Hello group,

I have a 2qm20 Yanmar. I have had it for 6 years but it was built in
1978. I don't know if the injectors have ever been serviced. I have 2
new injectors. How much work and how difficult is it to remove the 2 old
ones, put the new ones in and making it work again?. I know the lines
will have to be bled. Is there anything tricky about putting the new
ones in?. I was thinking about changing one, getting it to work, then
changing the other. I have a service manual on the boat but it's in
Mexico at the moment.

The motor has been running a little rougher than usual lately and the
revs have been 'pumping' by about 100rpm at around 1000rpm. Would new
injectors have an effect on this?

Thanks,

Jeannette

On Wed, 09 Apr 2008 22:30:41 GMT, Jeannette
wrote:

Hello group,

I have a 2qm20 Yanmar. I have had it for 6 years but it was built in
1978. I don't know if the injectors have ever been serviced. I have 2
new injectors. How much work and how difficult is it to remove the 2 old
ones, put the new ones in and making it work again?. I know the lines
will have to be bled. Is there anything tricky about putting the new
ones in?. I was thinking about changing one, getting it to work, then
changing the other. I have a service manual on the boat but it's in
Mexico at the moment.

The motor has been running a little rougher than usual lately and the
revs have been 'pumping' by about 100rpm at around 1000rpm. Would new
injectors have an effect on this?

Thanks,

Jeannette

The injectors use a copper seal ring. make sure that you have new ones
before you start. The biggest problem is prying the old ones out, you
will need a fairly stout pry bar for that.

After you get the old injectors out clean the hole where the injectors
mount and reinstall and torque the new injectors. Connect the
injection lines but do not tighten the connection nuts at the
injectors- leave them a couple of turns loose.

Flip the compression levers so that you have relieved the compression,
place the throttle fully open and spin the engine with the started
motor until you see fuel squirting out of the loose injector pipe
connections. Once you see that stop and tighten the injector lines.
Wipe up any spilled fuel.

Place the compression releases in the run position, throttle wide open
and start the engine. As soon as the engine fires pull the throttle
back to idle.

Run the engine for five or ten minutes, checking for leaks, squirt a
little oil around where the injectors fit into the engine - if you see
bubbles stop and re tighten the injectors.

That is about it. Enjoy.

By the way. Injectors are re-buildable so after you change the
injectors have the old one rebuilt and store them, well soaked with
diesel fuel in sealed plastic wrapping for the next time you want to
change them.



Bruce-in-Bangkok
(correct email address for reply)

"Bruce in Bangkok" wrote:


The injectors use a copper seal ring. make sure that you have new
ones
before you start. The biggest problem is prying the old ones out,
you
will need a fairly stout pry bar for that.

Make friends with your dentist.

An old dental pick brings out those copper rings with ease.

BTW, replace the copper washers on any fuel banjo fittings you break
open.

Make life a lot easier when dealling with a Yanni.

Lew

On Apr 9, 5:19 pm, "Lew Hodgett" wrote:
BTW, replace the copper washers on any fuel banjo fittings you break
open.

They're cheap enough to replace. That's what I've done. But, you can
also re-anneal them in hot water. On my 2GM20s the injectors are very
easy to remove. I presume the QMs are similar. I'd be more worried
about breaking the old fuel pipes than getting the injectors out of
the block.

-- Tom.

On Wed, 9 Apr 2008 22:58:40 -0400, "Roger Long"
wrote:

I just looked at the manual and Bruce is certainly right. Although there is
just a simple two bolt clamp ring holding the injectors in, there is enough
bury of the body in the head that those closely machined surfaces are going
to be a bitch to pull apart after who know how many decades since the last
time.

I'm wondering now if I could actually get the required tools into the
restricted space around the rear injector on my boat. I might find that my
engine had to come out if the injector was really tight with a little
corrosion in there. I could remove the bolts and clamp ring but the prying
part might be difficult.

Bruce has a lot of experience but I would want some face to face advice from
a mechanic and a lot of manual study myself if I was going to tackle this
job far from home. The appearance of the engine makes it look easier than I
now think it is.

Face to face is best (except for conning somebody into doing it for
you :-).

I don't really remember what I used to get the injectors out of the
last Yanmar I worked on but it wasn't anything I didn't have in the
tool box so it must have been a short pry bar or a big screwdriver
sort of tool.

I didn't mention it before but Yanmar recommends removing the
precombustion chamber and replacing the copper washer seals for that
when changing injectors. From the top there is the injector, next an
"o" ring, then a gasket, next the "heat shield and a copper washer,
then the precombustion chamber and a last copper washer. Yanmar
recommends pulling the whole lot and replacing all the gaskets, copper
rings and the "O" ring.

I'm certainly not recommending disregarding Yanmar's instructions but
I have personally changed injectors by pulling the injector and
inserting a new one, changing the seal between the injector and the
"heat shield". If you do pull the precombustion chambers note that
some of them have a pin so they must be inserted with the correct
orientation.







Bruce-in-Bangkok
(correct email address for reply)

"Roger Long" wrote:


he Banjo fittings are part of the fuel bleed points on me engine so
have been cracked open many times and I put all the old washers
back. Everything seemed tight against fuel pump pressure of
approximately 7 psi.

Probably crack the bleed fitting less than a quarter turn which isn't
enough to
change the registration of the bango fitting pieces.

Lew

On Thu, 10 Apr 2008 04:16:25 -0400, "Roger Long"
wrote:

"Lew Hodgett" wrote

BTW, replace the copper washers on any fuel banjo fittings you break open.

This is a point I've wondered about. Before becoming the owner of a boat
diesel, I'd always heard that copper washers are never reused. The Banjo
fittings are part of the fuel bleed points on me engine so have been cracked
open many times and I put all the old washers back. Everything seemed tight
against fuel pump pressure of approximately 7 psi.

This is all upstream of the injection pump however. Downstream, I expect it
to be a different story with the much higher pressures. More info from and
details of annealing appreciated.

Theoretically the soft copper washer deforms as the fitting is
tightened to form a seal. In the practical world it doesn't seem to
matter much. As long as they are there they usually seal. The biggest
problem I have had is dropping the little things in the bilge. If you
have your injection pump calibrated or the injectors rebuilt at the
local injector repair shop and you talk nice you can get a handful of
copper washers. Then you have a stock of spares and can scatter them
through the bilge like sewing wheat.

The one place that I have seen a solid copper seals leak was a Royal
Enfield motorcycle that I had in collage. It used a solid copper ring
as a head gasket and if you didn't properly anneal that ring the head
was guaranteed to leak. I've also always been suspicious of injector
seals and have always tried to use a new washer there although I have
annealed some and reused them and had no problems.

I really hate the Japanese Banjo fittings and on my present boat have
re tapped all the holes and converted to AN fittings.

Bruce-in-Bangkok
(correct email address for reply)

Bruce in Bangkok wrote:

On Thu, 10 Apr 2008 04:16:25 -0400, "Roger Long"
wrote:


"Lew Hodgett" wrote

BTW, replace the copper washers on any fuel banjo fittings you break open.

This is a point I've wondered about. Before becoming the owner of a boat
diesel, I'd always heard that copper washers are never reused. The Banjo
fittings are part of the fuel bleed points on me engine so have been cracked
open many times and I put all the old washers back. Everything seemed tight
against fuel pump pressure of approximately 7 psi.

This is all upstream of the injection pump however. Downstream, I expect it
to be a different story with the much higher pressures. More info from and
details of annealing appreciated.

SNIP

I really hate the Japanese Banjo fittings and on my present boat have
re tapped all the holes and converted to AN fittings.

Bruce-in-Bangkok
(correct email address for reply)


Soft copper deforms easily to seal minor gaps.
That part is pretty well known.

But copper work hardens very quickly.
Once hardened, it can crack and break easily.

I believe copper is annealed the same temps as aluminum.
Soot the surface with a really rich acetylene flame,
then heat with a neutral flame until clean.

Personally, I use a propane torch to anneal with because a neutral
o-a flame is just too hot and can melt small parts before you can
stop.

I'm guessing it's simpler, cheaper and safer to just replace the
little boogers when they get to the point of no return.


AND

Bruce, thanks for the banjo tip.
I'll for sure keep that one in mind.


Richard
--
(remove the X to email)

Now just why the HELL do I have to press 1 for English?
John Wayne

On Thu, 10 Apr 2008 07:40:11 -0400, "bushman" wrote:

If you have a stuck injector. Bump the starter and let the compression push
it out. Might want to wrap a rag around it and hang on tight. I removed mine
(Perkins 4-108) took them to the shop to rebuild and they refused to do it.
They said they looked and tested like they were brand new. Now that was a
good day. I have one that can not get a torque wrench on, it was leaking a
little, just tightened it till the spitting noise stopped. Copper washers
from TA Diesel.
-Allen

Good trick. Having disassembled many and various fittings, including
naval, here's another tip most without experience don't think of.
Sharply tapping a fitting with a hammer - repeating as necessary - is
often more efficient and safer than solely wrenching or prying.
Breaks various bonds quite well, especially corrosion and hardened
dope.
Not always possible, but usually is with some thought. Sometimes you
can back the other side with a suitable weight hammer.
Just can't overdo it, so apply some judgement.

--Vic

"Vic Smith" wrote:

Good trick. Having disassembled many and various fittings,
including
naval, here's another tip most without experience don't think of.
Sharply tapping a fitting with a hammer - repeating as necessary -
is
often more efficient and safer than solely wrenching or prying.

A 4 Lb drill hammer.

A must have tool when working on a boat.

Lew