I posted this on the SL forum, but didn't get any response, so I'll try here.

Hi, I have an 88' 560sl. For a long time now, my transmission has behaving weird when the car is cold. Lately it has been getting worse.

At first, if I drove it the first thing in the morning after a cold night, the tranmission would stay in 3rd for a long time. At some point, it would shift hard into drive and then not do it again until the next morning. The rest of the day it would shift smooth as ever. I think I read somewhere this is by design to heat up the cat more quickly. Never really happens in summer, more of a problem in winter (I live in northern california).

Lately, the behaviour has changed a little. Instead of shifting hard, it feels like it's in between gears and surging. If I keep the rpms fixed, it just surges back and forth like it can't decide. For what it's worth, the rpm to speed ratio doesn't match either gear. If I give it a lot of gas, it pulls hard, no more surging, but I don't feel it engage one gear or the other. If I put it in neutral, the engine revs smoothly. After a minute or two of this, it shifts kind of hard into a gear and doesn't do it again for the rest of the day. If I hit a lot of stop signs or lights, it seems like it never gets a chance to make the hard shift and it doesn't settle down till I can get up to speed for a while on a long stretch of road. So far, I've been living with it.

On a likely unrelated issue, every once in a while the engine will sputter if the car is warmed up and I stop for 10 minutes at the store. It start up right away, but I can't rev the engine at all, even if I stand on the gas. After 30 seconds or so of gently coaxing it, it will rev normally and I can drive away. Once, this happened when I first started it up in the morning, but mostly it ocurrs after I stop for a short time at a store or something. It probably happens twice a month. So far, I've been living with this too.

Both seem like a temperature/sensor issue. Any ideas? Thanks.

David

David -

I'm having similar intermittent misbehaviour with my '84 500SL. My indy and I suspect the K1 Spring but I haven't had it changed yet - search the forum for K! and see if the symptoms match. Other people smarter than me might also suggest a vacuum and/or modulator problem.

Your second problem sounds like the fairly common hot start problem - search for that also.

Kevin