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Knock if the engine running

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Ali

Knock if the engine running

#1

Post by Ali » Wed May 05, 2004 4:45 am

Hello,

if the engine running you feel something like a knocking. but only of the rear cylinder. And it will not realy change if the rpm goes up or down. Have any one a idea ?

Thank.

(and sorry for my great English )



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Re: Knock if the engine running

#2

Post by Jack_Hester » Wed May 05, 2004 1:20 pm

Ali -

Don't run it anymore, until you locate and fix the problem. Pull the rear head and take a look for something obvious. You may have to pull the cylinder. A knock that doesn't change with rpms is strange. Suspect the worst until you prove that it isn't. Not enough information to troubleshoot this one.

Jack

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Re: Knock if the engine running

#3

Post by Cotten » Thu May 06, 2004 1:57 am

Jack's warning is right. Damage can happen.
Please explain the noise: Is it 'tinny' (high frequency) or 'deep' (low frequency)?
In common English, "knock" makes us think of a problem with the connecting rods.
Normaly that will change with RPM, unless the wear is quite severe..
But you may hear valve lash, or even loose piston clearance that is an annoyance, rather than a catastrophy.
Before you remove the cylinder, inspect the valve adjustment. The noise may be adjustable.
Are all motormounts secure?
Noises can "telegraph" through the metal to sound like somewhere else.

Let us know what you find!

Ali

Re: Knock if the engine running

#4

Post by Ali » Thu May 06, 2004 8:50 am

Thanks for the information. I will look if I can find more information about the noise and will describe it better.

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Re: Knock if the engine running

#5

Post by Cotten » Thu May 06, 2004 11:43 am

Ali!

I forgot to mention the old "screwdriver-in-the-ear" trick:
By placing the handle of a long screwdriver against your ear, and the blade upon different places on the running machine, sometimes the sound can be located more accurately.
This is the "poor-man's" stethoscope, if you do not have access to a real one. Good luck!

Ali

Re: Knock if the engine running

#6

Post by Ali » Tue May 25, 2004 10:50 am

:wink: Thank`s Cotten I will check it with your trick Smile

In the moment I find nothing. The noise of the motor is changing it going warm. I know that is normal if the engine is warmer and warmer the noise will change but my motor have totaly different noise.

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