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1977 Volvo MD11C Fuel Injection pump leak

cedmunds

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http://www.marinepartseurope.com/en/volvo-penta-explodedview-7742230-23-15122C.aspx

Hello All,
Once again I need to rely on the expert knowledge here. I discovered that my older MD11C has a fuel leak around one of the cam driven nozzles that feed from the fuel injection pump to the injectors. I pulled the exploded view of the fuel injection pump and saw that there is an o-ring where that nozzle seats into the injection pump. The o-ring is #18 on the attached image. I figured that the o-ring must be the problem i.e. o-ring had gone bad. So after much hunting around I found ordered and received several crossover part number O-rings to try to replace the offending one. I have now tried replacing the o-ring 3 times and it still leaks at the same spot (note that in the cramped space, replacing the o-ring is not easy) I am at wits end and don't understand. Thinking about it and the fact that the nozzle feeds the injector I am wondering if it might be logical that the injector is partially clogged and is causing too much back pressure through the fuel line that connects it back to the pump nozzle to cause the leak?

I am able to restart the engine and run with the leak and don't think it is misfiring on either of the two cylinders. I did notice however that If I crack the fuel line on the involved injector while engine is running that there seems to be a higher pressure "spurt" from that fuel line than the other one. Any thoughts or suggestions would be appreciated. Florida Girl Carole.

Link to a better exploded view at top of this post.
 

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    MD11C Fuel Injectioin Pump.jpg
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I have had the same problem. When you change the O-ring part number 18 also replace the sealing washer number 15. You can get both parts from any Volvo dealer and should be in the neighborhood of $10.00. When you get the new parts in place torque the nozzle to 25 lbs-ft.

For any future readers this was a cheap repair especially for a Volvo. The repair cost me less than $10.00 in parts and did not take long to do. I did not even have to bleed the system afterwards. It is a straight forward repair, and these parts are not under pressure so thing don´t pop out and go flying. Just be careful and pay attention. The only regret that I have is I did not replace these items for both nozzles at the same time even though just one was leaking.

For the DIY person here is a list of tools that I used.

17 MM open end wrench for fuel deliver pipe
19 MM open end wrench for nozzle
12 MM wrench to remove fuel pipe from fuel filter housing (gives room to work)
19 MM standard length socket and ratchet for nozzle
6 inch extension
Torque wrench (To restate torque fuel nozzle to 25 ft/lbs)
Dental pick to help remove the copper washer/seal and reposition new one.

Hope this helps,
LT
 
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