R. Woods 81

I'm relatively new to this forum, having recently purchased a 1991 300SL (Black on black with tan leather interior... 80k miles and in beautiful condition. Will post pics soon.). I am admittedly far less experienced and knowledgable than many on this forum, and would certainly appreciate your insight on diagnosing what I've observed as some potential issues to address, as well as any thoughts/suggestions/words of advice on general maintenance...

DIAGNOSTIC HELP:
- Right Rear Wheel Clicking: A significant rattle when I go over any bump or crack in the road. Dealer has diagnosed this as possibly a broken clip in my e-brake assembly inside the rotor; not mechanically critical, despite how badly it rattles. E-brake function seems to be unaffected. Annoying, though.

- Right Front (?) Wheel Rubbing: At low speeds (10 - 15 mph, possibly faster, too - but I can't hear it) there is an occassional rubbing noise that seems to originate from the front wheel well area and whose frequency is dependent on wheel speed -- a distinctive rubbing noise once per wheel rotation. Rubbing noise is not present all of the time, but seems to be continually more prominent. Occurs independent of wheel orientation (e.g. driving straight or turning).

- Anti-Theft Alarm: The OEM anti-theft alarm (automatically set when locking the doors) will go off sporatically and unperturbed. I am rarely within earshot, so it is impossible to know how often this occurs, but I've heard it on more than one occassion. Kind of embarrassing. To my knowledge she has just recently developed this schitzophrenic tendency.

- Vapor (Steam?) Off Engine: When stationary after having driven at highway speeds for a little while, a faint white vapor will occassionally come from an area behind the engine block. Not billowing smoke by any means, but noticeably venting from the hood.

- Automatic Trans Shifting: When the engine is cold, it starts in and is often reluctant to shift out of first gear until abnormally high rpm... ~3500.

- Differential(?) Hum: When traveling between 40 and 50 mph, a faint but audible high-pitched hum can be heard... difficult to ID the source, but one indy shop diagnosed it as a failing differential, corroborating their assessment with the presence of metallic in the diff fluid. They wanted $4300 to replace. I laughed at them and drove away.

MAINTENANCE ADVICE:
Rubber: I've had my car evaluated by both a dealer and an indy shop for "necessary" maintenance. Because the car is 16 years old, they naturally tried to hit me for all sorts of rubber: gaskets (front timing cover gasket, trans L o-ring and pan gaskets), mounts (engine and trans), discs (front and rear flex discs), and a fan belt. The engine (esp. cam cover area) and trans are pretty wet, though no noticeable loss of fluids (steady levels, none on the ground)... I've been told that it isn't worth pouring money into trying to find and stop all leaks on these engines... will never be perfect, and if it isn't losing appreciable fluid or leaving large spots, it isn't necessary or worth it. Thoughts on what rubber to address and when?

Fluids: I'm due for an oil change and refuse to pay a dealer $150 to do this. Suggestions on types (natural or synthetic), weights and filters? Suggestions on coolant, trans, and diff fluids, should I need to replace?

Manuals: I am searching for a comprehensive service manual to use in diagnosing and fixing as many routine maintenance issues as I can myself. Does anyone have an R129 manual or know how I can acquire one?

Parts: Suggestions on where to get MBZ parts?

Shops: I've had little luck in finding a good indy shop that I can trust and whose prices aren't more ridiculous than a dealer... I live in central New Jersey. Anyone know of a good shop in the area?

....

I apologize for the length, gentlemen, and I appreciate the time of those who've managed to wade all the way through. Despite all of these ... observations ... the car runs absolutely beautifully. It may make a couple noises and have some weeping gaskets, but I see no adverse affects in function or performance, and everything else on the car is in perfect condition. Given my relative inexperience with the R129, I would really appreciate insight you may have on any of the above diagnostic or maintenance queries.

Thank you, in advance, for your time and consideration. I look forward to your replies. I am thrilled to be a part of the SL family!

Best regards,
Robert Woods

bobterry99

I think the dealer is correct on this one.

If you read diagnostic codes you can tell what triggered the alarm and go from there. The procedure for reading codes has been explained many times. You can use a search or send me an email for instructions. You need an LED from Radio Shack.

The best source for information is the R129 Tech DVD available from MBUSA for $75: http://www.startekinfo.com/StarTek/o...stedDocId=8002.

Parts: http://www.oempartsdirect.com/index.php.

This is normal, and it is to heat-up the catalytic converter quicker. If you want to disable this, you can remove the relay that plugs into the empty socket shown in the picture (K29).

MB-Dude

I think this may be nothing more than condensation run-off from your A/C. To verify, recreate the event with some highway driving. Stop the car, turn off the engine, and listen carefully under the vehicle. You may hear a 'sssst' sound (highly technical term) as the A/C condensation drips onto the hot exhaust component(s). The fix may be nothing more than rerouting the A/C condensation drain line a little, or extending the tube a bit.

jjay911

knowing how old your car is may help. And the conditions where it was drivin. My car has alot of issues because it was not driving much. Like your car not to many miles. Seems the higher mile cars are running better. Oh and if its a 91 congrats its almost 17 years old now... 8 more years and she is a classic..

R. Woods 81

Thanks for your help, gentlemen.

935k3

Hi,

is there a K29 relay on this model? Its for holding the gears in the transmission longer to warm up the cat when cold. I saw a picture of the relay box for a 1991 300SL, but mine dont look the same. Anyone got a picture of what the different relays in the box are for?

Cheers