L322 4.2 SC engine issue

GSF 109 · Jul 18, 2020

Hi all, I have a friend who has offered me his 4.2SC which appears to have bore washed and effectively lost meaningful compression on a few cylinders! It is on gas, so could this have been the issue?
Also, as these engines seem to be costing a fortune second hand - around 3k!!!. is there anyone with knowledge of this issue and any potential fix. I will probably pass on it and run for the hills if I can’t get an engine at a reasonable cost.....
It has just under 100k miles on it and is in reasonable condition. The supercharger needs a new bearing too....

Wazzajnr · Jul 18, 2020

Lost compression on "some" cylinders sounds more like broken valves/timing/cams to me.
"IF" it was the lpg caused it, it would be even across the cylinders.
Mine has done 35k that I know about on gas and its fine.
I'd be running for the hills tbh

tomcat59alan · Jul 18, 2020

Wazzajnr said:
Lost compression on "some" cylinders sounds more like broken valves/timing/cams to me.
"IF" it was the lpg caused it, it would be even across the cylinders.
Mine has done 35k that I know about on gas and its fine.
I'd be running for the hills tbh

And I would be overtaking you.

GSF 109 · Jul 18, 2020

Thanks for your reply. I think the gas conversion was done about a year from new and it’s a 2006, so it’s been running on gas for most of it’s life. The sump has a strong smell of petrol and it’s about a litre over the mark on the dipstick. I believe the AJV8 engines have nikasil type coating on the cylinders. Perhaps that has failed. It’s knackered anyway!!

tomcat59alan · Jul 18, 2020

GSF 109 said:
Thanks for your reply. I think the gas conversion was done about a year from new and it’s a 2006, so it’s been running on gas for most of it’s life. The sump has a strong smell of petrol and it’s about a litre over the mark on the dipstick.

As long as he's offering it to you for free,go for it.

GSF 109 · Jul 18, 2020

Nah, nothing is ever free....

tomcat59alan · Jul 18, 2020

GSF 109 said:
Nah, nothing is ever free....

Scrap value then, good luck.

Henry_b · Jul 18, 2020

If it has LPG and no flashlube, you probably have suffered Valve seat recession, common on an AJV8 that hasn't had flashlube..
do a wet compression test to rule out piston/ring issues.

GSF 109 · Jul 18, 2020

No flashlube is fitted as far as I can tell. I will do a wet test and see what happens. Still confused as to why the fuel is in the sump. The fuel would have to find its way down past the bores surely? Maybe they have been cranking it for a while trying to start it.

Henry_b · Jul 18, 2020

GSF 109 said:
No flashlube is fitted as far as I can tell. I will do a wet test and see what happens. Still confused as to why the fuel is in the sump. The fuel would have to find its way down past the bores surely? Maybe they have been cranking it for a while trying to start it.

They more than likely flooded the shít out of it trying to start it.

Pez will leak down past the rings, washing the oil away with it..

Drop some oil down the bores..

It is more than likely VSR which is almost guaranteed on an AJ without flashlube.

oakey · Jul 18, 2020

wots flashlube?

Henry_b · Jul 18, 2020

oakey said:
wots flashlube?

It is a valve lubricunt injected with LPG to minimise Valve Seat Recession on some engines, not all need it..

it forms a film of oil between the valve and the seat

oakey · Jul 18, 2020

Ok thank you. Is it added to the lpg at source?

Henry_b · Jul 18, 2020

oakey said:
Ok thank you. Is it added to the lpg at source?

It is stored in a reservior and it injected with the LPG

oakey · Jul 18, 2020

Ok thank you

ukadamwest · Jul 18, 2020

if the SC bearing has gone, the possibility of the SC vanes being worn are possible. finding a good used one is difficult.

GSF 109 · Jul 18, 2020

I took the supercharger off and the vanes have very light scores on the tips but everything else looks ok.

Wazzajnr · Jul 18, 2020

Mine was on lpg when I got it and the date on the ecu is 2009 (it's a 2006 model} so I suspect mine has been on lpg for all but its first 3 years. No flash lube on mine and no sign it was ever fitted.
Pretty sure if it was going to kill the valve seats it would have done so by now.
Nikasil was only very early Ajv8, long before they were fitted to the range rover this problem was fixed.
My vote is still on valve gear failure somewhere.

tomcat59alan · Jul 19, 2020

oakey said:
Ok thank you

Looks like this, lube is drawn into intake manifold and is metered by a screw on the side of the reservoir.

tomcat59alan · Jul 19, 2020

tomcat59alan said:
Looks like this, lube is drawn into intake manifold and is metered by a screw on the side of the reservoir.

The knurled screw and the sight glass are visible in the first photo,lube is metered at one drop per 5 seconds. IMMIC

L322 4.2 SC engine issue

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