Engine problems with lpg unit

[mistalrov]

I have a 2002 P38 ranve rover woth a 3.9 engine. A landi LPG unit was fitted, and since it keeps blowing head gaskets. Has anyone else had this problem and what could be the causes.

[rossko]

The gas setup might be bad on the lean side, causing overheating. Overheating = gasket death on rover V8

The gas regulator might be bad, leaking gas into the water jacket. Gas in water jacket = air locks and water loss = overheating = gasket death.

But gasket failure is pretty routine on RV8 anyway, and might be absolutely nothing to do with gas. Gasket failure = water loss = overheating if not dealt with immediately. Overheating = warped head(s). New gaskets fail again quickly, due to the warp. Endless loop .... except that every time it overheats, something else gets stressed, and it progresses to leaking radiator, hoses etc.

A fairly normal sequence of events would be a hose failure, due simple old age. But if being thrashed on the motorway at the time, it might overheat before the driver notices. The hose is fixed, all is well. Two weeks later a head gasket starts leaking internally, due to the past overheat. If no-one notices the water loss, we get another overheat ... the radiator seeps. That's noticed and fixed, but the leaky head gasket still exists. Weeks later its diagnosed correctly, new gaskets, but they won't last long because the head was warped at the first incident ... etc etc

In summary, gasket failure is unsuprising, the difficult part is identifying the original cause and fixing it properly. Else its a saga.

[Gilbertd]

When the head gaskets have been changed, have the heads been skimmed? Although standard practice on any engine, with the LRV8 you must do the job properly or it will quickly fail again. The block faces need to perfectly flat and spotlessly clean, the heads likewise and any slight warping or imperfections removed by skimming. Use the later composite gaskets, new bolts and make sure they are properly torqued down (tighten to 20Nm then 90 degrees on each and 90 degrees again). As long as it is done properly, the head gaskets will not blow because they feel like it, but because of something else. Any air locks will cause overheating as the air expands more than the coolant and the remaining coolant is pushed out. When the engine is hot, try squeezing the top hose and see if it is pressurising. You say it keeps blowing head gaskets, how often? There is also the possibility of cracks in the block allowing the cooling system to pressurise although this seems to affect the 4.6 litre engine more often. Theory says that the bigger engine produces more torque so the mapping of the autobox allows it to slog more at lower revs which can cause localised hot spots leading to cracking. If you do any towing, it's recommended to use the gearbox in sport mode so it changes down at higher revs too.

I suppose it is possible that the LPG system is the cause of the problems if the plumbing isn't up to scratch and is allowing air to get into the cooling system. Is the vap in series or parallel with the heater matrix?

[mistalrov]

Many thanks Blazegas for your advice and comments but I omitted to state in my email that the gasket failure is between two cylinders on the right hand bank. Each time it has been repaired the head has been reground. No significant heat has been recorded unless as you say one injector is running lean. Have you any more advice on this subject

[mistalrov]

Many thanks Blazegas for your advice and comments but I omitted to state in my email that the gasket failure is between two cylinders on the right hand bank. Each time it has been repaired the head has been reground. No significant heat has been recorded unless as you say one injector is running lean. Have you any more advice on this subject

[rossko]

that the gasket failure is between two cylinders on the right hand bank.

Sounds like a bowed or cracked head, re-used stretch bolts, or assembly error, or least likely the block face is dished. Always the same repairer?
Have to say I've never seen a V8 gasket fail like that, its nearly always at the ends not the middle ; though it is very unusual to be able to see where the failure has actually occurred at all.
Why is it thought that the gasket has gone, do you lose water?

unless as you say one injector is running lean.

Not impossible, but I'd be very very suprised if it gave a local heat effect like that. I was thinking more of a general leanness giving a general overheat.

If you suspect the LPG injectors, swap them one side to the other.
Some types can be stripped for inspection by someone who knows what to look for, but you haven't even said what brand you have.

[Gilbertd]

Between cylinders is almost certainly component or assembly error. As Ross says, bowed head (which it shouldn't be if it's been skimmed), damage (my P38 engine blew both head gaskets into the central V because whoever had rebuilt it before had nicked both heads by putting a screwdriver between the block and head), not torquing the heads down properly (in the wrong order or not tensioning them properly), not using new bolts, erosion of the block face caused by it being run with a blown gasket for a long time or, an inherent fault. The only fault I can think of that could cause this is if one of the liners has slipped or it has had top hat liners fitted badly, although in both these cases I would expect it to pressurise the cooling system too. What sort of mileage has it done?

In any case, I can't see it being anything to do with the LPG system.

[mat_fenwick]

Interesting...it's of no direct help to you but we did have a HG failure similar to yours a few years ago on a V8 Discovery.


(If you look closely you may be able to see where it has failed).

It overheated dramatically on the (long) journey after collecting it, due to a clogged up radiator (limescale) and lost water - my wife only stopped when steam started coming out from under the bonnet
Since then it developed pressurisation of the cooling system, and ran roughly on one bank. I never did establish whether it overheated at least partly down to HG failure, or whether the HG failure was caused by the overheating but after a head skim and reassembly it has run well since.

[Gilbertd]

For that gasket to have gone both between cylinders and into the V, I'd say that the bolt at that point wasn't torqued up properly. Maybe the bolt hole had water or oil in it so it hydraulic locked or maybe it just got missed for some reason. I know the LRV8 has a reputation for eating head gaskets and that is usually caused by overheating for whatever reason but most failures the second time round are due to them not being done properly in the first place.

[mat_fenwick]

(Apologies for the thread hijack…) It was actually to the outside of the V, which is the first time I've seen that!
What you say makes a lot of sense, BUT there was no evidence of any recent engine work. The only thing I can think of is that it was marginal enough to seal under normal use, but on a long journey, climbing a hill was enough to tip it over the edge.

Back to the OP, how many failures are we talking about - is this the second (or 10th ) time? Obviously the more times it has been done, the less chance of it being a mistake in the replacement process.

[tommo2009]

the head gasket may be going due to the liners in the engine being shot. they are notoriously bad engines.
for it to happen more than once would suggest there is something else wrong which is causing this issue