Outer Limits 4x4 Board

Neighbour has a 2000 model Pajero 5 door Wagon. Is a high mileage job and it is runs dual fuel.

Mechanic advises that it is suffering valve retention and would last probably another 12 months.

I know that the early V6's suffered from this when running LPG ( my dad's and sister's 3 litre's stuffed up ) but I thought that the 3.5 litre V6 was designed to run on that fuel.

You'd think by 2000 they would have designed an engine that was compatible with that fuel. Nissans are OK, and they too are alloy head, why not Mitsubishi.

Mitsubishi claim later model engines are LPG compatible.

How does mechanic know this is the problem?

Scott

No idea Scott, just what the neighbour had been advised by the mechanic.

So is it possible that this condition could still exist in high mileage units or not at all.

How do you check without taking the heads off.

My turn to say "no idea."

Was the term "retention" or "recession" - as in valve seat recession?

I understood the valve problems were from excess heat - LPG burns too hot for the head to cope with it. So I suppose overheating the engine could induce a similar effect?

I don't know how you'd diagnose this without removing the heads, which is why I was curious about how the mechanic knew. I hope he's not jumping to conclusions such as "Mitsubishi V6 + LPG = Valve problems."

Not saying mechanic is wrong - just that these motors are supposed to cope with LPG.

Cheers,

Scott

My 2002 NM Pajero has a section in the factory handbook stating it is compatible for LPG, im sure it is the same with the 2000 ......

Scott,

recession sounds better. Thought about it overnight and believe that a mechanic could probably diagnose if the valves were receding into the head due to the valve clearance.

Not sure if they gets tighter or more rattlely? Motor is not running correctly ( like a dog was the expression I had heard)

I know the heads should come off for a proper diagnosis . Are Paj's known for burning their valves out with LPG ?

RoadNazi wrote:Scott,

recession sounds better. Thought about it overnight and believe that a mechanic could probably diagnose if the valves were receding into the head due to the valve clearance.

Perhaps it's the recession he had to have?

You have a good point - if they recede too far the lifters will run out of "adjustment."

RoadNazi wrote:Not sure if they gets tighter or more rattlely? Motor is not running correctly ( like a dog was the expression I had heard)

I know the heads should come off for a proper diagnosis . Are Paj's known for burning their valves out with LPG ?

The 12V 3.0 have a bad reputation with gas, although some have got away with it and will tell you they are fine. I'm not sure about the 3.5 DOHC motor (released mid '90s) but the 3.5 SOHC (and 24V 3.0) is classified as LPG compatible, and I'm not aware of valve problems.

Hopefully, somebody who knows will post up.

Cheers,

Scott