Anyone know the cylinder PSI # (range) for a 5.9L 12 Valver ??

I need to do a Compression Test on mine.

 

hang on I will get ya some info

 

I guess this dont say nuttin bout compression.......however its a blowby test and will tell you condition of yer motor

this was a write up from my friend Bill Flemming

A better way to check engine condition is by a blowby test. This is what Cummins uses and is very simple.

You need a blowby tool. a blowby orifice tool is simply a tee with one .221" (15/64-in) outlet. Connect one end of the tee to the end of the blowby tube. Put a manometer on last tee outlet. That is your blowby tool. They sell them at the Cummins, but I have made my own plenty of times. A simple manometer can be made by looping into a U 6' of clear tubing with water in it half way. Measure how high the water level rises with a tape measure, multiply it by 2, convert it to LPMs

Rough conversion is 1"= 27 lpm, add 3 lpm for each one inch (1/2'' of rise in the tube) of water

New engines numbers are;
63 liters per minute(2.5" water rise = 5" of water) @ 2200rpm,
76 L/Min (3.5" rise) @ 2500rpm
85 L/Min (4.5" rise) @ 2800rpm.

Worn engine that needs rebuilding are roughly double i.e.
126 L/Min(10.5"rise) @ 2200rpm
152 L/Min(14.5"rise) @ 2500rpm
170 L/Min(17"rise) @ 2800 rpm

The valves could also be out of adjustment.

Another way, same idea, is to block the blowby tube with a 1/2'' pipe nipple with a cap that has a 15/64 hole drilled in it. Use 3/8'' id looped clear tubing with water in it slipped over the oil dipstick tube. Use sharp tipped felt marker to mark the water level with the engine off, have someone start an already warmed up engine and run the rpms up to 2.2, 2.5 & 2.8k rpms. Mark each water level with the pen, measure then multiply each by 2.

This is all very simple to do, just hard to explain with words.

 

This wont help much but a local parts store sells the compression testers and they use a 300 psi guage.

 

From the cummins manual:

New rebuild: 350psi
Good Used engine: 300psi
max allowable variance: 100psi

The actual compression is not nearly as important as how balanced the cylinders are. Also, the blowby test like mentioned above is a better route to go IMO

 

Good Information to have...