230sl sticking MFI.......HHHHHepl!!!!!!

[steven_first]

So my boss asked my brother and me over to do some work on his 66 230SL that has been sitting for about 10 years and only ran maybe once in that time.  We replaced some hoses and some various do-dads before moving on to the throttle system.

The return spring was sprung and the links were stiff and the throttle was sticking about half way.  We carefully removed the link connecting the fuel injector pump to the rest of the system at the ball joint taking care not to change any link rods.  We re-greased everything,  replaced the return spring and everything minus the MFI (not connected yet), was working like a charm.

Seeing that we were shining things up,  my brother (the actual mechanic) thought it would be a great idea to remove the link and arm from the MFI system without telling anyone.  Ok no big deal…needs a tune-up anyway.

Well, we put it all back together and everything seems great! Idles well, revs nicely…no water leaks…(original issue). So my boss takes the car for a spin with my brother as second in command and about 5 minutes later they come putting up the hill just barely making it into the garage before shutting it down.

Turns out the throttle was stuck open. They had to get out and jiggle the links for it to return to idle. They then drove it back to the garage without any throttle (automatic).  Anyway, they get back and we look it over…everything moves just fine. Start the car and give it some revs then BAM the throttle sticks half way open!

Grab the links and give them a quick twist and the drop back down to idle position.  I looked over the system to see if there was an over-extending link or something but found nothing that made sense seeing it was sticking at about half throttle.

I removed the link connecting the MFI to everything else and lo and behold something internal in the MFI is now jamming.  My question (finally) is what could it be?  We have a shop manual that more or less ignores this thing so it was no help.  After doing some minor research, I found that we have the newer style (I think) going by the pictures of the two types.

The label on the one we have is PES 6 KL 70 B 120 R11 and it has a red oil cap but no dipstick inside. I have no clue if there is any oil inside or not…  Everyone tried their hand at resetting the arm and link with no success at all.  With the engine off sometimes it sticks, sometimes not. but any time the car is running, it sticks about half way.

The issue here is that it DID work and now it does not.  A rebuilt pump is expensive and sounds like a pain in the backside to install, so is there anything else we can try first?

[Benz Dr.]

This is a bit like the paint question. You can try and fix it yourself but what sort of damage is there inside of the pump or even more importantly, will running it do more damage.

I'd say no, you probably won't be able to fix it. If you removed the arm, which is a big no-no, I think that something inside of the pump has moved to a position that's making it bind. Better pull the pump off and send it away to someone who can check it for you. It's not that hard to remove the pump. I'm sure there's some sort of instructions on the site which will detail how to do it.

[ja17]

Hello,

Not an unusual scenario for a car which has been stored.
Sometimes a piston sticks in the injection pump causing the main rack to stick.  This can cause the linkage arm in the injection pump to actually stick or bind. This is the result of the injection pump rack being stuck from the stuck piston. It's all interconnected.

You will find a 10mm bolt holding a cylindrical cover on the front end of the injection pump. Remove the cover and thread a metric machine screw into the front of the rack (it has a threaded hole). The rack should be easily moved back and fourth. It should also return to its rest position on its own. Let us know if your rack binds. We will give you some tips on freeing it up.

[steven_first]

Well thanks that is a good starting point.  I really wish we would have tried running it before my brother removed the arm so that we could have seen if it was doing it before the change...  I am not near the car now and probably won't see it for a few days but I can give that a shot I think.  Do you know the pitch and size for the threads?  And just to be clear we are calling the front of the pump the end point towards the front of the car right?  This is my first exp. with mechanical FI and it is quite amazing really.  If my boss gets his hands on a new pump I am going to try to get the old one off of him!

I read a lot of your posts JA, amazing stuff!  Thanks for the input I will be in touch sooner or later!

[ja17]

Hello,

I am not quite sure what eactly you removed on the pump.  Was it the linkage rod going to the pump or was it the actual linkage lever on the side of the pump?

[steven_first]

Hello,

I am not quite sure what eactly you removed on the pump.  Was it the linkage rod going to the pump or was it the actual linkage lever on the side of the pump?

The arm that connects to the side of the MFI.  My brother said when they tried to put the arm back on the shaft the shaft would push almost all the way into the unit.

http://www.glowfoto.com/static_image/15-101922L/8035/jpg/03/2010/img6/glowfoto

[steven_first]

I will be looking at the car this Saturday, can i get some hints on what to do if the injector pistons are hanging up?  can I take off the side plate covering them and look at them at all?  Would it be best to leave the MFI on the car or save the extra aggravation and set the car to 20 deg past TDC and remove the thing?  Are there any special tools I will need or any things to watch out for?  I first want to make sure there is oil in the MFI and second I want to see how much.  I am guessing I should have about 200 mL in it seeing it is the newer type?  Sorry but I am a 2 stroke guy at heart and haven't worked on much in the way of classics...  I did put a 600cc sports bike motor on a 125cc dirt bike frame once though 

[jeffc280sl]

I think the lever you removed is set by the factory.  Were you able to index the shaft and lever so you can return it to its former setting?   Its relationship to the internals of the fip are critical. 

You can remove the rectangular side panel.  It's a white glove area so make sure things are clean and no debree can fall in.

[steven_first]

I don't think my brother took any care in settings when he removed it.  I seen in the service manual how to set it but we need a special graduated disk thing to set it.  My Saturday visit is being postponed for now because my boss is busy this weekend so I will get back to you once I have more info!

[Cees Klumper]

I don't think my brother took any care in settings when he removed it.  I seen in the service manual how to set it but we need a special graduated disk thing to set it.  My Saturday visit is being postponed for now because my boss is busy this weekend so I will get back to you once I have more info!

Just maybe you can tell from the pump just exactly how this lever used to be positioned (as in different color on the housing where it used to be). There are instructions on this site (I think from JA17, Joe Alexander) that go into detail about how to get the internals moving again if the rack has become stuck or sticky.

[Benz Dr.]

Why won't people listen to me? I'm no pump expert and about as close as this whole site gets to that is Joe and he doesn't rebuild them either so I'm going to say that there are no experts here. 
Aside from checking the rack and a few other things the pump is now screwed. Taking the arm off the side of the pump is always a very bad thing to do. Something has likely come undone inside and you can bend things by running the engine. That's only an educated guess but I've seen this happen before so I wouldn't go any further without having the pump looked at. All other ideas here are at best ' guessing ' and it's not a place to use a crystal ball.
Send the pump out to Hans or Gus. A diesel shop won't do as it has to be a place that works on gas fuel injection pumps.

Richard V. ( Ricardo ) did the same thing once and I told him NOT to turn the engine over. It had already bent a plate inside of the pump which we were able to fix at a pump rebuilding place. The pump was OK other than the bent part thanks to not trying to run it while broken.
That car is still running well from what I've been told.

[thelews]

www.blackforestllc.com rebuilds and calibrates injection pumps as well. 

[ja17]

Hello Stephen,

The pump rack is a different issue.  Loosening the lever is a bad situation to be in. Not sure you have any good options at this point.  You may  want to take a look inside the pump to see if anything is obvious. The entire rear cover can be removed for inspection.

[steven_first]

Yeah, I am getting the picture now   Sounds like the best we can do is remove the pump and check it out.  To be honest we are kind of looking forward to checking the thing out any way.  We were amazed when we started reading about the whole pump and want to check it out for ourselves.  I really want to see the insides for myself and get some pics!  Seeing the car was ran with the pump like that it may be a little late to save it but...here is to hope!   I will get back at you guys with an update very soon.

[ja17]

Hello Steve,

If you want to give me a call I will try to give you some details on what you could try first.
Email me at ja17@att.net for a phone number.

[steven_first]

Hey guys!  Well we finally got a chance to work on the car and we got the pump off and I checked the injectors and they were nice and smooth.  I then took off the end with the solenoid and idle adjuster and found the problem.  When my bro took off the control link and put it back on it was put on in such a way that when the throttle was opened the ball joint that moves the 'computer' (the part that has all the injector data on it) the ball popped out and then clipped the spinning weights and was launched up into the oil cap thing and jammed up there!  I have pics and will post them in a day or so for ya' all.   We have the car running but the gas is 3 years old and the car doesn't like it so we need to try fresh gas before we run it much.

Man I am so happy I got to work on that thing...very cool device.  I wish I had one just to show it off.

[ja17]

Hello Steven,

Don't get too far ahead of us. We willl help you get it set back up and installed. Ask questions. The linkage arm that your brother removed is connected at the factory and is set on the shaft at a set position. You may have to "trial and error" with this until you get close enough to make it work. Look closely to see if you can see any signs of where it may have been set originally.

First thing set the engine at 20 degrees after top dead center with the number one engine piston just after the top. (cam lobes over #1 cylinder should be basically upward pointing)  At this point you can align the indexing marks on the end of the IP and slide it in to place. Do not forget the splinned coupling.

[steven_first]

Well I am somewhat ahead then.  We did everything the best we could but we ended up removing the pump about 20 deg off from where we was supposed to.  Seeing we was a bit pressed for time we just took our time and made sure we didn't spin either the motor or the injector system.  It has to be said that the car as not ran right yet.  We replaced the old gas, cleaned and gaped the plugs and a few other things but the car is still not running well.  I did notice that the plugs were BLACK with carbon despite only having ran on them a few times.  Today after all this the car was idling at over 1500 rpm and would not back down even with many turns of the idle adjuster.  It was missing periodically and shooting periodic white smoke out the exhaust.  We did a compression check on all cylinders and all seemed to be good @ 9.5 except #2 that was @ 8.5.  While trying to accelerate the car would miss some at low end and as the RPM's increased it would get to a point where it would choke itself out.  We did play around with the arm on the MFI some.  I loosened the 8mm nut and clamped some vise-grips on the shaft and had my boss run the car while I gingerly turned it at idle.  We got the RPM's down to about 1,000 and it ran a little better but still missing a lot.  It just seems to be getting too much fuel or not burning it as well as it should. We did not change any link distances other than the one my brother screwed up connecting the MFI   so really this thing should be running right now!  My boss is willing to become a paying member here if it can get his car ready for the summer!  he wants to try to get the adjustment parts needed to correctly set the MFI if he can.  

[dseretakis]

You might want to put in a new set of spark plugs. New plugs work wonders in these cars. Ask me how I know. NGK non-resistor plugs are a good match in these SLs. I know that you cleaned them but I would still put in a fresh set.

[steven_first]

You might want to put in a new set of spark plugs. New plugs work wonders in these cars. Ask me how I know. NGK non-resistor plugs are a good match in these SLs. I know that you cleaned them but I would still put in a fresh set.

That is a good idea.  The other thing we want to check is the timing to make sure that is right.