QuestionQUESTION: JOHN
am still having trouble here..my TDC is not where you said it should be at..my engine backfires really loud and there is alot of black dry soot in spark plug..you emailed me several times..originally i read somewhere that you pull out spark plug, put pencil in..when pencil comes all the way out of hole when you rotate crank, then go one quarter inch more, and that is suppose to be TDC..
My TDC is NOT at where the magnets meet the coil; thus I think I adjusted the valves wrong..my TDC is like at five o'clock, and the TDC you said to find with magnets at coil is at my 3 o'clock~did I break a flywheel key or am I doing something wrong???
do email, thanks
ANSWER: Hi Gail:
If you can Use a Pencil in the Plug Hole, then TDC is when the Piston has Pushed the Pencil Completely Out. When the Pencil Stops is TDC. Not Before or After. Usually the Flywheel Magnets will Get the Engine Close Enough to TDC to Set the Valves. Some Engine Have the Plug Over the Valves and it is Impossible to Locate TDC with a Pencil. Check the Flywheel Key for Damage Also. Remove the Blower Housing (metal engine cover). Remove the Flywheel Nut or Starter Cup (Depends on the Model). Now Attach a Steering Wheel Puller to the Flywheel Using the Threaded Holes in the Flywheel. Tighten the Puller. Now Hit the Puller with a Hammer. Repeat this Procedure Until the Flywheel Pops Up or can be Lifted Off the Crankshaft. On Some Models you Can Not Use a Puller and Must Use a Pry Bar and a Pipe Cap that is Slightly Larger than the Crankshaft. Place the Pipe Cap Over the Crankshaft to Protect it. Place the Pry Bar Under the Thick Section of the Flywheel and Pull Up Against the Flywheel. **BE CAREFUL DO NOT PUT A HOLE IN THE BLOCK UNDER THE FLYWHEEL** Now Hit the Pipe Cap that is on the Crankshaft (covered with the Pipe Cap). I Can Not Locate you Previous E-mail to Reference to. I Referred Back to 08/05/07 and will Go Further Back and Locate it. Once I Locate it and If I Need to, I will Follow Up to you. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: Still working on the valves..I have a few more questions..I never worked on these Murray riding mowers before as you can tell!! Some other forum said you must go PAST compression one quarter inch to adjust valves on OVC engines..is this true? They say once you find TDC , when pencil comes all the way out, to turn clockwise (flywheel one quarter inch further).
(1)Is this true?
(2) Why does my pencil come all the way out when I am like 6 inches PAST the magnets lining up with my ignition coil?
(3) How do I know if I have a burnt valve without removing the head..and can I just adjust valves to solve this backfiring problem?
(4)I did not pull the flywheel off yet..but so far, many, many thanks for all your help..this is a bear! Hope u can answer all these questions, John!
ANSWER: Hi Gail:
1: No TDC is When the Piston is at the Top of the Compression Stroke. You can Go Up To 1/2" In Past TDC and Still be Able to Set the Valves before the Cam Lobe Starts the Opening Cycle of the Exhaust Valve. 2: The Magnets Fire the Plug Before TDC. However, the Exhaust and Intake Valves are Closed as Soon as the Piston Starts the Compression Stroke. If Using the Magnets and Coil as a Reference for Setting the Valves, you Must be on the Compression Stroke for the Valve Setting to be Proper. Your Engine is Designed with the Plug Over the Piston; so you can Locate TDC with a Pencil or Rod. 3: The Head has to be Removed to Properly Examine the Valves for Damage. Save the Burnt Valve Diagnostic for After the Valves are Set and the Flywheel Key is Checked/Replaced. 4: No Worries. I am here to Assist you All I can. If the Valve Setting Does Not Correct the Backfire, then the Flywheel Key Will Unless a Valve is Burnt. I'm Leaning Towards the Valve Setting or the Flywheel Key. I have Not Located the Previous E-Mail, but I'm Still Looking. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: John
Gail, again..I adjusted the spark plug gap..the backfiring is less, but its misfiring,it surges, then almost cuts out like its going to stall..it revs and without touching the throttle,then it starts to die out..its starts, but nothing happens when I turn the key on..takes 3-4 cranks before it catches..but always did this before
(1) I changed the spark plug, had new plug, adjusted spark gap.
(2) I also flushed and cleaned fuel tank and cleaned carb.
(3) I do not know if I adjusted the valves the correct way, but its not backfiring, but something is smoking..maybe starter?? The smoke is coming from around and beneath valve gasket..it smells like something is burning..they say this can happen if valves have too much lash?????
(4) I did not take flywheel off as it has some kind of cap I cannot get off
(5) BURNT VALVE?? what causes this~~did not pull head off yet
ANY SUGGESTIONS???? MURRAY RIDING MOWER 13 Hp, TECUMSEH engine model 40541x99C OVH130-206810D
AnswerHi Gail:
No Worries. Sometimes it takes a Few Times to get the Valves Correctly Set. This is an OHV130 Engine, so the Valves are Set at; Intake: .004in - .006in and Exhaust: .10in - .12in. Reset the Valves Again. Did I Give you this Site Addy? Since this is a Tecumseh Engine, I have a PDF Site Addy that May Assist you Also. http://www.tecumsehpower.com/CustomerService/BSI.pdf. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
