Small Honda Gas 4cycle Engines NOISE

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  #1  
Old 09-23-08, 08:06 AM
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Question Small Honda Gas 4cycle Engine NOISE

I have identicle 2.0hp Honda air cooled engines throughout our system on liquid pumps and compressors. They are all over 2 years old. They all run fine and are completely serviced every 200 hours.
The original problem I am in a quandry about is with one portable Air Compressor powered by a Honda G-100 2.0 hp aircooled single cylinder engine.
After correct winter storage (done personally) we started this unit up (fresh oil, plug and gasoline) to a loud rattle sound that I thought was a rod knock. Time constraints allowed little or only minor diagnosis, but no tear down of this engine. Instead I just purchased a new engine from Honda.
The G-100 is no longer in production so I was directed to purchase the GXH-50 engine of the 2.5hp rating.
First glitch, I am sorry to say, this new engine did not bolt right up to the stamped steel Honda G-100 mounting plate (as was eluded to by the Honda dealer) since this was the next generation but replacement for our old engine. The new engine did not come with one either.
This caused some delay in mounting but did go on in the old G-100's place eventually and ran perfectly the 1st few times we used it.
After sitting for a week we had to use this compressor again so its oil was checked, gas tank was filled and we started it right up.
HOLY CRAP we now have that same noise in THIS new one?????????
The engine runs fine BUT the rattle/knock is almost deafening. Using a mechanics stethoscope this noise is most pronounced in the bottom end, near/at the governor shaft that exits the lower engine case below the carb.
NOTE: If you watch this mechanism while starting the rattle/knock seems to keep time with little shakes of the governor lever as it increases in rpm to the normal run condition.
Anybody have any suggestions?? What could have gone wrong or broke between the 2 seperate uses of this unit??
While waiting for some learned input here I am glad now I did NOT throw the old G-100 engine away...............
I am based in Detroit but this particular unit is at our Atlantic City station. I have been in the industrial equipment, Gas, Diesel, and LPGas service, industry (Hands-On) for 37 years but this one is a real head scratcher. Again the distance away and time constraints has me authorizing the continued use of this unit while I get some answers. I have not torn down the old nor this new engine.
Thanks,
Terry Bogusz
GSE Manager - Spirit Airlines
 

Last edited by GSE Terry; 09-23-08 at 08:38 AM.
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  #2  
Old 09-23-08, 04:08 PM
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Have you isolated the engine from the compressor to eliminate the possibility that the compressor is the source of the rattle??
 
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Old 09-23-08, 07:34 PM
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are your compressors oil or oilless, if oil you might have some oil entering the compression area causing it to slightly hydraulic lock. can you run the engine without it bolted to the compressor?

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Old 09-23-08, 09:03 PM
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I also would recommend disconnecting the coupling or belt to the compressor and run the engine without it to see if it's the engine or the pump. Often times, it's just the pulley loose on the crankshaft that causes knocks on compressor engines. The pulley was probably transferred to the new engine, and if the keyway is worn, it wouldn't take long for it to get loose enough to knock again.
 
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Old 09-24-08, 03:49 AM
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Smile Isolating the Engine

I took these steps when the original engine 1st started making the noise, which caused me to order the new one.
I 1st removed the drive belt, checked the pulley that it was tight (it was) but the sound did not go away.
The compressor is a single cylinder Oil Type.
2nd (when the new GXH50 engine arrived and I tried to re-use the Honda G-100 mounting plate) I mounted the old engine in my bench vise and started it up. Noise IS in the engine.
The compressor mounting plate probably is acting as a metal megaphone which only magnified it?
A small engine repair guy here wonders if after one final cycle of use the compressor was under a pressure stroke, when it stopped, and may have made 1/2 to 3/4 of a stroke in reverse afterwards.
Could this damage the governor, if that is even the problem?
Thanks
Terry
 
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Old 09-24-08, 04:13 AM
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shouldn't damage the gov.
good job of isolating the engine, unfortunatly that still begs the question what happened? did the fuel tank happen to drain to the crankcase and dilute the oil?-you state that the oil was checked so that is unlikely. ??? nothing exchanged between the engines correct?
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Old 09-24-08, 06:39 AM
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Smile Gas contamination?

Originally Posted by Speedwrench View Post
shouldn't damage the gov.
good job of isolating the engine, unfortunatly that still begs the question what happened? did the fuel tank happen to drain to the crankcase and dilute the oil?-you state that the oil was checked so that is unlikely. ??? nothing exchanged between the engines correct?
Equipment used on the AOA (Aircraft Operating Area) / Tarmac can not sit not in use or be stored with gasoline/diesel in its tank for more than 24 hours.
We drain any left back into a (1 gallon) storage can, held in another area, each time. Reason we keep the smaller factory tanks on the equipment too.
Pain in the ass but since 9-11, oh well........
Engine oil did not look or smell diluted.
Only the 5/8" bore cast iron 2" pulley and key were swapped over from the original engine.
Dying to tear into the old G-100 here soon to SEE what is up.
Thanks
 
  #8  
Old 11-18-14, 08:30 AM
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Dam rattling noise small Honda aircooled engines

Noise discovered. When an air compressor slows to a stop, after the gas engine is turned off, there is a common occurance where the compressor on a power stroke just starts this stroke. The compressor Drives the engine backwards 1+ revolutions. THIS causes the Recoil Starter dogs to contact the flywheel. This reverse motion bends them slightly into a semi contact position. The next time the engine is running the loud ticking noise IS THESE DOGS HITTING THE FLYWHEEL. This is also amplified by the recoil/fan housing. Taking the new Honda Engine's fan housing off and bending these dogs farther away from the flywheel eliminates their contacting the flywheel if/when the engine is forced for what ever reason in reverse rotation. Both old engines were repaired along with the 3rd one we bought. :NO NO NO:BTW: Thanks Honda of America for a total of NO HELP AT ALL. You're the BEST!
 
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