Author Topic: Revs increase when brake pedal applied...  (Read 4473 times)

Neil Thompson

  • Associate Member
  • Silver
  • ****
  • United Kingdom, England, Louth
  • Posts: 383
Revs increase when brake pedal applied...
« on: August 21, 2016, 20:11:37 »
... then stalls when gear selected.

230SL Auto with PAS, restored car thats been stood with poor fuel, see my other post re elec fuel pump.

I've cleaned all the fuel lines, set the points, adjusted the ignition timing and also adjusted the linkages/venturi as per the basic linkage tour on the forum. The car runs well and idles ok at around 800rpm. If I press the brake pedal the revs rise to around 1,300rpm, if i then put it into gear it stalls. There are some things in the tech manual I haven't tried to test yet such as the WRD and the CSV as I've ran out of daylight but I thought I would just throw my problem out to the experts hoping for a quick fix. Could the mixture just be too rich on tickover or could the servo be dodgy?

as always, any help welcomed

Regards Neil
1964 230 SL RHD DB304 Horizon Blue
1957 190 SL RHD DB180 Silver
1988 R107 300 SL RHD DB199 Blue Black
1978 C123 230C 2dr Auto RHD Silver

stickandrudderman

  • Vendor
  • Platinum
  • ******
  • United Kingdom, England, Richmond
  • Posts: 2924
    • http://www.colinferns.com
Re: Revs increase when brake pedal applied...
« Reply #1 on: August 21, 2016, 20:33:05 »
The search function is feeling hurt that you are ignoring it!

Neil Thompson

  • Associate Member
  • Silver
  • ****
  • United Kingdom, England, Louth
  • Posts: 383
Re: Revs increase when brake pedal applied...
« Reply #2 on: August 21, 2016, 21:32:31 »
I've searched Colin, but sometimes it's good to talk!

Neil
1964 230 SL RHD DB304 Horizon Blue
1957 190 SL RHD DB180 Silver
1988 R107 300 SL RHD DB199 Blue Black
1978 C123 230C 2dr Auto RHD Silver

dpreston Virginia

  • Full Member
  • Silver
  • ****
  • USA, VA, Salem
  • Posts: 275
Re: Revs increase when brake pedal applied...
« Reply #3 on: August 21, 2016, 21:39:45 »
Sounds to me like a bad brake booster.,
190SL 1960 Sold
280SL 1969
280SE 1969 cabriolet
Vette 67
Porsche 912 67

ejboyd5

  • Associate Member
  • Gold
  • *****
  • Southold, NY
  • Posts: 510
Re: Revs increase when brake pedal applied...
« Reply #4 on: August 21, 2016, 22:20:59 »
Plug the vacuum connection to  the brake booster to see if the problem goes away.

rgafitanu@gmail.com

  • Guest
Re: Revs increase when brake pedal applied...
« Reply #5 on: August 22, 2016, 17:22:21 »
I had the same thing,it is a leak in the brake booster. Take it to NAPA, they will rebuild it for about $100. Anything else on the internet and ebay is very expensive.

Radu

Rolf-Dieter ✝︎

  • Associate Member
  • Platinum
  • ******
  • Canada, ON, London
  • Posts: 3683
    • Best Pagoda Site second to none!
Re: Revs increase when brake pedal applied...
« Reply #6 on: August 22, 2016, 22:04:00 »
Colin is right ... Look at the search results

Here ----> http://www.sl113.org/forums/index.php?action=search2

Let us know how you made out, not just for us also for others that will use the search in future years.


Dieter
DD 2011 SL 63 AMG and my 69 Pagoda 280 SL

Cees Klumper

  • Full Member
  • Platinum
  • ******
  • USA, CA, Fallbrook
  • Posts: 5719
    • http://SL113.org
Re: Revs increase when brake pedal applied...
« Reply #7 on: August 22, 2016, 23:23:37 »
I had the same thing,it is a leak in the brake booster. Take it to NAPA, they will rebuild it for about $100. Anything else on the internet and ebay is very expensive.
Radu

Good advice, except TS is located in UK where NAPA may not exist ...
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

Pinder

  • Full Member
  • Platinum
  • ******
  • USA, NJ, Edison
  • Posts: 1032
Re: Revs increase when brake pedal applied...
« Reply #8 on: August 23, 2016, 12:58:41 »
I had the same issue. Was brake booster. I got mine from Rockauto. If Napa rebuilds original that would be a good option. Rockauto was pretty cheap at around 100 with core refund.
1970 280 SL Light Ivory DB 670. 4 Speed manual shift no AC Limited Slip Diff.
1997 Corvette C5 Silver. automatic
2015 BMW 320i xdrive
2021 Mercedes GLS450 Silver

Pawel66

  • Full Member
  • Platinum
  • ******
  • Poland, Mazowieckie, Konstancin-Jeziorna
  • Posts: 5494
Re: Revs increase when brake pedal applied...
« Reply #9 on: September 17, 2016, 07:35:08 »
Just a voice here and if you find it contrary to forum's wisdom, please ignore it.

I had the same thing - revs changed as the brake pedal was pressed. Before a major booster overhaul I replaced a simple oring between the booster and brake master cylinder. The symptoms are gone. Revs do not change.

I was reading Haynes and I spotted a sentence that this oring needs to be "vacuum tight" and needs to be renewed while working on booster. So I did that.

Pawel
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class