Brew69(SA) replied:

There are certainly lots of people who have had probs with the head on the TB42 when running gas. I have gas and have to say around the city its the only way i could afford to drive a 4x4. Being an 89 model with a points distributor i would stronly suggest you invest in an electronic ignition as the tuning problems are widely discuussed on this forum and this seems to be a good fix.(approx $300 for an ignitor module) Also remeber lpg is not widely available in remote areas so extra fuel will need to be carried. The biggest plus will be the $$$$$$ you will save on fuel bill.Hope this helps.

Swine Hunter replied:

Hi,
It is well documented as above that TB42's on Gas have their share of cracked head issues. If you are thinking of putting gas onto a motor with 360km on it, I would recommend you at least get the head of and have it reco'ed and have some additional cooling pipes installed into it so each cylinder has additional water flowing through it to keep it cool.

Also consider the cost vs benefit, if you plan on keeping it you may get your money back in saving on petrol costs in a reasonable timeframe, but how much longer LPG will enjoy lower state and federal excise is unknown.
If after the conversion you develop cracks in the head, although they can be welded in most cases, the rarley never crack again, so it be costly to source another head.

Patrols aren't cheap to run on petrol, but an older one with km similar to yours may present more trouble than the conversion and any expected saving are worth.

Cheers

outback epicurean replied:

Hi

We had a 89 4.2 on gas, carby model and have to say it was not good. Tried all sorts of tuning options but still liked to backfire, especially on hills when under pressure. Also, economy on gas was about 20% less than petrol so some of the benefit is lost. Also, as said in earlier response, gas is not readily available up north and what is there often seems to be stale and cause problems. Friend has a later model with electronic ignition and certianly seems better on gas. We traded to a diesel, best move ever!

gqpat replied:

As a gas fitter the best thing to do when fitting gas to this patrol s fitt an electronic ignition system most after market models still retain factory coil .You can make a system yourself if your handy with a lathe i used an old valiant 6 cyl dizzy pickup and machined cam lobe to suit reluctor and mounted an 024 bosche module in a dicksmith diecast alloy box the bosche module allows you to run a 716 or 723 bosche coil with full 12 volts also mig up the rotor end to add 1.5-2mm as they have a very large rotor to dizzy cap clearance the spark from this system will outperform absolutely anything around and is very reliable the whole system cost around $100 to make and 5-6 hours .
Dont worry about head until you have to and when you do get it done make sure all the plugs are removed and welded up or it will crack again once you do this it will be fine

maleny136 replied:

Thanks everyone for their thoughts and I wont go to gas maybe buy a diesel.

Truckster (Vic) replied:

IMHO
360,000klms on a petrol GQ is a world of hurt waiting to happen.

GQ heads only are good for repair once after cracking, but at $1000 to repair, or $1300 for a new 1, I know what I would be doing.

check www.gqpatrol.com for a check list of things to look for when buyin a GQ.. :)
I actually got more things to add to it, but that will keep you busy.