| Tools: |  |
Ratchet | |
8" extension |
| 10mm Socket | U-Joint | |||
| 12mm Socket | Torque Wrench | |||
| 12mm Long Socket | Compression Gauge | |||
| 16mm Long Socket | ||||
| Materials: | Anti-Seize goo | |||
| A bit of oil |
While you are here
| 1. | Check and/or replace plugs |
| 2. | Check and/or replace plug wires |
Instructions
| 1. |  Remove
the two 10mm bolts holding down the ISC pipe and the remove it by disconnecting the two vacuum hoses and large black hose on either side. |
| 2. |
Remove the 5 10mm nuts holding down the ignition pack cover and remove the oil cap. Now carefully remove the ignition pack cover and then replace the oil cap.
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| 3. |
Disconnect the CPS connector on top of the CPS.
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| 4. |
Disconnect the Solenoid Resistor Connector between the fuse box and strut tower cover.
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| 5. |
Using a 12mm long socket remove the 3 nuts holding the throttle body linkage assembly to the exhaust side of the head. Remove the throttle body linkage arm and remove the 12mm bolt holding the throttle body linkage assembly to the center valley. Now you can maneuver this out of your way when you need to.
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| 6. |  Disconnect
the ignition pack connector, the 6 spark plug wires and using a 12mm wrench remove the bolt holding the grounding wire to the intake valve cover. Now remove the ignition pack from the car.
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| 7. |
Carefully remove the 6 spark plug wires.
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| 8. | If you have compressed air now is a good time to blow out the spark plug wells to get the crud and oil out before you remove the plugs. |
| 9. |
Using a 16mm long socket and an extension remove the 6 plugs. Plug #4 will be difficult because the PCV pipe is in the way. so attach your universal joint to that socket then you extension to that and it should work fine. When you take the plugs out keep them in numbered order.
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| 10. | 
Now hook your gauge up to one cylinder. Make sure both connections are secure and the gauge is in a safe place, or have a helper hold it, and crank your engine 4-5 times. You should crank it until the needle no longer moves. I did 4 times each and got about 165, when I did 5 I got 170. So I should have tried more, but I am lazy. You also don't want to drain your battery cus that will effect your test, but I wasn't showing any signs of weakness after I finished my dry test. I didn't do the wet test so I don't know what repeating it would do to my battery strength.
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| 11. | Repeat for each cylinder writing down the results after each test. |
| 12. | If one or more of the cylinders are "low" then pour 1 Tbls of oil in to the cylinder, let it sit for 2 minutes then repeat the test. This is called the wet test. If your results improve then your rings are bad. |
My results we as follows with extra data for the record.
| Cylinder | Pressure | Plug Gap | Plug Wire Resistance |
| 1 | 162.5 PSI | 0.029 inch | 2.87 kOhm |
| 2 | 162.5 PSI | 0.040 inch | 2.61 kOhm |
| 3 | 165.0 PSI | 0.030 inch | 3.85 kOhm |
| 4 | 165.0 PSI | 0.026 inch | 5.28 kOhm |
| 5 | 165.0 PSI | 0.028 inch | 6.95 kOhm |
| 6 | 162.5 PSI | 0.027 inch | 8.02 kOhm |
This test was done "soon", 30 minutes, after I stopped and with all the plugs removed. The weather conditions were 29.87inHG, 66.2F, and 79% Humidity. I did the test with 4 cranks though when I did 5 the 165PSI test moved to 170PSI. The head has been shaved once by an unknown amount. I do have oil smoke in the morning which I think is from bad valve stem seals, so that might cause the carbon. I certainly have a lot of oil in the IC piping that could cause it, but low oil consumption (1 qt/3000 miles). I looked at the plugs and they are all a light brownish, a bit darker than normal but nothing extreme.
My car had 126,568 miles on it and the plugs themselves had 27377 miles. It was 6:30PM on 28 September 2002. The oil was also changed a week ago, Mobil 1 Synth, but I doubt that effects anything. The vacuum is a steady at 21.25inHG, needle fluctuating less than a hair. I will be readjusting all the gaps back to 0.030 inch. I didn't install the plugs to begin with, so I can't verify that they were installed with the proper gap, but #2 is really bad at 0.040. No high speed missing or poor idle was noticed so this is just a preventative change. The plug wires are all nicely in spec, though it is quite vague at 25 kOhm maximum.
How to interpret your results
OK, now you have your data points. If they are significantly higher than stated then you could have carbon build-up or your head was shaved increasing your compression. If they are lower and adding oil brought them back up then your rings are probably bad. If the oil didn't do it then you could have a bad valve, or a blown head gasket. If two adjacent cylinders are low the HG is probably blown between them, if just one is low and your coolant isn't doing the over-flowing dance then suspect valves. Either way the next step is a full "leak down test".
Reassembly
| 1. | Clean the wires, plug threads and try to sop up any extra oil in the plug valley before starting. |
| 2. | I recommend putting anti seize on the plug threads. I had a plug strip out of a dead cold block once, luckily it was an extra head that I was taking apart. This $0.99 item could save you loads of hassle. |
| 3. | Reinstall the spark plugs torquing them to 13 ft/lb with the 16mm long socket. |
| 4. | Replace the plug wires. |
| 5. | Replace the ignition pack connect the 6 plug wires, connect the electrical connection, bolt the 12mm grounding wire to the head, and tighten the 10mm bolt. |
| 6. | Replace the throttle body linkage, tighten the 3 bolts to the exhaust side of the head, and tighten the bolt to the center valley gasket. |
| 7. | Reconnect the CPS and Solenoid Resistor connectors. |
| 8. | Replace the ignition pack cover and tighten the 5 nuts. |
| 9. | Replace the ISC pipe, reconnect the hoses to both sides, and tighten the 2 10mm bolts that hold it to the 3000 pipe. |
| 10. | Fire it up, hope it all works :). If you added oil it will smoke like hell until that is all burned off. |