Help with compression readings

Hi,

My 140K mi 88 Accord DX has a compression spec of 170 psi, min 135 psi,
max difference 30 psi.

My readings are from a cold engine: 160 190 130 210. They numbers
increased steadily during several revolutions of the engine. Plugs are
uniform, with some fluffy white deposits.

My reason for making the measurement is a sudden loss of power,
stalling, backfiring, etc., after making a short stop and restarting.

No overheating on the limp home, no sign of water in oil or vice versa.

Can any conclusions be drawn from the cold readings? If the warm
readings are similar, would these numbers explain the symptoms? or do I
just have excessive wear in one cyl, and carbon buildup in two?

Thanks,
JB

I think I would be looking elsewhere for the trouble. Backfire usually
implies faulty spark or a burned valve and your compression is too high
for a burned valve. I think I would be looking electrical.

Your odd compression almost makes me want to think timing belt
though.... If it jumped a tooth it might explain all.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

wrote:
>
> Hi,
>
> My 140K mi 88 Accord DX has a compression spec of 170 psi, min 135 psi,
> max difference 30 psi.
>
> My readings are from a cold engine: 160 190 130 210. They numbers
> increased steadily during several revolutions of the engine. Plugs are
> uniform, with some fluffy white deposits.
>
> My reason for making the measurement is a sudden loss of power,
> stalling, backfiring, etc., after making a short stop and restarting.
>
> No overheating on the limp home, no sign of water in oil or vice versa.
>
> Can any conclusions be drawn from the cold readings? If the warm
> readings are similar, would these numbers explain the symptoms? or do I
> just have excessive wear in one cyl, and carbon buildup in two?
>
> Thanks,
> JB

Timing checked out OK. Did find some corrosion at a distributor tower,
and it runs fine again.

Mike Romain wrote:

> Your odd compression almost makes me want to think timing belt
> though.... If it jumped a tooth it might explain all.

If it jumped a tooth all cylinders would suffer the same loss of
compression. Several cylinders are still in the normal range.
Typically T-belts slip in the cam retarded direction, which lowers
cranking compression readings.

A quick cheap maintenance operation that could alleviate your problem
would be to replace the distributor rotor with a Honda part. Check the
cap too. If it looks bad, or if it has "Made in Italy" stamped on it -
seriously - get a new Honda cap.

The compression variation isn't good, and I'm quite certain you are
burning some oil, so this engine is pretty worn; it could use at least
a ring job. They are mechanically stout though, so I would expect it
to run (burning oil) for a long time if you fix the misfiring /
stalling problem, which is most likely fuel or spark related.

Toyota MDT in MO

I had a low reading on my '89 Festiva due to carbon buildup on one of the
exhaust valves. I could see soot on the underside of the valve cover near
the #3 exhast valve when I took it off. A chemical cleaner solved the
problem. I tried adding a cleaner to the gas tank without effect. The one
you add to the oil and run the engine for 5 min before changing oil and
filtre did the trick. I've been advised here that could dislodge carbon to
foul the engine elsewhere but it didn't happen with me. I checked the
valve clearances sometime after the cleaning too.

Now that the engine is running you could re-read the compression with the
engine warmed up, and do both dry and wet readings.

A vacuum guage will show ignition problems pretty clearly. The needle
jumps with each ocassional miss, or vibirates from bad connections.

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Thanks all. Spoke too soon. Runs much better, but idle is definitely
rougher than is was. It never idled especially well, and maybe those
compression numbers are to blame.

More tests to run. Cap was first thing I checked, but will look again.
Also have spare igniter, coil and ECU to swap.

Good info about oil burning causing carbon buildup. Never knew that.
Makes sense.

But do rubber belts actually slip? Looking at mine yesterday, it seemed
impossible under normal conditions i.e. short of something seizing.

> wrote in message

> My 140K mi 88 Accord DX has a compression : 160 190 130 210.

I'd been following your posts for years. I was expecting a 130 or below
reading (which is not drivable with my standards.) Finally, it appears you
have a head gasket problem or other known issues.

My car which is identical to yours (but nearly 300K-miles Lxi) idles
smoothly. No engine problems whatsoever. Compressions
reads: 185, 185, 185, 185. The reason for this reliability is the bug fix
on the Lxi version (which includes a fan timer.) Without this electronic,
your engine temperature will rise beyond the safety limit after engine
shuts down.

I remember warning you (a few years ago) that you may protect your engine if
you install this electronic. Anyhow, if you find a ring problem, don't settle for any
motor less mine. Since I will be selling my reliable Honda for $700, you may find
many exceptional motors for cheap.

Problem solved. One of the two plastic plugs inside the distributor,
that cover up the screws holding the plate, broke and was fouling the
stator blade, preventing any spark advance. I just removed it. Thanks
for all the suggestions.

At least now I know my compression numbers, and I can think about
putting on a rebuilt head and installing new rings.

On further investigation, it WAS the rotor: Had a carbon button
underneath the arm that showed spark damage; I dismissed this
initially. $3 repair. Plastic plug is back in, runs fine. Added
Vavlemedic for sticky rings too. Good call.

Thanks for the follow up!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

wrote:
>
> On further investigation, it WAS the rotor: Had a carbon button
> underneath the arm that showed spark damage; I dismissed this
> initially. $3 repair. Plastic plug is back in, runs fine. Added
> Vavlemedic for sticky rings too. Good call.