1999 Ford F-150 compression

Tiny
JOE1953
  • MEMBER
  • 1999 FORD F-150
  • 5.4L
  • V8
  • RWD
  • AUTOMATIC
  • 206,000 MILES
Misfiring on number 2 cylinder water is getting on number 2 spark plug how much you charge to do a compression test?
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Tuesday, March 31st, 2015 AT 9:45 PM

5 Replies

Tiny
CARADIODOC
  • EXPERT
We aren't a repair shop. We just dispense the best advice and answers as possible.

You need to include a lot more detail. How do you know cylinder number two is misfiring? Are you sure it's water you're seeing? Are you losing coolant? Does your engine have an EGR valve? What has led you to want to do a compression test?
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Tuesday, March 31st, 2015 AT 9:55 PM
Tiny
JOE1953
  • MEMBER
It was check and they said number 2 cylinder was misfiring and they remove the spark plug and it had coolant on it and they also said the cylinder head gasket need to be replace. I am not sure about the EGR valve, I just thought a compression test would give a better way of showing what the problem is.
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Wednesday, April 1st, 2015 AT 8:07 AM
Tiny
CARADIODOC
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You can have a leaking cylinder head gasket or any of a number of other problems and the compression will be fine. In fact, oil and water don't compress, so if either is leaking into the cylinder, that will make the compression readings higher than normal. Fluids will seal leaking piston rings too and make compression readings go higher.

The best test to verify this type of leak in a head gasket is to add a small bottle of dark purple dye to the coolant, then check a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. If a head gasket is leaking you'll find the dye inside the tail pipe.
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Thursday, April 2nd, 2015 AT 3:45 PM
Tiny
JOE1953
  • MEMBER
After I add a small bottle dark purple dye to the coolant do I need to start the engine up and let it run are do I drive the vechile?
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Thursday, April 2nd, 2015 AT 6:01 PM
Tiny
CARADIODOC
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How long you wait depends on the severity of the leak. Real bad leaks usually result in pretty obvious symptoms and observations that are easy to diagnose. It's the slower leaks, including those where the leakage dries up and evaporates before you get to see it where this dye is the most useful.

If it takes, lets say, a thousand miles for you to lose a quart of coolant, you may need to drive 50 to 100 miles to have enough time for the dye to work its way to where it can be seen. If you lose a quart of coolant in a day, perhaps 50 miles of driving or less, you can probably drive just five miles, then check for the yellow stain. If you can't find any indication after a hundred miles, just keep checking at regular intervals until it shows up.

Auto parts stores will have the dye for the fluid you're leak-checking, and those that rent or borrow tools should have the black light.
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Thursday, April 2nd, 2015 AT 6:44 PM

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