Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-07-2016, 10:34   #1
Registered User
 
Mike OReilly's Avatar

Join Date: Sep 2011
Location: Good question
Boat: Rafiki 37
Posts: 4,033
Perkins 4108 diesel leak at fuel line connections

I know there's another 4108 thread going with similar issues, but I have a specific leak problem that I can't seem to resolve, and I don't want to hijack the other...

The fuel lines that feed in and out of my engine-mounted fuel filter housing (the secondary) are leaking at the connections. They are steel lines which attach to the filter housing using compression fittings that consist of a sleeve and a small plastic grommet (an olive) that both slide onto the end of the fuel line.

My filter is more or less like this one:

Perkins Fuel Filter Assembly Kit

The problem is, I can't seem to make a perfect seal. It leaks at the fittings while running.

Is there some trick to making this seal work? I've cranked it on pretty hard. Perhaps I'm over-torquing and crushing the grommet? Or perhaps I need to line up the sleeve/olive and line more accurately?
__________________

__________________
Why go fast, when you can go slow.
BLOG: www.helplink.com/CLAFC
Mike OReilly is offline   Reply With Quote
Old 02-07-2016, 13:17   #2
Registered User
 
Mike OReilly's Avatar

Join Date: Sep 2011
Location: Good question
Boat: Rafiki 37
Posts: 4,033
Re: Perkins 4108 diesel leak at fuel line connections

No one? Come on folks. I know you Perkins experts are out there.
__________________

__________________
Why go fast, when you can go slow.
BLOG: www.helplink.com/CLAFC
Mike OReilly is offline   Reply With Quote
Old 02-07-2016, 13:46   #3
Guy
Registered User

Join Date: Feb 2013
Location: So. Oregon, USA
Boat: Seafarer36c
Posts: 4,308
Re: Perkins 4108 diesel leak at fuel line connections

I installed a spin on filter. I bet you are over torquing. That is the same kind fitting I've seen used on other stuff and they only need to be snug, like inch pounds tight.
__________________
Guy is offline   Reply With Quote
Old 02-07-2016, 13:51   #4
Senior Cruiser

Cruisers Forum Supporter

Join Date: Feb 2012
Location: Carrabelle, Florida
Boat: Self-built 44' steel trawler
Posts: 873
Re: Perkins 4108 diesel leak at fuel line connections

I'm no Perkins expert, but I can tell you that I hate compression and flare fittings with a passion. Made just right (in the case of flares) and aligned just right (both of them), they work and take quite a lot of pressure without leaking. If not, nothing will stop them leaking, witness several flares in my steering system. They do not take torquing beyond what you would expect for the materials at hand. My suspicion, without seeing it but based on your description of what you've got and what you've done is misalign them and then over torque them. Take it apart and see what shape everything is in. If the collars are dinged or bent or the tubing scored or twisted then yes, you've screwed the pooch. Probably, the two tubes you are dealing with are too short to cut off, re-route, align, and compress with new collars. You're dealing with a low pressure situation; something is likely to be mangled. I don't know the size of your tubes, but likely replacement tubing is available at an auto parts store and the fittings certainly are stocked at my nearby Ace Hardware store.
__________________
tkeithlu is offline   Reply With Quote
Old 02-07-2016, 13:58   #5
Registered User

Join Date: Dec 2011
Location: Massachusetts
Boat: Formosa 41
Posts: 569
Re: Perkins 4108 diesel leak at fuel line connections

I have found that with compression fittings with a ferrule the trick is to push the pipe and ferrule into the hole and keep it straight, (by eye,) and barely snug the nut.


I don't know what to do if it's over tightened and distorted and it leaks.

Sorry. We need the person who can suggest what to do if it's over tightened.
__________________
Jason Flare is offline   Reply With Quote
Old 02-07-2016, 15:25   #6
Registered User
 
Mike OReilly's Avatar

Join Date: Sep 2011
Location: Good question
Boat: Rafiki 37
Posts: 4,033
Re: Perkins 4108 diesel leak at fuel line connections

Thanks guys. I'm going to zero in on the over-torque possibility. I have more olives (grommets), and I don't think I've managled the fuel line. It's 5/16" stainless fuel line running to the injector pump. The other line is a return line from the injector pump.

I'll pull the line tomorrow (too tipsy now ) and replace the olive with a new one. Then I'll reinstall with less torque.
__________________
Why go fast, when you can go slow.
BLOG: www.helplink.com/CLAFC
Mike OReilly is offline   Reply With Quote
Old 02-07-2016, 15:33   #7
Registered User
 
NoTies's Avatar

Join Date: Nov 2005
Location: Vanuatu
Boat: Whiting 29' extended "Nightcap"
Posts: 1,378
Images: 2
Re: Perkins 4108 diesel leak at fuel line connections

As a field fix I have had success wrapping a few turns of plumbers tape around the olive where it contacts the pipe. This is often the only way to get a seal when the pipe is distorted from over tightening.
__________________
Pete

Positively, socially deviant.
NoTies is offline   Reply With Quote
Old 02-07-2016, 16:13   #8
Registered User
 
Kokanee's Avatar

Join Date: Jan 2013
Location: Adelaide Australia
Boat: Cuddles 30ft Motor Sailer
Posts: 216
Re: Perkins 4108 diesel leak at fuel line connections

Make sure the fuel lines aren't slightly ovalled from being bent, and have no nicks or deep scratches in them. Polish them up with some steel wool.

Also, make sure the filter housing and fittings are matching threads. It could be leaking from there. I've seen similar filter housings with UNF, UNC, BSP, and SAE threads. The fittings have to match.
__________________
Kokanee is offline   Reply With Quote
Old 02-07-2016, 17:25   #9
Senior Cruiser

Cruisers Forum Supporter

Join Date: Feb 2012
Location: Carrabelle, Florida
Boat: Self-built 44' steel trawler
Posts: 873
Re: Perkins 4108 diesel leak at fuel line connections

I think you have your marching orders, and should have it back in shape very soon. Think of the olive as being an 0-ring that you are pressing against the crack between the tubing and the fitting you have stuck the tubing into. That doesn't take much pressure, given the tiny surface area, but it does take cereful alignment. The tube should enter the fitting dead straight and round, and the cap thread on very smoothly.
__________________
tkeithlu is offline   Reply With Quote
Old 02-07-2016, 22:19   #10
Registered User

Join Date: Dec 2011
Location: Massachusetts
Boat: Formosa 41
Posts: 569
Re: Perkins 4108 diesel leak at fuel line connections

When I was installing my new belly tank I was reading some diesel forums online and someone referred to Teflon tape as, "The devil's toilet paper."

You don't want it in the injection pump.
__________________
Jason Flare is offline   Reply With Quote
Old 02-07-2016, 23:21   #11
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: Perkins 4108 diesel leak at fuel line connections

Quote:
Originally Posted by Jason Flare View Post
When I was installing my new belly tank I was reading some diesel forums online and someone referred to Teflon tape as, "The devil's toilet paper."

You don't want it in the injection pump.

Loud second.

While Teflon Tape is great stuff I don't want anywhere near a flare or ferrule fitting
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 03-07-2016, 00:48   #12
Registered User
 
NoTies's Avatar

Join Date: Nov 2005
Location: Vanuatu
Boat: Whiting 29' extended "Nightcap"
Posts: 1,378
Images: 2
Re: Perkins 4108 diesel leak at fuel line connections

Despite the fact that when properly used it works? The compression fitting use actually poses considerably less risk of getting where it shouldn't than conventional use on a thread.
__________________
Pete

Positively, socially deviant.
NoTies is offline   Reply With Quote
Old 03-07-2016, 08:34   #13
Registered User

Join Date: Aug 2012
Location: Cruising the Gulf of Mexico.
Boat: 1980 Morgan 415
Posts: 1,439
Re: Perkins 4108 diesel leak at fuel line connections

Quote:
Originally Posted by NoTies View Post
Despite the fact that when properly used it works? The compression fitting use actually poses considerably less risk of getting where it shouldn't than conventional use on a thread.

The cost of a new fuel line complete with fittings is much less than the injector pump rebuild that would be required if a piece of Teflon tape clogs the works.

The threads on a flare or compression fitting just provide the tension for the surface area of the seal. They have no sealing surface.
__________________
Working on spending my children's inheritance.
Cap Erict3 is offline   Reply With Quote
Old 03-07-2016, 08:47   #14
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Re: Perkins 4108 diesel leak at fuel line connections

Mike, there are lots of comments on the forum about getting rid of the CAV filters. Seems as though they like to leak. No personal experience though.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 03-07-2016, 09:49   #15
Registered User
 
Mike OReilly's Avatar

Join Date: Sep 2011
Location: Good question
Boat: Rafiki 37
Posts: 4,033
Re: Perkins 4108 diesel leak at fuel line connections

Quote:
Originally Posted by DeepFrz View Post
Mike, there are lots of comments on the forum about getting rid of the CAV filters. Seems as though they like to leak. No personal experience though.
Yes. I'm thinking my real solution is to replace the whole filter housing. It's a PITA to change anyway. Maybe a double racor on the engine room bulkhead. Right now I have a single, which is the primary.
__________________

__________________
Why go fast, when you can go slow.
BLOG: www.helplink.com/CLAFC
Mike OReilly is offline   Reply With Quote
Reply

Tags
diesel, fuel, perkins

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
4108 perkins rear main leak :/ Svsilvergirl Engines and Propulsion Systems 16 16-02-2017 14:52
Perkins 4108 air leak? SV gypsy spirit Engines and Propulsion Systems 17 03-05-2015 20:57
Perkins 4108 Smoking and Fuel in Exhaust JPT Engines and Propulsion Systems 5 10-10-2011 09:02
Perkins 4108 Fuel Problem Wainui Engines and Propulsion Systems 23 29-08-2011 13:24
1970 Perkins 4108 w/fuel system issues cmesiam Engines and Propulsion Systems 41 25-02-2009 11:44



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:05.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.