Ever since I purchased my '87 560SEL (approx. 6 months ago) the engine temp gauge has never worked, it would just sit at "40" unless I got the engine up above 2500 rpm, which would cause it to wiggle up and down a bit. Since this has been a relatively minor problem, I haven't gotten around to getting it fixed. I have been slowly replacing/repairing the minor problems with this car. Last week I replaced the air filter and aux. breather (purchased here, of course). Since doing this the temp gauge now works up to 80, and then begins flickering if the temp rises above 80. My question is, is it possible that replacing the air filter is in any way connected to this (I don't see how...), and if so, what would be the next step in getting it to work completely? Thanks for any help!