Volvo Penta md5a 1982 diesel Delphi 296 replacement

Sailor96

Cadet
Joined
Dec 31, 2022
Messages
12
Hi everyone,

I'm new here so forgive me if this is asked in the wrong section.
Last summer I purchased my uncle's 27 foot sailboat.
At this moment the engine does vibrate heavily on more than 3/4 throttle.
This occured when motor-sailing and a gust of heavy wind made me heel quite a bit. I heeled over to starboard and my fuel tank is on my port side.

I immediately suspected that the fuel system is clogged. And upon visual inspection of the filter, it looks really bad. I asked my uncle, and he has never replaced the fuel filter in the 13 years he had the boat. So I ordered an entire new unit, instead of only the filter.
I have added a picture of the current unit. You can see how dirty the see-through glass is.

My question:
I have heard/read that when you change this unit or filter, air comes into the system and the engine wont start. Where can I find proper information on getting the air out once I've installed the new filter unit? Does this have to be done on the engine itself?
Does the lower glas have to be filled with diesel after installing, or the filter itself? To make purging the air easier I guess.

Another thing I thought it could be:
Engine misalignment in regard to proppeler.
This could be confirmed by the fact that the engine doesn't vibrate in neutral.

I can upload a video of how the engine sounds if necessary, as it sounds as if it is getting not enough fuel.
 

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Sailor96

Cadet
Joined
Dec 31, 2022
Messages
12
Thank you,

Should I fill the entire filter or just the bottom see through glass?
Do you also suspect the fuel system how I described it? Or do you think it could be engine misalignment?

I also feel vibration in the helm stick when the propeller is rotating. Have not noticed this before. Perhaps something in the propeller? Like a rope or piece of plant maybe?
 
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Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
You have to systemicly look everywhere for the cause of vibration

Could be any of the following:
Debris on prop
Bent prop
Bad prop bearing in strut
Bent prop shaft
Bad cutlass bearing
Severe misalignment
loose flywheel
One or more dead cylinders (however you only have 1 cyl)

However some vibration in the boat will be normal with a single cylinder diesel.
 

Horigan

Chief Petty Officer
Joined
Jun 12, 2016
Messages
526
To properly bleed a diesel fuel system you need to completely fill the filter bowl. Then find the downstream lift pump and there should be a small lever on it. There should also be a bleed valve on top of the lift pump. Crack the bleed valve and pump the lever many times until you get a continuous flow of fuel from the bleeder, with no bubbles. The first time you start it be ready to give it half or 3/4 throttle if it starts to stumble due to any residual air.
 

QBhoy

Admiral
Joined
Mar 10, 2016
Messages
7,176
Hi. Good idea to fill it with diesel for sure. You should have a manual lift pump on the engine mechanical fuel pump. This allows you to manually pump fuel to the secondary Engine filters. With the bleed screw open on these and using the manual pump, you can bleed up to that point.
If the engine has ran and run out of fuel prime, you will most likely need to bleed the injector(s). This will involve cranking with the injector supply fitting cracked open until you see fuel. Don’t take it right off and keep yourself away from it whilst doing so. It will be a 17mm spanner most likely
 

Sailor96

Cadet
Joined
Dec 31, 2022
Messages
12
Thank you.
I couldnt really fill it with diesel as it came apart when unscrewing. The diesel would flow out before tightning.
After connecting the hoses to the unit, it filled up in no-time. My uncle sad the engine bleeds itself when started. But we have no idea whether we had to open/unscrew something for that to happen. Allthough, it started on the first try within a second. Seems to run much smoother now and even a better cold start. It used to take like 2-3 seconds to start the engine prior to filter change.

I wonder how they got the old filter in, there's no way i'm getting it out of there, I can't see or reach the bolts. Luckily I was able to drain it and take the fuel lines of, But now it is still in there. The only way I could reach it, is by taking the engine out which seems impossible. The engine is alot bigger than the cabin opening so I guess the engine was put in the boat before building the upper side of the boat. The new unit is now mounted in a more accessable area for future maintenance.

I have briefly tested in the marina to see if the vibration gone away after changing the filter but I don't think it has. I guess I'll have to wait untill June to check the proppeler, when she is coming out of the water 3 weeks for painting.

What would be my options if I were to decide to mount an outboard engine? Can it actually be done? I have a Defender 27. All it has to do is take me in and out of harbor and perhaps a good hour on canal (depending on the wind, tacking on a canal is a chore..) before reaching sea.
 
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