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15-11-2010, 01:49
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#1
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Registered User
Join Date: Jun 2010
Location: London
Boat: Endurance 35
Posts: 109
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Perkins 4108 Bleeding Problem
Help !!!! This is driving me insane, every so often my engine wont start, I go through the whole process of bleeding it, then in runs very well for about 2 weeks, or days then the whole thing happens again, I have opened the fuel tank and it was infested with "The bug" cleaned it thoroughly changed the filters 3 - 4 time over, then the same thing happened again, so I replaced the fuel lift pump and it worked fine then a phew weeks later it stopped again where could this air be coming from, any ideas this ahas stumped my Marine engineer to the point where he has stopped charging!!!!!!!! Do I get a new engine?
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15-11-2010, 03:01
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#2
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Registered User
Join Date: Jun 2007
Posts: 853
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First Suspect : You have an air leak in the delivery system ! somewhere a connection is NOT good, between shutdown and start up - air replaces diesel.
Go over the whole fuel delivery system replacing
soft washers, tightening glands etc etc - Look for bubbles!
Get a new mechanic who knows what he is doing.
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15-11-2010, 03:11
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#3
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Registered User
Join Date: Oct 2008
Posts: 358
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Air leak is probably correct. Suggest you check...
Racor bowl fot cracks-especially around the drain tap.
Fuel line that goes into the secondary filter housing. This is an npt tap (on my 4.108) and must be sealed properly.
Bob
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15-11-2010, 03:12
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#4
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Registered User
Join Date: Jun 2010
Location: London
Boat: Endurance 35
Posts: 109
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Where though, I have bled the system so many times checked the bowls under the filters tightened up all joints etc!!!
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15-11-2010, 03:13
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#5
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Registered User
Join Date: Jun 2010
Location: London
Boat: Endurance 35
Posts: 109
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Cheers Bob I will check that!!
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15-11-2010, 03:24
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#6
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Registered User
Join Date: Jun 2007
Posts: 853
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Quote:
Originally Posted by JulianGullsway
Where though, I have bled the system so many times checked the bowls under the filters tightened up all joints etc!!!
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It's not bleeding the system that is required - All the components of the system:
Filters . gaskets, lines, nuts, bolts, washers have to function as per SPECIFICATION - these must be checked replaced and re-secured so that air cannot enter the system.
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15-11-2010, 03:35
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#7
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Registered User
Join Date: Apr 2007
Location: Middle Chesapeake Bay
Boat: Cheoy Lee Clipper 36 - Rapport
Posts: 95
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I had the same problem with my 4-108. Mechanic found a hairline crack in the #1 injector fuel line.
__________________
"I got some place I gotta be, but I don't know where it is"
John Borland (1949-1994)
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15-11-2010, 04:50
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#8
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Registered User
Join Date: Apr 2010
Location: Western Australia
Boat: Boro
Posts: 89
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I had a similar problem on mine (4107). Eventually I replaced the aluminium washers on a few critical fittings with fibre washers that the PO left in the tool kit with fuel pump parts. I was having fuel leaks even with brand new aluminium, and couldnt source copper.
Also put a tap on the return fuel line and I shut both main tank and return taps on shutoff. I believe this gives less opportunity for a leak, as you need two holes (hole being any part of the line open to the atmosphere) for an air leak, and will only get air bubbles between the two holes... I cant swear that this is correct, anybody like to comment?
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15-11-2010, 05:02
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#9
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Registered User
Join Date: Jun 2010
Location: Bahamas - Maine
Boat: '88 Passport 41' Magic Moments
Posts: 197
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Try stopping up the tank vent & return line and pressurizing the system, looking for a leak. You may have to work in sections with this method. If air is going in then fuel should come out.
A
__________________
.............< Alan >..............
><((((º> ¸.·´¯`·.¸¸><((((º>
........AD4HE & KD4LGZ........
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15-11-2010, 06:09
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#10
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Eternal Member
Join Date: Jul 2006
Posts: 4,046
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I feel your pain! Been there, done that with my 4-108. It was driving me crazy.
One day, after bleeding and checking and backing and filling I was pumping the little lever on the fuel pump and....
....heard a little whoosh, whoosh.
It was very quiet in the marina or I would never have heard it.
Turned out to be a pinhole in the BOTTOM of the copper fuel line. This line ran low in the bilge, was often in water from the occasional stuffing box leak, and had corroded. Found it with my fingers (stopping the whoosh whoosh sound); it wasn't visible.
Replaced the copper line with a high-quality fuel hose. No problems since (about 15 years).
Good luck...it's sure to be an air leak somewhere.
Bill
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15-11-2010, 08:22
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#11
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Registered User
Join Date: Jun 2010
Location: London
Boat: Endurance 35
Posts: 109
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I am meeting the mechanic tomorrow, so I will suggest all these points.
Thank you all!!!!
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17-11-2010, 15:17
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#12
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Registered User
Join Date: Oct 2010
Location: Southbound, NY
Boat: TBD
Posts: 20
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As an aside, in case someone doesn't know this, in the diesel engine world of equipment we used to use chassis grease on the connections until we found the issue. If the grease moves you've found the issue.
I'm not entirely certain this technique would be of much help in the case where the prime is leaking off as is apparently the case here.
I must say I like the idea of step by step going through the whole shootin' match.
So what did the mechanic have to say?
Jim
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17-11-2010, 15:26
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#13
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Registered User
Join Date: Jun 2010
Posts: 726
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I would run a temporary hose from the tank to the lift pump, assuming the tank is reasonably clean.
If that fixed the problem I would replace all the lines and filters I bypassed.
If it continues, you need to look again at engine pump, lines and secondary filter.
My money is on a missing or cracked seal in a primary filter.
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17-11-2010, 15:56
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#14
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Registered User
Join Date: Jan 2009
Location: Eastern Caribbean
Boat: Cal 44
Posts: 159
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On my 4-107 after 5 years with this issue I found a mechanic in Gloucester, Ma who asked me right off if there was a pick up tube on the return line where it enters the tank. We pulled the return fitting and braised a piece of copper tube to it, no more problem. It seems as if sometimes when the engine shuts down it sucks air out of the return
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17-11-2010, 16:24
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#15
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Registered User
Join Date: Jun 2010
Location: Narragansett Bay
Boat: '70 Soverel 33 (v.1)
Posts: 72
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Quote:
Originally Posted by btrayfors
One day, after bleeding and checking and backing and filling I was pumping the little lever on the fuel pump and....
....heard a little whoosh, whoosh.
Bill
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I hear this same noise on my 4-108 when pumping the same little lever on the fuel pump.... but I don't experience the problem the OP reported. But that may be because I haven't let it sit as long between start ups as in his case. I am assuming I shouldn't hear a sound that sounds (faintly) like air... but managed to get the boat from FL to RI this summer running the engine most days and then hauled it out... Will the pressurization routine suggested in this thread work/help to locate a minute crack?
Thanks,
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