M818 knocking sound?

[jd-ford-hd]

I am sure this has been asked and answered so apologies in advance What is the persistent knocking or tapping sound coming from the firewall area? Sounds like an elf with a tack hammer hitting the firewall (one tap every 3 or 4 minutes) while the engine is running. Have heard this on other trucks besides mine. Thanks.

 

[DaveP]

I am sure this has been asked and answered so apologies in advance What is the persistent knocking or tapping sound coming from the firewall area? Sounds like an elf with a tack hammer hitting the firewall (one tap every 3 or 4 minutes) while the engine is running. Have heard this on other trucks besides mine. Thanks.

you are probly hearing the governer for the air system.

 

[ARMYMAN30YearsPlus]

RE: Re: M818 knocking sound?

I saw the elf there with the hammer one time that I could not sleep and went out to admire the cummins he was napping on the rear valve cover and vanished as soon as my flashlight hit him.....

Sorry I agree it is most likely the air regulator cycling

 

[jd-ford-hd]

RE: Re: M818 knocking sound?

Thanks guys. I held the governor during its cycle and it does "hammer" slightly. Have owned lots of air brake vehicles and never heard a air governor make a sound. This one does!! Thanks again.

 

[DaveP]

Re: RE: Re: M818 knocking sound?

Thanks guys. I held the governor during its cycle and it does "hammer" slightly. Have owned lots of air brake vehicles and never heard a air governor make a sound. This one does!! Thanks again.

They are not normaly mounted to a tin drum!