Cold start and running problem

[circle]

I have 230sl 1966 automatic and when the engine is cold it is hard to get it stated and it is nearly no way to rev it up (only 500rpm) no matter how I push the accelerator petal and it looks like it is not working on all cylinders, and when it is beginning to warm up and I´m able to drive (slowly at first) suddenly all works fine until I stop on next traffic light all happens again and it is hard to rev it up again.  I have new spark plugs and wires and I have tried to take the small air filter of the wrd.
Thanks
 H Baldvinsson

[ja17]

Hello,

Check to make sure that the WRD is not stuck.  Check the condition of the fuel tank for rust. Also if you can do a fuel pressure and volume test it would help with the diagnosis. Let us know what  you find.  Sounds like a fuel starvation problem.

[Paul99]

I have 230sl 1966 automatic and when the engine is cold it is hard to get it stated and it is nearly no way to rev it up (only 500rpm) no matter how I push the accelerator petal and it looks like it is not working on all cylinders, and when it is beginning to warm up and I´m able to drive (slowly at first) suddenly all works fine until I stop on next traffic light all happens again and it is hard to rev it up again.  I have new spark plugs and wires and I have tried to take the small air filter of the wrd.
Thanks
 H Baldvinsson

I had EXACTLY the same, (plus my car is the same as yours (230 1966 Auto.)   I removed the WRD (warm running device.  You remove the top section which has two water pipes running into it.  Then remove the two screws holding the device to the fuel pump.  You will find a small plunger inside which SHOULD move up and down around 1 inch. Mine was fully stuck.  A few goes with plus gas and wd40 and I could move it up and down with ease.  Cleaned every thing, Replaced it - INSTANT start, zero running problems.
 i could not believe the differance it made to starting.   Total cost of fix Zero.   Try this before replacing anything.  A new WRD ( in the UK )is around £1,000.! £600 just for the wax stat part.

[Paul99]

I am sure this has been covered before, but just in case.  My 230 1966 auto just would not start from cold.  Real churning, eventualy started, seemed to be running on 3 plugs etc.  Once hot - perfect.

Having scanned the forum -    I removed the WRD (why its called a warm device as the problem is that it works/doesnt work when its cold I am not sure!)  The small plunger had got stuck.

I removed the top section which has two water pipes running into it.  Then removed the two screws holding the device to the fuel pump.  You will find a small plunger inside which SHOULD move up and down around 1 inch. Mine was fully stuck .  A few goes with plus gas and wd40 and I could move it up and down with ease.  Cleaned every thing, Replaced it - INSTANT start, zero running problems.

i could not believe the differance it made to starting.   Total cost of fix Zero.   Try this before replacing anything. a lot simpler job than I thought.   Hope this helps anyone with similar problems.

[66andBlue]

...  You will find a small plunger inside which SHOULD move up and down around 1 inch. ....

What - 1 inch or 25 mm? 
More like 4 mm for a R11 pump! See: http://www.sl113.org/forums/index.php?topic=5460

[Paul99]

What - 1 inch or 25 mm? 
More like 4 mm for a R11 pump! See: http://www.sl113.org/forums/index.php?topic=5460

Mine seemed to move a lot more than that. It is the early one not the one described in that link were they different ?  There seems to be two wax stats, one shorter than the other. Mine is the long one.  But it's working now which is the main thing for me. 

[66andBlue]

Which injection pump is installed in your 230SL? It should be a R11 pump as shown here. The pin on the WRD on those pumps only moves about 4mm or less.


The 250SL car have the R18 pump and the 280SL cars have R20-25 pumps:
http://www.sl113.org/wiki/Fuel/Injection

The housing of these WRD is much shorter than the ones on the R11 but the pin in them travels a bit longer, but most likely not 25mm. See also: http://www.sl113.org/forums/index.php?topic=17350.0

[Paul99]

its an R11 pump from the badge plate, but funny thing is when i ordered a new air filter for it (just in case) classic MB said it was for a 250 pump? The screw thread was larger.   So the 25mm i spoke about was the travel of the plunger which goes into the engine, not the plunger on the wax stat.  i didnt check the travel on that.

All seems ok - does run very rich on start up now, but starts instantly which is the main thing.