OK, have a question regarding a 1980 Lincoln Mark VI. Car has the "premium" AM/FM sound system with the manual on/off amplifier and the factory wired CB radio and manual up/down power antenna.
The radio has horrible engine noise. We changed the ground, put in an in-line RF filter, made sure none of the speakers were grounded out and nothing made any difference. The owner will not agree to remove the factroy radio and wants the problem solved. We're out of ideas any help out there???
Describe the details of the noise. Engine on/off, only with radio, only on CB etc.
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sparky
Engine noise is a contant hum, not the regular whine but it still varies with engine RPM. It does it with radio on, AM/FM doesn't matter, gets REALLY bad, to the point where the speakers start falling apart when you use the antenna switch to raise the antenna. We disconnected the little amp in the trunk to elimate it as a cause and no difference, but the system sounded a ton better with it not hooked up.
Just that with a car of this vintage, we're not sure where to even start troubleshooting, especially with the integrated CB radio...crazy 80's cars.
If the noise is only affecting the AM or FM bands than it may be an antenna issue. If it is on all sources (tape or 8 track) then it is probably a ground issue. The old units were usually chassis ground. Try attaching a wire to the radio chassis and ground it to the metal in the kick panel. Check that the battery cables are clean and tight (probably not being that is likely a top post) and make sure that the ground wire from the battery to the body is good. On a car this old, you need to do a voltage drop test of the ground cables. With your meter set to DC voltage measure the voltage from the battery negative post to where it contacts the body. You should have less than 0.5 volts. Unplug the antenna to see if the noise goes away. Try hooking the radio to a outboard power supply and not from the car (both power and ground). Have the car running to see if there is still noise. You may have a defective radio too. Try any or all suggestions and post your results.
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sparky