Rough Idling 560SL

[aharley1]

I went thru the same thing with rough idiling when hot & hard starts. I finally went to a different shop & they diagnosed it right off...leaking intake seals. It took $1800 worth of labor to get the injection system straight from what the first guy had done but it runs F-I-N-E now.

"Da Stable is full"
99 Harley Heritage Softail
88 20 Ft Wellcraft
94 30' Sun Sport Motorhome
98 Dodge ram
40 Chrysler convertible
88 560SL

[230/8]

kbflorida:

re: your question on what type of vacuum hose was used, plastic or fat rubber, the answer is both were used. The hard plastic is available in colors so MB used it to make some of the hook-ups a bit easier to keep straight. The soft fat rubber hose was/is used at the ends of the plastic line where connections are made to a fitting and/or sharp bends are needed which could crack the plastic tubing.

My old 72 SL is filled with this mixture. I replaced all the soft hoses, had the fuel injectors re-sealed and now the car runs fine. I also run Techron through the fuel system all the time. It's cheap at Costco, so I am adding a can with each fill-up for the next few thousand miles to see whether it cleans the injectors. If it does not then I may send them off the this place...

http://www.cruzinperformance.com/

for a good cleaning. I understand some folks have used this service with good results. His prices seem fair.

230/8

[ctaylor738]

The 560's have semi-modern electronic engine controls, but no modern diagnostics. There were some proprietary tools from Merecedes, but most of these probably quit working a long time ago. And the mechanics who were trained on these cars are retired or retiring. And no tech is at a dealership is interested in fixing a cranky 560 because he/she won't make any money on a repair that involves a lot of diagnosis. And they will probably get it wrong and have the owner yelling at them the next day. So the dealers throw parts at it and hope for the best because they really don't have any other answers.

We are really running out of talent to work on these cars.

Forget about the dealer techs knowing more than you do. Educate yourself, and insist that the techs work there way up from the basics like plugs, wires, coil, cap, rotor, vacuum leaks, temp sensor, EHA, air flow sensor, and only then look at the exoensive stuff like fuel distributor and engine control module. I think all this stuff is 'way beyond its design life expectancy.

All IMHO - I am currently wrestling with a rough idle during warm-up on a 560SL.

[kbflorida]

[QUOTE=230/8] The soft fat rubber hose was/is used at the ends of the plastic line where connections are made to a fitting and/or sharp bends are needed which could crack the plastic tubing."

Thanks 230/8. That answers my question. Over the years my SL not only had the soft fat rubber at the ends of the lines - but sometimes slapped in the middle of a hard plastic section.

I see the previous point about the diameter change probably not making a difference, but all the repairs to my vacuum lines over the years had the effect of adding many more places for leaks/loose connections - not a good idea.