OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs 13 series Bottom Seal

G'day Guys. Can the bottom seal be replaced without splitting the case, and how does te v belt pulley come off the shaft?

cheers
matt

The V belt pulley is supplied by the mower manufacturer, not Briggs, so there is not a standard way to attach it. There will be a key between the pulley and the crankshaft, and a grub screw or something else to locate the pulley vertically. (It could be a screw axially in the end of the crankshaft.) Remove whatever it is, apply some Penetrene to the shaft above the pulley so it soaks into the joint, wait a couple of hours, and apply a gear puller. If it is a large pulley and therefore not hugely robust, and if it is really tight, supply pictures and we'll discuss solutions. Large pulleys break if you try to pull them with a gear puller.

Here is the instruction from Briggs for installing that seal:
http://recoveryvehicles.tpub.com/TM-5-4240-501-14P/css/TM-5-4240-501-14P_259.htm

Some mechanics remove the seal by using a hook behind the front part of the seal outer (not the sealing lip: never try to get behind that). The new seal can then be tapped into place carefully. However I think most dealer mechanics would prefer to remove the crankcase cover and do the job on the bench: outcomes are more assured that way.

cheers thanks for that grumpy

yeah forgot to mention its a double v belt pulley from a rover colt 5hp. The bottom V has one side a lot bigger in diameter to "hold" the belt when disengaged. Its got two grub screws and i found an IPL for the engine and can see a key in there as you suggested.

Ive ordered a new seal should be here in a week.

I'll let you know how i get on


thanks again
matt

Got the pulley off this arv - didn't have a puller i used a long brass drift and some light taps, not ideal i know but i didn't hurt anything. Looks like my old man put some antiseize compound on the shaft about 10 years ago when replacing the rings. I thought ide may as well split the case to see what it was like inside - no surprises and clean as a whiste. Got the old seal out just waiting on the new one.

cheers
matt

Be sure and put the seal in square, matt. If you use a press, or a vice, to put it in it's pretty easy to keep it square. If you have to just tap it in, check it for squareness constantly, and use very small taps in just the right place. Examine the crankshaft right where the seal's lip runs against it. Worn out seals usually have been worn by either metal filings from the crankcase, or dirt from the outside. This often wears a groove in the crankshaft. You can't remove the groove, but you can put the seal in slightly more or slightly less than where it was before, so the sealing lip runs on a fresh bit of crankshaft.

Also, check the fit of the lower main bearing (which is a bush pressed into the timing cover) on the crankshaft. If it is a bit slack, you aren't giving the seal much of a chance: they can't deal with wobbling shafts. If the bearing has any wear, replace it while you can.

cheers thanks for the tips, i have a press so no worries there. I'll have another look at the crank - there is a shiny spot where the seal runs but don't think its grooved out. - if so i'll do your trick of putting it in slightly less.

The bottom main bearing is tight no detectable movement. come to think of it i don't think mine is a brass bush looks more like white metal? Or maybe just white metal lined brass bush?

I think the old briggs engines are bullet proof, this thing has done a lot of work (been in the family since new in 81). All its had is a few sets of rings and regular oil change. The bore is perfect. bigend is tight etc. I think the automotive type filter element helped it a lot.

cheers
matt

matt, if it is a synchrobalance engine, check that mechanism for wear or any sign of dirt or scoring.

I am inclined to agree that the iron-bore Briggs engines are likely to be very durable if you keep the right amount of clean oil in them. However when you say "a few sets of rings" it sounds as if this one has done an exceptional amount of work. I suggest you inspect the valve seats - unless it has been done a couple of times along the way, it is likely to be due for recutting the seats rather than just lapping them. Check the valve stems for fit in the guides, and reset the tappet clearance after you attend to the valves. Take a look at the camshaft lobes, in case they are worn. Naturally, check your ring gaps if you haven't done it in a long time. I hope you have been looking at the fit of the rings in the grooves each time you replaced them. Check the other main bearing (flywheel end) for wear (just looseness of crankshaft in the bearing).

G'day Grumpy, it doesn't look like a synco balance engine. The valves look good, my old man would have cut the valves and seats last rebuild (we have a W&B valve refacer and seat cutting tools). They are a little worn in the guides but it runs OK. It was bought new in 1981 and cut 1/2 acre of grass for 25 years on a weekly basis. The frame is a little worse for wear but the engine is still strong. Only needs a new seal, it was leaking over the belts and has buggered them

cheers
matt

OK matt, that sounds good. I understand you not wanting to worry about the valve guides until you have no choice. Did your father make his mandrel for recutting the seats of that engine's valves, or did he get one from Warren and Brown back when they still made them? I have 10 cutters, but only one "official" mandrel, in an old car engine stem size. To cut seats, I have to turn up a mandrel on the lathe.

I think 13 cubic inches is below the minimum size for synchro balance models, so I'm not surprised yours doesn't have that mechanism.