James Reina

Hey guys, I just picked up a beautiful 1987 SL560. Previous owner took great care of the car (at least cosmetically) but there's a few hiccups I need to deal with.

1. When in neutral or park, she idles around 1,600 RPM and surges every 60 seconds. This makes the transmission lurch when I shift into D or R. When in drive or reverse, she idles completely fine around 800 and no surging. Is this a possible vacuum leak issue?

2. There's a red light on directly to the left of my 'anti-lock' light. I don't see any info about this light in my owners manual. What could it be? Pic attached. *not my pic, that yellow light isn't on in my SL.

3. Does anybody have a trusted MB mechanic in or close to NYC area who can do a general tune-up? Shoot me a DM.

Cheers and thank you guys,
James

Ceckman

With regard to the idle surge..... I am having the same issue and have had a couple Mercedes shops look at it (one being the dealership here where I am near Palm Springs, CA and the other being a local independent shop). In total they fiddled with my timing, fuel settings, cleaned my idle control valve, installed new spark plugs and ran injector cleaner through it. No change.

BTW - car starts and runs great and smooth other than the idle speed issue. Also - sometimes (rarely) it goes away for a bit - once really warmed up (but not always) 🤷*♂️

They have concluded / believe I have a vacuum leak (which I gather is pretty common) and it is "under the intake manifold". I was quoted "something like $1,600.00" by the independent shop and they discouraged me from doing it..... in effect they thought the car ran great and did not see why I was bugged by it.

Needless to say - I still need it fixed but have not taken the next step.

James Reina

Hey @Ceckman check out this parallel thread I posted in Benzworld. It ended up being a blown fuse on my OVP relay, behind the passenger side kick panel. 25 cent fix just added a few thousand dollars in value to my SL. I can only hope your fix is as easy as mine. Is your ABS light on by any chance?

McLovinMyBenz

Not the same idle issue but my engine idled at about 1100 RPM when in park and recently replaced the overload protection relay and solved the issue. It also seems to have eliminated a hiccup I would get when automatic transmission shifted gears at about 30-40mph when pressing gas pedal to the floor as I would get up to desired speed.

steve sl550

Curious ...was your ABS light on B4 the OVP replacement and now off or was he OVP light always off?

I have the 1100 in park idle but, my ABS light is not on..

Need to know about your observation to determine if changing my OVP relay might solve the 100 RPM in park idle issue where I don't have the ABS lighgt on

THANKS

McLovinMyBenz

My ABS light was never on. However, the OVP relay only temporarily solved my issue as a few weeks later the car started idling at 1400-1500. I took it to independent MB shop and they tested the Idle control box, idle control valve and air intake but all were functioning fine. Ultimately, I replaced all 8 fuel injectors, injector seals, etc. They did clean them first which would have been less expensive but 1 of 8 wasn’t functioning properly and the other 7 were functioning at full capacity so I paid $900+ to replace since it was no additional labor charge necessary parts already removed. Motor idles and runs like a charm since ... granted it should after spending $3K for repair.

McLovinMyBenz

I had same issue as others with idle surge to 1500-1600 rpm recently. I had most of the items you and others in thread have listed either tested or replaced Which improved idle but only temporarily. Finally, when my mechanic tested my fuel injectors, all the seals around the area the problem was solved. After cleaning the injectors, he found 1 of the 8 was not working at all and the other 7 were functioning but not at optimal levels. Because the process of diagnosis required a fair amount of labor, the only additional cost to replace all 8 were the parts I decided to replace all 8 fuel injectors with new OEM. Ever since the car is running like it was designed to run ... idling at 650 rpm, very smooth transmission from 0-90+ mph. Total cost was approx. $3K in Atlanta market at independent MB shop. The following is a summary of all my service items related high idle ...

• $300 - installed new overload protection relay (Mar 2019)
• $600 - diagnostic for high idle (April 2019)
• $1875 - replaced all fuel injectors, seals, hoses, end caps, buffer, fitting and throttle switch (April 2019)

Dtfm109

Kraft German Automotive is a very good mechanic that specializes in only Mercedes. Located in Brooklyn. And as expected with any good Mercedes mechanic its always going to be expensive

FVAL

I am in Atlanta as well and will be bringing home a 1989 560 SL at the end of this month.
Being new to this forum I cannot DM yet so reaching out directly over this thread. Can you let me know which mechanic you are using? Thanks for the help.