Author Topic: Low idle cut off  (Read 5975 times)

ConfusedBrit

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Low idle cut off
« on: July 23, 2013, 21:26:50 »
Hey Guys,

After having the car babied in a heated garage and constantly being professionally looked after we have made the journey from west germany to london!
We originally bought the car over as a weekend car, but as I love driving it so much its looking like it will be a bit more regular than that.

I have a few quick questions that you all might be able to help me out with (hopefully)

The scene change is seeing a bit of a rise in temp, instead of open roads sitting in traffic sees the temp rising fairly rapidly I assume this is just normal and its a 40+ year old car and I shouldnt worry too much?

The idle is really low when coming from speed to a stop, sometimes even causing the engine to cut out, someone at home mentioned to me there is a way of adjusting how much injection pumps in at idle? or adjusting the idle basically? is this fairly straightforward? is there another reason this could be happening?

Thanks in advanced:
Here is a few photos of the car on the journey over as a bonus (cross posted from photo gallery thread)

Jordan




Rolf-Dieter ✝︎

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Re: Low idle cut off
« Reply #1 on: July 23, 2013, 23:05:48 »
Hi Jordan,

I have had similar issues with the low idle ... see this thread ---> http://www.sl113.org/forums/index.php?topic=18504.25

My post 25 and Dan's reply (Benz Dr,) in post 26

As you can see you need a simple adjustment on the throttle valve and the injector air valve ,,,

As for the heating issue I have it too ... the jury is still out if I need a new clutch fan or not meanwhile I will avoid traffic jams (stop and go traffic) also I purchased some "Water Wetter" today. I don't know if you can find it over there it is a red liquid you add to your radiator. The claim is that it will somehow reduce your water temperature and make the water wetter in your radiator.

I found my water wetter product in a Performance Bike Store. This time of year with high temperatures people use it quite frequently.

Good luck.

PS. If your car is a 280 like mine then it is apparently a common problem (engine high water temperature). The reason for this is that the engine block for the 230, 250 and the 280 are all the same and the cylinder bores for the 280 is larger then the 250 and 280. So consequently the engine block internal wall sections are thinner and therefore more engine heat penetrates or for a better word radiates into the cooling water passages of the engine. There is good background information in the Technical Manual ---> Search Radiator or Cooling and you find it. Don't run your car with the water temperature in the red zone your engine block will warp / distort and or you blow your engine.

EDIT ---> I see you are not a member, since you are not a member yet, I don't think you can access the Technical Manual on this forum (worth it's member fee in Gold BTW) so do join if you plan to keep the car. It has lots of good stuff in there one of the best resources I've seen on any forum.

Anyway, I made a photo for you of the Water Wetter and a similar product Flex-a-Chill ... I'm sure you find something similar that people use over there if you cannot find one of the two in the photo.

Note, when you add it to your radiator first remove about the same amount, do not overfill the radiator. Check your manual the black overfill tank should be about half full when the cooling water is cold. 



web sites are;

http://www.redlineoil.com/product.aspx?pid=74&pcid=10

or

http://www.flex-a-lite.com/accessories/radiator-accessories.html

One more Tip ... I see your car is an Automatic like mine ... If in heavy traffic or long traffic lights I now shift from being in gear to Neutral ... that helps a bit as well.
« Last Edit: July 24, 2013, 01:18:41 by Rolf-Dieter »
DD 2011 SL 63 AMG and my 69 Pagoda 280 SL

ConfusedBrit

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Re: Low idle cut off
« Reply #2 on: July 24, 2013, 13:25:02 »
Hi Rolf,

Thank you so much for your reply!

I am going to look into all of this now and see what we can do.
The water wetter seems interesting, once I have the idle sorted going into neutral in jams will be a little easier, as before it would cut out, probably not helping the heating issue sitting in gear the whole time as well.

We have had the car for 4 years now so definitely will be in our possession for a long time . I am going to sign up for the proper membership and access all of the technical information.
I am not hugely technical but would like to start working on the car myself, I am sure it will save me a few pennies as well.

I will let you know how I get on, thanks again!

J

Benz Dr.

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Re: Low idle cut off
« Reply #3 on: July 24, 2013, 16:38:10 »
Water wetter will lower running temps about 5 degrees. That may not sound like very much but it's acually quite bit and may be enough to keep your engine out of the danger zone. Easy help for under $20.00
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Cees Klumper

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Re: Low idle cut off
« Reply #4 on: July 24, 2013, 16:59:30 »
Most automatics have a thing called the 'idle speed solenoid' whose function it is to raise the idle when the car is put in gear, so the additional drag on the engine is compensated for and the engine does not stall. They can be adjusted (it's a round/pod-like thing on top of the intake manifold). But they also lose their capacity over time and then have to be replaced. So check if that's your issue, or contributing to it.

On the overheating, My car only raises about 10 degrees (from 80 to 90 celcius) in hot stop and go traffic. You really don't want the engine to get anywhere near the red zone and although it's a common problem, there's always causes that can be remedied.
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

garymand

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Re: Low idle cut off
« Reply #5 on: July 24, 2013, 23:41:50 »
If your car is running that hot op[en the heater and turn on the fan.  Then stop by a radiator shop and find out what is wrong withyour cooling system.  The dash gauge should sit at 80 degrees C allways.  Mine went up when my fan clutch went bad, then again wen my radiator had a problem. 
Gary
Early 250SL German version owned since 71, C320, R350, 89 Porsche 944 Turbo S

Benz Dr.

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Re: Low idle cut off
« Reply #6 on: July 25, 2013, 03:46:45 »
It will slowly warp the head over time - I'm sure of this.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Richard116e

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Re: Low idle cut off
« Reply #7 on: July 25, 2013, 08:54:12 »

Hi Jordan

Great looking Car  I saw you driving through East London yesterday I was on my push bike.

My Dad has 65 230sl manual.  The website does have a whole load of great information.  I have got classic Fords but it has been great working on the Merc for my Dad.

Regards

Richard


ConfusedBrit

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Re: Low idle cut off
« Reply #8 on: August 05, 2013, 10:18:01 »
Hi Richard, Nice to see you :)

Car seems to have sorted itself out no more dogging low idle and no more sudden heat spikes... doest seem to fluctuate more than 10 degrees now.
Going to keep a close eye on it, but it feels like its driving better than ever (Touch wood ) Now that its get a daily run through.

Thanks a lot for your help guys, I am sure ill be asking some more questions soon!