4BD1 Knocking

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Originally Posted by justinc

Hi Mike, What year of manufacture was the engine? The pre 1988 N/A engines had non turbo spec pistons, and weren't up to big boost levels and EGT's. I have a 9/1984 build 4bd1 at 300,000km example here that has holed a piston, even running low (12psi) boost pressures and conservative fuelling.

Lots of pressure from the crank case and misfiring/ rough running. Head off and voila, a hole in number 3 and cracks in 2 of the other piston crowns.

Hope it isn't the case with yours :(

JC

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Way to cause an Isuzu endemic paranoia:eek:

Quote:

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Originally Posted by justinc

Hi Mike, What year of manufacture was the engine? The pre 1988 N/A engines had non turbo spec pistons, and weren't up to big boost levels and EGT's. I have a 9/1984 build 4bd1 at 300,000km example here that has holed a piston, even running low (12psi) boost pressures and conservative fuelling.

Lots of pressure from the crank case and misfiring/ rough running. Head off and voila, a hole in number 3 and cracks in 2 of the other piston crowns.

Hope it isn't the case with yours :(

JC

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AAAAARRRRRGGGG:(
Now you tell us. :)

one incident out of all the 4bd1 engines I know of certainly isn't a rush of failures:mad:

next you'll all be condemning all the LT95's because I have had my transfer case apart twice in 2 years.

Like Ben says there are many of these engines that never have a problem, so don't read too much into it.

JC

Also keep in mind that IIRC Mikes engine had a full overhaul a while back, in which case all bets are off regarding what pistons etc are actually in it.
The other thing I recall hearing is that the engines have been known to pick up #3 piston if pushed hard when still cold. Not sure how much evidence there is to support that.

Steve

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Originally Posted by justinc

one incident out of all the 4bd1 engines I know of certainly isn't a rush of failures:mad:

next you'll all be condemning all the LT95's because I have had my transfer case apart twice in 2 years.

Like Ben says there are many of these engines that never have a problem, so don't read too much into it.

JC

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You've now planted a seed of doubt, I can see people rushing out to wind in their fuel screws now:D

I'm hoping they will all be selling their engines cheap on eBay ;)

Steve

Knew I should have bought a landcruiser:p

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Originally Posted by isuzurover

My engine is an '87 model with ~200k on the clock post turbo fitment running 21 psi Boost and no IC. Maybe I have been lucky???

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More boost and lower EGT is far better than low boost and high EGT.

Running 700C sustained, at least you know it's a true measurement. Not like running a 900C tune and using the lag in the gauge to pretend that it's only 700.

If you run into to much trouble I'm located at lake Macquarie and would happily come and give you a hand or even a tow with my car trailer (yes I'm isuzu crazy aswell) 0404686632 don't hesitate to call mate

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Originally Posted by isuzurover

I think that is going too far. There are heaps of turbo'd 4BD1s running NA pistons without a problem.

Mine in fact did the whole nullarbor sitting on 700+ EGTs before I turned the boost up and reduced them.

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ok I was a bit harsh, I should have qualified the statement. The weakness that sparked my comment was

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The pre 1988 N/A engines had non turbo spec pistons, and weren't up to big boost levels and EGT's.

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A rebuild also places additional questions on the pedigree.