QuestionQUESTION: I inherited a JD STX 38 3 years ago and have stored it since. Last fall, I loaned it to my father-in-law who decided it wasn't running fast enough so he messed with the governer. When he returned it this spring, the engine was running high RPMs, missfiring occasionally, was very load and bogs down under the load of engaging the deck. The tractor also now vibrates significantly when running. My fear is that the engine is now damaged internally due to running so fast and hot. Can you please shed some light on what could be wrong and how it can be repaired? Other than this engine issue, the tractor is in great shape. It has a Kohler Command 13 12.5 HP engine, and the JD Serial # is WOOSTXJA276701. If you could point me in the right direction, I am up for a crack at repairing as a new engine is way too costly.
ANSWER: Hello Glenn:
How Exactly Did the Engine was the Governor Tampered with? Was the Governor Arm Moved on the Governor Shaft, was the Governor Spring Shortened or was the Linkage Bent? Does the Mower Vibrate when the Blades are Engaged as Well as When Disengaged? If the Engine Vibrates with the Deck Disengaged, then Check the Engine Pulley and Ensure it is Tight on the Crankshaft. The Valves May Require Adjusting. This is the Clearance Between the Rocker Arm/Tappet and the Valve Stem. The Clearances are; Intake is .002in - .004in and the Exhaust is .080in - .010in. Also the Counter Balance Weight Inside the Engine May have Broken. If the Mower Vibrates Only When the Blades are Engaged, then the Blades May be Out of Balance or a Spindle Bearing May be Going Bad. If the Valve Clearance is Good, then The Bogging Down May be the Carburetor Needs to be Removed, Disassembled and Soaked Overnight in Carburetor Cleaner. Then Blow Out the passages with Compressed Air. Install New Kit. You can View a Breakdown/IPL of the Mower at this Addy, http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.H and Enter the Model Numbers STX38 and Click Go. Then Select the Model Mower you Have (Black or Yellow Deck). The Select Sectional View. 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: Hello John,
The governor arm was loosened and moved. I have adjusted it back to a more normal speed (by sound)but it doesn't seem to be able to handle the load of the deck now. With increased engine RPM, the deck functions fine. The vibration is without the deck engaged and the engine pulley seems plenty tight. I can try the valves and clean the carb next weekend, but it is running so erratic, it just seems like the racing of the engine at high rpm has damaged the engine internally. Where is the counterbalance weight located? Could the cylinder/rings be damaged?
AnswerHello Again Glenn:
Check the Exhaust Port for Carbon Blockage. The Counter Balance Weight is Inside the Crankcase. It is Possible that the Problem is Internal. Is the Engine Knocking or Making Unusual Noises from the Crankcase? Hope his helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.
Good Luck
Respectfully
John
