HELP!!!! Overheating V8. Going mad here....

Help, anyone please?

I have a P38 2002 4.6 Vogue. Proper LPG conversion.

Lets face it here and now, I and most of the users of this forum cannot afford the amazing high prices of LR and most other garages so would rather get an opinion from the 'real experts' to try and save a mortgage or two.

So here goes...Ever since I bought it 6 months ago it has used a litre of water a week, sometimes more, sometimes less, sometimes nothing. Within a week it overheated. It didn't creep up it just exploded. Amazingly a LR service guy was passing and had enough water to get me home, saying that there was nothing he could see wrong but would come over and sort it. He didn't come. I filled it up again and apart from using water nothing seemed wrong. The oil is clear.

I have had advice from a lot of people over the months, some experts and some not. The most regular and boringly obvious suggestion from those who know on the web is that the liners have shifted and the bored have turned to cheese. This initial lazy scare diagnosis caused me to buy some strange ceramic snake oil from the net and get a mechanic to fill the system up etc etc. This seemed to stop the leak for a week but it then resumed at the normal pace. I tried a couple of Halfords own stop leaky things which just go straight into the system. Hey presto two weeks without a leak!!!

Then it overheated. There was now an obvious leak from the water pump, the bottom of the engine and bits were now covered in an oily/water mess. Diagnosed as a knackered water pump, the fault was fixed last week at great expense and seemed to do the job for 5 whole days. No leaks, no mess, everything perfect. Then last night it overheated.

With this chronological list of problems can anyone with knowledge suggest, sort, repair, hit it with hammers? The last advice is an airlock in the system behind the thermostat. Perhaps it needs something as simple as a thermostat as the old one may be glued up with all the rubbish I've poured down it?

I'm in Bucks by the way...

I reckon initial diagnosis was right. The block will be knackered. I've had three Rovers with 4.6 motors and they all went the same way.

get a sniff test done

a snif test and check around the lpg sytem. Rad is also a good un?

nathan5346 said:

get a sniff test done

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Would the results of a sniff test have anything to do with overheating?

Yes.
Do a search on overheating theres plenty of em on ere but i reckon from the things that have been done youve got a knackered engine but dont take that as gospel

gavbriggs said:

a snif test and check around the lpg sytem. Rad is also a good un?

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The rad seems to be OK, it is not leaking and the engine runs top dead centre temp wise.
The strange thing is that the physics of a cooling system are very simple. I haven't been able to get a straight answer from anyone. I you remove the engine from the equation then you are left with a pipe of coolant with various bits controlling the flow to and from the header tank. I assume this is a universal solution and to test it would involve removal/replacement of these parts in some kind of order.
I would love somebody to explain why, if the 'block is knackered', the symptoms above in my initial post would physically happen. No one, even those who claim to have had many Range rovers goes bang on them, has been able to explain what, how and why.
If the block isn't knackered then it has to be part of the cooling system going wrong.
Come on all you experts, someone diagnose this so I can give one of you a few hundred pounds to fix it for me....?

nathan5346 said:

Yes.
Do a search on overheating theres plenty of em on ere but i reckon from the things that have been done youve got a knackered engine but dont take that as gospel

Click to expand...

Yes but....
I just don't believe it as a 'knackered engine' would be knackered full stop. A knackered engine would imply major parts being dead or dying. The engine at the moment runs perfectly when it isn't overheating (3 times in six months). I ran up to Yorkshire last month at 90+ both ways and it didn't use a drop of water or oil.
Something just doesn't add up with the 'knackered engine' diagnosis.
Thanks for replying though...

You need to get a sniff test done 1st then if thats ok its a process of elimination starting with the cheapest.
What are the specific questions you want answers for?

treborretnim said:

Yes but....
I just don't believe it as a 'knackered engine' would be knackered full stop. A knackered engine would imply major parts being dead or dying. The engine at the moment runs perfectly when it isn't overheating (3 times in six months). I ran up to Yorkshire last month at 90+ both ways and it didn't use a drop of water or oil.
Something just doesn't add up with the 'knackered engine' diagnosis.
Thanks for replying though...

Click to expand...

Knackered = slipped liners/porous block, but like i said a sniff test must be done to confirm whether or not there gases in the water

treborretnim said:

Yes but....
I just don't believe it as a 'knackered engine' would be knackered full stop. A knackered engine would imply major parts being dead or dying. The engine at the moment runs perfectly when it isn't overheating (3 times in six months). I ran up to Yorkshire last month at 90+ both ways and it didn't use a drop of water or oil.
Something just doesn't add up with the 'knackered engine' diagnosis.
Thanks for replying though...

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What's the pressure like in the coolant pipes? My TD5 has NEVER overheated on me yet overpressurises and chucks out a litre of water every now and then when it feels like it. I got the head gasket done last year and had the problem come back within a few months. Turned out the head was cracked in 2 places. For some reason they never showed up on the pressure test. Prior to having the headgasket done my landy had passed 3 sniff tests and 3 compression tests. I have travelled 8000 miles on an engine running with 2 cracks in the head.

still believe it doesn't add up?

nathan5346 said:

Knackered = slipped liners/porous block, but like i said a sniff test must be done to confirm whether or not there gases in the water

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Oh I see... I thought you meant sniff test the LPG system.
Anyway, to address this dropped liner/porous block thing. Would a problem like that not always and consistently be showing? this car has times when nothing is evident and it runs without a fault?

Ta ratty, but one sunny day doesn't make a summer does it?
Having said that you are quite experienced. Do you know anyone who can look at it for me and/or do the work?

My discovery did the same thing. Some days it would be ok and others it would boil up and blow the coolant out.

I think that what was happening with mine was when the engine got to a certain temperature the expansion in the block would open up the crack and allow the pressure from the combustion in the cylinder to leak into the cooling system. This would cause the engine to over heat and blow the water out. However if the engine neve got to this temperature threshold the problem would not occur. Furthermore, if the engine did reach that temperature, but only for a couple of minutes at a time, the pressure in the system would leak away and again the problem would not occur.

That's my theory anyway. I did spent a lot of time thinking about it and tried everything on the way before finally acceping that the block was fubar.

davieladd said:

My discovery did the same thing. Some days it would be ok and others it would boil up and blow the coolant out.

I think that what was happening with mine was when the engine got to a certain temperature the expansion in the block would open up the crack and allow the pressure from the combustion in the cylinder to leak into the cooling system. This would cause the engine to over heat and blow the water out. However if the engine neve got to this temperature threshold the problem would not occur. Furthermore, if the engine did reach that temperature, but only for a couple of minutes at a time, the pressure in the system would leak away and again the problem would not occur.

That's my theory anyway. I did spent a lot of time thinking about it and tried everything on the way before finally exceping that the block was fubar.

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Finally!
That sort of sounds right, denial is a strange bedfellow, makes all suggestions sound like accusations! So is there anyway of stopping it getting to that temperature? Fitting different thermostat of bypassing it etc? It's not that I can't afford to get the engine replaced it's just that right now I'd rather bodge it until next year. The shiiit who sold it to me should be hung, I know he knew about it before and simple glossed over the fact...

treborretnim said:

Finally!
That sort of sounds right, denial is a strange bedfellow, makes all suggestions sound like accusations! So is there anyway of stopping it getting to that temperature? Fitting different thermostat of bypassing it etc? It's not that I can't afford to get the engine replaced it's just that right now I'd rather bodge it until next year. The shiiit who sold it to me should be hung, I know he knew about it before and simple glossed over the fact...

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Finally?

I meant finally an explanation rather than just 'it's knackered'

Youve had possible causes earlier in the thread you misunderstood them

ok i understand where you are i been there, you say you have put stuff in the cooling have you tried iron tite? if you got pluris block it seels it i know i have it in mine now after doing the heads twice in two weeks i would not beleve the engine was beyond fixing i tried this stuff and that was it back to happy days, but i must warn you if it is slipped liner it will not be any good to you. first thing you need to do is clean out your water easy with hose pipe and let it run for a while if you have tried this my fingers are sore for nothink and i am sorry for wasting your time j

I couldn't find a way to make mine work. I tried EVERY THING. I lived with it for a while but it boiled over on me whilst I was towing a heavily loaded horse box in a single lane contra-flow. My pride wouldn't let me cause a traffic jam so I plodded on. By the time I pulled over the oil had burned away and when I poured fresh oil in, in boiled on the rocker! It got me home, but that was the end of it's useful life!

I'm currently trying to convert a 3.5 motor to run in place of a 4.6 in a p38. Replacement second hand 4.6s are IMHO a waste of time as they'll either be cracked already or about to crack. You could get the liner machined out, the block welded up, re-bored and a top hat put in but that'll be expensive. I'm told that Land Rover didn't see this as being an acceptable solution for warranty repairs so they commisioned Cosworth to make a replacement block. I've never seen one but I would imagine they'll cost more than a quid.