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A cautionary tale about oil filters.

I bought a used mower a little over a year ago. The engine had oil leaks at the valve covers. I fixed that and a few other things. Got it back together, changed the oil & oil filter, and used it last season. About an hour & 45 minutes per week. At the beginning of the season, it ran great, cut great, and no leaks. At about the 2/3 point in the season, it started using oil. I thought. Then, close to the end of the season, I noticed that it was actually leaking oil. Luckily, I check the oil before every use, so I just topped it off every time. After the end of the season, I realized that it leaked even sitting parked. The mower is a commercial Cub Cadet with a Kohler EZT750 engine. I like the mower. It does a good job, but engine access could be better, and the engine weighs about 100lbs. I'm over 60 with a bad back, so there's no way I'm able to just lift the engine out of the engine bay. Pulling the engine solo is something of a job, so I decided to wait until after the end of the season, and do it when I did my annual maintenance. I pulled the engine, and found the oil leak. It was the oil filter, which was also Kohler. It had loosened. I had tightened it up just like I do automotive oil filters (snugged by hand), and those get tighter by the next oil change. I've never had an automotive oil filter loosen up on me in about 45 yrs of changing oil. This one loosened, and made a mess. It could have destroyed my engine. So now I'll be checking my oil level AND my oil filter before every use.

This was the 2nd time I pulled the engine, and I AM getting faster at it. If I need to pull it this coming season, I won't wait till the end of the season.

More common on Kohler filters than people realize. I see 1-2 every year that I had installed by hand just like you and by the next spring tuneup are leaking and can be removed with two fingers. Kohler had issues a few years ago with filters coming loose from the factory. Had to due with how the O ring is installed at the filter factory and had manufacturing oil trapped under the gasket. Briggs must of been having the same issues a couple of years ago also because they now have a torque spec for the filter. Depending on where you look it is 87-100 lb/in.

Changed oil in my Kioti tractor back in April of last year. and after running 40 hours started leaking. Had to take the filter another 1/2 turn with a wrench to stop the leak. Pulled the filter shortly thereafter and replace it.

ILENGINE said:

More common on Kohler filters than people realize. I see 1-2 every year that I had installed by hand just like you and by the next spring tuneup are leaking and can be removed with two fingers. Kohler had issues a few years ago with filters coming loose from the factory. Had to due with how the O ring is installed at the filter factory and had manufacturing oil trapped under the gasket. Briggs must of been having the same issues a couple of years ago also because they now have a torque spec for the filter. Depending on where you look it is 87-100 lb/in.

Changed oil in my Kioti tractor back in April of last year. and after running 40 hours started leaking. Had to take the filter another 1/2 turn with a wrench to stop the leak. Pulled the filter shortly thereafter and replace it.

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So should I be using a different oil filter? If so, which one?

I started using my torque wrench set at 100 lb/in a couple of years ago, and haven't had a loose filter since. The recommended torque spec is tighter then what one gets by tightening by hand. Have always used Kohler filters and the loose filter issue seems to be hit and miss, but seems to always occur on the same mowers every time.

ILENGINE said:

I started using my torque wrench set at 100 lb/in a couple of years ago, and haven't had a loose filter since. The recommended torque spec is tighter then what one gets by tightening by hand. Have always used Kohler filters and the loose filter issue seems to be hit and miss, but seems to always occur on the same mowers every time.

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What kind of oil filter wrench to you have that will fit a Kohler filter, and mate to a torque wrench?

I use one similar to this one https://www.oreillyauto.com/detail/...pfm0/w54063?q=76+mm+oil+filter+wrenches&pos=1

ILENGINE said:

I use one similar to this one https://www.oreillyauto.com/detail/...pfm0/w54063?q=76+mm+oil+filter+wrenches&pos=1

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Thanks.

We have received some isolated reports of oil seepage/leaking at the base of the oil filter. The condition is usuallynot evident until the engine has been run.The filter manufacturer uses oil as a lubricant when the end cap is crimped into the filter canister. In some cases,excess oil was captured in the groove when the gasket was installed. The oil would form a hydraulic lock underthe rapid tightening/compression speed of the assembly line air wrench, giving a false indication that the filterhad reached proper torque. From the heat and vibration of operation, the oil will thin and begin to seep out of thegroove, allowing the gasket tension and joint to relax. The oil from the groove may seep to the outside, and oilmay also leak past the relaxed gasket joint.If a complaint is received, or a Kohler-powered product is being set up/serviced in your shop, the oil filter shouldbe checked to ensure that it is sufficiently tight. The recommended installation procedure is hand-tightening3/4-1 turn after the rubber gasket contacts the adapter. The tension on the gasket is applied more graduallyduring hand tightening, so any oil in the groove has a chance to escape. The filter manufacturer will also stampfour V-impressions in the inner groove ring, so oil can escape to the inside, even during machine tightening.As we reprint owner’s and service manuals we will change the recommended hand-tightening from 2/3-1 turn to3/4-1 turn after the rubber gasket contacts the adapter. Torquing the oil filters is no longer recommended, so thetorque value of 10-13 N·m (90-110 in. lb.) will be removed

hlw49 said:

We have received some isolated reports of oil seepage/leaking at the base of the oil filter. The condition is usuallynot evident until the engine has been run.The filter manufacturer uses oil as a lubricant when the end cap is crimped into the filter canister. In some cases,excess oil was captured in the groove when the gasket was installed. The oil would form a hydraulic lock underthe rapid tightening/compression speed of the assembly line air wrench, giving a false indication that the filterhad reached proper torque. From the heat and vibration of operation, the oil will thin and begin to seep out of thegroove, allowing the gasket tension and joint to relax. The oil from the groove may seep to the outside, and oilmay also leak past the relaxed gasket joint.If a complaint is received, or a Kohler-powered product is being set up/serviced in your shop, the oil filter shouldbe checked to ensure that it is sufficiently tight. The recommended installation procedure is hand-tightening3/4-1 turn after the rubber gasket contacts the adapter. The tension on the gasket is applied more graduallyduring hand tightening, so any oil in the groove has a chance to escape. The filter manufacturer will also stampfour V-impressions in the inner groove ring, so oil can escape to the inside, even during machine tightening.As we reprint owner’s and service manuals we will change the recommended hand-tightening from 2/3-1 turn to3/4-1 turn after the rubber gasket contacts the adapter. Torquing the oil filters is no longer recommended, so thetorque value of 10-13 N·m (90-110 in. lb.) will be removed

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The above oil filter was installed by hand. If this problem has only been observed when using air tools, that doesn't explain what I experienced.

Thanks for the heads up @GearHead36 - I just put a new filter on mine and like you, I tightened it by hand because that is what I have always done with autos. I haven't had a chance to run it yet because it is still too cold. Now I will make sure it is sufficiently tight before mowing starts this year. I put a Rotary brand filter on mine but regardless I will check it out.

I only had seen oil filter to loosen here on a Briggs. But when I install the filters I put oil the mating gasket and hand tighten to max turns indicated. Lube on the gasket is necessary to prevent sticking, doesn't take much just a smear. I had filters on vehicles that were nearly impossible to remove because these gasket where not prelubed.

Also not I one Purlator filter to fail after getting hot due a factory problem where they form the cup and had produced stress cracks. The heavy held until the filter got hot then it leak quite a bit; like 2 qts on a 25 miles drive.

Something I got in the habit of doing before I install an oil filter is to remove the gasket and wipe out the channel the gasket goes in to remove any possible oil that could be there. Like ILENGINE mentioned, Kohler and others had an issue with oil getting in that channel where the gasket goes. If you install the filter with oil under the gasket over time the oil will squeeze out and then the oil filter becomes loose. We had to warranty a couple of engines due to that issue. So now I make sure the channel is oil free. I always tighten oil filters one full turn after the gasket touches the mating surface on the engine. Sometimes I can do it by hand but most of the time it takes an oil filter wrench.

We get mowers in all the time with loose oil filters. All makes and models with all types of engines. Expansion and contraction due to heating and cooling will make the gaskets shrink and cause it to leak.

hlw49 said:

We get mowers in all the time with loose oil filters. All makes and models with all types of engines. Expansion and contraction due to heating and cooling will make the gaskets shrink and cause it to leak.

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hlw49 said:

We get mowers in all the time with loose oil filters. All makes and models with all types of engines. Expansion and contraction due to heating and cooling will make the gaskets shrink and cause it to leak.

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I always hand tighten oil filters with both hands and a grunt. Never had a come back or complaint for a loose oil filter. Fill with oil, put oil on gasket, and firmly install oil filter. Easy but very important.

I also see loose oil filters from customers when servicing equipment.

hlw49 said:

We get mowers in all the time with loose oil filters. All makes and models with all types of engines. Expansion and contraction due to heating and cooling will make the gaskets shrink and cause it to leak.

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I can understand that this could happen, but the same thermal expansion & contraction occurs with automotive engines. And I've learned over the years to tighten automotive oil filters less & less, as it usually requires a wrench to get them loose. They are ALWAYS tighter when I take them off than when I put them on.

Sometimes the issue may be related to the filter itself. Had the last 3 filters in a box of 12 leak within minutes of installation. The previous 9 in the box didn't leak or the filters in the new box. My Kioti DK45S filter started leaking after 9 months and 40 hours. None of those filters were physically loose and couldn't be tightened by hand.

ILENGINE said:

Sometimes the issue may be related to the filter itself. Had the last 3 filters in a box of 12 leak within minutes of installation. The previous 9 in the box didn't leak or the filters in the new box. My Kioti DK45S filter started leaking after 9 months and 40 hours. None of those filters were physically loose and couldn't be tightened by hand.

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In this case most likely it was a manufacturing defect such crimping the cup not tight enough. Or like the Purlator here where when they made the cup they over stretched the metal and the heavy paint hide the defect.

ILENGINE said:

Sometimes the issue may be related to the filter itself. Had the last 3 filters in a box of 12 leak within minutes of installation. The previous 9 in the box didn't leak or the filters in the new box. My Kioti DK45S filter started leaking after 9 months and 40 hours. None of those filters were physically loose and couldn't be tightened by hand.

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In my case, though, the filter WAS loose. The gasket was still in contact with the block, but just barely. I could move it with two fingers.

GearHead36 said:

In my case, though, the filter WAS loose. The gasket was still in contact with the block, but just barely. I could move it with two fingers.

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I have seen two different riding mower engines destroyed last year due to the oil filter being too loose. Of course the filters require an oil filter wrench to remove, that’s what you want! Not being able to spin it easily with your left hand only-oil leaked out and broken connecting rod.

Tiger Small Engine said:

Of course the filters require an oil filter wrench to remove, that’s what you want!

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Ideally, I'd like for the filter to be tight enough for me to be barely able to loosen it by hand. I've found that point for automotive filters about 80% of the time. I already have 5 oil filter wrenches, but will need a 6th to fit this filter where it's located. My mower works great, but engine access is not the greatest, and it's fuel injected, with a huge fuel pump right over the oil filter. Getting to the oil filter is a pain.

Just pulled the oil filter for that one that just put the solenoid shift starter on and the filter on it was loose. I know for a fact that the filter was installed at the proper tightening amount because I did it myself last spring.. Wasn't leaking yet put would of occurred in the near future. Put it on this time with the gasket contact mating surface and then one complete turn so we will see what happens.

When I reinstalled the filter that started this thread, I used a wrench. I may have to remove the engine to get the filter off, but that's still better than a destroyed engine.