Injector Pump

[n/a]

Greeting all
I have a 1965 230SL that I believe has a stuck "rack" in the Injector Pump.  I read through all the threads I could last night and began the day armed with a 4mm screw to thread into the front of the rack.  I can't get any movement other than a few thousands fore and aft.  I assume I should get some rotation?  The rack doesn't move when the throttle linkage is moved, either.  I'm thinking of sending the pump into H&R for overhaul but thought I'd see if anyone had any additional suggestions before doing so.  I just bought the car and have no idea how much varnish and debris is in the fuel system.  The fuel tank is next on my list of "things to do".  The previous owner claims to have driven it in the spring but I have my doubts.  If anyone has any suggestions or shops they've had good luck with, I'm all ears.  Thanks in advance.  I can't wait to get this beauty running!

[ja17]

Hello RV,
Freeing-up stuck rack can often be done without injection pump removal. Read through the "injection pump tour" to familurize yourself with the differnet parts.
In actuality a stuck rack is  usually the result
of injection pump plungers getting stuck in their cylinders. Contaminated fuel may have been cranked up into the injection pump and allowed to sit and work on these plungers and cylinders. Extended inactive storage can also allow fuel to break down and varnish up these plungers. Clearences in these parts are in millionths of an inch.
The rack moves six gears attached to the six injection pump  cylinders. When one or more plungers are stuck The rack is unable to move.
Your first step is to unhook all six injection pump lines at the pump. Start at the back and work your way forward, sliding each fitting up on the metal fuel line as you go making room to loosen the next. Now remove all the 19mm fittings where these lines were attached. Beneath these fittings are the fuel check valves. You will see their threaded ends. These simply pull out. A special tool is reccomended, however I found a metric fitting which fit and works fine. The check valves are not difficult to remove with a little tugging. After you remove these check valves you will see the injection pump plungers and cylinders. Spray a lot of penetrant (WD40 or such)onto these parts. Rotate the engine and you will probably see that one or more of these plungers are not moving up and down. Allow the penetrant to soak a day or so adding more when needed. If the plungers do not free-up on their own, use a hard wood or plastic peg (a golf tee works fine) and push downward on the stuck plunger. Keep exercising it by turning over the engine and pushing on the stuck plungers until free. When all plungers are moving up and down the rack will move freely. I will add some photos as time permits over the next couple of days. I have several dis-assembled pumps here to help illustrate the process. Keep us informed. Good luck.


Joe Alexander
Blacklick, Ohio

[n/a]

Thanks Joe!  I'll give this a shot and let you know how things work out.
Tony (RV6Boxer)

[rwmastel]

Joe,
I will display my inexperience with FI pumps with this question:
I thought all these components were physically connected.  That is, the engine crankshaft turns a gear which turns the FI "crankshaft" which pushes the plungers up & down.  How can you turn the engine with a stuck plunger and not break something?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[graphic66]

You may also try a product commonly refered to as decarbonizing fluid, called by a few different names, it is ussually availible at marine supply stores. OMC has a product called Engine Tuner, Yamaha has Combustion chamber cleaner and there are many more. This product melts away the varnish residue left by gasoline better than any thing I have used. I also use it at every oil change as directed to clean the combustion chambers in my SL by spraying it in the intake and letting it sit in the cylinders. There is a companion product to add to your fuel to help your car keep carbon buildup from forming and I use that in my fuel every so often. The decarbonizing fluid also is great for cleaning heads when you have them removed, it melts away carbon fast from the combusion chamber and valves with very little effort. It is only availible for off road use, Marine or motorcycle so you have to go to those stores to get it. I think it may really help getting the varnish out of the injection pump, it may be worth a try.

[ja17]

Hello Tony and Rodd,
Here are some photos to illustrate the situation;

Download Attachment: 1 injection pump plungers.JPG
33.82 KB

As the engine turns the plunger is pushed upward by the injection pump camshaft. Any rust or contamination will cause the piston to stick in
the upward position. Nothing breaks, the return spring can no longer force the piston downward. The rotation of the cylinder and movement of the rack is also prevented causing a "stuck rack".



Download Attachment: 1 injection pump fuel delivery.JPG
35.38 KB


This photo  is to help you understand what goes on in these injection pumps. Do NOT ever dis-assemble your pump this far. A sixty thousand dollar Bosch Injection Pump Stand will be needed for re-assembly and adjustment!
Thanks for the tips on decarbonizing!

Joe Alexander
Blacklick, Ohio

[rwmastel]

Oh, OK.  Makes total sense now.  Thanks for the pics, Joe!

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[ja17]

The injection pump check valves can be easily removed without the "special tool", by using a correct size metric fitting as a homemade tool.

Download Attachment: check valve removal.JPG
60.46 KB

Joe Alexander
Blacklick, Ohio

[n/a]

First of all, I'd like to thank everyone for their advice on this.  I tinkered with the IP "rack" and never did get it free.  In an effort to be somewhat productive, I moved onto the fuel tank.  After pulling the tank and witnessing the contaminates it contained, I've decided to pull the Injection Pump and have it "gone through" by a professional.  What's in the tank is in the IP and probably the injectors, too.  The tank is being cleaned and coated as we speak.  I'll flush the fuel lines (replace the rubber ones), replace the fuel filter, etc.  The electric fuel pump is new but I'll run some clean gas through it.  I spoke with Hans at H&R injection in Long Island, NY on Friday.  He was very helpful and suggested I have the injectors and CSV checked as well, whether I did business with him or someone else.  I think that's good advice.  Anyone out there had any experiences with H&R?
Thanks in advance, I appreciate all the efforts
Tony 1965 230SL Auto

[J. Huber]

Hey Tony.

I haven't actually used Hans at H&R but I know he has been deemed  the number one "go-to guy" on Bosch equipment. Good luck and keep us posted on how it all goes.

James
63 230SL

[graphic66]

Hans at H&R rebuilt my CSV fast and reasonable, no problem. Highly recommended

[Douglas]

In fact, my car is going to Hans on Monday morning. Something is up with the injection. The mixture isn't leaning out as the car warms up and it ran so rich after I pulled the car out of storage (to prepare for a 250-mile trip to Tom Sargeant's get-together in VA), that I threw up my hands, cancelled the trip, and decided to let Hans figure it out. It runs perfectly when the motor is cold. Does this sound like CSV issues?

Douglas Kim
New York, NY
#018260