Since you do not appear to be prepared to do the work yourself, I doubt that it is practical to repair the engine. Shops in this area charge $55 - $75 per hour. IF it is worth considerable to you for sentimental reasons, you need to determine if the crankshaft is bent. Remove the spark plug, fasten a stiff wire or thin pc. of fat stock to the edge of the mower deck so it just touches or nearly touches the crankshaft and turn the engine over slowly by hand watching the clearance between the flat stock and the crankshaft. You should be able to see wobble if the crankshaft is bent.

Grasp the crankshaft or blade and move the crankshaft side to side. These engines routinely wore out the bottom bushing which is not a replacement item although several guys have bored them out and installed an "F" series engine needle bearing.

These two thing can be determined without disassembling the engine and they would not be anxious to disassemble the engine FREE, see rate above.

These parts are fairly often available on ebay, I don't know if they are still available from Toro or not.

Good luck,

Walt Conner

One step at a time. Many thanks!

"as demonstrated by loose screws swirling around where the crank comes out of the muffler,"

I'm not sure I follow you here on this quote. I can't think of any screws from the seal area. Do you mean the muffler bolts?

Neal

There are no bolts associated with the bottom seal. The loose bolts he mentions is probably indicative of excess vibration due to bent crankshaft. Loose bottom bushing in connection with badly out of balance blade could also cause this or even badly out of balance blade alone.

Walt Conner

Well there are three(?) little bolts that hold the gear case on the bottom of the engine but the seal its' self just presses in the bottom of this case as others.

Walt Conner

An out of balance blade was one of the things I ruled out-
two back up blades were put on-
one freshly sharpened/balanced at the shop, and
one brand new blade were tried, w/ no change in vibration.

Muffler bolts are not the problem- the heads can be seen on the upper surface of the deck, and the ends/bolts are seen secure on the muffler plate bottomside.

The 1st repair I noted from 2001 were described as replacing the 'lower seal bolts' on the receipt. The shop manager said there are 4 of them.

In looking at the LB parts blowup on

https://lookup2.toro.com/partdex/index.cfm?xCaller=lawnboy

There are four bolts (part #314576-'40' on the diagram)

These come up from the bottom of the crank, where there is a crankshaft end cover. The bolt threads pass up thru the top of the muffler plate, thru the lower crankcase seal, and into the lower part of the crankcase. I do not see nuts on the diagram, it is not clear where the ends of the bolts go.

I am fairly sure these are the origin of the problem.

That all said, QUESTION- I am wondering if the rod and piston are degraded by a bent crank?

I should note I still have to perform Walt's 'wiggle' test as note in his original post to see if the crank is bent, or if we are just dealing w. loose lower crank bolts.

Walt- can you clarify your statement- 'These engines routinely wore out the bottom bushing which is not a replacement item although several guys have bored them out and installed an "F" series engine needle bearing.'

What is this bottom bushing? Is that integral to the crankshaft- and that is where the shaft has an hourglass shaped 'bulge'?

Thanks again everyone!

"These come up from the bottom of the crank, where there is a crankshaft end cover. The bolt threads pass up thru the top of the muffler plate, thru the lower crankcase seal, and into the lower part of the crankcase."

If you check the exploded engine view that you pointed out in your post, you will see that the lower crankshaft seal is separate, no bolts no bolt flange, bolt holes or anything. You should see, what you call, "crankshat end cover", which is actually the gear case cover which I mentioned earlier. It encases the self-propelled gear and shaft that you see in exploded view to the right of the case and seal. The crankshaft seal presses into the lower end of this gear case, it is not bolted. Now there is a gasket between the gear case and the crankcase which may be what you and service tech may be calling a seal. Unfortunately, the exploded view for this model number does not list the part name as most do.

There is a bronze bushing in the bottom of the crankcase which is cast into the crankcase and is not a replacement item. A search of this site should turn up posts describing how people bore this bronze bushing out and replace it with a needle bearing used in "F" series LBs.

I don't know what you are talking about the crankshaft having an hour glass bulge. The end of the crankshaft is tapered where the blade drive plate goes on.

Walt Conner

Hi Walt

The part you said about "....cast into the crankcase and is not a replacement item."- matches word for word what the man at the shop said to me!

I'll know more Friday afternoon- my work place will let out early, and give me a chance to check to see if the crank is bent, as you suggested in your 1st post.

Thanks for your kind advice and for hanging in there with me.