Re: Strange Overdrive Noise

Posted by HH56 On 2008/10/7 11:12:46

The only two things I can think of that would cause a buzz would be the relay or solenoid. If the relay is not getting full current either because of high resistance in a connection or a bad switch, it might not have enough strength to fully pull in which would result in a buzz that would affect everything downstream. The relay contacts may also be burned and not providing full current to solenoid..

The solenoid has 2 coils--a heavy pull in coil and a lighter hold coil. The pull in coil is released by the internal contacts when the solenoid is fully engaged and the hold in coil is supposed to do it's job. If the hold in coil isn't holding, then the solenoid will vibrate or buzz and be fairly loud. A bad connection or poor ground would be suspect there. If the contacts are mis-adjusted or something is preventing the solenoid from fully extending and not allowing a complete quick opening of the contacts, that would cause the buzz and also burn the contacts. Is that what you meant by badly burned or was wrong with the first solenoid. If the pawl is gummed up or possibly burred, that might cause a slow engagement.

EDIT: You didn't mention any clunks or harshness but in the 47 service counselors, page 69 there are some mechanical things that might apply to your slow engagement--and there might be the ratcheting your mechanic refers to. In a later counselor, they mentioned a lot of corrosion and shorting problems being reported with the bakelite connector in the OD harness. Don't know if your 41 has that connector but might be worth a look.