Well after a tuneup (thanks again for your help Eluder200K) we did a compression test on my ITR.
Car = 2001 ITR
Mileage = 56,500 (daily driven beeotch)

Results from left to right (distributor side first - tested per Haynes manual instructions)
225, 226, 205, 212

The factory spec for '01 cars gives a minimum of 135 psi - this isn't an issue, with not more than a 25 psi difference between cylinders (uh-oh). This worries me a little cause the #3 cylinder seems to be pretty close to the service limit. I need to adjust the valves to be sure that the reading is exactly correct - and measuring with a newer gauge wouldn't hurt either. Any thoughts on these results?

Note: The car has been fed a steady diet of Mobil 1 5w30 since about 7,000 miles, and I usually change the oil every 3 to 4 thousand miles or so. I always try to baby it when it's cold (don't rev over 4 grand) but is a daily driver...

Are these readings average? Should I worry about the #3 cylinder?


Modified by Philly_NBP_R at 11:13 AM 4/28/2003

 

How many times did you perform the test? I say do it again just so that you have more samples. I do mine 3 times whenever I do compression tests.

BTW, what page on the Helms is the compression test on?

 

We checked at least twice for all cylinders. Don't have the manual handy. Actually my buddy had a Haynes Manual that we used as a reference. Basically just pull the ecu fuse, pull out spark plug wires, (we pulled injector clips too - but probably not necessary), open the throttle all the way, and crank the motor at least 7 or eight times to get a reading.

 

Left to right would get you 4-3-2-1.

Your low reading is on #2 cylinder. You are just under 10% from high to low readings. Do a leak down test on the engine. I don't have my notes handy but George's car had the worst cylinder at 5% or 6% while the others were around 3%-4%. Engine should be at operating temp with all plugs pulled before doing the leak down test.

edit: George's car has 70+k miles

 

Thanks for the info... I am going to adjust the valves before I test again, and I will also do a leak down test - any pointers for this procedure or an online reference anywhere?

There isn't anything wrong with the engine - car runs strong (pulled a 14.9 first time out last year...) but I just wanted to get a handle on how healthy the internals are after 50,000 miles of fun...

Note: I did the compression test with all spark plugs removed, and throttle fully opened, I'm not sure if the engine was completely up to operating temp though - I will double check this next time - thanks again!
Nick


Modified by Philly_NBP_R at 12:02 PM 4/28/2003

 

oops, the motor was not up at operational temp it had been sitting for an hour or more I think

 

that miiight have something to do with it...
oh well not a big deal (this just confirms how we-todd-did we are )

 

your results wont differ much if it was sitting for an hour

 

interesting

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Philly_NBP_R &raquo;</TD></TR><TR><TD CLASS="quote">and I will also do a leak down test - any pointers for this procedure or an online reference anywhere?</TD></TR></TABLE>

What exactly is a leak down test?

 

It tests the % of blow by you have via the rings and head gasket and valve seats if there are problems there. If you do the test and then squirt oil into the cylinder and the numbers decrease then your rings/cyl walls need help.

The test is done at TDC with all the plugs out and at operating temp. The test would yield more accurate results if done at mid stroke.
Check this link out for more on the tool.

http://www.tavia.com/08015_instructions.html

 

Thanks for the info Dave...

 

What options do you have if your car fails a compression/leakdown test, and how much does it usually cost to fix?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by io_burn &raquo;</TD></TR><TR><TD CLASS="quote">What options do you have if your car fails a compression/leakdown test, and how much does it usually cost to fix?</TD></TR></TABLE>

New rings.

Big job in terms of labor hours.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Big Phat R &raquo;</TD></TR><TR><TD CLASS="quote">

New rings.

Big job in terms of labor hours.</TD></TR></TABLE>
Yeah, pretty much a complete engine overhaul - which is why I wanted to know how long she is gonna last...