Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Popping noise


Jack B.'s Avatar
Member

Join Date: Jul 2003
Posts: 590
AL

09-25-04, 06:56 PM   #1  
Popping noise

I have a Tecumseh LEV115 (6HP) engine on a lawnmower, that occasionally (every 10 - 20 seconds) makes a "sucking or popping noise". I have long thought that this was caused from a valve sticking. I pulled the head off and re-seated and adjusted the valves (everything looked good). I have also rebuilt the carburetor twice...cleaning out all the small passages. The carburetor has a primer and I have to push the primer about 15 times to get it to start. Could anything else cause the noise? The only other thing I would know to do is replace the carburetor. This is an emissions carburetor with no adjustments.

 
Sponsored Links
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-28-04, 12:32 AM   #2  
Hello Jack B.!

Two things come to mind...one which you've already addressed. 1) The carb is still partially restricted, causing a slightly lean-running condition. Have you replaced the small O-rings on the pickup nozzle? You might be able to use an orfice drill to open up the small orfice nearest to the top of the bowl screw just a tad to correct the problem. I wouldn't go more than .002". This would be a last resort before deciding to replace the carb.

2) The flywheel key could be just partially sheared (pushed). Not enough to draw attention to itself, but enough to cause your problem.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Jack B.'s Avatar
Member

Join Date: Jul 2003
Posts: 590
AL

09-28-04, 04:07 PM   #3  
Thanks for the suggestions Cheese. In a rich running engine, one thing that tips you off is black smoke coming from the exhaust...what are the tip offs to a lean running engine?

 
cheese's Avatar
Forum Topic Moderator

Join Date: Jul 2001
Posts: 16,567
GA

09-29-04, 12:37 AM   #4  
Most lean running engines will surge or hunt. Sometimes, if it is just a tad lean, it will get a throaty sound coming from the carb intake, or the sucking sound you describe, and then level off for a while before doing it again. Another lean run symptom is poor throttle response when throttling up from a lower speed, also when the governor throttles it up. Sometimes it will spit or pop before it decides to rev up. Engine temp will get higher in a lean engine, and the exhaust will get hotter. Idle speed will be a bit fast and uneven. The spark plug will develop a very light tan or white color on the electrode if the engine is in good enough shape that oil fouling doesn't keep the plug black. Also, a lean running engine will sometimes be hard to start and keep running when it is not up to operating temp. You may start it, and then it dies, and you have to start it again a time or two.

A lean running engine doesn't always exibit all of these symptoms, but usually more than one.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
Search this Thread