Small Engine Repair - Part III - PeachParts Mercedes-Benz Forum

kknudson · #1 09-12-2009, 03:44 PM

Well after the last two threads, knew it would happen my old Simplicity with a 12 hp Briggs started acting up.

I am not much of a small engine person, pretty good mechanic, great weekend warrior and extremely handy.

Now this is a 18 year old lawn tractor that really has seen better days, I measure time in quarts (as in oil) more than gas.
But it generally runs great, I have a fair amount of spare parts, plus a snowblower and thatcher that will basically only attached to this tractor.

The other day it started acting up, sputtering and stuttering.
Initial diag the fuel filter, replaced it ran fine for a short time, then sputtering.
Took the carb apart, ran fine then stuttering.

Got it running again, after a few minutes it stuttered, and stalled.
Would not restart, diag No Spark.
I had replaced the magneto a year ot two ago so this didn't seem rught.

Pulled the cover off, the magneto didn't look like it was positioned right.
So I removed it, cleaned it and cleaned the magnet (???) on the flywheel, replaced it positioned correctly (I think).
Runs fine.

This is where either I got lucky or maybe don't run w/o the cover.
While giving it a test run, I left the one engine cover off, I get a HUGE thing of BLACK smoke from under the hood then normal.
A few minutes later I look under the hood and there is something smoldering between the cylinder cooling fins YIKES.

Cleaned it out with a screwdriver and my compressor.

So was this caused by running w/o the cover, or have I been lucky up to now. There was a lot of crud in there.

Here's the real question, did my cleaning/adjustment fix the magneto, or should I assume it's going bad after it warms up and at least have a spare on hand ?

I did run it for a lot longer the final time than either of the earlier times w/o and issue's. The earleir times I ran it it generally acted up after 3 to 5 minutes.
The final test run was 20 +.

And generally, I adjust the carb by turning the needle valve in until it sputters, then back out a bit correct ??
This would mean I am running lean ( as lean as possible).
Or should I back it out until it stutters, then bring it back in ??

Again, not a great small engine guy.

Thanks

rscurtis · #2 09-12-2009, 07:17 PM

It's possible your clogged cooling system was overheating the coil. Your carburetor adjustment procedure (lean to smooth) is correct.

kknudson · #3 09-12-2009, 07:28 PM

Possible, I didn't notice the condition of the cooling fins before.

I do clean the engine semi regularly, with the compressor. But not with the covers off.

Funny too, when I bought this tractor (almost 20 years ago) I was always worried more about the Hydro Tran, they were somewhat new on consumer level products back then. And now the engine is dying.

Wish I could get a rebuild kit, searched some online, absolutely zero.
Partly just so I could have the experience of rebuilding a small engine, partly as the rest of the tractor is in good to excellent shape.
Even a replacement motor, but I couldn't find anyway to get matching bolt patterns.

rscurtis · #4 09-12-2009, 09:20 PM

That engine will respond very well to a replacement chrome ring set and a valve adjustment while you're in there. It will run as good as new. If it has an aluminum cylinder bore don't even hone it- just clean it and put it together. Since flathead engines are no longer made, an OHV replacement may not fit in the available space, and the exhaust configuration could be a problem.

kknudson · #5 09-12-2009, 09:32 PM

I would love to get a ring set, but don't know where.

When I did cars, the rings etc were very engine specific, and then to all the gaskets etc. Although I can make many of these.

It is a cast Iron bore (sleeve if I remember).

lutzTD · #6 09-13-2009, 08:50 AM

In my past small engine experience (mostly 5hp mini bikes and gocarts single cylinder), specially briggs and tecumseh, whenever there was an ignition problem it was due to a pertially sheared moon key. this holds the flywheel to the crank in the correct position to get a correctly timed spark. if it shears partially it can throw your timing off by a good amount. with a mower crud can get in there and spread the spark coils away, but I think you already set that gap.

rscurtis · #7 09-13-2009, 10:05 AM

Quote:

Originally Posted by kknudson

I would love to get a ring set, but don't know where.

When I did cars, the rings etc were very engine specific, and then to all the gaskets etc. Although I can make many of these.

It is a cast Iron bore (sleeve if I remember).

Any B&S dealer. All you'll need is the model, type and code #. Also, get a gasket set while you're at it. Briggs parts, (except the chrome rings), are also relatively inexpensive.

kknudson · #8 09-13-2009, 01:46 PM

Well this got me going.
Found the correct engine number and a place that has parts.

Need to figure out which gaskets I need. Several noted included in ..., but I couldn't find ... NOTE I just popped down here sunday quickly during a break from my outdoor chores so I did not go through it in detail.

Other issue is they list 3 different ring sets, each one std and oversized.
I assume I will go oversized and hone the cylinder, but I have to narrow down which of the 3 I need.

This could be a really fun winter project.

lutzTD · #9 09-13-2009, 05:37 PM

Quote:

Originally Posted by kknudson

Well this got me going.
Found the correct engine number and a place that has parts.

Need to figure out which gaskets I need. Several noted included in ..., but I couldn't find ... NOTE I just popped down here sunday quickly during a break from my outdoor chores so I did not go through it in detail.

Other issue is they list 3 different ring sets, each one std and oversized.
I assume I will go oversized and hone the cylinder, but I have to narrow down which of the 3 I need.

This could be a really fun winter project.

Pull it apart before you order anything. no hurries right? then you can inspect and measure the bore to determine the best option The oversized will require more than a hone, you will need to get it bored then honed. best to stay standard if it is within tolerance

kknudson · #10 09-13-2009, 05:53 PM

Quote:

Originally Posted by lutzTD

Pull it apart before you order anything. no hurries right? then you can inspect and measure the bore to determine the best option The oversized will require more than a hone, you will need to get it bored then honed. best to stay standard if it is within tolerance

I was considering the same thing, tear it down first.
I should be able to hone .2, slow but

But again, they had 2 or 3 different part #s each for Std, .1, .2 and .3 piston/ring sets.
All out of Ring onlys, except std, but I'll look more too before I buy.

The wife has declared it the tractor that will never die.

rscurtis · #11 09-13-2009, 09:58 PM

The chrome ring sets will accomodate some cylinder wear. I have rebuilt many of these engines. The rings will wear many times faster that the cylinder. I have never rebored any of these engines. I once had a Kohler CH 20 Command engine on a stump grinder that used 3 quarts of oil per day- and it holds less than two! New pistons, new rings, no honing (cylinders too hard) - good as new. A flathead Briggs is not a high-tolerance engine- it is made just good enough. Unless the cylinder is damaged from a wrist pin retainer coming loose or some similar malady, give it a light honing (cast iron only) and put it back together.

lutzTD · #12 09-13-2009, 10:02 PM

Quote:

Originally Posted by kknudson

I was considering the same thing, tear it down first.
I should be able to hone .2, slow but

But again, they had 2 or 3 different part #s each for Std, .1, .2 and .3 piston/ring sets.
All out of Ring onlys, except std, but I'll look more too before I buy.

The wife has declared it the tractor that will never die.

if you try to hone out that much it will be oversize in the middle. as you go up and down the middle will get much more cut time.

kknudson · #13 09-13-2009, 10:05 PM

Thanks, don't know what the rings are made of. It appears, I sent them an email, that I have to go piston and rings, not just rings if I go oversized.
IF I can use stock rings, I can get just rings.

Thanks though, this is the input I need.

I've rebuilt big blocks, 383/440/390 even a 427 (sweet engine) and an assortment of smallblocks, but that was almost 40 years ago. And while the process of rebuilding is similar there are a number of differences.

Thanks

kknudson · #14 09-13-2009, 10:13 PM

Quote:

Originally Posted by lutzTD

if you try to hone out that much it will be oversize in the middle. as you go up and down the middle will get much more cut time.

Actually the guy that showed me how to do it said to always do it in one direction. It takes more time, but eliminates issue's of un even cutting.

Depending on the engine, circumstances etc slide in release, remove and in again. Or pull (his prefered) depends on the engine.

Except for the last polishing step.

If I need to bore it, I will probably toss it, although I can get a new cast for 200.

kknudson · #15 09-15-2009, 12:44 AM

Well I'm gonna order the rings, gasket set and a few non rebuild related parts soon, next month.
I need to get it done in that gap between mowing and Snow, although I have a small snowblower. But more than a few inches and it takes forever.

Hoping thats all I need.

I don't figure I need to replace the valves, good cleaning should do them.
Might order valve springs and clips (10 bucks total) figure while I'm in there.

Any other parts I should get initially ??

I figure I can order others IF I need them, I want to do it right, but don't want to spend a lot of bucks on it.

Talked to a buddy too, he thinks his dad has a honing tool, well now it may be in his collection of tools.