new gasket, I stopped using it and began keeping an eye out for a similar one at thrift stores.

 

[tomturbomatic]

Sometimes after searing meat before pressuring I notice that I have to wipe the top edge of the pan before putting the lid on because there is stuff that will prevent a good seal from forming and would lead to steam escaping and, as the Presto instruction book states, it is important to conserve all of the liquid you put in when cooking meats because so little liquid is used to begin with.

 

[rp2813]

SUCCESS!

The S-9891 replacement gasket arrived today.  At first glance it appeared to be larger than the original, but I rinsed and dried it to put it to the test.

 

It didn't want to fit into place at first.  A small ripple would pop up as I went around the lid with it.  With some massaging of the gasket to fit firmly against the side all around, the excess went flat and provided a perfect fit.  I can see how some people would think the gasket was the wrong size if they gave up too quickly.

 

I brought a couple of cups of water up to 15 pounds of pressure and let the weight jiggle for about ten minutes.  I removed the cooker and placed it under cold water for a quick depressurization. 

 

The lid came off like butter!  I could have done it with one finger!

 

Thanks again to Allen for confirming the S-9891 to be the correct replacement for the 396M cooker.  I'm looking forward to this being my go-to cooker, the Goldilocks size that's not too small and not too big, but just right.