Most likely it's caused by a damaged head gasket when the head warped. Has the engine overheated at any time in the last few thousand miles?
Blown head gasket, cracked head, busted piston, etc. Run a compression check on all cylinders.
This sounds like your head gasket has blownbetween cylinders 2 & 3.this will cause a compression loss on the affected cylinders.you need to have a compression test carried out on your engine.AnotherIf you're CERTAIN that the spark is good and it's timed properly, next I'd check the compression in those two cylinders. It's suspicious to me that the two non-functional cylinders are adjacent. If the engine has overheated any time in the last year you have probably warped the head. A simple compression test will tell the story.
Check the spark plugs and wires Do a compression test
If any two adjacent cylinders have low compression it's probably caused by a blown head gasket.
I'm not sure of the exact values; they should be in your Haynes repair manual. However, if you compression test all of the cylinders and find one that is lower you have a compression problem with that cylinder. It is also possible to have 2 that are lower, this would most likely indicate a warp in the head between those two cylinders. Other causes for compression loss are damaged or gunked up valves that do not close all the way or a crack in the head.
The compression on the cylinders of a 2001 Holden Rodeo diesel 2.8lt is not stated. It is stated that the 2001 Holden Rodeo diesel 2.8lt has a high compression g200z motor.
it depends if you have a 305 or 305ho , 305 8:1 compression cupped cylinders 305ho has 9:1 compression with valve cut pistons
If you have no compression in all 4 cylinders your timing belt is broke.
It depends on equal compression between all cylinders.
do you seriously think that theres a hole in the piston in all the cylinders? or the rings are gone in all the cylinders.. highly unlikely.. the main cause of loss of compression is the rings are burnt gone. the rings are stuck, the valves are stuck, hole in the piston and/or head, bent valves, or the timing chain/belt came off, or broke. with all the cylinders being down, i'd look into the last one. that's the only thing that would be logical to effect all the cylinders evenly.
On one or all cylinders? a single cylinder compression loss may be a stuck or bent valve, or even bad piston rings. Engine wide would have to be some kind of massive valve train failure.
Start by testing the compression. It should be consistent within a few PSI on each cylinder. Any cylinders that have little or no compression probably have a burned valve. If all cylinders are up, check the plugs, wiring and distributor.