LPG Consequence
Submitted: Tuesday, Feb 21, 2012 at 20:57
ThreadID:
92027
Views:
2587
Replies:
6
FollowUps:
3
This Thread has been Archived
garytee
I have an NM Pajero that has done 175000km. I put it on gas about 3 years ago - injected, the dearer option - by LPGAS1 in
Lilydale.
Last weekend I was driving and I heard a large explosion and then a flapping-type noise - very strange. The car had never missed a beat and has never missed a service.
Had to arrange a tow-truck and, to cut a very long story short, I had blown a sparkplug out of the head.
My mechanic said he hadn't seen this sort of thing very often - less than a handful of times - but in every case, the car was on gas. I'm unsure about keeping the car now, have lost a bit of confidence. My mechanic suggested only running it on petrol.
Has anyone heard of anything similar and what do you think about the longevity of the motor now?
Reply By: Dust-Devil - Wednesday, Feb 22, 2012 at 00:42
Wednesday, Feb 22, 2012 at 00:42
Gary
In 1981 I purchased a Brand New Datsun Series I Bluebird StnWgn. It had a 200B engine in it that was in reality a bored out Datsun 1600 engine. That was their ideaand extent of engine development in those days.
Anyway I put it on LPG gas in 1986 and it never ever ran on petrol again. As a matter of fact I removed the fuel pump and all the petrol lines in the engine bay.
I played around with the Head a tad and raised the compression from 9:1 to 13:1 which made it fly like it had a rocket up it's behind. The down side was cracked heads - clean across the middle which was later found to be a design fault in
the block.
Point is - in 360,000Kms on LPG and at the outrageous compression ratio's I played with, that engine never ever blew a spark plug out by stripping the thread etc.
The spark plug threads were always coated with 'never seize' on install and torqued up to the correct settings.
I believe your problem is as stated above - over torquing/tightening of the spark plugs themselves.
Remedy: Repair the damaged head thread with a Heli-coil or similar product and all will be okay. Use a never seize type product from now on and ensure the sparkplugs are torqued to the correct setting.
It you don't have a tension/torque wrench, then screw the spark plugs in by hand until they
seat on the heat expansion ring, and then turn approx half a turn.
NOTE:
Check them after a 100Km or so and if necessary tighten a fraction more.
Even better - get hold of a torque wrench and do it correctly.
DD
AnswerID:
478384