: More pressure test questions



bobvondutch
06-15-04, 03:18 PM
Eldo1, thanks for the info: TDC, DUH!!, what was I smoking. Anyhow, went at it again today. Figured that in order to turn engine over to find TDC on each cylinder, I needed to remove right front wheel and plastic to get to harmonic balancer with socket. Now, unless you have help (I don't) or arms like an orangutang, you can't feel TDC while turning it over. So I get a bright (?) idea: put a pressure gage on the end of a quick-change, snap it on my pressure test pipe, turn the engine over by hand to get the highest reading, and put the air to it. Did I mention I had taken out all the plugs?? 120 PSI will spin that engine over quicker than you think!!!!
SO, now I'm back to square one with some questions: can you turn the engine over by hand with all the plugs in but the cylinder you're testing, using the gage to determine when you have TDC or close to it?? If that works, will the 120 PSI still turn the engine over even though the plugs are in??
Would I be further ahead to put the plugs in, leave the coil pack out, put the gage on the cylinder I want to test, and turn the thing over with the starter to find max compression and then test??
I'm not lazy, but at 6'4 it's getting hard on the back bending over a car that's only 30 inches tall. I managed to get cylinders 1 & 3 tested, no leaks so I'm getting optimistic. Need some help, and as always thanks for everyone's input!!

zonie77
06-16-04, 01:13 AM
You can use the firing order to determine which cyl is on the compression stroke. Make a paint or chalk mark at 90 deg intervals on the harmonic balancer. You've got #1 already marked. You should get close enough this way.

It is easier with two people as one can use a wire to feel TDC but you should be very close with the balancer marks if you are careful marking them.

eldorado1
06-16-04, 01:43 AM
can you turn the engine over by hand with all the plugs in but the cylinder you're testing, using the gage to determine when you have TDC or close to it??
I doubt you can turn the engine over by hand with all the plugs out... Now if you mean with a 2' wrench, then yes you can. Very easily.



If that works, will the 120 PSI still turn the engine over even though the plugs are in??
More than likely, yes. I think you're gonna need someone to hold the wrench ;) I think what you need, is a person to stick their finger in the spark plug hole, while you turn the engine over to find when their finger wants to pop out (tdc compression). At that point, you should have 4 cylinders that you can test (don't ask me which ones, cause I don't know :p) Or maybe it's 2 cylinders? I can't remember... anywho, hold on to that wrench tight unless you want a cracked windshield. Good luck!

cadillacstars
06-17-04, 01:32 AM
Solo TDC finding: put a long screwdriver into the spark plug hole, turn engine over by hand, Watch Screwdriver!, you can still be 180 off but that will be evident when you begin the testing.

BeelzeBob
06-17-04, 02:37 PM
Actaully, the screwdriver idea works great....but....use a piece of wooden dowel instead of a screwdriver incase something gets jammed in the process it won't take a nick out of the piston or spark plug hole threads. Otherwise, the idea is fine....just slide the dowel into the cylinder thru the spark plug port and turn the engine and watch it rise up or down as you cross TDC.