How to use Compression Tester on my Ford Windstar 88

[raybaloy]

I shall be very grateful if anyone could help me how to use my compression tester on my windstar 1999 model which I bough yesterday. Please kindly tell me step by step procedure, as well as the PSI required for each cylinder since I do not have the service manual for this vehicle. Your prompt reply is greatly appreciated.
Thanks and best regards.

[12Ounce]

1. I would find it easier to first remove the plastic cowling beneath the windschield. Removal of the cowling makes it easier, for me, to reach the rear of the engine. This is covered in chapter 13 (IIRC) in Haynes.

2. Remove all spark plugs. To avoid the possibility of getting shocked, disconnect the ignition pack. ... of course, you could just choose to avoid the spark cables instead. Pull the fuel pump fuse/relay or somehow disable the injectors.

3. During the compression test, intake air must be free to the engine. There are several ways to achieve this: ...(a) have assistant hold gas pedal down ... or, (b) prop the throttle "open" somehow underneath the hood ... or, (c) remove the air filter cartridge and throttle body this is my favorite. Allthough I have also removed the upper intake manifold if I'm about to do upper engine repair.

4. Conduct the test. Depending on what kind of tester you have, insert (screw) test prong/tip into spark plug holes. Keep tester in place while the engine is cranked several revolutions until the tester gauge reaches its maximum reading. Record gauge reading. Reset gauge and move to next cylinder. After all are completed, review readings ... retest any cylinder that has readings you suspect are in error.

Depending on engine condition and tester, the readings will be approx 175psi. Piston ring and valve wear will make a reading lower. Excessive carbon build-up will make a reading higher. You hope the highest reading will be no more than 20% of the lowest reading.

Some folks recommend taking a second set of readings after dropping a few drops of oil into each cylinder. The idea is to wet the rings with oil to identify worn rings versus worn valves. I do not recommend this procedure! It is indefinite ... you are never sure if you have the rings completely wet, but do not have excessive oil in the cylinder. All it takes is one experience of forcing oil back into the test gauge and you will do this procedure no more. Ask me how I know!

Happy hunting!

[wiswind]

Take some extra time to label the spark plug wires!
It is SUPER easy to get them crossed when more than one is off at a time.

Also, take extra time to avoid bumping any of the many vaccum lines loose....and carefully inspect to make sure that they are all connected.

These 2 hints can save you hours of frustration and troubleshooting.

If you decide to replace your spark plugs.....do NOT use the multiprong Bosch plugs that they push at the part stores......they don't seem to be the best in the windstar application.
The correct spark plug would be a double platinumn plug.....sold under the Motorcraft and Autolite brand names.
These have platinumn enhancement on BOTH the center electrode and ground tab.

Another hint.....while in there....double check that the linkage to the IMRC is present. On the newer windstars (1999 and newer) the nylon clips are known to come off.....one possilbe cause for pinging...and other issues.
The IMRC linkage is in the lower intake manifold....passenger side.....there is a shaft that passes through the air passeges for the front bank of cylinders....and another shaft for the rear bank.....connected to a motor that drives both shafts.