Injection pump removal

[autocomman]

Hey there, new to the forum, and im a 10+ year automotive diagnostic and drivability tech.  Ive got a 59 300sl im workin on now ( i know its not a w113, but i think u guys may have some answers for me.)  Its a low mielage car, been sitting for about 6 years.  Long story short after draining the tank, cleaning old fuel from the lines and replaceing the filters, no fuel is coming outa the injection pump.  (yes the electric is working, 50psi when the pump is on)  Im guessing the rack and/or pistons are frozen.  Cause of the age and mileage (and owner) we are gonna have the pump rebuilt, but ive got limited service repair info on this car.  What do i have to look for in terms of alignment marks when removing this pump?  Its a early one, with a self contained oil supply and its supposed to be fully sequential (6-piston)  Its also along side the motor driven by a shaft.  Are there alignment marks as the later ones?  set it to 20BTDC  and line it up?  any thoughts or suggestions before i dive in this beast?  Also other than standard maintenance such as al fluid changes, what should i know about making this beast road worthy again.  Im a compitant mechanic, just wonderd if there are any particular points i should look out for

But the main question is removal and instalation of the inj pump and the alignment marks

Mark

[Shvegel]

I can't help you with your timing questions but there are plenty of threads here that deal with how to unstick a pump that has been sitting. Usually a little carefull prying and wiggling in the presence of proper solvents is all it takes. I unstuck mine after 26 years of sitting and it was just fine. That was 30,000 miles ago.

[Benz Dr.]

The 300SL has direct injection and is a lot more like a diesel pump. It needs to be set to 60 degrees ATDC on number one piston. It will run set at almost any position but only runs properly when timed right.
 I would turn the engine to 60 degrees ATDC number one piston and make a small mark on the engine block, the intermediate shaft and the pump for reference. Remove the pump and replace it in the same position as you removed it. I believe you can use the drip tube method to fine tune the pump timing if needed. I had one out by 180 degrees and it ran very rich. I had to remove the pump and start over to correct it.

The 300SL has two fuel pumps. The main pump on the engine and the electric pump at the fuel tank. A good electric fuel pump can put out as much as 90 PSI. The pump at the fuel tank only needs to run while starting the car. Once the engine fires the main pump will take over and the charge pump is supposed to shut off through an oil pressure switch. There's a foot valve in the main fuel line not far from the fuel tank. I've seen this valve get stuck and not allow fuel to flow. You can remove it and check to see it is opening or closing properly.
I would imagine that there's a fuel  pressure regulator or valve and that could also be stuck from sitting. I'm not sure where it is but most are right on the IP.
The IP has no mechanical linkage going to it and is controlled by vacuum. You can put a vacuum on the line to see if it holds and wether or not the rack is moving. This isn't a really hard car to work on but it's hard enough. Anything you break is going to set you back a months pay so be carefull. If you don't have a work shop manual, don't even touch anything until you do. This engine is not like anything else you may have worked on and it has some odd things about it that the book explains better than I can.

[glenn]

Bring it, the 300SL, to PUB.  The folk will help for free........  There will  no charge for test drives,  braking exercises,  on the road consultations, etc.....

[autocomman]

Good info benz dr. Ive spent over 5 years as a tech working on german cars, 3 of those bmw poirsche and benz specifically.  Im in teh process of tracking down a manual, and while im comnfident working on this car and the engine, i do want the book at hand if somehting isnt obvious.  After much examination and some online research, I understand that the elec pump only runs with no oil pressure, and if ned be can be turned on manually by the knob on the dash, also i know about the cold start knob u have to pull.  ive got the elec pump which is working, ive made sure ive got fuel flow al the way into the inj pump.  I did see the mech pump on the side of the inj pump.  Loks like it goes tank, elec pump, pre filter, steam trap, mech pump, canister fuel filter, inj pump.  Ive got fuel all the way at the mech pump verified at the outlet of the canister, and im pretty sure a good cleaning and un sticking of the inj pump should do the trick, im just waiting for the ok to dissassemble.  And believe me, im well aware of anything that breaks, either not finding, or not being able to replace for a while.    thanks for the info, we shall see what happens!  I havent taken a close look at the crank pully, i assume there is a 60 atdc mark on the crank pully?

Thanks for the advice!!!

Mark

[Benz Dr.]

I believe there's a 60 degree mark for pump timing. Very interesting cars those 300Sl's.

[autocomman]

Yeah they are.....sequential injection, dual point ignition with 2 coils, direct injection, OHC, the list keeps going....ive always been into benz stuffs but never worked on one like this, im pretty stoked to get into it.  SO there is a 60 deg mark on the crank, is there a mark on the pump?  Obviously im gonna mark everything before disassembly, but how would u like one up from the box?

[Benz Dr.]

I'm sure there would be a mark on the pump similar to any other pump. Line the marks up and install the pump. If you want to fine tune delivery point I think you would remove number one check valve on the top of the pump and install a dip tube. Turn the pump on and turn the pump towards the engine or away until you see a drop of fuel coming out every 3 or 4 seconds apart. This should be right at the start of delivery. I wouldn't bother with this unless the engine seems to lack power.

Make sure the cold start enrichment valve is fully closed when the engine is warmed up. You can look into the open throttle assembly with a mirror. All of the holes should be fully closed or any extra vacuum signals going to the IP will make it run rich. When you start test driving the car keep an eye on the oil level in the dry sump tank. If it goes down quickly ( 2 liters in a 50 mile run ) and the oil has a definite gas smell, it's running too rich. Check the cold start device again and you may need to turn the adjustment a few more turns which makes the pin move forward deeper into the casting.

The oil in the tank should go down very slowly ( maybe 1 liter in 1,000 - 2,000 miles ) and it should have a sweet smell to it.

[ja17]

Hello,

Injection timing on these cars is critical.  They must be drip timed like a diesel.  Timing should be within one or  two degrees. If the car has been setting' most likely it needs a leather diaphragm in the injection pump. I have been called into both MB dealerships here  to assist with 300SL repairs. Email me direct if you like, since this is not a 300SL specific web site. ja17@att.net

[tel76]

Hello Joe and Doc,
If you fit an injection pump to a 280sl pagoda to 20 degrees BTDC rather than the correct 20 degrees ATDC what symptoms would you expect?

[Benz Dr.]

20 degrees BTDC would be 40 degrees advanced and it will run very rich. I've seen a few cars that had the IP timing set wrong and that was the result. I always set the crank to the pump timing ( 20 degrees ATDC ) before I remove the IP so I can check wether it was timed to the engine properly.

Joe is correct, this is a site devoted to 113 cars. Part of why he and I know anything at all about 113's is because we've worked on almost all of the other MB models from the 50's or 60's. These different models often have the same componets but some of them are very different in how they're designed. Having a good general knowledge of the '' hows and whys '' of MB manufacture from this time period can be a real asset. The fact that Joe is called by MB to consult on 300SL's only proves this point.     

[glenn]

The Bosch CIS(Continuous Injection System) ignores timing.  At 6000 rpm, inertia, flow dynamics, etc.. trump timing.