Fix it? kick it? or buy a new problem?

whydididoit · Feb 23, 2012

I've recently bought a Range Rover P38 4.0 v8 on LPG which is misfiring and has an awful lot of milky sludge in the breather pipes, so i have the crazy notion the head gasket has gone(just a hunch).
Soooooooo do i fix it or cut my losses and buy a diesel 2.5 i've been offered for sensible money.
It ticks over lovely but when i rev it it makes a pretty 'orrible banging so i'm just hoping there's nothing more serious wrong, i'm guessing that the knock could be the water getting into the cylinders.
I did drive it a short distance(7 miles) and it ran very well until it was under load and then it was popping and misfiring.
Advice from higher beings appreciated.

6704nathan · Feb 23, 2012

as you have a misfire under load i would say an electrical component breaking down under load would give banging noises when revved start with diagnosing the misfire first could be plugs leads coilpack so good ignition service first.
the sludge in the breather is not a surprise you will allways get some and as you say it has been stood would be worse anyway, clean the breathers.
so fix the misfire clean the breathers first cheaper than buying another p38 for what sounds like a simple fault.

whydididoit · Feb 23, 2012

It's had a new coil pack, new leads, new plugs and a compression test which showed all cylinders at between 155 -175.
The breathers were completely full of beige sludge and there does seem to be a slight oil residue in the header tank but the sump oil is clean.
It would be nice if it wasn't the head gasket but i'm not sure what else would cause all the sludge, i know you can get a bit through damp/condensation and lack of use.
Could it be air flow meter?

jt_armstrong · Feb 23, 2012

whydididoit said:
It's had a new coil pack, new leads, new plugs and a compression test which showed all cylinders at between 155 -175.
The breathers were completely full of beige sludge and there does seem to be a slight oil residue in the header tank but the sump oil is clean.
It would be nice if it wasn't the head gasket but i'm not sure what else would cause all the sludge, i know you can get a bit through damp/condensation and lack of use.
Could it be air flow meter?

When you changed the plugs did any of them look steam cleaned compared to the rest?
If not then water in the cylinder is unlikely to be the problem. You need to check electrical issues as mentioned by Nathan earlier.

Coolant can get into the oil if the block has a crack in it (normally at the back where the rear cylinder and coolant channel are very close). This wouldn't necessarily show up on a compression test. Same sympton could come from a bad gasket which has split in the same area mentioned above.

whydididoit · Feb 23, 2012

No all the plugs looked fine. It doesn't overheat at all and there is no steam/smoke from the exhaust but the breather pipes were full of gunge and the plastic insert in the O/S rocker cover breather outlet was solid with crud.
I can rule out fuel because it's the same on gas and petrol so it has to be air or electric, but where the hell do i start

Hawaii · Feb 23, 2012

might have been an old problem that the previous owner fixed but then didn't clean out all the crud.

Before you start tearing things down, try removing all the crud, making sure all fluids are clean and see how it goes

whydididoit · Feb 23, 2012

Yes i think i will, i've ordered some new breather pipes but i need to get it running properly first.
Misfires are bloody annoying because it could be so many things. I don't have any error codes showing though.
I can get it on a diagnostic check but not for 2 weeks

because they're booked up so i thought i'd try and do it myself and hope someones had the same problem and tell me exactly where to look.

ovalandrover · Feb 23, 2012

Are the plug leads on the the right plugs check firing order

whydididoit · Feb 23, 2012

I assume they're on right because it ticks over lovely and only starts misfiring under load.

jt_armstrong · Feb 23, 2012

whydididoit said:
I assume they're on right because it ticks over lovely and only starts misfiring under load.

Check them to make sure. Costs nothing.

whydididoit · Feb 23, 2012

Worth a try but i don't have a manual so would you know off hand which lead goes to which plug?

Fix it? kick it? or buy a new problem?

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