How to Tell if Your Car’s Engine is Bad


Rev up your engines! Time for the Scotty
Kilmer Channel. OK, I’ve got a customer
who bought this old truck. And before he starts
fixing all the rust, he wants me to check out the
engine to see if it’s any good. So we’ll open it
up and take a look. Now it’s obviously not
the original engine. It’s a much newer
engine, but he doesn’t know anything of the history. So today I’m going to show you
how to check out an engine. All you need is a simple
compression test kit like this. I paid less than $45 for
it at Harbor Freight Tools. And in this case, we’re going
to do a wet and dry compression test to see if the
piston rings are worn. So first we’ll take all
the spark plug wires and the spark plugs out. We’ll just get a wrench in the
socket and take them all out. And out they come. Then we’re going to analyze
the spark plugs first. Not a good sign. They’re black, which
means it’s running rich. And there’s also some
oil filing, which means it’s burning some oil. And when I look at another
one of the spark plugs, it has even more carbon buildup. So that’s not boding
well for this engine. But we’re going to check
out the compression to see what’s happening
inside to know for sure. We’ll get the
compression tester, then screw the hose into
one of the spark plug holes. Get it nice and snug. And then plug that
into the gauge end. Then we’ll crank the engine over
and see what the pressure is in that cylinder. Now in this case it’s
about 125 pounds, which is relatively
low for this engine. But now we’re going to squirt
some oil in that cylinder. We’re going to unscrew the
hose that goes in the hole. Then we use a funnel and a
hose to poor a little oil inside that cylinder. We just stick it in the
hole, and pour some oil in. Then we’ll take another
compression reading. Now the pressure went
up to about 160 pounds. Since it’s got all
that extra pressure, that means the piston
rings are worn. Because adding oil
to the cylinder can help seal the piston
rings and make the pressure go higher, it means that the
engine’s just flat and wearing out inside. Now I’m going to test the rest
of the H cylinder on this car because the customer’s
paying me for it. But really, I know I’m
going to end up telling him, don’t bother fixing
a truck unless you want to put a new engine in it. Because when you factor
in all this rust that’s going to have to be
cut out and fixed with new metal and a new
engine, he might just give up on the project. So if you want to know what
kind of shape your engine is in, now you know how to test it. And remember, if you’ve
got any car questions, just visit the Scotty
Kilmer Channel.

About the Author: Michael Flood

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