compression on 98 civic SOHC Non Vtec

Hi there,

Did a compression test on my 98 Civic LX (canadian) today.

243000kms (151000mi)
5 spd

Steps I took were (as per haynes):

1. Disconnect Main PGM FI Relay (its above the ECU in my vintage of civic)
2. Disconnect plug at the distributor (its right behind it)
3. Remove all spark plugs.
4. Plugged compression tester into each hole and turned over 5-7 times.

Readings as follows:

Min 160
Max 194

#1 - 190 lbs
#2 - 192 lbs
#3 - 193 lbs
#4 - 202 lbs

All readings rose very quickly, leading me to believe there is a good seal at
the rings and minimal leakage in the valve train. I assume there must be
some carbon buildup in #4 causing a higher reading.

Any comments on my findings?

I did not do a leak down test on it yet.....

Any thoughts are appreciated!

Terry in Winnipeg.

 

PS plugs all looked really good, and all the same. nice reddish brown color..
...


t

 

I don't see anything wrong - are you having trouble?

Mike

 

Not really, just kinda surprised that the reading is as high as it is....
lotsa hard miles on that engine.

Is it possible that all the combustion chambers have carboned up and the
reading I got is artificially high?

Is my diagnosis on Cyl 4 correct? What would a carbon buildup be indicative
of? timing issue?

Just bought the tool, so its kinda cool. Gonna do a test on the fiancees 87
prelude today... should be interestin....


Thanks
t

 

oh yeah, and to add some fuel to the fire on Air Filters, I have been running
a K&N stock replacement (drops into OEM airbox) since about 70000kms.

If it wasn't filtering properly, shouldn't the compression reading be a lot
lower?

I drive tonnes of gravel roads (lotsa dust) and live in winnipeg (tonnes of
salt and sand on the roads)

t

 

<SNIP>
Did you forget to prop the throttle open? Don't forget the measuring
tool could be inaccurate, but the 'range' of the readings look great.

'Curly'

 

Ah yes, i did use Wide Open throttle as well, forgot about that.

What would be a good way to calibrate the compression tester?

t

 

I'm not surprised bout the readings being good. I don't keep up with the
advances in engine technology, but modern engines do so much better than
those of my youth it really is amazing. It used to be that the engine life
determined the life of the car.

I don't really know about the higher reading on #4. Your guess is as good as
any I have. My son bought a used Subaru engine from a wrecking yard, and it
had one cylinder that was something like 20% higher than the others. I
assumed it had dirt in the combustion chamber, but we never took the head
off to see.

But I sure agree - compression guages are a nice thing to have, and it never
hurts to do a baseline check on a working engine.

Mike