Leaking filter assembly bleed screw - Yanmar

viva

New member
Joined
2 Nov 2009
Messages
132
Visit site
The secondary filter assembly bleed screw has started to leak fuel. A Yanmar agent says it's probably the aluminium threads have been stretched and I'll need a new assembly at £56. My question is would a washer be a possible solution and if yes should it be copper or fibre?
 

cryan

New member
Joined
5 May 2013
Messages
2,217
Location
Kirkcaldy, Fife
www.cryco.co.uk
I would think that a copper washer would do the job. I've never heard of threads being stretched on a bleed screw. Most bleed screws come fitted with a copper washer from new so I'm slightly surprised that yours doesn't have one? A fibre washer will probably seal as well if it's all you have but it won't last as long.
 

l'escargot

New member
Joined
16 May 2001
Messages
19,777
Location
Isle of Wight / Jersey
Visit site
You could find tightening the screw down on a washer might strip the threads. I have a similar problem on a Volvo filter to resolve. I have heard of people sorting it by using a washer and a slightly larger self tapping stainless steel screw which cuts a new thread but haven't resorted to trying it yet.
 

Cloven

Active member
Joined
17 Oct 2003
Messages
2,231
Location
Scotland
Visit site
Unfortunately it is very easy to strip or damage the threads on these units - don't ask me how I know!

Worth trying a new washer first and yes, they are copper. If that doesn't work then its a new unit I'm afraid.


The secondary filter assembly bleed screw has started to leak fuel. A Yanmar agent says it's probably the aluminium threads have been stretched and I'll need a new assembly at £56. My question is would a washer be a possible solution and if yes should it be copper or fibre?
 

xeitosaphil

Active member
Joined
12 Aug 2004
Messages
1,239
Location
paignton south devon uk
Visit site
Pete, not sure if the OP engine is a 2GM20 like mine but as you say filter does seem to be made of very soft metal, probably aluminium. Can't remember what the inside of the filter looks like now but it might be possible to drill out socket and re thread it with bigger gauge Machine screw maybe?
 

ga1135

New member
Joined
13 Feb 2008
Messages
83
Location
Hong Kong
Visit site
It is real that very easy to strip or damage the threads.
I re-thread it for a bigger dia screw for 1 or 2 times, then will require a new unit.
 

cryan

New member
Joined
5 May 2013
Messages
2,217
Location
Kirkcaldy, Fife
www.cryco.co.uk
I'm surprised to hear so many people having bother with bleed screws? Not really familiar with small Yanmars (although I must have bled thousands of fuel filters on small engines over the years) but are the screws really that bad?
 

CET1

Member
Joined
5 Sep 2005
Messages
255
Location
Northumberland
Visit site
We found that the previous owner had striped the threads on our secondary fuel filter and I fitted a helicoil insert to repair the threads. Also used Hylomar Blue sealant on the threads and washers. seams to have worked as we have had no leaks for over three years now.
 

garvellachs

Member
Joined
23 Mar 2002
Messages
913
Location
Dorset
Visit site
Google will show that it is a widespread problem with the old small Yanmars. We bought a new filter case for our 3HM after wrestling with the problem for a while. I'd be reluctant to use sealant that close to the injector pump, but drilling and tapping it for a bigger bleed screw should work. It's a copper washer, but remember it needs to be new (or newly annealed) because they are said to work harden - an old one will not seal well, encouraging us all to over-tighten the screw and strain/strip the threads?
 

Cloven

Active member
Joined
17 Oct 2003
Messages
2,231
Location
Scotland
Visit site
Yes. Danger is over tightening on an old washer to prevent leaks. Best practice is after bleeding, if you notice a leak, do not just "nip it up" a bit more but replace with a new washer and then tighten just enough. I carry spares of these washers for just this purpose.



I'm surprised to hear so many people having bother with bleed screws? Not really familiar with small Yanmars (although I must have bled thousands of fuel filters on small engines over the years) but are the screws really that bad?
 

Mel

Member
Joined
18 Jun 2001
Messages
191
Location
Live in South Norfolk
Visit site
I have had this problem on my 1GM10- soft metal top on filter. Stripped threads resolved by drilling and tapping to a larger size.
Still have problems sealing the blead screw and I resolve this by slackening a little and wrapping a little PTFE thread tape on top of copper washer - works well with just a nip.
 

charles_reed

Active member
Joined
29 Jun 2001
Messages
10,413
Location
Home Shropshire 6/12; boat Greece 6/12
Visit site
The secondary filter assembly bleed screw has started to leak fuel. A Yanmar agent says it's probably the aluminium threads have been stretched and I'll need a new assembly at £56. My question is would a washer be a possible solution and if yes should it be copper or fibre?

Sadly an all-too-common failing - there should have been a copper washer under the bleed screw.
If all else fails I used some green Hermetite gasket cement.
 

prv

Well-known member
Joined
29 Nov 2009
Messages
37,361
Location
Southampton
Visit site
I'm surprised to hear so many people having bother with bleed screws? Not really familiar with small Yanmars (although I must have bled thousands of fuel filters on small engines over the years) but are the screws really that bad?

Fortunately I never stripped the threads on mine, but the Phillips or pozidriv head was fairly mashed when we got it (hence don't know which it had once been) and I must admit I completed the mullering fairly early on. That's how I know it's soft - it stripped far more easily than I expected. A ring spanner around the hex head that it fortunately also has, is much kinder and what I should have used from the beginning.

Pete
 

xeitosaphil

Active member
Joined
12 Aug 2004
Messages
1,239
Location
paignton south devon uk
Visit site
Having not stripped the threads on my 2GM20 filter either, I am aware that the filter body is a very soft material and need to be careful when servicing. I suppose some problems arise out of not being able to find the correct tool for the job at the time you need it?

My problem is I know I have one, but just can’t remember where I put it!

I must say though I find it quite strange that people in general find it necessary to crank up the torque on screws and bolts etc to their maximum. Same thing tends to happen with plumbing joints and tap washers?

I have found in the past, that things leak far more often from over tightening than from under tightening, and if they do leak they only usually need an extra nip up or 1/4 of a turn at most to sort it.

It’s a different matter when specified torques is not adhered too though.
 

misterg

Active member
Joined
31 Oct 2003
Messages
2,884
Location
N. Wales
Visit site
...are the screws really that bad?

The screws are fine, it's the silver coloured cheese that the filter head is made of that is the problem (ask me how I know). Helicoil is the best fix (better than new), but re-tapping oversize also works. The situation isn't helped by the filter bowl only having a marginal seal to the head (the clamping ring bottoms out on its thread before it compresses the sealing o-ring: a thicker o-ring cures this), so you can get diesel dripping from the filter which makes it look like the bleed screw might be leaking, encouraging unnecessary 'nipping up' of the bleed screw.
 
Top