> "danielr" > wrote in message
> ...
>> I ride a 1997 SL SOHC, 185.000 Km, standard transmission.
>> Oil is changed every 3500 Km, I use Castrol Synthetic 5W30, and K&N
>> oil filter.
>> I know; some of you might believe it is a waste of money; but I am a
>> FIRM believer of preventive maintenance.
>> I am VERY satisfied with this car.
>> Question:
>> Which should be range (max / min) of values resulting in a compression
>> test for this engine?
>> Thanks in advance for your assitance.
>> Regards,
>>
>> danielr
>
"Oppie" > wrote in message
...
> Rule of thumb is 125-150 psi depending on the compression ratio of the
> engine. Make the compression test with all plugs removed, the ignition
> coil disconnected and wide open throttle. Crank for 5 seconds to get a
> stable reading. Log readings, do all cylinders and then repeat. Make sure
> you get consistent readings on each cylinder. Readings between all
> cylinders should be within 5-10 psi. If you get a cylinder that reads low,
> put a couple of squirts of oil into the cylinder and repeat the test. If
> the reading comes up, most likely worn piston rings. If the reading stays
> low, could be head gasket or valves. Don't forget to label the plug wires
> as you remove them to make sure they all go back in the right places.
>

@278,000 km my 96 SOHC 5sp pumped to
155 lbs dry and warm, and 230-270 lbs with oil added,
(the 230 cylinders had less oil than the 270 ones.)

Adding more oil will seal the rings better but will also raise the
compression ratio, I should have measured the added oil better by counting
the oil can squirts and adding the same number.

Previous test @178,000 km pumped 130/128/131/130 warm and 128/126/128/125
cool and 220/185/225/215 oiled warm and 190/155/185/185 oiled cool. The
center cylinders were retested 1,000 km later both 160 psi warm. I suspect
a piece of crud on valve in #2 cyl during first oiled test.

YMMV depending on accuracy of your gauge, I think mine is OK and was top
quality and quite expensive in its day but is about 35 yrs old. As Oppie
topposted, your results are probably more important relative to each other
cylinder after dry and wet testing, as these results will all be with the
same tester. Record your results in your maintenance log and then you can
compare them in another 50 or 100,000 km to detect any trends.

Many mechanics will debate the value of compression testing and will often
advocate for a cylinder leak down test as being a superior test, but a plain
compression test is easier and uses simpler tools and will quickly find
large problems like one bad cylinder or valve.

Good luck, YMMV, make sure you have locked the throttle butterfly valve in
open position for test, IMHO warm is best for reliable results and
consistency.