First, knocking USUALLY comes from a bad bearing. A hole in the piston will
cause fumes in the crankcase and will easilly be noticed by taking the oil
fill cap off while the car is running, and looking to see if there are fumes
coming out. OR you can pull the dipstick and smell it for unburned gasoline
in the crankcase.
It really depends on what you want to do with the car as a whole. If you
are going to keep the car for a while, pay for either a quality rebuild, or
a recondidtioned motor. If you plan on getting rid of the car in the near
future..get yourself a junkyard motor or repair the one you have. Most
reputible yards will offer at least a 90 day warranty. You can tell if
something is wrong within 90 days. Currently in that situation with a F**D
Mustang in my driveway. My friend broke the crankshaft. I had to convince
him that it was cheaper to just rebuild the bottom end than buy a whole
motor. Would have paid $800 for a junkyard motor, plus $350 to put it in,
,plus a nothe $100 for incidentals. Now he is paying about $700 to have the
motor pulled and a new lower end put in.
Bottem line..how long you keeping the car??
I pulled the oil cap and see no fumes, I can't really tell if theres a
gas odour from the dipstick.. if there is it's not strong. I tried using
some injection cleaner in hopes it was just a dirty injector making it run
lean. Any way of checking the vacuum hoses or any telltale signs of a vacuum
How do I know if its a bad bearing?
P.S. planning on keeping the car awhile (4th car on road this year)
A bad bearing will sound like a little man tapping the inside of your motor
with a hammer. the sound may get louder with the RPM of the motor, or may
level off depending how bad it is worn.
Now do not get it confused with pinging. That usually sounds the same, but
only under heavy acceleration, or load. (caused by a number of things)
What kind of fuel do you run? have you changed the type (grade/octane)
What you need to do also is a compression check, to see if there is a
problem inside. Sears...heck any auto parts store shiold have one in the
neighborhood of $30-40. Follow the directions or ask someone here how to
use it if you do not already know how. If you have good compression in all
the cylinders, you are looking at an ignition problem, and a through tune up
usually solves it.
I would pull out ALL the troubleshooting possibilities before I yank the
Hope this helps.
Sure..it can. But it would have to be substantial enought that the ECM could
not compensate with more fuel. Plus a really big vacuum leak usually shuts
an engine off. Get a vacuum gauge and see if there is a fluxuation at idle,
and see how it reacts at a little higher RPM. The gauge should go down in
vacuum as the RPM's increase. I could be wrong...but it may only need a
timing chain replacement. If it is worn, it will cause a miss, and a rough
running condition. How many miles on the motor?
If your vacuum gauge fluxes more than 5-6 lbs at idle, I would point at the
timing chain. DON'T take my word for it....it is just where I personally
would look next, if all othe things were exhausted...did you get the
compression check done yet? That would rule out a hole in the piston.
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