Engine was warm ish. 140 and 135 on 3 and 5......is that normal..?
It could be but what are the other cylinder's pressures?
Not sure what the factory compression pressure would be on a L98 or LS3 but on smaller engines I've played with around 175psi is normal.
The thing with compression readings is that each cylinder should build pressure in a similar way over the the 8 revolutions it takes to get 4 puffs of compression reflecting on your pressure gauge. Also the difference pressure reading between each cylinders shouldn't be greater than +/- 10% in a good engine. I've always worked with these tighter 10% spec for rebuilt engines and in service engines. As long as the pressures are all consistant, I was happy
Oddly, the holden service manual specifies what seems a lower standards but then again they think LS3 sounding like a diesel is normal
The VF service manual lists a compression test for the L77/LS3 on page 6575 of the pdf (you can find
here). It states:
- The minimum compression in any 1 cylinder should not be less than 70% of the highest cylinder. No cylinder should read less than 690 kPa (100 psi). For example if the highest pressure in any 1 cylinder is 1035 kPa (150 psi), the lowest allowable pressure for any other cylinder would be 725 kPa (105 psi). (1035 x 70% = 725) (150 x 70% = 105)
- Normal - Compression builds up quickly and evenly to the specified comression for each cylinder
- Piston rings leaking - Compression is low on the first stroke. Compression builds up with following strokes, but does not reach normal. Compression improves considerably when you add oil (15mls)
- Valves leaking - compression is low on the first stroke. Compression usually doesn not build up on the following strokes. Compression doesn not improve much when you add oil.
- If 2 adjacent cylinders have lower than normal compression, and injecting oil into the cylinder does not increase the compression, the cause may be a head gasket leaking between the cylinders.
Why provide all that info and not list the cylinder compression pressure in the later L77 or LS3 specification section? Bloody Holden...