The Truth About Cars » compression tester http://www.thetruthaboutcars.com The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Mon, 28 Jul 2014 21:27:46 +0000 en-US hourly 1 http://wordpress.org/?v=3.9.1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars editors@ttac.com editors@ttac.com (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » compression tester http://www.thetruthaboutcars.com/wp-content/themes/ttac-theme/images/logo.gif http://www.thetruthaboutcars.com Piston Slap: I’m on tonight, you know my Gauge don’t Lie! http://www.thetruthaboutcars.com/2011/12/piston-slap-im-on-tonight-you-know-my-gauge-dont-lie/ http://www.thetruthaboutcars.com/2011/12/piston-slap-im-on-tonight-you-know-my-gauge-dont-lie/#comments Mon, 05 Dec 2011 21:07:51 +0000 http://www.thetruthaboutcars.com/?p=421334

 

Dave writes:

Hello Sajeev,

I just bought a 2000 Saturn LW1 6 weeks ago.  It has a L4 2.2 Liter engine with 200,000 miles on it.  After 3 weeks out of the country I came back and started it up.  Was a little rough then smoothed out.  I just changed parking spots.  Did this one more time.  The third time starting it up it would not fire.  No strange noises, just no running engine.  I suspected bad ignition coil.  I had just changed the spark plugs before my trip and they had about 50 miles on them.  Ignition coil was fine at all four points using a ignition tester.  I even put new plugs in again.  Fuel rail has the specified 60 PSI.  Theorizing that may the fuel injectors were shut down i tried starter spray in the air intake.  The motor will not fire.  A compression test with a gauge picked up at advance gave me less than 10 PSI on the two outer cylinders and about 24 on the two inner.  The Haynes manual is very unhelpful and only states for compression specs. that the lowest compression cylinder value should be no less that 70% of the highest compression cylinder value.

I read on-line (http://www.saturnfans.com/forum/showthread.php?p=1781795)  the same but that no cylinder should be less than 100 PSI.  While cranking the engine there was some light smoke visible behind the engine above the exhaust manifold, but unable to determine the source.

My question is: are you aware of catastrophic head gasket failures on these engines?  I am surprised that the engine will not fire at all even if the head gasket does have a problem.  I have removed the valve cover and see that the timing chain is still there and working.

When I changed the plugs last month I applied anti-seize thread sealant to the plugs as instructed in the manual.  I am now having wild imaginings that the anti-seize thread sealant got into the cylinders and impregnated the gasket and is somehow responsible for this catastrophic failure.   I am going to tear into the engine tomorrow and try to replace the head gasket, because i need to get this car running again ASAP.  I am being hopeful and unrealistically optimistic that I cold get some input/ thoughts from you before morning when I start this laborious task…

Ideas?

Sajeev Answers:

You are in a tough spot: a seemingly severe mechanical failure. This is when we tend to trust everything we see or read, even if we shouldn’t.  It’s not your fault, but you need to verify what you are seeing.  It’s like getting a second opinion when a doctor tells you that you have 6 months to live. Because the lack of compression has sent you down a path of diagnostic madness. Which truly sucks.

So try another compression gauge.  I don’t know why, but these things are terribly unreliable and not durable. Bang it around in a toolbox in your garage (or the rental counter at your local parts store) and the needle won’t move nearly as much as before. The odds of you losing that much compression on all cylinders that quickly just doesn’t add up: so I think the tester is bad.

I think you need to check for spark the old-fashioned way…put a screwdriver in the end of a spark plug wire and lay it near a piece of metal…you should see a spark when you crank, and it should be pretty strong.  Google this for more information.

Good luck.  I suspect the ignition module finally crapped out.  Did yours ever get the recall?

Send your queries to sajeev@thetruthaboutcars.com . Spare no details and ask for a speedy resolution if you’re in a hurry.

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