Pressure Canner Troubleshooting – How To Fix Problems

Pressure Canner Problems

Pressure canner troubleshooting tips, originally posted by ‘Christine Coburn’ for Modern Survival Blog.

“There is nothing more frustrating when you have worked hard to get a batch of food prepared to can, and then your canner doesn’t work right.”

After 30 years of canning I have learned several canning “tricks”, All of them the hard way.

In order to understand what’s causing a problem and how to fix it, you first need to understand how each part of the canner works together with the rest of the parts.

My pressure canner is the normal run of the mill canner:

Mine is a Mirro 22, made in 1980. It has been in service full time for 31 years.

Today’s Mirro pressure canner is one of the most popular:
>> Mirro 22-Quart
(view on amzn)

Pressure Canner Troubleshooting – Various parts of the pressure canner

First, a quick look at basic parts:

See the locking lugs all the way around.



Canner Racks
One is always placed on the bottom of the pot under your jars. The other is placed on top of the first level and then a second level of jars on top of it. This is when you are canning pints or half pints and are doing a second level. You can not stack quart jars. Failure to use these will cause your jars to break in the canner.


Pressure regulator
This is what regulates the amount of pressure in your pot.

High pressure relief valve
This is the safety mechanism to keep you from blowing the lid thru your ceiling.

Lid locking mechanism
This is also a safety mechanism to keep the lid from blowing thru your ceiling.

Troubleshooting Pressure Canner Problems

A list of various problems and solutions:

The lid will not fit on right

The locking lugs are not properly lined up

Place the lid on top of the canner with the lid handles a little off set from the pot handles. Line up the lugs by sliding it back and forth until the lugs fit together and the lid slides down. Then turn the lid until the handles on the pot and the lid line up.

If your lid doesn’t not want to slide easily once it has seated on the lugs then coat the gasket with a small amount of vegetable oil to help the gasket to slide on the pot.

Pressure Canner not building pressure

Turn off your burner and slide the canner to a cool spot to cool down before troubleshooting the problem.

Gasket not sealing
– Soak gasket in hot water for 15 minutes.
– If gasket seems loose on the lid then you can stretch the gasket by working your way around with both hands pulling on it.
– Try a coating of vegetable oil.
– Replace gasket (good to have a spare on hand !!)

>> Mirro Pressure Canner Gaskets
(view on amzn)

>> Presto Canner Gaskets

If your pressure canner won’t build pressure, it might just be not enough heat.
– Increase heat.
– If you have a canner with wing nut type clamps then it is possible one of your clamps is not tight.

New Gasket Won’t Seal

You just bought a new gasket for your Canner and now it won’t seal or the gasket only lasts a few times of running the canner before it fails again.

Turn your pot over and look at the manufacturing date. You see the 12 80 on mine (See picture below). The Mirro 22qt made before 1983 requires a different gasket than is sold at the hardware store now. You probably have the wrong gasket.

There are several sites on the internet that sells the older replacements. You can call the manufacturer to make sure of what part you need.

Gaskets that are used regularly should last 3-5 years. Usually what causes them to fail is not using them and they dry out.

Old faithful erupting on stove

Steam is pouring out from under the lid. Slide the canner to a cool spot to cool down before trouble shooting the problem.

Lid locking mechanism did not lock
– Try Jiggling the lid to get the mechanism to lock. Some canners are very picky about the lid placement and this mechanism.

Food is hung in the lid lock mechanism
– Make sure your lid and jars are clean before processing.
– Check the gasket, under the gasket and the lid lock mechanism for pieces of food.

Gasket not sealing
– Soak gasket in hot water for 15 minutes
– If gasket seems loose on the lid then you can stretch the gasket by working your way around with both hands pulling on it
– Try a coating of vegetable oil
– Replace gasket if it is dry, hard, cracked or torn.

If you have a canner with wing nut type clamps then it is possible one of your clamps is not tight.

The high pressure valve just popped

(Hurry and throw a damp rag on top of the valve so that you do not lose your jars, do not get your hand in the way of the steam it will burn you). Slide the canner to a cool spot to cool down before trouble shooting the problem.

Stem is clogged
– Always make sure your pot and lid is clean before you use it and make sure your jars are clean when you put them in.

The pressure regulator quit jiggling and is now just blowing a steady stream of steam

Too much pressure in pot
– Turn down your heat a bit

The pressure regulator quit jiggling and is not blowing steam out

Not enough pressure in the pot
– Turn up your heat a bit

Lids not sealing

Rims not clean when lids are placed on
– Wipe the rims with a clean damp cloth before placing your hot lids on them

Pressure being dropped too fast
– Never drop the pressure artificially. Allow the pot to cool on its own. By dropping the pressure it causes negative pressure in your pot and will pull the jar contents out into the pot from under the lids.

Using used metal lids
– Never reuse a metal lid. The only lids suitable for repeated use are Tattler lids with gaskets.

Not enough headspace
– Leave about ¾ of an inch between the top of your food and the top of your jar. The jars will boil in the canner and if you do not have enough empty space in the jar then the contents will be pushed out of the jar causing grease and food to get under the lid.

Rings not tight on metal lids
– Tighten rings over metal lids prior to processing

Rings too tight on tattler lids before processing or not tightened down after processing.
– Tighten and then back off the rings over a Tattler lid ¼ inch then tighten the rings after the jars are processed and removed from the canner. Use an oven mitt the jars are HOT!!!

 Today’s Top-Of-The-Line Pressure Canner Brand:
>> All American Pressure Canner
(view on amzn)

Pressure Canning Tips

If at any time you lose the pressure in your pot you have to start re-timing the food from the time you rebuild pressure!!

Always let the canner vent steam for at least 10 minutes before placing the weight on the stem. This allows the air to evacuate the pot and makes sure the stem is clear.

Always make sure your canner is clean and the jars are clean before canning or you can clog your stem. Inspect it before each use.

Always make sure you have enough water in the pot to run the entire processing time. If you let a canner run dry you will warp the pot and break your jars.

NEVER drop the pressure purposely by removing the weight or running cold water over the pot. Always allow the pot to cool naturally by only sliding it to the cool side of your stove or counter. Failure to do this can cause steam/burn injuries, broken jars and seal failure.

Any time there is a problem with your canner gently and carefully slide it to a cool place and then leave it alone until the pressure has subsided. If too much pressure builds it will make a howling sound from the steam escaping the escape valve or from under the lid. The escaping steam will burn you!!!

[ Read: Home Canning Tips And Lessons Learned ]