Holden Jackaroo Engine Problems
It could be a blown head gasket as your mechanic suggests, but he should be able to test it to determine if it is blown or not. You should also be able to see evidence in the form of a milky substance in the coolant if it is a blown head gasket.
Ask Smithy Xtra LPG for Holden Jackaroo
The 2.6-litre engine should be fine, but there were some concerns with the early build 3.2-litre engines in the Jackaroo.
Jackaroo fuel consumption
On average and depending on conditions I would expect 9.0-11.0 L/100 km. There were no concerns about the cylinder heads on the Jackaroo.
'roo the day
IT'S not recommended that you convert the Jackaroo to LPG because the engine isn't really compatible. Holden had an LPG option available on the Rodeo with the Isuzu V6, but it proved troublesome. It was an Impco air-valve system and had many driveability problems. If you really want to convert to LPG, George Peake, of Victorian Autogas Supplies, recommends you take your car to a cylinder-head specialist and have the heads fitted with hardened valve seats and valves, then find an installer who will fit it with a generic injection system.