QuestionI have a late 90's MTD rider with a 17.5 HP OHV Briggs & Stratton engine (Model 313707. Type 0132). I've started the season out with new oil, gas, spark plug and charged up the battery. The old plug was fouled with what looked like a small amount of oil sludge and carbon.
When the engine does run, there is a slight amount of smoke in the exhaust. Not enough to really be noticeable when you're moving, so I don't think the head gasket is completely blown.
Another issue is that when I try to start the engine, it turns until the piston is just shy of TDC and stops. I can turn the screen on top while holding the starter on to get it past, but it stops on the next rotation. My first guess is that the compression release isn't working properly.
I've pulled the valve cover and checked the valve stem clearance at 1/4" past TDC, and everything seems to be ok. I had .004 clearance on the intake and .006 clearance on the exhaust.
I'm wondering where to go next. I'm thinking I need to pull the head off and replace the head gasket to be safe and possibly the intake valve seal (and clean up the carbon/gunk in there). For the compression release issue, should I look at the connecting rods or go straight to tearing the engine down and checking the cam? Also, for the head and rocker cover gaskets, should sealant be used?
Thanks!
AnswerHello Douglas:
Do Not Go 1/4" Past TDC on the Compression Stroke. I have Found that Going 1/4" Past TDC when Setting the Valve Clearance Usually Causes the Compression Release Not to Operate Properly. **I Do Not Use the Setting Called for by the OEMs. I have Found that the Following Works Best. Remove the Valve Cover (on the Dead Cylinder for Twin Cylinder Engines). Set the Cylinder you are Setting the Valves on to Top Dead Center on the Compression Stroke When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .004in -.006in and the Exhaust to .006in - .008in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. Be Sure the Piston is at TDC on the Compression Stroke.** If the Valve Clearance is Correct, then Check the Flywheel Key before Opening the Engine to Inspect the Cam. Are you Sure the Starter is in Good Condition? You can Use a Sealant on the Valve Cover, But NEVER Use a Sealant on the Head Gasket. You can View a Breakdown/IPL of the Engine at this Site Addy; http://www.briggsandstratton.com/maint_repair/manual_and_more/doclist.aspx?categ... and Enter the Model Numbers (XXXXXX) and Type Numbers (XXXX) in the Appropriate Boxes and Click GO. Then Select Download PDF. You can View a Breakdown/IPL of this Unit at this Site Addy, http://www.smallenginepartswarehouse.com/parts.asp and Select the Shop Online Parts Look Up. Then Select the Model Tab. Then Select the OEM (MTD) and Enter the Model Numbers. Then Double Click on the Model in the Results Area. Now you can Select the Section of the Unit you Wish to View. If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. 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 8pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
