My compression test, help!

Bapfoutz · Mar 25, 2015

so after I replaced head gasket and all the seals truck wouldn't start. So I did fuel test and it was 36 psi. Then did compression test
cylinder 1 - 40 psi
Cylinder 2 - 55 psi
Cylinder 3 - 150 psi
Cylinder 4 - 120 psi
Cylinder 5 -145 psi
Cylinder 6 - 110 psi

None of them are leaking air, so does it mean 1 and 2 the rocker arms are not torqued all the way or does it mean the valves are sticking? And cylinder 6 is alittle lower, any ideas for the three compressions?

RonD · Mar 26, 2015

'99 fuel pressure should be 65-70psi.
You need to cycle the key on, count to 3, and off, 3 times to get true pressure

Compression test needs to be done with all spark plugs removed and throttle propped open(put something on the gas pedal

)
Yes your results could be from poorly adjusted valves.
With spark plugs removed rotate crank manually so TDC mark is at 0deg

Check if both #1 valves are closed, if one is open, rotate crank 360deg back to TDC, both #1 valves should be closed now.

That is A position in this guide: http://www.therangerstation.com/tech_library/diagrams/30_valverockerarm.gif

Follow it

Torque 32Nm = 24ft/lb

Bapfoutz · Mar 26, 2015

I'll check the fuel pressure again after I Get better readings on cylinders, I did take air filter hose and opened throttle with a wire with sparks out while doin compression. I'll do tdc again soon when weather clears up, I do have a problem seeing the markings for tdc I have a fan in the way and all I can get to is the crank pully how do I get to the timing chain?

RonD · Mar 26, 2015

But it would be best to get underneath crank pulley find the line and mark it with white or light color paint.
Picture here of the 3.0l TDC marks: http://www.fordrangerforum.com/3-0-vulcan-tech/81760-crank-mark-tdc.html

If you can't see the TDC line then you just need to do the cylinders one at a time.
Remove both valve covers
Crank turns clockwise, put a socket on it, rotate crank while watching #1 valves, you should see #1 push rods going up and down, spin the crank a few times until you see the rhythm of the up and down, there will be a obvious "gap" when the push rods don't move, that's the spot you want, both valves are closed so the cylinder can fire.

When crank is in that "gap" you can loosen #1 rocker nuts and then re-tighten as per spec, 24ft/lbs, loosen the nuts and wiggle the rocker and push rod making sure rocker is seated and push rod is in the center of lifter(you can feel it).
Tighten rocker nut to 24ft/lb
You should still be able to spin the push rod, with a little effort, with your fingers.

Rotate crank 120deg clockwise, 1/3 of a turn, now do the same on #4 valves.
Repeat 120deg turn for the rest of the cylinders using the firing order 1-4-2-5-3-6

Bapfoutz · Mar 26, 2015

Thanks a lot for the help! I'll do this sometime this week and try to get better readings. Will let you know if I got it! Thanks again!

Bapfoutz · Apr 1, 2015

okay so i took the valve covers off and re-torqued the rockers didn't see a difference in the turn, re-gap spark plugs. did another compression test it was like 40 psi in cylinder one, 50 when i did wet test. so i don't know whats going on with the valves, the psi doesn't move down after test.

i hooked everything up. cranked it and it wanted to start so i hold the pedal down and it started! but it was a hard start, now i see rough idle,Enigine shakes , and a small back fire when i hit gas. the engine doesn't shake as bad if i push gas half way down.

any ideas after this?

i really hope i don't have to replace the valves...

RonD · Apr 1, 2015

The cylinders with 40 and 50psi can not fire at startup, or at idle, it is physically impossible, compression needs to be above 100psi for the air/fuel mixture to be ignited with a spark.
When you rev the engine the compression will come up a bit so those cylinders may begin to fire now and then which is why is smooths out, back firing could be the unused excess fuel from non-firing cylinder going into the exhaust manifold and then being ignited by the hot exhaust from a working/firing cylinder.

The compression is needed to pre-heat the air/fuel mix so a spark can ignite it, compression = heat, without enough compression(heat) the spark can not start the 'explosion' in the cylinder.

01b3000ds · Apr 1, 2015

You might considering looking into this:
http://www.greenerplanetenterprises.com/rvs.html
http://rvs-tec.com/
There are other, similar products, but I can only speak to this one. Inbox me if you'd like...I'm not sure how mods feel about product testimonials.

Bapfoutz · Apr 1, 2015

Is that greener site a joke? So Ron should I replace the valves? Or rockers? The truck ran fine before I took engine apart except the over heating.

01b3000ds · Apr 2, 2015

Bapfoutz said:
Is that greener site a joke?.

No sir.

RonD · Apr 2, 2015

Bapfoutz said:
Is that greener site a joke? So Ron should I replace the valves? Or rockers? The truck ran fine before I took engine apart except the over heating.

Well, I can't really say.
Did you remove the timing chain?

Valves and seats don't just start leaking.
Piston rings are the same, they don't just fail.

So best guess, and it IS a guess, is that rockers are either to tight so valves are not closing or to loose so not enough air is coming in.

Compression is way to low for a head gasket leak, assuming there was a goof in the install, I could see a 20-30psi drop maximum, not a 100psi drop.

My compression test, help!

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