M-18 running rough/missing - Page 5

john hall · #41 02-01-2017, 10:27 PM

OK, here's the plan. Like a few have said either on the forum or by PM, it should run just fine with a valve job. That said, I decide to go ahead and at least put rings in but will probably go ahead and put in pistons. Dad felt real strongly about going ahead with a set of rings--plus I get the feeling he really wanted to open up a Cadet engine again. My engine machinist just retired. He's done all our work and the work for the IH dealer dad worked for the last 35 years or better. He suggested rings as well. Fortunately he still works a couple days a week so he'll be doing my machining--I'll face the heads myself.

I pulled the jugs to measure the pistons. One is a little scuffed on the side wall, the other is burnt away real bad on the top edge. I measured and the piston dia is about .001-.0015 below the book value where it says to measure at. I'll probably go ahead and get a set of pistons and be done with it, a little more than double what rings will cost. Jmechs parts guy has them listed.

Pulled the flywheel so I could clean the gunk from the charging system. There may have been a hint of oil. I just put in the PTO side seal so I'll change this one while its in front of me. I bought a can of high temp paint the other day, the block and tins are going to get a fresh coat.

So that's the plan, hopefully get parts ordered and jugs sent to machine shop tomorrow. Now somebody please give me a good recommendation on whatever sealant goes between the jugs and the block--that is readily available? The machine shop is in a BIG real parts store so they probably carry something adequate.

yeeter · #42 02-03-2017, 08:24 AM

Thanks for sharing the progress update John. Some very useful information in this thread so I look forward to hearing how it goes to completion.

yeeter · #43 02-25-2017, 06:51 AM

Any progress updates?

john hall · #44 02-25-2017, 07:11 AM

Valves are ground, jugs honed. Ordered aftermarket pistons, got them. Last week I got one piston and jug put on the engine. Then I had some field work to do. Hopefully I can do the other side some time today, got to fertilize hay land before it rains later. Hopefully this afternoon I can at least get the other jug and piston in.

john hall · #45 02-25-2017, 05:21 PM

Got the other jug/piston installed. Man is this thing hard to turn over. Put a 5/8 wrench on the PTO bolt and it takes a lot of effort to roll it over. Yes, I used LOTS of oil when I put the pistons in. We'll definetly spin this one over with the starter a bit as soon as I get the block painted, want to make sure the starter is up to task.

Sam Mac · #46 02-25-2017, 06:13 PM

If you have the plugs out it should be easy to turn over. Sounds like something is too tight.

darkminion_17 · #47 02-25-2017, 06:45 PM

Quote:

Originally Posted by Sam Mac

If you have the plugs out it should be easy to turn over. Sounds like something is too tight.

Maybe the jugs are out of round, hehehe.
Did you bore them to the next oversize or hone them?

john hall · #48 02-25-2017, 07:58 PM

Heads aren't on yet. Cylinders honed when valves ground. Jugs measured in spec for standard bore. It was tight when I put the first jug assembly on, got worse with the second. Pistons were not exceptionally tight driving them in, just the normal bump with a hammer handle. With these you have to drive the wrist pin hole out the bottom so you can install the pin. It didn't take much effort to rotate the jug to line up the studs once the pin and locks were in. Only engine I can ever recall being tight like this was a couple Farmall Cubs, but I think it had something to do with the rods/pistons being ever so slightly twisted. After a couple turns with the hand crank those freed up, then I re-torqued the rod. FYI I did not bother the crank and rod bearings, so whatever is going on is certainly something to do with the pistons and rings. I did squirt some oil in the small drain back hole in the valve chamber to add more on the pistons. Don't see any scoring/scraping. I'll probably oil everything up real good and put a pull handle on the crank and see if it spins better after a few revolutions. Oh yeah, piston pins were very snug in the piston but fit the rod just fine. It was all I could do to push the pins through the piston by hand, any tighter would have been a "bump" fit.

J-Mech · #49 02-25-2017, 10:44 PM

Did you check the ring end gap before putting them on the piston? Most aftermarket rings are oversized and have to be filed.... sounds like you need to take it all back apart.

john hall · #50 02-25-2017, 11:41 PM

I thought about that---afterwards.

I measured one of the pistons against an old one and it seemed pretty close. Not a huge deal to pull back apart, other than cleaning up the silicone. I can honestly never say I've had to file the gap on a set of rings. Most of the time I've always used OEM packaged rings other than a couple times using "name brand" aftermarket (such as Perfect Circle). Guess at this point there is nothing to do other than pull one side down and check them.

How about the oil expander ring, shouldn't have to file that one, right?