ZC Engine

  • Thread starter Thread starter JR Lomas
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J

JR Lomas

I have a JDM ZC 1.6L engine I just put in my 1994 Honda Civic LX.
Everything is working all right. No loss of power, performance or anything.
However, I can hear this dull knocking noise when the engine is running. I
am pretty sure it is not the timing or the gas I am running (timing set to
16 DB TDC and 92 octane). I'd say it sounds like piston slap but the again
I never heard what piston slap sounds like. By the way, the sound is always
there, whether the car is cold or at normal temperature. I did a
compression test and here are the results (from cylinder 1 to 4):
150psi, 184psi,182psi,184psi
I did some more testing on cylinder 1 and the pressure build up quickily
during the first two strokes but at the third stroke the pressure maxed out
and further strokes only increased the pressure buildup marginally. After
this I added three squirts of oils through the spark plug hole and retested,
and the pressure came out to be the same. No increase. I thought I might
have been hearing piston slap at cylinder 1, but I guess this means it is
probably not the piston rings? Could the noise come from one the
accessories? Could it be the valve or the camshaft?
Thanks in advance for any help,

- JR
 
I use an automotive stethoscope to find strange knocks. Most auto parts
stores sell them cheap.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
 
JR Lomas said:
I have a JDM ZC 1.6L engine I just put in my 1994 Honda Civic LX.
Everything is working all right. No loss of power, performance or anything.
However, I can hear this dull knocking noise when the engine is running. I
am pretty sure it is not the timing or the gas I am running (timing set to
16 DB TDC and 92 octane). I'd say it sounds like piston slap but the again
I never heard what piston slap sounds like. By the way, the sound is always
there, whether the car is cold or at normal temperature. I did a
compression test and here are the results (from cylinder 1 to 4):
150psi, 184psi,182psi,184psi
I did some more testing on cylinder 1 and the pressure build up quickily
during the first two strokes but at the third stroke the pressure maxed out
and further strokes only increased the pressure buildup marginally. After
this I added three squirts of oils through the spark plug hole and retested,
and the pressure came out to be the same. No increase. I thought I might
have been hearing piston slap at cylinder 1, but I guess this means it is
probably not the piston rings? Could the noise come from one the
accessories? Could it be the valve or the camshaft?
Thanks in advance for any help,

- JR
Click to expand...

It sounds like the rings on cylinder 1 are not sealing properly (as the wet
compression test brought compression up to the other cylinders). Valve
problems typically show no compression, low compression is typically
indicative of rings.

-Bruce
 
I just bought a automotive stethoscope and listened to the engine. I
can't be sure, but it seems like the sound is strongest when I place
it on the engine block near the bottom where the #1 piston is. The
waterpump, however is very close to it, so it is hard to tell whether
is the waterpump or piston slap. I'd say, nonetheless, it DOES sound
like it is the piston slapping against the block. What do you guys
think? Any ideas to try to pinpoint it? Should I be worried if it IS
piston slap. I just swap this engine into the car and I would hate to
have to yet swap it again.

- JR
 
You should do a good valve adjustment for the hell of it just to rule out
valve clatter. May be your timing belt is off one tooth? Take off your
accessory belts and check them for bad bearings or noise. It could be a
bent rod or valve even. It could be alot of things.
 
Well you guys, here is the update. The engine that I just put in my car
DOES have piston slap. I did a compression test once again, and the dry
test for cylinder #1 was 140psi. The wet test showed 190 psi. I guess last
time a few drops of oil were not enough My worst fear is now confirmed.
Cylinder #1 has a ring problem. It is fortunate that the engine came with a
12 month, 12,000 mile warranty. However, I just wasted all that time taking
the old engine out and putting the new (broken) one in. Of all things that
could be wrong with an engine, this is the one problem that can't be fixed
without taking the engine out [sigh]. Anyway, the moral of the story is
"test your engine BEFORE you drop it in", I didn't and I certainly regret
it; nonetheless, I will not let this experience deter me from fixing my car
properly, the broken engine is coming out and a new one is going in. Well
hell, like my dad said, learning IS expensive.

- JR
 
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