L322 2005 4.2l with LPG - Cylinder Head

Hi all, looking for some advice.

After getting the gearbox and torque convertor rebuilt (that's some job to remove and refit...), took my my 200k miles 4.2 SC MY 2006 with LPG (run on LPG for about 150k miles with valve saver oil) for its MOT. Failed the emissions test big style. So did a compression test - almost no compression on cyl 2, v low compression on cyl 3. Then ran a leak down test which indicated no leakage to the coolant but defo leakage out of the exhaust valves - enough to blow up the rubber gloves taped over the end of the exhausts

My guess is that the cylinder head / valve seats are shot, but welcome other views.

Question is what to do ? Pull it apart and get the heads rebuilt ?, buy s/h heads and swap or part it out ?

I'm not fussed about a perfect repair, would just like to get another couple of years out of it given all the work thats been done of late...

Thanks all, Andy

The 4.2s don't do lpg very well you have got 200k out of them it will be vsr that has caused the damage. Even with valve lube they can die.

You would be better off with sh heads if you want todo a repair personally I would cut my loses .

Take the heads off & have a look to see what the issue is.

Thanks... yes I'm assuming VSR also.

I'm thinking that getting the heads off (to replace them with S/H heads - cost about £400-450 for the pair, parts only) is pretty major operation. I'd be happy to give it a go, but the car is not at my home address, so have been phoning round looking for a LR garage / specialist to do it, east coast Scotland, but struggling to find anybody to take it on. Cost of transporting it home to Surrey is over £700.

... if anybody has a transporter or trailer and fancies moving it south, happy to have a chat about £££.

Given she's done 200k, trying to keep the costs under control, would be happy to get another couple of years use. If I hadn't just done the torque convertor, the gearbox and all the front suspension, cutting my losses would be easier decision.

Anybody taken the heads off the 4.2 engine ? and any views on how best to approach ? or any recommendations re small independent shops thatr might take it on ?

Thanks all.....

Andy

Ratae said:

Take the heads off & have a look to see what the issue is.

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So took the heads off, just got finished last night.

The cylinder with no compression (#2) has a cracked exhaust valve - so pretty obvious why no compression (pic below), no damage to piston. The valves on the cylinder with no compression (#3) look okay, but that was just a quick glance at the end of the night. Piston #3 has a slight mark on it, near the centre, can just feel it with the fingernail test, so suspect something has happened with #3.

So, thoughts on next steps ?

I’ll see if there are any s/h heads available and the cost, or look to get the heads rebuilt ?

Then there is the challenge of rebuild, assume I’ll need a head kit, timing chain kit and also the tool to set the timing ?

Again, due to the age/mileage, looking to keep the costs under control. If I can get another couple of years out of it I’ll be happy.

All suggestions welcome.

Thanks

Andy

I had my P38 heads skimmed by Classic & Modern Engine Services in Bracknell. They certainly know what they are doing.
Give them a call or better still pop in there.

onebounce said:

So took the heads off, just got finished last night.

The cylinder with no compression (#2) has a cracked exhaust valve - so pretty obvious why no compression (pic below), no damage to piston. The valves on the cylinder with no compression (#3) look okay, but that was just a quick glance at the end of the night. Piston #3 has a slight mark on it, near the centre, can just feel it with the fingernail test, so suspect something has happened with #3.

So, thoughts on next steps ?

I’ll see if there are any s/h heads available and the cost, or look to get the heads rebuilt ?

Then there is the challenge of rebuild, assume I’ll need a head kit, timing chain kit and also the tool to set the timing ?

Again, due to the age/mileage, looking to keep the costs under control. If I can get another couple of years out of it I’ll be happy.

All suggestions welcome.

Thanks

AndyView attachment 295899

Click to expand...

Never seen a valve with a failure pattern like that

Datatek said:

Never seen a valve with a failure pattern like that

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Spoke to an engine shop a while back and they had a pic or two of similar, not Rangie, but similar Valve failure. Question is, rebuild or replace with s/h heads (if I can find any !)

pwood999 said:

I had my P38 heads skimmed by Classic & Modern Engine Services in Bracknell. They certainly know what they are doing.
Give them a call or better still pop in there.

Click to expand...

Thanks - will give them a call.

onebounce said:

Spoke to an engine shop a while back and they had a pic or two of similar, not Rangie, but similar Valve failure. Question is, rebuild or replace with s/h heads (if I can find any !)

Click to expand...

You already own "secondhand heads" why buy more of unknown condition and then have to rebuild them? Unless the heads are seriously damaged, much better to rebuild your own heads.

When we did the full rebuild on my L322 we fitted all new valves both heads so worth doing if yhe heads are OK them selvesm

Datatek said:

You already own "secondhand heads" why buy more of unknown condition and then have to rebuild them? Unless the heads are seriously damaged, much better to rebuild your own heads.

Click to expand...

Thanks, good point.

My worry is that these heads have done nearly 200k miles, 150k of which on lpg, so might be better to replace with a set of ‘petrol only’ heads ? Which might be less subject to vsr.

Also thinking that the broken valve might have damaged the valve seat.

Maybe next step is to remove the valves and see the condition in n the seats. Not sure how to measure for vsr though.

If I do replace them, does anybody know if the 4.2 SC RR Sport AJV8 heads are the same ?

biketeacherdave said:

When we did the full rebuild on my L322 we fitted all new valves both heads so worth doing if yhe heads are OK them selvesm

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Interesting, thanks
I haven’t looked at this option yet, wondered if you had an idea of the cost to refurb the heads ?

I’m expecting to also need a cyl head gasket and bolt kit, timing chain kit and engine timing tools.

onebounce said:

Thanks, good point.

My worry is that these heads have done nearly 200k miles, 150k of which on lpg, so might be better to replace with a set of ‘petrol only’ heads ? Which might be less subject to vsr.

Also thinking that the broken valve might have damaged the valve seat.

Maybe next step is to remove the valves and see the condition in n the seats. Not sure how to measure for vsr though.

If I do replace them, does anybody know if the 4.2 SC RR Sport AJV8 heads are the same ?

Click to expand...

Valves and sat may have suffered from running on LPG but I can't see it would have affected the heads.

onebounce said:

Interesting, thanks
I haven’t looked at this option yet, wondered if you had an idea of the cost to refurb the heads ?

I’m expecting to also need a cyl head gasket and bolt kit, timing chain kit and engine timing tools.

Click to expand...

Yes you will need the lot, it wasn't to bad to be honest I will see if iv got the costs somewhere.
I bought a complete timing chain kit, did the vanos reseal new hg bolts and lapped all the valves in.

Runs like a dream and unlike the 4.2 the 4.4 loves lpg. Shame I mite have to part with it due to ulez

Pulled the first exhaust valve, not from a cylinder showing any compression related problems…

After a brief lapping, seat looks okay and valve, although pitted, not too bad.

Will push on and pull the rest…

onebounce said:

Pulled the first exhaust valve, not from a cylinder showing any compression related problems…

After a brief lapping, seat looks okay and valve, although pitted, not too bad.

Will push on and pull the rest…

onebounce said:

Pulled the first exhaust valve, not from a cylinder showing any compression related problems…

After a brief lapping, seat looks okay and valve, although pitted, not too bad.

Will push on and pull the rest…

Click to expand...

So I made a bit of a mistake when removing the camshafts. The manual clearly states to note the position and number of each of the camshaft bearing caps. Unfortunately I didn’t. Equally unfortunately the position number is not noted in the manual. So I know don’t know which cap goes where.

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onebounce said:

Does anybody have this detail noted anywhere - either from a detailed AJV8 manual or from their experience ?

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Think I found it on the Jaguar site… for an AJV8 4.2 litre, but not SC, but assuming its the same…

onebounce said:

Thanks - will give them a call.

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Top tip re Classic and Modern Engine Services in Bracknell - dropped the heads off for them to skim and review the exhaust valves, thanks

Just got them back, lovely job.

Lightly skimmed, valves and seats re-cut, new guides fitted. <GBP500