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Hello.

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Right on this short video,
we're going to have a look at engine diagnostics.

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Engine diagnostics we've got electronic faults and we've got mechanical issues.

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So this one, we're going to do mechanical issues,
health check for an engine without stripping it.

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Really, there's not many options.

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So the one test we're going to do now
is we're going to do an engine compression test.

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If you've got a cylinder with low compression,
it can lead to poor performance,

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misfire and other general issues in the engine.

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So what we're going to do
is we're going to form a compression test.

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So first thing's first,
we need to remove the spark plugs from the engine.

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Right, so removing

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spark plugs, keep them in the same order
because they'll be going back into the same cylinders.

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So we use a socket with a rubber insert in to hold the plugs
when we take them out.

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What I would advise is that you keep the spark plugs
in the same order that we take them out in

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so we can then do a visual check.

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And if there's an issue on one cylinder we can tell
by the condition of the Spark plug what that issue is.

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Generally, we're looking for a kind of beige biscuit
kind of color.

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If they've gone black,
then they've got too much fuel or oil running through them.

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If they've gone white, then they've overheated.

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OK, so this is a good indication.

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If the spark plugs are really clean and their old plugs,
you could have a head gasket issue.

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So I'd be checking the coolant level
to see if water's getting into the cylinders.

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OK, so we're going to take the other three plugs out

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and then just give them a visual check
before we start on the compression test.

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Yep, that one's good as well.

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So we're checking for gap and wear as well,

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if they are worn and beyond on their service limits,
I recommend replacements.

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I would say
they're probably getting close to being replaced.

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But for the purposes of this test,
we can still kind of refit them

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just to confirm our results afterwards.

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OK, and that's cylinder four, so they're all pretty good,

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so they're all kind of running so
that's quite a good indication for the state of the engine.

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Right what we've done is we've removed the spark plugs.

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So now we're going to fit this adapter,
which has got the same thread.

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And then we screw into the individual cylinder
and then we can add our compression gauge

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to take a reading off of at the end.

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OK, you've got a bar scale on the outside
and then we've got a PSI size scale on the inside.

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We're generally looking for four readings the same.

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Now because it's an older vehicle and it's done
quite a lot of miles.

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The readings might be lower than a new engine,
but that's not necessarily an issue.

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As long as all four cylinders are somewhere close, then that's generally a good indication of the health of the engine.

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So the basic compression kit will include a standard set of adapters.

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Some vehicles, you might need to purchase
additional adapters to hook the kit on.

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So there are two types of compression tests
you can do dry or wet compression test.

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A dry test is where we don't press the throttle
and we have the the injectors disconnected.

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Just crank the engine or a wet test
is where we have our foot full down on the throttle.

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And that's probably a more realistic kind of diagnosis
for the engine to see whether there's any issues.

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OK, so we make sure we've got a good connection.

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Hand tight is fine. We don't need to over tighten those.

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We press the gauge to make sure it is zero'd out
and then we have a colleague in a vehicle.

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You don't want the vehicle to start
because we've taken all the plugs out.

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It can't start.

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And we've left the coils plugged in.

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So from a safety point of view, it's OK to take the test.

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What we need to do is crank the vehicle for long enough
until the reading settles down.

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So if I ask my colleague now
to crank the engine then we'll try cylinder one.

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OK, thank you.

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Right, that's an extremely low reading,
and that's not what I'd expect, so what we're going to do

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is move on to the next cylinder, double check that reading.

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And then if we've got an issue,

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we can come back to the diagnostic equipment
and check our connections before we do the next part.

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Right.

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So following on from where we'd hooked
the diagnostic equipment up, we had quite low reading.

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Checked through it
and there was an issue with the connection on this adapter.

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So what I've done for the rest of the test

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is now I'm going to remove this piece
and will directly connect the gauge in.

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Okay so we can now hook the gauge up back up to the adapter
and repeat the test on cylinder one.

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OK, so shows the value of checking things
and making sure we've got good connection.

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So if we crank the engine now, please.

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OK, thank you.

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Right, so that's showing 100 PSI.

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Fluctuated slightly higher than that, but you need to
do your test for long enough for its settle on a reading.

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OK, so cylinder one, 100 PSI.

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That's not bad for a vehicle
that's kind of nine, ten years old.

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That's not a bad start.

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So we're going to run through now
and connect the gauge to cylinder two

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and then repeat the tests across the board.

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Right, OK,

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so we've rectified our poor connection
now, in our compression tester.

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We've double checked our battery voltage and the connection,
so now we can carry on

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and proceed with cylinders two, three and four.

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OK. 

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Okay, thank you.

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Right, so quite low reading there,
we check in with the gague.

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It's just creeping up towards the 100 mark.

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OK, so we can take that as a note.

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That's what I mean about letting the engine settle down
before you take the readings,

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so we can now move on to three and four.

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OK, thank you.

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OK, thank you.

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Right, so slightly higher for that cylinder,
a small variation.

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Not a massive issue.

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So as long as we're somewhere close
with all the readings we can,

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then kind of move on to the next part
of the diagnostic process.

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So just cylinder four to go through now.

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So double checking the connections
every time, save for false readings.

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Okay, thank you.

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OK, that's great.

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Right, so there we go.

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So another reading just around the 100 PSI mark.

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So somewhere close.

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So for for a full readout on this test,
I'd recommend that we do it when the engine's hot as well.

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Some vehicles will have less of an issue
when the engines are cold,

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but as items expand inside can lead to greater clearances later on.

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And then we can check it.

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I would also be checking the oil and the cooling system
to see if there's any cross-contamination.

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The next test on from
this will be to do a cylinder leakage test,

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which we'll cover in another video
that involves the same setup.

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But we're pressurising in the cylinders
to see if there's any gasses leaking.

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They can either leak through the dipstick tube
or they can leak through

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from the exhaust system
or back through the oil filler cap as well.

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OK, then we can do both mechanical tests,
and that saves us having to strip the engine.

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From the results from these tests, we can
then decide what we've got to ring the customer and advise

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we're going to have to dismantle the engine,
or we can proceed with some electronic diagnosis instead.

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And that concludes this video.