| Author |
Message |
    
matt
Advanced Member
Username: matt
Post Number: 42
Registered: 04-2006
| | Posted on Thursday, April 24, 2008 - 07:09 pm: | 
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Well, today we tried a few things to track down the mysterious noise from our P55.
I started by running exhaust straight through and not going through the muffler, no change in noise.
Took water pump off and ran engine with water being gravity fed through engine, again no change in noise.
I got my dad to push a piece of nylon bread board against chain to increase tension in drive chain again no change in noise.
I changed magnetos as impulse mechanism on original maggy put quite a pulse in chain, again no change in noise.
Besides a really shot bearing or the bottom section of a connecting rod hanging off i am at my wits end to explain the noise, i must admit the engine starts and performs very well, but i just want to fix what ever it is that is making the noise.
Our other older P55 on a trolley in the shed is very quiet and does not make any internal noises at all.
Has anyone got any suggestions besides ignoring the noise?.
Matt and Ron |
miro
Senior Member
Username: miro
Post Number: 324
Registered: 11-2001
| | Posted on Friday, April 25, 2008 - 12:47 pm: |
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When you turn it over by hand without the sparkplug, can you feel any back and forth looseness or sloppiness?
Is there any maybe rubbing up against the flywheel?
Is it a clinking sound?
Does the sound have a sharp knock to it, or is it ( sort of) mushy? |
jb_castagnos
Senior Member
Username: jb_castagnos
Post Number: 358
Registered: 07-2002
| | Posted on Friday, April 25, 2008 - 09:26 pm: |
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Slightly loose flywheel? Doesn't take much movement to make noise. Does it have an inspection cover on the base? Place piston half way down the cylinder, listen and look if possible. Loose rod bearing, loose wrist pin, piston flopping back and forth, any of these will make noise. End play in the crank, when the prop thrust if will drive crank against the case. |
matt
Advanced Member
Username: matt
Post Number: 44
Registered: 04-2006
| | Posted on Saturday, April 26, 2008 - 06:58 am: |
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All bearings and seals seem to fine , played today with ignition retard and advance noise still there.
Last throw of the dice is to remove gearbox[again] and check sprocket on the crankshaft that drives maggy and water pump as this seems for sure where the noise is coming from,
At least i know now that the forward cone nut has a left hand thread, which might explain why i couldnt budge it the first time i had the gearbox off. |
johnny
Senior Member
Username: johnny
Post Number: 166
Registered: 03-2006
| | Posted on Thursday, May 01, 2008 - 06:17 pm: |
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You say that all the bearings seem to be fine. How did you check the bearings to determine that they were fine? You should be able to take a long screw driver or a stethoscope and figure out if the noise is coming from the engine or tranny drive. Miro & JB have already mentioned what My first guess would be. lower con rod is worn or upper con wrist pin bushing worn. Flywheel only has to be loose just a little and some times they will make a clicking or clunking noise on the key and key way. |
bpineo
Member
Username: bpineo
Post Number: 4
Registered: 05-2008
| | Posted on Thursday, May 29, 2008 - 08:37 am: |
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Sometimes on the older magnetos with spring loaded/centrifugal retard, the spring will break and let the mag advance and retard in a flopping fashion with a noise especially at low speed or any change in engine speed. This is usually accompanied by an engine that heats up/cools sporatically sometimes even overheat due to high speed retarded. I would check to see if your mag has all the springs intact. |
