The GM engine on Terex is a two stroke engine that has double output because it uses blower to send high pressure air into combustion chamber. So every upward piston movement is explosion. That is why output of 4 cylinder GM engine is far bigger than 6 cylinder engine of equivalent bore. The engine is dry sleeve, so no sleeve seal. The engine enjoys the advantages of all engine with sleeves which is that each time the cylinder kit is changed the engine is back to new advises not to operate a compressor at low air pressure to avoid malfunction of reclaimed wool in the oil Separator tank leading to oil discharging with compressor oil.
Machine diagnosis and if your trouble shooting is correct, the repair is 50 percent solved.
If these issues are not put into consideration while buying equipment, the buyer must have reduced output of the machine by introducing downtime or out rightly scraped the machine at the point of purchase by making it use and throw away irrespective of whether the machine is new or used. Considerations for machine quality will follow later.
Maintenance Manual: - this will provide engine timing, valve clearance, toque values, and other specialized information that makes it your mechanic’s mate.