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post #1 of 6 Old 08-31-2009 Thread Starter
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Bleeding a Universal M25

I just purchased my Catalina 30 1984. I'm getting around to replacing all the filters (already changed oil and coolant) and am not sure how to bleed the fuel lines. It has a universal M25 diesel in it. If someone could explain in detail I would really appreciate it. I looked on the universal website and they have some instructions there but I am not exactly sure where the bleed plugs are. I think I found the one near the fuel filter, but the other one eludes me. Obviously I'm not very familiar with diesel engines. Also should I be trying to start the engine while bleeding these plugs or is just having the key in the on position enough?

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post #2 of 6 Old 08-31-2009
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Might check to see your specific model. I might be mistaken but some of the M25's are self bleeding (mine is). I don't remember the specifics, but after a certain year they were manufactured to be self bleeding.

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post #3 of 6 Old 09-07-2009
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I have an M4-30 that is self bleeding...but every once in a while, depending on how intrusive my maintenance may have been, i find it necessary to bleed in order to get her to run.

The process is simple on mine...hope it helps you with yours:
Be sure to have the area very clean in advance and have rags on hand to sop up any spillage.

Next, be sure you need to bleed. Double check that you have fuel being delivered to the engine's high-pressure pump by first bleeding that connection.

If you see clean, bubble-free flow to this unit, proceed to the injectors.

Begin with the injector nearest the engine's high-pressure pump output line.

Have someone crank the engine while you 'crack' open an injector. By "crack," I mean attempt to unscrew the fuel supply at the injector. An injector is 'bled' when you see a steady stream of fuel for a 5 to 10 seconds with no air bubbles.

Repeat on all injectors continuing in the order of fuel flow.

Good luck.

FYI. I am not a deisel mechanic...but I have hacked my way to partial compitence through trial and error. Please take my advice with an understanding that there may be a better, safer way to do what you're attempting....but if no one else answers and you're stuck...hey...give it a try.
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post #4 of 6 Old 09-07-2009
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I have a 1984 M25 in my C30

1) Just turning the key on is enough, since the fuel pump is electric
2) The bleed screw is approximately above the dipstick. I'll take a picture next time I'm at the boat.



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post #5 of 6 Old 09-08-2009
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If you are careful you won't need to bleed the system after replacing the fuel filter. Eliminate as much air as you can by filling the filter with fuel before putting it back together.
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post #6 of 6 Old 09-08-2009
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There should be a round knob about a half inch round adjacent to the injectors. Turn the key on and open the knob for a few minutes. You can also leave thyis valve open for a week or so and close it after that and all the air will beo out of the system.
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