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Replacing Injection pump-Engine block gasket

Mercedes 240D 123.123 619

Finally, I got around to replacing the gasket between the injection pump and the motor block. What a massive amount of work to replace such a small gasket! It seems that cars just were not designed with servicing in mind.

I could not find the Hylomar Blue and, based on a discussion in this group in the past, I picked Aviation Permatex from a lot of others. It is supposed not to harden and that should make it more effective in the long term. What surprised me is the width of this gasket and the width of the metal-metal contact. In places it is only

3/16". I would think that a wider bearing surface would give much more resistance to leaks.

Of course I had to remove the complete injector pump, after disconnecting the vacuum line (just pulling it off the pump), the two control rods, and the eight fuel connections:

1 Below the hand pump - the fuel inlet from the tank via the small transparent filter. 2 Right beside No. 1 - again below the hand pump - is an outlet that goes up to the top of the main fuel filter. 3 This is the fuel outlet from the main filter down to the front connection of the injection pump. 4 This one is the fuel return line that starts on the engine side of the injection pump, goes to the top of the main fuel filter and then attaches to the return line that goes back to the tank. 5 The other four are the metal fuel lines to the injectors.

Lastly, I removed the three nuts and washers that held the front of the pump to a bracket at the front of the engine, and another three that fixed a small bracket to the rear of the pump and to the engine block. The pump then was removed, with the rear end down to keep the oil from running out the front. I placed it level on a bench top and noticed the oil coming out the front. That was the area where the gasket was to be located and, to prevent any more oil mess, I turned the pump with that end down and drained about two cups of oil. I sure didn't want it dribbling out after I had the gasket and cement in place.

The Permatex - Aviation comes in a 4 oz bottle with very few instructions. Basically: "Apply to thin film to each surface. Allow to air dry for a few minutes before assembling." This was all that applied to what I was doing. I went online and came up with a PDF (

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that gave far more instructions. What about people who can't go online? Undoubtedly everyone has noticed that the instructions in English on all containers are getting less all the time, to make room for the Spanish traslation. Another cost of the illegal migrations? When will we learn? The gasketting went smoothly but, when I had everything reassembled, I had trouble starting the engine. I had released the air on Line 3 at the main fuel filter and, after the bubbles stopped, I tightened the nut and went on to Line 4 where it attaches to the main fuel filter. While doing the manual pumping I noticed a stream of fuel heading downwards. I had oscillated the plunger up and down by about 1/4" on each stroke and I guess that it is worn or defective. I set up two plastic containers, one under the main fuel filter, and the other below the injection pump and then vigorously repeated the venting. When I was finished the container around the main fuel filter had about a cup of fuel and the other one had about three. I tried a few times to start the engine and it came very close at the last try. I stopped and the battery is now recharging. It seems like I am near the end.

What a ghastly, messy, stinking - especially in a hot garage - and primitive process this is. Why not a liquid-air separator valve attached to the tops of lines 3 and 4 with the air line heading into the air intake and the liquid heading into the return line to the tank? Now that would be civilization! :-) Anyone heard of such a gizmo?

Is it possible to buy the manual pump plunger itself, or the washer that presumably attaches to it?

I want now to stop all the drips from the engine and I noticed that there was a small leakage at the corner of the cylinder head gasket - the left front side. I tightened the nuts to the correct torque and I suspect that the cover may be a little distorted. The gasket is only a few years old. I am thinking of removing the cover and gasket to clean them up and then use the Permatex at that corner, or possibly the complete gasket. This sealant seems to have an alcohol base so I doubt it would bother the plastic of the gasket.

I won't be able to identify other leaks until I get the car to a radiator shop to have the engine box and the outside of the radiator very clean. Anyone know what this typically costs?

Reply to
RF
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In my experience, MB does design with servicing in mind. Most jobs require limited number (usually only one) of tools. For example, oil change (13mm socket or wrench), brake, alternator, light bulbs (your fingers, most time), etc. I had at least twice experiences on GM cars where both metric and SAE are used on a same job.

Injection pump itself usually does not need service. Removal is even harder, especially because it needs precise timing when putting back. I assume that is why the engine does not start now. For later diesel engines (OM60x series), adjusting timing requires special tool (probably dealer only). I am not familiar with OM619. You may need to think about sending to repair shop.

RF wrote:

Reply to
Wan-ning Tan

Thank you for your comment W.T.

When the pump was off the car I did not rotate the shaft and neither did I rotate the engine crankshaft, so why would the timing be different? Does the black collar that fits over the front of the pump shaft have anything to do with the timing? It has internal gears that mesh with gears on the end of the pump shaft. That collar had no alignment markings that I could see.

The engine did run today a few times for a few minutes but it was very rough. This may be due to changed tuning settings - I SURE hope so.

Wan-n> In my experience, MB does design with servicing in mind. Most jobs

Reply to
RF

RF ha scritto:

Sure you need to tune up injection timing after disassembling it. You might want to check the procedure, for example 'buying' an Haynes manual.

Reply to
Cordy

Thanks Cordy for the comment.

The MBZ manuals indicate that, when the injection pump needs to be REPLACED, the crankshaft should be set at a particular angle and the front of the pump has a few moving components that need to be aligned with a particular mark on the pump body. I can find no description that suggests tuning after replacing the gasket. Now the manual is a bit of a mess, with no index, and covering a large number of models so I might have missed it. If anyone knows where it is, I'd appreciate the information.

PS I didn't disassemble the pump. I just removed the various external connections, replaced the gasket and did not disturb the internal components.

Reply to
RF

Mmmm... did you correctly purge air from ducts going from pump to nozzles (diesel injectors...)? Even a small bubble under pressure creates problems...

Reply to
Cordy

All one can do in that situation is to keep pumping until the bubbles stop coming and there is a steady fluid flow. That's what I did at the two locations. It took me much longer than at previous times and it was probably because of the pump washer needing a replacement.

I think small bubbles would be pushed along the line and eventually into the cylinder once the engine starts revving. I'll have another try later today. One little problem I have is the engine idling speed knob. It is a piece of plastic with a hole in it that is pushed onto a spike sticking out of the dash. The hole in the plastic is chewed up. I think I'll just put a blob of glue into it and that should fix it for now. Back soon and thanks for the "conversation." :-)

Reply to
RF

Success, at last :-) I finally got the engine idling adjustment made and drove around the block.

Reply to
RF

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