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Hello.

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Right on this video, we're going to have a quick
look at leak off testing for injectors on diesels.

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Due to the high pressure now in a lot of modern diesels.

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We can't open the high pressure side of the fuel system
with the engine running.

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Serious injury, mechanical damage or both.

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OK, so what we're going to do
is we're hooking up a leak off test kit.

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So what this does is all the fuel
that's supplied into the injectors, not all of it gets used.

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So the leak off is the low pressure return
back to the fuel tank.

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What we've done is we've bypassed this system

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with these pipes we've removed those
and what we've done is fitted these bottles instead.

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OK, so what we're doing is measuring
how much fuel comes back from each injector.

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OK, so the bottles we fit in sequence
four cylinder engine, four bottles.

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And what we can do is we can measure it at idle speed
and we can measure it by blipping the throttle.

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What we're looking for is the same as the compression test,

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which is we're looking for roughly the same amount
for each injector.

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OK, if there's too much fuel in one cylinder
compared to the other three,

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then that injector is not using all of the fuel and it's

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sending it back to the tank instead, so it's working poorly.

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Likewise, if there's one low reading,
that means that injector is leaking fuel into the cylinder.

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So that, coupled with black smoke from the exhaust, means
we need to do an emissions test.

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And then the next step will be to remove these injectors

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and send them off to have them tested on a specialist rig.

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OK, but this kit is relatively cheap,
but it enables you to do

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a lot of tests without dismantling the vehicle itself
to find out what's wrong.

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So another video will cover connecting the kit,
but for now, we'll run this test with the kit hooked up.

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What we've got to do is we've got to wait for the fuel
to make its way up to the bottles

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before we can take a measurement, so there'll be a slight
delay at idle speed while the injectors are running up,

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we've connected them electronically and we've got
the fuel supply pipes are still fitted as standard.

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OK, so now what we're going to do is going to run
let it idle for 30 seconds to get the fuel up to the bottles,

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and then we can perform an idle speed test
and then we will give it a few brisk acceleration tests

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and then we'll switch the engine off
and then we'll compare our readings to see where we can go

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from there.

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Right, so straight away from there, we can see

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we've got cylinder
one is the gearbox and it's a French engine.

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So one, two and three are producing
virtually the same amount of fluid at the same time.

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Cylinder four, however, does seem to be a little bit behind at this point.

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So what we'll do to see if this is an issue to our operations

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will now rev the engine of three times
just to see what difference it makes to the delivery.

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Right.

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The other thing you can do with these pipes
is because they're clear now we've switched the system off,

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we can check to see if there's any pressure
behind these injectors even though the system's not running.

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If we're losing pressure
and these levels, drop back into the pipes quickly.

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That would suggest we've got an issue
with holding system pressure in the rest of the system,

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which we can then diagnose with OBD equipment.

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So if we have a look at these bottles
now between the four of them,

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they've started to even out a little bit.

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But I would say I would be looking at cylinder number four,
especially

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because it is a lower reading compared to the other three.

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So my advice to the customer
there will be that we will test them electronically.

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We can do resistance tests with a meter.

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And what we can do is
we can unplug them and we'll do that test now.

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We can unplug them, test them

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electronically with a multimeter,
it takes ten seconds an injector.

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If we've got four readings that are the same, I would

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then be recommending
they're removed and sent off for specialist testing.

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So what I'll do now is our disconnect them electronically

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because we don't need to have it running.

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What I'll do now

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is I'll get a multimeter,
and we'll just test those connections across.

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Super right, so standard multi meter,

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we want it set on the resistance scale of Ohms.

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Units, disconnected.

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So what we're going to do now
is we'll do a quick test across the four injectors.

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So we're just basically going across the two pins

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to see what the resistance reading is.

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Okay,

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we should have a reading of about 0.7,
depending on temperature.

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So we move across to cylinder three, because it's
a French vehicle and we're going in the other direction.

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0.6, 0.5.

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0.5 again.

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0.4. Right, so there's a little bit of variation
between those.

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So my recommendation for the customer
would be to have the injectors removed.

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And we'll send them off
and we'll have them tested on a high pressure specialist rig.

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Once we get the results from that,
the injection repair specialist will come back to us

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and say whether they're rebuildable
or they're going to need replacement.

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Again, general engineering practice if one or two faulty,

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if budget allows I'd replaces as a set of four, OK,
and we'll cover that in the next video.