Robio361

Hello all, I just finished my compression test and was wonder if these numbers sound about right? These are on a 96 GT with 143K miles. Also I was wondering if they are within specs? One more question. I'm replacing the valve stem seals because they are leaking oil and is burning on start up and at idle. The car is stock and don't need to mod it, so can I just use the less expensive Fel-pro seals or do I need to get oem ones from Ford?

#1-175 #5-180
#2-180 #6-180
#3-175 #7-180
#4-175 #8-180

Thanks Rob.

stevednmc

Those look pretty good to me.

cliffyk

They look good, did you remove all the plugs, and block the throttle plate open, when you did the test?

That's the prescribed procedure and will provide the most consistent numbers from test to test as it provides the best airflow, and removes much of the battery's state of charge from the picture...

TRUEBLUE3934

I'm with Cliffy. That method is the way I was taught to do it.
Those numbers look pretty good!

stevednmc

I agreee with the above as well.

Old Mustanger

Those numbers look good for 143k miles. Are you removing the heads to replace the seals? If so, I would do a valve job while it is apart, especially with that many miles.

Robio361

Hey guy's thanks for the quick response. No I didn't block the tb open I just pressed the gas pedal down all the way. Will that change the numbers? Should I do it again? I pulled all the plugs, disconnected both coil connectors and pulled the fuel relay.
No I'm not going to pull the heads to replace the valve stem seals. I'm going to use the TrickFlow valve spring tool and use air to hold up the valves and plug all the oil passages so nothing falls in. Could someone let me know about the seals themselves?

cliffyk

Same thing, you're cool...

Sounds like you have things under control, as to the seals a picture is worth 1024 words:

Robio361

Hey Cliffyk thanks for the info. Quick question. Should the piston be at the top position or bottom before removing the seals?

cliffyk

If using compressed air to hold the valves the piston should be at BDC. That way the engine cannot rotate against the air pressure. If it were not at BDC, and the crank suddenly decided to rotate, from the air pressure, the pressure might drop and if it could not be made up fast enough the valve could drop--to where it cannot be retrieved without pulling the head.

If not using air then the piston needs to be at TDC, that way the valve can only drop 1/4" or so before hitting the piston--this can make getting the retainer keys out a bit more difficult...