Loud whine
 

My 380 SL has developed a loud whine that seems to be coming from the back of the car. Very noticeable with top up and not so loud with top down. Have not been able to trace it down. Any suggestions.

Thanks in advance.

Is the whine present when the car is under load and goes away when your foot is off the gas? It could be in the differential.

I wondered about the same thing and did a search for transmission noise. I learned that some noise is normal with age and the first thing to do is do an inspection and check for anything obvious like bearings falling apart and bad
CV joints and boots. Do a test drive and jack the car and feel for hot bearings.

If it appears to be wear related noise the consensus seems to be empting the differential, checking the drain plug magnet for unusual metal bits, and refill with redline 85W140 synthetic gear lube.

It works because its much more viscous then standard 75W90 gear lube when running. But because its synthetic it doesn't turn to pudding when it gets cold.

Redline oil is a speed shop thing, I couldn't find it locally and ordered a brand called Royal Purple. If you try this just don't try it with petroleum oil only synthetic.

My apologies for not being clearer on the noise. It is there from first starting the car and just idling and not moving at all, a consistent noise that does not change. ???????

Hi Robert:

Could it be your fuel pump? an SL owner describes a whine from the rear of the car in the following thread:

http://www.peachparts.com/shopforum/tech-help/7902-buzzing-fuel-pump.html?highlight=whine+fuel+pump

John,

Thanks much for the info. I am sure that this is probably the answer but will check it out closer tomorrow. Sounds like a new fuel pump in my future. Keep up the good work and greet your wife and son for Mary and I.