Swapping A Mower Engine – Part 1

I have a DR Field & Brush Mower from the early 1980’s.  This is an amazing tool for clearing land and property maintenance.  However I’ve been having problems with the engine for the last two years and finally it seized up this month.  I considered trying to fix the engine, but after 35 years of use I’m not sure how worn out this engine might be.  A replacement Briggs was something over $500, however the 8HP Harbor Freight Predator brand was a bit less than $250 so I decided to give that a try.

The first step is removing the old engine and making sure the replacement is as close as possible.  In this case the old engine was an 8HP horizontal shaft engine with a 1″ keyed shaft.  I needed the pulleys from the output shaft and if I couldn’t get them off I was going to take a saw to the shaft and then drive it out.  However the puller worked easily.

You do have to be careful with the 3 jaw pullers and they can exert a tremendous force on the parts involved.  If you get to the point where you are really putting some force on the screw you have to start considering which part you might have to sacrifice.  If you need to save the shaft you can cut the pulleys of if the engine is bad anyway cut the shaft.

Another trick is to heat the parts with a torch.  if most of the heat is directed on one of the two parts stuck together you will get expansion that could be enough to break the connection between the two.  You will not be able to see it with your eyes, but the differential rate of expansion is there and you only need a small amount of movement to free up a joint or connection that is stuck.

Next mounting the new engine.

Author: Jerry Ward

Working on creating a 10 acre urban homestead in S.E. Michigan. To pay the bills I work as a product manager/business analyst in the IT field. Now the admin of Save Our Skills