fuel injection pump seized up

[travellerdogs]

The car has been sitting with old gas in it for a number of years. I've rebuilt the whole fuel system, tank, lines, pump, cleaned the injector lines. rebuilt the fuel damper etc. Basically gone through the whole system. Ready to fire the car up but can't get any fuel out of the injection pump. I got fuel going in and fuel returning and plenty of it. The pump is putting out big time. However, the plungers are seized up.I  tried to move the rack with the 5mm threaded bolt after I removed the rubber cap on the end of the pump toward the front of the engine. It won't move. I have taken the fuel feed line and fitting and return line and fitting off the pump. I have pumped some carb cleaner into the pump and plugged the holes with pipe plugs. I also have put carb cleaner in the injector line fittings on the pump. I don't know how to get the valves out that are under the line fittings, by researching I need a special tool to pull them out with. Any ideas how to remove them as I can then put some carb cleaner down the holes so as to drench the plungers with. They are obviously seized from sitting all those years and the gas has turned to varnish. I would like to take the side plate off but it's in a hell of a spot to get to, probably if I removed a bunch of things I could get at the plate from underneath on the hoist.  I don't want to take the pump off as that's a **** of a job also. I've been on this site  now for several evenings and reading and checking everything I can find on the pumps and am familiarizing myself on them. Would like some suggestions as I am stumped. thanks, carey

[w113dude]

Did you try to move the crank at the lower pulley? this should move the pistons in the pump, I would try and give it about ten rotation while adding some carb, cleaner in the lines. Your next option and my choice would be to take the pump off, it really isn't that bad. a couple of hours you should have it out.

[ejboyd5]

Take the pump off the engine.  You will save time in the long run and the end result will be much better.

[Benz Dr.]

That pump needs a full rebuild.

 If I could find fault with this site for anything, it would be for leaving the notion that you can fix things like this yourself with limited info gleaned from reading here. It is possible to make some simple repairs but most of the internals require the knowledge and tools to do so and I don't know of any pump rebuilders on this site.

[Kayvan]

U might want to try liquid wrwnch or fogging oils and leave for 7 days

[travellerdogs]

To Dan, I never said I was trying to rebuild the pump myself. Just trying to free it up. If a person doesn't try to figure things out by researching then how would anybody learn anything in this world. If you never try to solve a problem then you've never tried to do anything in your life.

[Benz Dr.]

To Dan, I never said I was trying to rebuild the pump myself. Just trying to free it up. If a person doesn't try to figure things out by researching then how would anybody learn anything in this world. If you never try to solve a problem then you've never tried to do anything in your life.

Well, you can try.  Even if you are sucessful it still may not work right. After working on MB cars for 35 years I think I've earned the right to voice my opinion.


External adjusments on FI pumps can be done by anyone with average skills. Once you get into the gut works it's a whole different deal.

[travellerdogs]

Dan, I was only trying to do the external adjustments as well as freeing up the pistons and rack which by all accounts from our members can be done successfully. I will have it rebuilt if I feel I can't get this right. I probably am going to have to remove it from the engine which looks like a nasty job. I am going to check it this morning and see if the carb cleaner is doing anything. I am going to try to remove one of the valves under the #1 injector line fitting as this is seems to be held down by the injector line fitting when  it is torqued down. I want to get some carb cleaner down on top of the plungers.  Meanwhile I appreciate your input and I do know when something is beyond my capabilities. That being said I will send it off to New York for a complete rebuild. Carey

[ja17]

Hello Travellerdogs,

Dan's right, you probably cannot fix it yourself. However we will help you fix it using your hands and your eyes! Ask questions, keep us up to date.

The rack will not move since some of the pistons are stuck. Remove all fuel injection lines from the injection pump. Next remove the 19mm fittings on the IP.  Below  you will see the check valves. They are threaded on the outside. You can remove them by simply screwing a fitting over them  then pull them out. It is a metric thread, however you can find a brass SAE fitting close enough to start and do the job. When all the fittings are out, soak them with penetrant then rotate the engine. You will see that some pistons do not move up and down. These are the ones causing the problem. Re-soak the pistons with rubbing alcohol.  Alcohol is best for desolving fuel varnish. Rotate the engine again. Allow penetrant and alcohol to soak in.  Exercise the rack by hand also.

If the pistons still do not free up, gently tap them down. Use a soft metal rod or hard wood. If the piston does not tap down, the cam under it may be holding it up. Turn the engine till the piston does tap down. Be gentle.  Keep working on all pistons until they are free and move up and down when the engine is turned. The rack will be completely free after all the pistons are freed up. Take your time and let the solvents work. During re-assembly it is critical to torque the 19mm fittings on the IP to 21 ft. lbs.

Keep us up to date. Ask questions for more details.

Joe Alexander (ja17)
Blacklick, Ohio

[travellerdogs]

Hi Joe and thank you very much for clear and concise "how to do" instructions. I have got oone injector fitting off #1 on pump, wasn't clear on how to get the little valve out, I do see that it is threaded on the outside. I can probably come up with a brass fitting in either metric or SAE that can fit on the treads. I am using carb cleaner but I do have a big can of pure alcohol. One question, can I get the rack to move while the injection pump is installed on the engine. I did remove the rubber cap on the front of the pump and managed to thread a 5mm threaded bolt into the rack, but by pushing on the bolt nothing moves and I don't want to force it. I have removed the fuel inlet and return lines and fittings and pumped carb cleaner in the pump and plugged the holes with a pipe plug to keep the cleaner in and also blew some compressed air into one of the holes. So far no movement. I took #4 fuse out to disable the fuel pump and turned the engine over with the injector lines undone, nothing. I have some carb cleaner in each injector fitting so if anything loosens it would blow the cleaner off the fitting. Although, in the beginning I was getting a small amount of fuel leaking out of the #1 injector fitting.  Was going to take the pump off but will follow you advice first to see if anything works. I have good pressure at the inlet line as I loosened the fitting on the cold start line off and it shot gas clear across my shop. Anyways, thanks so much. Carey

[ja17]

Hello Carey,

The pistons in the IP rotate as well as move up and down. The rotational movement of the pistons is what regulates the volume of fuel while the upward movement is what creates the compression pressure. When the bores of the piston get corroded or varnished, the pistons go to the top of the bores and stick there instead of following the cam back down. The rack is the device which rotate the pistons, the cam below move the pistons upward. So when a piston sticks in the bore it also refuses to rotate and thus the rack becomes stuck.

You can use some slight force to move the rack. Movement of the rack will help free the pistons since you will be rotating the pistons in their bores.  You will need to remove all the pressure valves to see the top of the pistons and to soak them. Turn the engine to see which ones stay stuck at the top of the bores. Once all the pistons begint to move up and down with engine rotation, the rack will become free and easily moved.

In some cases the "cylinder" or bore will move upward with a badly stuck piston during the procedure. If this occures it must be carefully moved back down  into place, since it is critically "keyed" to be in one position.

[Benz Dr.]

If the bore moves with the piston isn't already screwed up? Any rust in the cylinders and they're not going to work very well even if you are able to free them up.


  My point is simple. This can get you going sometimes but not every time.

[Peter h]

You can use some slight force to move the rack. Movement of the rack will help free the pistons since you will be rotating the pistons in their bores.  You will need to remove all the pressure valves to see the top of the pistons and to soak them. Turn the engine to see which ones stay stuck at the top of the bores. Once all the pistons begint to move up and down with engine rotation, the rack will become free and easily moved. [/i


I had the same problem a few weeks ago. A piston was stuck up and not be separated from the outside. We had to remove the injection pump. "Injection Ernst" our friend and specialist in the MB club had to take the pump apart and was able to solve the problem after some time. The pagoda is also not moved 13 years and everything had to be cleaned. The tank had to be replaced. We have also installed new injectors.
Now it runs like new.
"Injection Ernst" Reinkemeier  comes also to Willingen to the meeting. He is  been 81 years " old " now, but like a young man.

Peter

[450sl]

Gentlemen, i recently bought a spare engine out of a 280SE , is there something i can do to prevent my IP from freezing solid ?

Thanks
Mark

[w113dude]

Gentlemen, i recently bought a spare engine out of a 280SE , is there something i can do to prevent my IP from freezing solid ?

Thanks
Mark

Hi Mark,

I think if you keep the pump indoors without being exposed to moisture I think you'll be fine.

[230slhouston]

My 230sl was standing for 20 plus years when I rescued it. I took of the pump, it was easier to work with and worth the effort. My rack was not moving and the pistons where stuck. Take Joe's advice, use a golf T or a rod with a  nice flat end and give the piston a solid tap. Don't hammer,, just a solid tap....art to it.
Freed mine up, the car still runs like a dream, 4 years on. Try it, you may be lucky.

Hope this helps.
MBP

[travellerdogs]

Hi Joe, finallly got the rack freed up. It returns on it's own. Took a quite a bit of fiddling. I used pure alcohol, tapping the pistons down gently,
I had several cylinders move up, tapped them down with a piece of 1/2 inch copper pipe. I tapped the pistons down with a piece of 1/4 inch coated steel brake line with a piece of electrical tape on the end so as to not damage the top of the piston. But the thing that really made it possible was this special penetrating lubricant that I had on the shelf for a few years, quite expensive. It's called Fluid Film and its made by  NLS Products in Bobcaygeon, Ontario. Beats WD 40 by a mile. I also used alcohol with it. This stuff works by capillary action and doesn't dry out, drip, impregnates exposed metal and and keeps moisture and oxygen out. Incredible stuff and I've used it for a few years on my Bobcats. I made a check valve puller out of a brass 5/16 steel brake line connector, the treads were close to the ones on the check valve and then I used a 1/2 inch bolt screwed into the other end of the connector, worked like a professional tool. I'm letting it soak for the weekend and will work it continually over a few days and then  clean it out and hook the feed and return lines up and see what happens. I took the injector lines off as a unit in preparation of removing the pump so there lots of room to get at things. The rack pushes in easily and returns quickly, so far I'm cautiously optomistic. Thanks to  everyone who offered their help. Will keep the site informed. The posting of this kind of information is invaluable for guys like me that want to learn about our cars and do most of our own work. I love a challenge also. Thanks, Carey

[ja17]

Sounds great Carey. Once the rack returns on its own, all cylinders of the IP should be able to pump fuel.

Make sure the injection pump fittings are installed at 21 ft. lbs. for your 280SL. Soaking your injectors in some of your solvent can also be helpful in case they are stuck.

 Before  start up you should remove the spark plugs. Crank engine with the injection lines off to see fuel emerge from each fitting of the fuel injection pump. The fuel which emerges from the pump will be quite small in quantity. Hold the accellerator linkage full open to increase fuel delivery quantity. Once fuel emerges from all fittings, install the injection lines, leaving the fittings at the injectors loose. Crank the engine again until fuel emerges from the injection lines at each injector. Tighten each injector as fuel emerges until all injectorlines  are primed and tightened. Install the spark plugs and attempt start up.  You may have to do a bit more cranking.

Keep us up to date!

Joe Alexander (ja17)
Blacklick, Ohio

[travellerdogs]

Thank you again Joe. Several questions: can I buy the seals that fiit under the check valve. Also you mentioned that the cylinders in the IP are keyed, so if they were pushed up when I was freeing the pistons does that mean they could be out of wack. They only came up maybe 1/4 to maybe 3/8 inch or so. Then on to the injectors themselves, when I remove them are there specific seals under them and can you buy them. I can soak them in carb cleaner and alcohol and blow them out if that's permited. Another thing I  read in the tech articles that the car should fire on the CSV even if the injectors are not getting fuel. \makes sense as the fitting come off the fuel inlet before the IP. I undid the little #8 metric head bolt on the CSV and nothing came out of it but could there be a blockage in there also as the gas could have gummed it up. I had the engine fired up several days ago by squirting fuel in the intake, it fired up several times and it blew a mouse nest out of the tail pipe, lots of seed and sunflower seeds and carbon. When I bought the car 4 years ago I filled the cylinders with tranny fluid and had all the lines off and cleaned and painted and baked them. New  plugs, points, cap,  condensor, points at 14 or 16, ballast resistor etc. have to check my notes. The whole fuel system as been gone over and I got 1 litre fuel in 11 seconds on the bench test. I have gone over everything possible all new rubber lines on the engine, fuel lines, rebuilt my old style Bosch fuel pump, had it apart several times till I got it right. So I hope I'm getting close. Been a long restoration.  Sincerely, carey

[450sl]

Carey : great to hear you managed to free the Ip  :  its persistance that acomplishes it.

I have had some luck in the past using ultrasonic cleaning ; anyone with similar experiences?


Shaun : Quote "I think if you keep the pump indoors without being exposed to moisture I think you'll be fine."
The problem is a bit bigger then you imagine i think , i have had an engine sit for a year showing already gummed up petrol/soot in the injection system.

[ja17]

Hello Shaun,

The CSV is probably stuck.  Remove the metal line going to it and the fitting. The metal intake fitting has a very fine filter screen It can be varnished up. Clean it, check it.  Before installing the fitting, check the small "cone valve" in the body of the CSV,(in front of the fitting) to make sure it is free, probably stuck also. The electric solenoid pushes it open from the other end.  Check the electrical solenoid to see if it works.

Yes the IP seals are available. The part number is on this site somewhere. Not sure where the best place is to get them. Maybe the dealer or an authorized Bosch store if you get the Bosch part number.  It usually will work to re-use them, but best to replace them.

The copper seals at the injectors are never an issue. Low pressure and it is a suction situation at that end. I have seen these seals left off altogether with no issues. If you re-use them, apply a little grease to help the bare metal parts seal up without gaulding. Do not over-tighten  them. Treat them like a spark plug, same thread diameter i believe. Here again new is best, but re-using these is no problem. They are solid copper and really do not wear out. They are easily available from the MB dealer if you have the MB parts number.

The engine may not fire up on the CSV unless all the starting aids are working. Not much chance of this after the long period of storage. We can go through this system next as needed.  

First start will require some cranking, as only very small quantities of fuel are delivered from each cylinder of the IP. Those long injector lines take a lot of revolutions to fill. As mentioned, leave the spark plugs out to prime up the system.

Sounds like the engine is run-able if it starts on starting fluid. Your close. Keep us up to date.

[travellerdogs]

This is an update on the seized IP. Think this thing is toast. I now have two IP cylinders rotating with the pistons when I turn the engine over. Joe mentioned something about the cylinders being keyed. I am imagining there are something like a key that keeps them from rotating when the piston rotates as it is pumping up and down. Also the rack gets stuck when the cylinder rotates. I am going to remove the pump from the engine, and take the side cover off on the bench. Not sure what to do next, maybe remove one of the affected cylinders and pistons, #3 and #5 are both rotating. I have the blow up photo from Joe of the dismantled pistons, cylinders, spring, check valve, gear etc. Will call H&R and check about sending it for rebuild if I can't figure this out. On the subject of the seals for the IP check valve, one of the seals has a slight scoring on the face, I'm assuming that these are for the purpose of sealing and if they seal then it shouldn't be a problem. I can get copper washers locally from equipment supply houses ie: Bobcat, Kubota,  John Deere dealers providing they are not something special. Would appreciate some input on this as it is very welcome from all of you that weighed in and I thank you all,  Carey. Shaun, can I put 12 volts to the solenoid to see if it clicks with out hurting it.  I could undo the wires before hand. I have no one to turn the engine over while I listen.

[ja17]

Don't throw in the towel too soon Shaun, you are close.

If the cylinders are rotating with the pistons, the pins holding them in place backed off when the cylinders were pushed back down into the IP.  The other ends of the pins are visible after the outside cover of the IP is removed.  Simply remove the cover and tap the two pins back home. You may have to move the rack back and fourth and feel your way back into the groove. Once the pins are in place the cylinders will no longer rotate and the rack may be once again stuck. Just free it up as you did before. Just five or six screws hold the cover on. You will see the pins that moved out of place once the cover is removed.  The cylinders have a verticle slot milled in them to meet the pins. IP removal not needed, but it is your choice. Here is a picture.

[ja17]

Here is a close up of the IP piston and cylinder. Note the verticle groove which recieves the pin to keep the cylinder from rotating.

[travellerdogs]

Thanks again Joe, that`s a relief, will try that tomorrow. Gonna be a tight fit to work down the side of the IP, will move some of the fuel lines and anything else in the way. will have to use a piece of mirror as it`s hard to see down the side being that the pump is mounted on an angle. Got my fingers crossed this will work.  Could take the pump off if all else fails. Carey