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Small Engines (Lawn Mowers, etc.)/Craftsman Lawnmower leaking oil


QUESTION: My Lawnmower, Craftsman 917.6732, started to leak oil through the bottom after I had the housing replaced at a local repair shop. Could it be an oil seal that got damage in the crackshaft?

ANSWER: The model number is missing a few numbers so I can't look up your engine but based on the information I would suspect the lower main oil seal is leaking.

Double check the model number and see if there are some additional numbers.

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QUESTION: The model# is 917.376732

ANSWER: Thanks for the numbers.

You have a Briggs and Stratton engine, model 124T02-0736-EA (model, type).

The lower oil seal is Briggs and Stratton part number 399781S ($5.62 from Sears).  These engines are pretty durable...why did the lower housing (sump) need to be replaced?  Do you know if they charged you for a new seal?

I have installed a lot of seals...always a little nervous if they will leak or not as it is very difficult to get the crankshaft really clean, aka new, to ensure there are no minor burs or other issues with the old crankshaft.

They (Briggs) do sell an oil seal install protector set and I use a protector everytime I have to replace a seal.  I've had good success with replace seals but you have to really clean the crank before installing.  The seal can be replaced without removing the lower housing and you really don't have to remove the engine...although removing the engine makes the job easier.  Either way if the shop replaced, and they should have, they should replace it again so it does not leak.  

Let me know why the lower housing needed to be replaced.

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QUESTION: I think I would rather try to replace it myself. Where would I buy the
oil seal install protector set? What is the part number? I had to replace the housing because it was rusted around the base of the engine. Here where I lived rains a lot and the accumulation of wet grass and dirt caused the housing to rust (lack of proper maintenance).

The old part number was Briggs and Stratton 19356.  After doing some research the part is now obsolete...Briggs isn't selling them.  You may be able to find the kit but it may take some work.

Another option I've read about is to use a plastic soda bottle or old plastic microfiche card as a substitute.  You will need to cut the bottle and form it around the crankshaft.  Basically you are just wrapping the crankshaft with plastic to protect the seal as you slide it down the crank.  I have used old microfiche cards and just wrapped them around the crank and started the seal. Once the seal is on the plastic the seal will hold the plastic protector in place as the seal is installed.

A piece of PVC pipe and a cap works well as a seal driver.  The key is to lube/oil the seal, place it around the protector, and then tap it in place using the PVC pipe and a small hammer.  The seal needs to be installed straight and not too deep or too shallow.  Just drive the seal in slightly past flush with the bottom of the housing.  It wouldn't hurt to measure the depth of the old seal before remove.  The measurement is not critical but I like to get a rough guess of where the original seal was before removing that way I know how deep the new one should be installed.  Other signs such as clean shiny parts are also clues as to how far to install the new seal.

Have you searched You Tube for videos on installing oil seals?  There are lots of videos with some very interesting techniques.  Pretty rough ways to install seals but I guess the way I do it, with the protectors and other tools, isn't a bad technique as I can't recall the last time I had one leak after replacing.


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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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