Changing the diesel filter

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Eric Steege

I am curious to know how often I need to change the diesel filter on my 1984 Hunter 31. I have owned my boat for two seasons, and the filter has not been changed since I bought it. I believe I need to change it, but I have heard horror stories about how hard it is to change the filter, and get the diesel back in this system. From what I can tell there are several very complicated and difficult procedures that need to be completed in order to get the diesel fuel primed after changing the filter. One thing that I have thought of is hiring the marina to change the filter for me, but I'm concerned that if it's this difficult they might no do a good job. Does anyone have any advice from me concerning the diesel filter?
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Not that difficult.

Eric: If is really not that difficult. Depending on the type of primary filter that you have fram (which was originally on our '85 H'31) or a Racor which is a common replacement. Get another filter before you begin. You will also want to change the one on the engine too. Then you turn off the fuel supply at the tank if you have a shut off valve. Then get a coffee can and some old rags to catch any fuel (in case of any leakage). Remove and replace the primary filter. I think that it is usually good to use a little grease on the gasket to help seal it better. Then change the filter on the engine. There are a couple of bolts on the engine with a phillips slot in them. These are the bleed screws. It is best to use a wrench on these and not the phillips to prevent stripping the bolt. Then you need to find the *thumb pump* on the engine (this is the difficult part). Once you find the thumb pump you can open the first bleed screw and just start pumping until fuel starts comming out of the bleed screw. You can now tighen this one and open the next one. Keep pumping until fuel is comming out of that one too. Then you can try to start you engine. If it starts make sure to put your engine in gear while still in the slip and let the engine run for 10-20 mins under load. This way you now that the engine is getting fuel and not just running on what was left in the system. If the engine stalls then you need to re-bleed the two screws. Note: be sure that you do not mess with the high pressure side of the system (at the injectors). Also have a few paper towels or old rags to clean up any diesel fuel. It tends to stink up the boat if it gets on things. If you have clean fuel and you tank is clean, you could probalby go several years without changing these filters without any problem. The real problem is the fact that if you do have dirt in your system, the engine will always quit at the most in-oppurtune times. Not too sure if I got everything but I would recommend that you get a manual for the engine and the procedure is detailed in there too.
 
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Eric Steege

Thanks for the detailed response

part of the bid but why is for the detailed response. But I do have
 
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Ray Bowles

Farm boy filter changes

Eric and Steve, The procedure Steve wrote up is great. I thought I'd offer a suggestion. When changing an engine oil filter or diesel fuel filter we always fill the filter with the appropriate fluid if the filter is in a vertically mounted position and can be installed without spilling the fluid. This helps reduce the bleeding effort or helps your engine build oil pressure sooner. DO NOT FILL ANY GASOLINE FILTERS THIS WAY!!!! ANY GAS SPILLED WILL CAUSE A FIRE. Good luck and a clean bildge. Ray
 
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hp

changing filters

Eric, just a thougth first it is not that diffecult a job to change filters (you need to do all them if you have more then one). I do understand that it might be intimidating if you have never done it before,however the previious post have given good step by step instructions.If you still don't feel comfortable get the marina mechanic to do it the first time with you there to explain how and why he is doing what he is. It should not be over a one hour labor charge and you will have learned a valuable lesson. I would also suggest that you change your filters every year when you winterize so that you are all set in the spring. you should also carry extra filters on board all the time in case of emergency! Hope this helps and good luck!
 
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Tim Op't Holt

no need to bleed!

My $.02 on this topic: I change my filters 1-2 times annually. Whenever changing them, I fill the filter cup with fuel. While reattaching them, there is some overflow. I have not, after four seasons, had to bleed and pump. I keep rags handy to catch the overflow, which is usually a few ccs. Tim S/V Brigadoon II '85 H31
 
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Bill

Bleeding

I think that the biggest fear that any new owner has about a diesel engines is the bleeding and fuel issues. I know that is the way I felt for many years but I think that with today's engines and fuel products that the majority of mysteries have been removed. Unfortunately, the manuals I have are not very clear on the bleeding of systems and could be made much simpler with a little forethought.
 
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Roy Mosteller

Color The Bleed Screws

I watched a mechanic do the first filter change on my 2GM20F. He suggested coloring the head of each bleed screw with a dab of paint or nail polish. I took his suggestion and find it invaluable when I make an annual filter change as all bleed screws are easily recognized. Be careful to not fill up the phillips slot with paint.
 
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Les Blackwell

Roy, Great idea

Nice idea on painting the bleed screws. I'm having my mechanic watch me change the oil and filter--I'll get him to point out the bleed screws. Thanks for the idea. Les
 
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William Berson

need to bleed

Whoops! Tim. Good idea to pre fill the filter housing with diesel, but only the racor pre-filter please. If you do that on the engine-mounted filter, then the engine is getting a gulp of 100% unfiltered fuel, which is the ultimate no-no. I guess it would be ok if you kept a container of specially filtered fuel handy, but bleeding the final filter, when the rest of the line is filled is not too hard, I find.
 
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