Inline diesel filter, is it needed?

[wetspot]

I have an inline diesel filter in my boat but over time it collects air (would imagine small bubbles from the fuel splashing about in the tank), is it needed?
the engine is a 300hp D-Tronic, some time ago someone suggested I fit this aditional 10 Micron particle filter but now I am not to sure I did the right thing, anyone any ideas?

It hasnt hindered the operation of the engine yet but at sea if it can go wrong it usually does eventually.

 

[Latestarter1]

Yes, yes yes.

Your on engine filter has to be considered your last chance filter. If any water/**** gets past rhe on engine filter next stop is fuel pump then injectors. Bosch VP44 pumps are over a grand to repair if rotor head gets taken out. Debris from the rotor head gets carried down into injectors. If injectors start to hose, pistons melt.

I assume by the term inline filter you are referring to your pre-filter?

Your logic requires a re-think. If you are getting air in your pre filter you have a design problem with your fuel system. Builder or whoever installed the engine obviously did not read the Mercruiser installation guidelines, flow and return for this engine MUST come from stand pipes going down to the bottom of your tank and be a certain distance apart, all in the installation guidelines.

I think you have to assume that the engine installer was on whacky baccy and go back to basics and check out everything. One thing for sure air is not just getting into your fuel by splashing about.

Forget other filters at the moment your installation is fundamentally unsafe as it is pulling air, motors will have nasty habit of failing at just the wrong time.

 

[pappaecho]

I had a similar problem with entrained air, which made the engine hard to start. Found ultimately the cause was a fractured copper pipe, which once found and replaced problem ws solved.
I also had had problems with both diesel bug on one boat and a lid steel tank on another, wher rust was the problem. The primary filter cuagth all he ****, which if it was not there would have clogged the fuel filter, and stopped the engine in each case.
All RNLI lifeboats have two primary filters in parallel (switchable) for exactly the reason above, and also no doubt, they have rescued hundreds of boats whose filters were blocked, and thence engine stopped.
Old plumbers used to use a soap or faily liquid solution, to detect leaks, and this will work, so your should initially coat any joint with fairly liquid in water and see what happens. If it starts moving or bubbling then your have a suspect joint. If that does not work, replace the inlet pipe from tank to primary filter. If there is any sort of shutoff valve in the line, probbly worth replacing that as well. Lastly of course you should also try fiary liquid and water round the seal to the filter to ensure it is not sucking air. Clealy do this before replaing pipes etc.
Good luck

 

[hlb]

I did not bother answering this question at first. It seemed suck a numb question.

However If the pre filter has trapped air, it has done part of it's job. However there should be no air and it will have come from some bad joint some where. It must be before the pre filter. I dont beleve that it can come from surging fuel. Less you insist on running on empty. So mend the leak, or put some fuel in. They dont run well on empty.

 

[PaulGooch]

Yes, yes yes.

Your on engine filter has to be considered your last chance filter. If any water/**** gets past rhe on engine filter next stop is fuel pump then injectors. Bosch VP44 pumps are over a grand to repair if rotor head gets taken out. Debris from the rotor head gets carried down into injectors. If injectors start to hose, pistons melt.

I assume by the term inline filter you are referring to your pre-filter?

Your logic requires a re-think. If you are getting air in your pre filter you have a design problem with your fuel system. Builder or whoever installed the engine obviously did not read the Mercruiser installation guidelines, flow and return for this engine MUST come from stand pipes going down to the bottom of your tank and be a certain distance apart, all in the installation guidelines.

I think you have to assume that the engine installer was on whacky baccy and go back to basics and check out everything. One thing for sure air is not just getting into your fuel by splashing about.

Forget other filters at the moment your installation is fundamentally unsafe as it is pulling air, motors will have nasty habit of failing at just the wrong time.

If you read the OP again you will see that he fitted the "in line" filter, not the builder.

 

[PaulGooch]

I have an inline diesel filter in my boat but over time it collects air (would imagine small bubbles from the fuel splashing about in the tank), is it needed?
the engine is a 300hp D-Tronic, some time ago someone suggested I fit this aditional 10 Micron particle filter but now I am not to sure I did the right thing, anyone any ideas?

It hasnt hindered the operation of the engine yet but at sea if it can go wrong it usually does eventually.

Please explain the complete fuel filtering system. Is this a 3rd filter, between the pre-filter and engine filter, or what ? What is it, how did you fit it, where did you fit it ?

 

[Latestarter1]

Please explain the complete fuel filtering system. Is this a 3rd filter, between the pre-filter and engine filter, or what ? What is it, how did you fit it, where did you fit it ?

You are quite correct Paul I did misread the original post, and also you a proper overview is spot on.