Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
Kent

Diagnosing carbon buildup??

Recommended Posts

Kent
As I was using my trusty old tractor yesterday, I thought of this one...

I bought my tractor last year and have no idea of the previous engine maintenance performed (it's a 1989 replacement engine in a B-210). I haven't done anything to the engine other than routine maintenance: oil changes, fuel filters, clean the air filter, and replace the spark plug...

It seems to run fine, other than an occasional puff of white smoke on starting (doesn't use measurable oil between changes), and a slight bog in acceleration especially when the mower is engaged. I have adjusted the carb a bit trying to minimize this (and no, I haven't touched the governor adjustments)....

1) How do I tell if I need to remove the head and clean out the carbon buildup?

2) Can this be contributing to the bogging down on acceleration?

3) What's the cost of the necessary gasket set?

Any thoughts from the experts would be appreciated....

Kent

Share this post


Link to post
Share on other sites
JohnA
Try this one !!

A customer brought in a Coleman 1200 W gen. Pulling on the rope wouldn't turn the engine over.
I thought it could be something jambed in the gen,since he lent it to someone .I took that end off --no problem !

Then I started on the B&S engine , Took the gas tank,covers and rope start mech. off.

I found out it turned backward --almost a full turn .Free as a bird -both ways .

I then took the head off ,easy to do .

The combustion chamber and especially on top of the piston had so much carbn that it wouldn't let the piston all the way up

I cleaned it all out ,used the same gasket, torqued it up according to the manual ,put it all back together .Tried it ,started right off a little smokey for a while but it worked fine.

CAUSE -- The cardboard air filer was almost completely plugged .

He paid the bill and was happy .



Share this post


Link to post
Share on other sites
tej
Although I'm far from an expert, I'll take a crack at this.

Carbon build up can cause a variety of symptoms including pre-ignition and loss of power. If your engine bogs down when the mower is engaged or has difficulty accelerating with the mower engaged, it sounds like a lack of power, and I would think that checking for carbon is a reasonable troubleshooting step, especially if the engine otherwise runs well.

Jack's Small Engine's has head gaskets for $3.49.

If you don't already have it, buy the appropriate B&S service manual. You'll need this for the head bolt tightening sequence, as well as for some service techniques.

Although you'll have to remove the engine from the tractor, I've found that the B&S head is one of the easiest to take off (compared to the car and motorcycle engines I've worked on). This is assuming you have an L-head engine. You will have to remove the sheet metal flywheel cover (which is about the only reason the engine needs to removed from the tractor), and if my memory serves me right, you should have full access to the 8 or 9 head bolts.

Remove the head bolts, and the head should lift right off the cylinder.

Cleaning the carbon off can be tricky. You don't want to scratch any of the combustion chamber, since any gouges will become hot spots during operation causing similar symptoms as the carbon. Although I have yet to find and try it, I was recently referred to a GM product call X66A, which is an aeresol carbon dissolver. The person claimed the only product he could compare it to is the military issue gun barrel deposit cleaner. I guess it just about immediately liquifies the carbon, making it as easy to clean as a grease spill.

After cleaning the head, clean the top surface of the cylinder, and the tops of the valves. If you really want to go to town, remove muffler and exhaust pipe, the carburator and intake manifold, and the valve access cover and remove both valves. Now you can clean all the carbon and deposits that have accumulated in the intake and exhaust chambers. Just be very careful to avoid damaging the valve seats. While you're here, it would be worth inspecting the valve seats and the valves for wear. Again, the service manual will illustrate how to do this. Replacing a valve at this point is not much work, just purchase the appropriate valve, and check the fit with the valve guide. If valve guide is oversized, it will have to be replaced with special tools and experience, and the valve seat will have to be replaced or reground. Replacing or regrinding a seat requires special tools, and should be done by someone with the tools and experience. Whether reusing the old valves, or replacing the valves, be sure to lap the valves to the seats. This ensures a good fitment of the valve to the seat.

Good luck,
Greg

Share this post


Link to post
Share on other sites
tej
Kent, I cleaned the carbon out of my B112 this past spring. I don't remember the cost of the head gasket but it wasn't much. When you scrape the carbon the hardest part is getting all the little particles out of the cylinder. To do this I have the piston all the way to the top, you need it there to clean it. Then after cleaning it and the block off I put oil on the top of the piston and move it down. The oil sticks the carbon dust to the cylinder wall and you can wipe it off. You might have to do this several times to get it clean. There may be a better way to do it, I am no expert on such things. I think cleaning the carbon is a good routine maintenance item. Tim

Share this post


Link to post
Share on other sites
B-Man
When doing any cylinder bore work involving dust, shavings, etc..etc.. I will run the piston to TDC and pack wheel bearing grease around the outside of the piston where it meets the cylinder wall. Just enough to fill the gap and hold the particles. Then when finished I use a small plastic scraper to remove the grease, run the piston to the bottom and wipe off the excess grease.

VOILA!

Share this post


Link to post
Share on other sites
tej
I think I would agree with Ford but its really you're call at this point. Carbon buildup today is not the problem it used to be with the older leaded fuel - in fact if the carburetion and ignition are kept up the combustion chamber will remain fairly clean. The spark plug is the easiest way to read this without disassembly. If you do decide to have a look rotate engine to TDC so that everything is closed when you give it the "clean scrape" but it would be good also to have a shop vac present in case any particles drift over to the ring area - more harm than good could be done if this is neglected! The greatest affect on power would be the valve and ring seal - valves usually being first.

Every so often though I run into a simple governor adjustment that will stop an RPM drop - it can be amazing sometimes. But this is if the RPM drops and stays there - not for a stumble where it will pick back up again - if that is the case I would look first at the carburetion.

Share this post


Link to post
Share on other sites
tej
It is not necessary to remove the engine to access the head on a 10 or 12 hp cast iron Briggs. The fan shroud stops short of the head. You have to remove the upper starter/generator bracket and the voltage regulator if it's mounted on the bracket. Then the engine is accessible while still in the tractor. Tim

Share this post


Link to post
Share on other sites
tej
I'm FAR from an expert[just ask f.o.]BUT I've found on these older engines the carb. to manifold flange sometimes warps over time causing power loss. To check this on your eng. just spray a LITTLE carb/choke cleaner on the carb./manifold gasket area while eng is idling.If it immediately picks up speed when cleaner is sprayed there's your problem.Also most times just changing the gasket won't fix it because the new gasket is paper thin.Fixing the warpage[by surfacing]is the only proper repair to do,as well as replacing the gasket. Good Luck dlc

Share this post


Link to post
Share on other sites
B-Man
I have had a few instances where somebody complains of a distinctive knock when engine is running and little else seems to be wrong,pull the head and find a perfect piston mark encrusted to the carbon in the head. Clean head, reinstall and knock is gone. In most cases engine is far oversized and rings were never seated in. I told the owners to cut some three foot grass to make it really heat up and seat rings.

Share this post


Link to post
Share on other sites
Fred
I stand mega-corrected on the engine removal. I warned you I was a rookie...but I was basing my opinion on my 16horse I'm rebuilding. Since it wasn't in the tractor when I bought it, I guess it was only a guess.

Does anyone have a technique for actually removing the carbon without scratching the head?

Greg

Share this post


Link to post
Share on other sites
Kent
Anyone with carbon build-up is either British or has
a larger engine than my 7.25 hp B-1. British cars used
to recommend frequent head removal for carbon build-up.
My B-1 works so hard carbon build-up is non-existent.
Years ago I did have a push mower that would stick the
exhaust valve open occasionally with carbon. That was
the only engine I've owned on anything that required
carbon removal as a preventative maintenance item.
Hope everyone takes this in good humor.
Roy

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

  • Who's Online (See full list)

    • marksr
    • LalanP111
    • s_stephen
    • tadams
    • CTD01
  • Today's Birthdays

    No users celebrating today
  • Recent Status Updates

    • F.U.N.

      F.U.N.  »  sandyhillbill

      Dear Sandhillbill
      Can you please copy me on this data, for Sun Star parts list.
      :
      September 12, 2004 Mike I sent you a PM and have all the mfgs. available for the tiller/hitch/pto/liftgroup if you need me to send them to you. Let me know. Thanks, F.U.N.    
      · 0 replies
    • gwiseman

      gwiseman

      Club banners are available  for members use during show season https://simpletractors.com/forums/topic/57849-simpletractors-club-banners-available/
       
      · 0 replies
  • Adverts

×