OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Walk Behind Lawn Mower Frames Question On Scott Bonnar Cylinder Mowers Removal of Muffler - Scott Bonnar Model 590

Howdy

Got a nice new shiny muffler for my Scott Bonnar 590 mower. Are there any tips & tricks for removing the old muffler. The fuel tank is obstructing the screw out of the old muffler. Do you need to move/remove the fuel tank to get the old muffler off? I'm assuming it's just an anti-clockwise screw out of the old muffler?

Details of Briggs & Stratton engine:

Model 80102 Type 0233-01 Code 77040401

Cheers
Pat

Pat, we need pictures of your engine to discuss it usefully. It was made on 4 April 1977. Here is the Illustrated Parts List:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6jmvGVJ1DajI.pdf

Here is the Operator's Manual:
http://bsintek.basco.com/BriggsDocumentDisplay/lrvvA-wU7eL7hAxB91ObQ.pdf

You routinely remove the cowl, fuel tank and carburetor whenever you need working room on that engine.

Briggs used several mufflers on that model, and most others. Let's see which one you have, then we can talk about it.

Hi Grumpy

I've loaded a photo. The new muffler that I sourced was was part no 392811 from the Briggs and Stratton parts list.

Cheers

Your original muffler is the optional one shown on the Briggs Illustrated Parts List. Note that because of its offset shape it has to be "timed" rotationally, to clear the breather tube going to the carburetor. To make this timing possible without the muffler being loose in the thread, it has a locknut on the thread holding it screwed into the exhaust port. You have to loosen this locknut first, before you can unscrew the muffler from the port. It is a normal right hand thread. I doubt your new muffler came with a locknut - if it didn't you will need to reuse the original one. You will also need to soak the threaded part of the old muffler with Penetrene or something similar for a day or so to get it out of the exhaust port without it just breaking off and leaving you with a problem. Putting some anti-seize agent (such as Kopr-Kote) on the new thread before you screw it in, should help make it easier to remove next time. Screw the new muffler in by hand until it is firm, then undo it the minimum amount necessary to achieve the required rotational position, then tighten the locknut to hold it in that position.

Note also that your original muffler had an exhaust deflector on its outlet hole, to keep the mower operator from being in line with the exhaust blast. You may decide you need to source a deflector, depending how tolerant you are of getting blast-marks on your knees.

I understand the Briggs exhaust fittings use standard US National Pipe Taper (NPT) thread. Remember that US pipe threads, like British ones, (BSP, also known as Gas), are sized by the inside diameter of the pipe, not the outside diameter of the thread.

Thanks for the info Grumpy - very informative. Just a note for a newby on this site - do I need to close off Posts that I initiate, or mark them as 'Closed' ? I can't see an option to do this.

Cheers
Pat

The moderators close the threads, Pat, but it is helpful if the poster comments that the thread can be closed, rather than the moderator making his/her own assessment (which might be wrong).

Post edit: Pat, I initially closed this thread but I've re-opened it, as I believe you have something more to post.

Hi Grumpy , I just wanted to know the part number of the 'optional' muffler you mentioned in your comments.

Cheers
Pat

There are actually several Pat, but some of them are not illustrated. Here are the illustrations:


Here are the part numbers:


P/N 392811 looks to be the same as your old muffler.
P/N 89966 is probably the long, symmetrical tubular muffler shown in the illustration.
P/Ns 292064, 295905, & 297934 are used on various other versions of the 80102 but are not illustrated.
P/N 91810 is a 45 degree exhaust elbow.
P/N 91943 is a 90 degree exhaust elbow.

Ok cheers thanks for that Grumpy.

This post can be closed out.

Regards
Pat