Can someone tell me the easiest way to do a vacuum check on a 1998 F150 and how to determine if I have a 4.6 or a 5.4 Engine

 

Look at the belt routing diagram.

 

A 98 5.4 looks something like this

 

A 20-30 dollar vac gage will pump the lines up themselves for a leak down check.. Make sure you don't push those 90 degree elbows on the 3/16 vac lines on to far - you'll block the flow . Been there done that

You can also insert a 1/4" line in the side of your head and use it as a stethoscope to check for leaks while she's running..

 

In 98, 4.6's had spark plug wires and coil packs, 5.4's had COP's (coil on plugs).

 

HAHA!! YUP!! That's the best way to tell right there..

Just look for Spark Plug wires - 5.4L's never had them..

 

Yeah but it could be a 4.2l v6...

So make sure you at least count the number of plug wires. If you count 8 then you have a v8, if you count 6 you have a v6. See the pattern? Mysterious, eh?

 

Plus a 4.2 will only have 1 big coil pack having 6 connectors! ooooh spoooky!

 

Wow... this thread must be spooky... and creepy. At the same time.

 

BOO!!!

 

oooohhh... creepy v6 coil pack...

 

Thank you all for your help. I now know that I have a 4.6 and how to do a vacuum check. You people are very helpfull. Sorry for the late reply but I was waiting for email notification that someone had replied and never recieved one. Decided to check and found out I had lots of help.