Idling and Other Woes

[anthrope]

Hello all,
    I own a 1967 250 SL 4-speed that has been very badly treated over the years, which I am trying to get in working order. Here's what's been done so far:

- The Fuel Injection pump has been redone by Hans
- 6 new fuel injectors have been installed
- The fuel pump has been replaced (brand new Bosch)
- The points have been replaced and the engine apparently tuned
- The exhaust system (minus the front pipe) has been replaced. Unfortunately, the chap who replaced it used an ANSA unit, and not the Eberspächer unit.
- The entire front tie-rod assempbly has been replaced.
- The brake servo has been replaced.

Per Hans, the pistons are all fine, as is the head gasket.

(FYI, I am no expert on cars in general and my not use the right technical terms, so please do bear with me while I describe my issues!)

The car starts nicely almost all the time. When cold, it idles at around 10000 rpm and settles down to about 5000 when warmed up. But, the idling is far from constant. The idling is very, very uneven. In addition, the car simply seems to not be firing on all cylinders. When I start off in first gear, the car seems to take off just right. But, when I shift to second, the car loses power in a big way. However, it seems to respond a bit better if I were to take my foot off the accelerator and step on it again. When I do step on the gas, it feels as though there's too much gas going in. Does anyone have any idea what the problem could be, with this? I've got to believe that the car can basically be made to idle evenly and accelerate and decelerate smoothly, with the right fixes being put in place. I am frankly running out of ideas and patience here, and would love to get any help from this forum.

    The next issue is that the car smells of deadly gaseous fumes all the time. I looked into the trunk and can see that the expansion tank is basically broken. The trunk smells very strongly of gas. I have ordered an expansion tank from Bud's Benz and it is on its way to Hans (whose lads are also fixing these issues for me). The main tank itself has no apparent leaks. When installing the expansion tank, we will basically change ALL of the hoses and fuel lines, since the car hasn't been used as a driver for a long time. Hopefully that will take care of the gas fumes. Are there any other areas I must look at, to solve this deadly gas issue?

Thanks much in advance,
Prashanth Nandavanam

[merrill]

do not forget to check the cork gasket for the fuel sender in the tank

easy to check and easy to replace.

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[merrill]

do you mean 1,000 rpm?  10,000 is over red line.



I bet your inj pump is too rich, do the richness test.
at idle, after the car has warmed up disconnect the linkage from the cross linkage to the inj pump.

push down on the inj pump linkage, the car should only increase in rpm's by 50 - 100.  if the idle goes up too high then you need to adjust the richness of the pump.

let us know what you find

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[ja17]

Hello anthrope,

Setting all the linkages correctly is a good place to start. Look up "Linkage Tour". If you do not do the work on the car yourself, your job will be to educate yourself and supply the technician with the information without bruising his ego.

Mis-adjusted linkage is often the root of many problems.  Other places to look are bad spark plug wire ends, the warm running device on the injection pump and a leaking cold start valve.

Joe Alexander
Blacklick, Ohio

[nick350]

regarding the petrol smell, also check that the fuel breather pipe is there and is long enough. It, or at least mine hangs down beyond the rear fender by about 2 inches and it makes a big difference.

Like all these things this wont be the definitive answer but is one thing to get sorted.

[jameshoward]

Hi Anthrope,

There are a number of threads detailing similar problems currently running over the first 2 or 3 pages of threads on this site. Have a read through them (2 are mine - we have similar-ish problems) and you'll learn a lot. Ja17's linkage tour is excellent and easy to do. But it seems to me that if you're having the work done for you by a mechanic - Hans - he will decide what needs doing and will then do it. Read my post about my FI pump and variable idle. My problem, I am now convinced, is caused by having the mixture too lean, i.e. not enough fuel. My symptoms are not dissimilar to yours, but I wouldn't wish to mislead.

If you want to do the work yourself, and much of it really isn't that hard, honestly - it will take a bit longer but with all the advice on this site (use the search function) you will find the process more rewarding. And cheaper!

[Benz Dr.]

Actually, this sounds a lot like a vacuum leak - car falls flat on its face when you throttle up.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[anthrope]

quote:Originally posted by Benz Dr.

Actually, this sounds a lot like a vacuum leak - car falls flat on its face when you throttle up.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

All,
    Thanks for all the information so far; this forum is phenomenal. I fiddled with the distributor and points yesterday and the car runs a lot smoother now. But, the dying-upon-acceleration isn't quite fixed. And, I also discovered that the front pipe is cracked, which explains some of the noxious fumes. Here's what I am planning on doing:

- Replace the front pipe (with an ANSA pipe for now)
- Replace then ignition system with an electronic ignition unit from 123ignition in The Netherlands
- Install a new Bosch Red Coil and matching ballast resistor to go with it (although the resistor isn't necessary for electronic ignition, from what I can tell)
- Replace the broken expansion tank
- Replace all of the fuel-related hoses
- Potentially replace the fuel-lines?
- Adjust/potentially replace the linkage components: bushings, ball sockets, link rods
- Potentially replace the linkage dampener dashpot
- Have Hans have a look at the injection pump to see if the car is running too rich or thin
- Apparently there's a diaphragm next to the FI pump that can get ruptured, so replace it as well (sorry, I don't have the technical term for the part in which the diaphragm sits)
- Check the cork gasket for the fuel sender
- Ensure that the breather pipe in the to-be-installed expansion tank is long enough

Does this approach make sense, or am I simply flailing here? I am somewhat wet behind the ears as far as this stuff is concerned, so please let me know if I am on the wrong path.

Dan, pardon my ignorance, but could you please elaborate on what you mean by a vacuum leak?

This is all rather promising indeed. I suspect I'm looking at a 2-3 year horizon to get this car to be a daily driver.


Thanks much!
Prashanth Nandavanam

[J. Huber]

Hey Anthrope (sorry easier for me to not mispell than your name!)

I would not call your list flailing at all -- I'd say it is a very thorough and respectable plan. I think as you check off each of these you will see some great results. Good luck!

James
63 230SL