engine tapping

Discussion in 'Mechanic and Repair' started by lurchy98, Jun 13, 2005.

  1. lurchy98

    lurchy98 LawnSite Member
    Messages: 6

    hello everyone, this is my first post here and any help would be greatly appreciated. I have a poulan lawnmower with a 15 hp briggs and stratton engine. The Problem is that at idle I can hear a tapping or even a knocking sound coming from the engine when I speed the engine up I can't hear it anymore. It still runs great but has been worrying me, so any ideas that you might have will be appreciated. Thanks.
  2. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    When was the last time the oil was changed? how about age of the mower, hours of use, the basics.

    I commonly see cars with the tapping sound because nobody changed the oil for about 10K miles.
  3. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,555

    On the Kohler 25HP I had bad tapping and I decided to try Seafoam and that took care of the problem for the present. Kohler factory repair guy made the suggestion since my unit had(2000hrs.+). Since it is a backup unit I will probably put in hydralic valves in the winter.
  4. C&KLawnCare

    C&KLawnCare LawnSite Member
    Messages: 246

    Just run it , When i had my small engine shop opened full time , i can not rember how many of the 14.5hp to 16 hp one lungers i had come in here with the same thing , My 1999 Craftsman has the 14.5 Hp briggs and that sucker at idle has always knocked . Shove in on the clutch and it would ease up in sound let back out and was noisier, over 3,000 hrs later the SOb still is knocking at idle and still runs , I tore it completly down once cause it was bugging me . Damned if i know what it is cause their was not a thing out of spec nor loose. I think its in the spark timing making the knock my self . but since ya cant adjust it i guess it will just knock away
  5. lurchy98

    lurchy98 LawnSite Member
    Messages: 6

    well here are some more details about the mower that I left out. This is it's 3rd year of use, the oil was changed at the beginning of the season and is run about 3 hrs. a week. That's all I can think of off the top of my head, if you have anymore questions just ask them and I will try to answer them. thanks for all the replies.
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Briggs is a little sloppy with getting the crankshaft end play adjusted properly when they assemble there engines. Thats probably the knock you hear in yours and why it changes when you push the clutch,They have 3 different thickness gaskets and for really sloppy ones a special shim washer that can be installed on the PTO end of the crank to get a more precise end play adjustments. At one time they had a batch of 16 and 18hp twins get out the factory that knocked so bad they had to have the washer installed and proper end play adjustment before we could even sell the darn things.
    Just thought you'd like to know a possible cause.
  7. mini14

    mini14 LawnSite Member
    Messages: 236

    if its an ohv engine its time to adjust the valves

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