rev up your engines, today I'm going to show you, how you can check if your
engine is worn out or not, over the years I've had quite a few customers that came
to me from another mechanic, and spent a bunch of money on a vehicle that still didn't
run right and so I said hey, first thing we're gonna do is check your engine
because if that's worn out, forget it you don't go any further or you gotta put
another engine in your car that's where good compression tester comes in
basically car engines are giant air pumps, they suck air in through the air
filter mix it with fuel and put it inside the engine where the Pistons are
then the spark plugs in the ignition system fire that creates the power that
moves the Pistons down using gas, then once that power of the crank is moving
the car the exhaust valves open, then that burned air fuel mixture comes out
the exhaust and then exit out the tailpipe it's all just pumping gas, now
the more efficiently your engine runs the more power it has the better gas
mileage it gets, but of course over time friction wears parts out inside the
engine and with a good compression tester you can test to see how worn the
inside of the engine is, the more worn it is the less efficient it's going to be
and of course eventually it can get worn enough that the car won't even start
anymore it won't even run, now technically it's a relative compression test you
want to test the compression relative to each cylinder because the absolute
accuracy of the gauges and how you're doing it changes a lot, you have to do it
consistently though, you can't check one cylinder one way and one another way now
today I'm gonna do it the easy way and it's pretty accurate, because a cold
engine will often show its problems better than a hot engine, so you make
sure the engine is cold then remove all the spark plugs, out they all come
and here's the last one, so now when you crank the engine it's gonna crank the
same all the time, there won't be any spark plugs in so the engine won't start
and like I say I'm doing on a cold engine cuz you'll often find a problem
on a cold engine easier, like I said you can test it lots of ways you can test it
like I am just with the cranking, you can test it cranking with the throttle open
to get more air inside, but it's easy just to be cranking it with your foot
not on the throttle with it just sitting there so each one will be tested exactly
the same, now there's also various ways to test but this has adapters for each
spark plug in this case here's the one that matches our spark plug, as you can
see the spark plug is the same as this so we can put this in just like the old
spark plug, using our spark plug socket cuz it's the same size then screwing
it into the engine, you want it snug so it's not leaking, then you just screw the
hose in, it goes to the gauge, sometimes you have to wiggle a little to get them
in cuz it's kind of a weird angle but after a while you get it on tight, then
you just get the gauge and it snaps right on the other end, then you crank
it over and in this case it's 190 psi which is pretty good for an engine that
has over 240,000 miles on it and then of course you do the other three, and
in this old Toyota engine hey it went between a hundred and eighty five
hundred ninety psi, that's pretty good for an engine with two hundred and forty
thousand miles on it, now I generally work by myself, so screwing in it is the best
way to do it, but if you've got a helper you don't have to do the screwing in you
can just use this it pushes in by hand, just push it in the hole and crank it up
here we go by 189 psi that's even faster now of course things never wear evenly
so you're always going to have some type of difference between the cylinders but if
you have more than let's say 12 to 15 percent differential, that means that the
lower ones are much more worn than the higher ones and in that case either the
piston rings that seal the pistons going up and down are worn, or the valves that
are inside the head are worn and don't seal right, either way it's gonna be a
super expensive repair, you got to take the engine apart
either do a valve job or put new piston rings in, but if you want to find out
which one it is that's a pretty easy test too, all you have to do is put about
a teaspoon full of oil in the cylinder, then do a compression test and if you
find that the pressure goes up quite a bit that means that the piston rings are
worn and the oil sealed them a little bit to give you a higher read, but if the
pressure remains low that's often a sign of the valves are bad and they're not
sealing and if a valve doesn't seal a little bit of oil isn't going to help
because that's metal on metal and if the valve is cracked or the heads got a crack
in it, the air is still going to go through and make the compression pressure low
so now you know how to check if your engine is actually physically worn out and
since this is mechanic Monday, I'm giving away one of these blue driver
compression tester kits to have a chance to win just place a clean non offensive
comment on the YouTube comments below, and the winner will be chosen randomly by
computer to be able to figure out if their engine is worn up or not, so if you
never want to miss another one of my new car repair videos, remember to ring that
Bell!