QuestionHoward:
Thanks again for your help. I triple-checked compression readings and valve clearances, and wonder if this additional detail will further pinpoint the problem on my 4.2.
Compression Test (Dry)
1-130#, 2-143#, 3-0, 4-0, 5-140#, 6-130#
Valve clearances, inches
Exhaust:
1-0.012, 2-0.014, 3-0.013, 4-0.012, 5-0.013, 6-0.012
Inlet:
1-0.017, 2-0.012, 3-0.020, 4->0.035, 5-0.011, 6-0.013
I wonder if the intake valve clearances on #3 and #4 alone would indicate this is a valve problem, and likely rule out a head gasket problem. What think you? And in your opinion, what would cause such a thing to happen at 13K miles? True, it has never been routinely driven, but also has never sat un-run for more that a couple of months at a time. In any event, looks like the head must come off, yes?
I wanted to also do the pneumatic test that you suggested, but haven't yet gotten clearance to the crank nut so I can roll over to exact TDC on #3 and #4 pistons. I'll remove the upper shroud and fan and get at that tomorrow. Also, what size is that crank nut? Feels like about 1-5/16, which I don't have - will have to go out and get the right size.
Thanks again for your invaluable assistance!! Regards, Bill
Answer#3 and #4 intake valves may be bent, thus the added clearance.
It is difficult to pressurize the cylinders on a 4.2 with an automatic so when you have -0- compression do this. Remove the 12 gauge white w/read tracer wire from the starter relay on the fire wall (The metal one) and put the car in park (key OFF) and connect a jumper wire (12 gauge)to the loose wire and keep touching the jumper to the positive post of the battery to bump the starter. With the plugs out you can bump the engine over a little at a time. Put your thumb over the #3 plug hole and when you feel compression have someone watch the front pulley mark to get it close to TDC. It does not have to be perfectly at TDC because you can just blow a little air into the plug hole of #3 (no fitting necessary) and remove the "L" intake pipe on the throttle plate and listen in the intake with a small hose in your ear with the throttle open. You will clearly hear the hiss in the intake if the valve is bent. It does not require the combustion chamber to to be pressurized to run this test.
Howard
