Leaky fuel filter on Onan MDKD

[BruceK]

The spin on fuel filter,currently a Baldwin BF1253, is continually popping the rubber seal on the filter,at 1 o`clock. The Manual says only ever hand tighten it.

When we surveyed the boat it was leaking, the mechanical surveyor refitted it,and later put on a BF1253 which was ok,but since replacing it, it seals at first,then leaks. We tried hand tightening,hand tightening plus some tool force,lots of tool force,still leaks. Usually it`s fine after fitting,then next time using it,it stops running due to fuel leaking and not getting to the injectors, or I discover it is leaking but still running on inspection,or by fuel in the bilge overflowing the tray under it.

The Sydney Onan agent was unresponsive.I had a mechanic fit the filter last time, it leaked as usual,he wants to try a Fleetguard filter. He says the seat in the filter head was ok,though it doesn`t feel all that deep to me. We both wondered about a pressure build up at the second use,but how and why?He`s not seen this problem.

While typing this, the mechanic called to say he is trying a different (?non Onan) filter head, and it is not leaking (not yet, I add, resignedly), and now says, with the old filter head off, that it looks like the filter was going on at a slight angle. So I guess wait and see,but,if anyone has a clue, please respond anyway.

BruceK. Sydney Australia


-- Edited by BruceK on Tuesday 6th of March 2012 12:21:11 AM

 

[swampu]

with out knowing the exact set up it's hard to give advice. I have an onan mdjf and it has 5/8" bolts on top that tighten the filter to the housing. You screw it on and then before you get to tight you just crank on the bolt and voila its tight. I've seen other onans bypass the filters all together and use a racor with sight glass to filter the fuel. I would take a picture of the affliction.

 

[BruceK]

Thanks for responding. The set up on the MDKD is a typical filter head taking a spin on replaceable all metal filter,with drain screw, it sounds quite different to yours. The mechanic left me the filter head and filter he replaced, the filter screws down slightly unevenly, part of the rubber seal gets fully compressed, part (the bit which pops out) does not. It was still sealed,not leaking,this morning.

Not game to ask the mechanic where he found a used Onan filter head housing. I think this problem is peculiar to my genset and not of general interest and have no objection to Moderators replacing it as a topic for something of wider interest. BruceK

 

[C lectric]

From your description it sounds like the threaded spud that the filter itself screws onto has been damaged or bent a bit OR the recess area the seal fits has been tweaked a bit. Not enough to see when hanging upsidedown in poor lighting but there nonetheless.

I wouldn't have thought of that from here but I can see it happening after your description.

These filters usually seal very reliably with very little twisting force, handtight + a bit, so maybe the head was faulty from square one or was damaged when a PO overtightened it and had to hammer the filter off. I've seen that happen, the hammering and other removal means resulting from a hamfisted installer on the theory a bit tight is good, a lot must be better..

 

[BruceK]

C lectric wrote:These filters usually seal very reliably with very little twisting force, handtight + a bit, so maybe the head was faulty from square one or was damaged when a PO overtightened it and had to hammer the filter off.

*Could be, and each time the filter went on it needed more force to seal,worsening the defect until it did not seal, however tight. It`s good now,we were able to do espresso coffee for visiting USA T/F members while showing off Sydney Harbour.

I`ve seen a mechanic remove filters by driving a screwdriver right through the filter creating a lever,seemed to work, should apply an even force. Certainly very effective. BruceK


-- Edited by BruceK on Saturday 10th of March 2012 09:57:03 PM

 

[Steve]

" He says the seat in the filter head was ok,though it doesn`t feel all that deep to me. "

Are you sure there is not an old O ring, from a previous change, up in there?

Steve W

 

[BruceK]

Hi Steve, I wondered about that too, ran a finger around the seat,definitely nothing remaining. The seal is on the filter set into little lugs, it`s like an oil filter except it has a drain. With the old filter housing off the genset, the obvious fault is the uneven screwing on of the filter.

The ever resourceful mechanic found a working Onan fuel solenoid in his workshop and will try it today, might save me visiting the ER to hold the solenoid arm over manually to start the genset. Once it runs,it is a great little machine, quiet too. BruceK