Taking the '92 1500 in for a leak-down test this week but looking at some youtube "mechanic videos" the testers mechanics use seem to be cheap and not as accurate as one can expect.


So is this the best way to find out the exact cause of my misfiring before ripping the engine apart?


If it's a top-end problem I might just dump a bunch of $ into this truck instead of parting it out and buying a newer truck. Less debt. I hate debt.

 

What's it doing that leads you to think it needs to have a leak doen test run? Not that I'm saying don't do it, but like throwing parts at something it's good to justify the test first.

 

I took it in to a shop so they can look at that stuttering problem. Hooked their computers up and couldn't find anything. The mechanic took it for a test drive and poked around and thinks it's #5 and 6 cylinder... or vaguely possibly the camshaft.

Leak-Down test seemed to be the most accurate way to find out if it's in the top end or bottom end... and what it is.

And this is just a guess, but doing the leak-down test would save me $150 skipping out on a compression test?

 

You can do a compression test yourself if need be and rent the tester from AutoZone

 

i agree wiht mr. dragon do the test yourself a compression test isnt very hard alls you do is take out one spark plug screw the testor adapter in the plug whole and start the truck to read what the compression is then if that cylinder is good proceed to the next and so on
trust me spending the money to rent one versus paying some one over 100 bucks is well worth renting the compression testor from a parts store

 

I live in Vancouver, Canada... I've been searching for months to find auto tool/shop rentals and have had no success

A Canadian Autozone would be a great idea though! Especially in Van.

I guess for the cost of a shop doing it I could just buy the tool... everyone has strict return policies though LOL

 

lol i would keep the tool ya never know when you or your buddy may need it again

i have returned tools and kicked myself in the but the whole way back to teh store the same day cause my friend needed his truck fixed lol

 

So you're saying scrap the Leak Down Test and just do compression???

 

What exactly did the mechanic do when he "poked around" to determine a cylinder 5 or 6 issue? Do a compression test on all cylinders and report back the numbers to us.

 

If you have a leaking headgasket or cracked head, you will not get correct compression readings if you remove plugs one at a time; the cylinder can pick up compression from the adjacent cylinder and display an incorrect reading.
Always remove ALL plugs after engine is at operating temperature.






Ford truck test procedure:

• Warm engine to operating temperature
• Remove ALL plugs and leads (ignition voltage will reach 40KV and may cause serious injury if boots are contacted during testing)
• Screw compression tester in tightly
• Throttle body plate should be held FULLY OPEN during testing
• Turn over engine the same number of times (5-7 cycles) for each cylinder tested (Do NOT start engine)

Results:
Compression should jump up at first crank and increase for each stroke.
If needle is erratic, look to valves,
Hi and Low readings for each cylinder should not vary by more than 75%
If low reading is found, add a few drops of motor oil onto the questioned cylider's piston head through the sprk plug hole; if it does, look to the rings for your problem. If not, most likely valves not seating correctly.