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Subject: Fuel filter leak

Hi Tony

Thanks for providing the excellent Marine Diesel & Maintenance course, which I attended in June. I have carried out various maintenance operations on the boat since. However, I have one problem, which I can't seem to resolve.

I have a Mikuni diesel heater on the boat (one year old), which I have removed, serviced and replaced, and it is working fine. At the same time I also changed the heater's fuel filter (Crossland 489), but was not supplied with replacement seals. I refitted the old seals, but have not been able to stop the filter unit from leaking.

I have reinstalled the filter four times, but without success, which seems to be coming from around the main seal. Unfortunately, the main seal has now broken, so I will have to get a replacement. I am worried about over tightening the retaining nut (as instructed on the course). I think the filter cartridge has been inserted the right way up, i.e. the wording on the cartridge is not upside down. Other than replacing the seals, have you any other suggestions as to where I might be going wrong.

I'm surprised that the design of the filter unit hasn't improved over the years, as it is quite a fiddly item to deal with, and should be easier to service than I have found - unless I am making some fundamental error.

Kind regards

Dean H



Dear Dean

I am sorry to hear about your filter, but unfortunately I do not know exactly what design your heater uses. I think it is like the filter in that Volvo engine with a metal bowl that bolts up to the filter head with the element inside.

If this is the case I do not think fitting the element upside down would make any difference at all.

Email me a sketch or photo of the filter if you want to.

Often the sealing rings swell and are a right ******* to get back into their groove (hence me saying leave them alone until you are confident). I suspect that a small part lay outside of the groove and got cut by the filter bowl. If that is the case a new seal should solve the problem and be easy to fit. You might consider taking the whole thing off and assembling it on the bench if it's difficult to get at.

I fear that there is not much more that I can say without seeing the filter.

I do not think that you are making a mistake, but just check the sizes of hole in the element and the "spigot" you are trying to push it on. Also it is always best to check that new filter against the old in case you have been supplied the wrong one. Carefully compare the element height with the space inside the bowl and allow a small amount of protrusion for compression to make a seal against the head.

Tony Brooks



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