P38 V8 4.0/4.6 engine question

Hello All
I have just joined and this my first thread. What is the problem with the V8's fitted to the P38s. In particuler the cooling system. I hear of liner displacement, porous blocks and head gasket leaks. What is the cause of these defects. Is it down to poor servicing, lack of coolant strenght or abusive driving.
Many thanks for any comments
Roger 47

Hello and Welcome,

its down to all the above and the fact that the basic engine design was robbed from buicks scrap bin over 50 years ago, some of these engines go on and live long and active lives, however, some just blow up and die!.

Hi
I am still learning about the quirks of my P38 and as such I have had extensive discussions on this with rpi in Norfolk. They tell me that it is a casting problem with the block leading to fractures behind the liner that lets in water to the oil under load/high temperature. the waterway between the cylinder bores is in some cases very very close to the wall leading to fractures that effectively allow high pressire fluid movements. They reckon that all p38 V8's will at some point need a new engine. Apparently LR had to re cast a new block with finer tolerances to sort the problem.

If you have a V8 that is OK (check for smells of oil in the coolant and excess pressure when you remove the coolant cap) then a revised ecu (a pricey £600) will re map the fuel system and lessen the problem by reducing the running temp. These are also vital if you are running on gas. For LPG, RPI suggest OMVL single point with milenium lambda.

Check this on the RPI ebay shop, if you scroll down you will see a cross section taken from a V8 showing the irregularity of the casting and very thin walls twixt water and oil.

4.6 Land Range Rover P38 Morgan V8 HSE Engine Discovery on eBay, also, Range Rover, Car Parts, Cars, Parts Vehicles (end time 03-Dec-08 15:40:43 GMT)


Cheers

[email protected] said:

Hi
I am still learning about the quirks of my P38 and as such I have had extensive discussions on this with rpi in Norfolk. They tell me that it is a casting problem with the block leading to fractures behind the liner that lets in water to the oil under load/high temperature. the waterway between the cylinder bores is in some cases very very close to the wall leading to fractures that effectively allow high pressire fluid movements. They reckon that all p38 V8's will at some point need a new engine. Apparently LR had to re cast a new block with finer tolerances to sort the problem.

If you have a V8 that is OK (check for smells of oil in the coolant and excess pressure when you remove the coolant cap) then a revised ecu (a pricey £600) will re map the fuel system and lessen the problem by reducing the running temp. These are also vital if you are running on gas. For LPG, RPI suggest OMVL single point with milenium lambda.

Check this on the RPI ebay shop, if you scroll down you will see a cross section taken from a V8 showing the irregularity of the casting and very thin walls twixt water and oil.

4.6 Land Range Rover P38 Morgan V8 HSE Engine Discovery on eBay, also, Range Rover, Car Parts, Cars, Parts Vehicles (end time 03-Dec-08 15:40:43 GMT)


Cheers

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Mmm....... What a load of crap.

eightinavee said:

Mmm....... What a load of crap.

Click to expand...

care to elaborate???

Have a look through the RPI website,they are still peddling cooker ring LPG systems for Gems controlled LP RR's.Anyone who knows anything about Gems will laugh at the suggestion of using such a crude system.The other stuff about using chips to prevent slipped liners/porus blocks is just sales patter - talk to anyone who really knows about the larger capacity Rover v8's and they will tell you its caused by overheating from poorly maintained cooling systems that shows up a weak engine.Week by poor design and sloppy build quality.The story they tell about weak mixtures is rubbish and is easy to prove wrong.

Hi
I recently replaced a 4.6 engine because of a water leak... other answers will give you details, but suffice it to say that There can be a very rapid deterioration as the block generally started life with smaller cyls and they were bored out. So the water and frire bits are overly close and if a leak develops it may be a crack in the block. I've never heard of one being glues as it were - it needs a new block. If you get this problem its a VERY good idea to go to a builder (eg Turner Engineering - Remanufacturer of Land Rover Engines and supplier of Land Rover engine parts) who uses ductile iron linings in the cyls, and this prevents a recurrence of the prob. Don't get a new block from Landrover - they are pricey and will be as the current blocks and therefore likely to fail in the same way. Best of luck

My understanding is that the liners move because of overheating top hat liners are supposedly the solution - as fat as single point with Gems dont bother just get as hammer and smash the air intake it will give you the same result and is a lot cheaper

Hi Roger,
P38 is a great car. Yes it has problems but so do many other complex cars, look on the Merc and BMW sites.
The forums are full of doom and gloom because we don't have one for just the good times.
If you buy one , buy it with the expectation you will have to pay out for repairs then things can only get better.
Enjoy your car.
Fred

4.0 is slightly modded 3.9 and generally more reliable in fact it's same 3950 cc as 3.9. 4.6 can be reliable with stepped linners. I bought a 4.0 se as a bargain fixer upper.

Today was the day I've been dreading but knew was coming. The day the engine block cracked. The cause of the crack, besides the weak block, was the thermostat going and the engine overheating, not by much, on a long journey. I replaced the thermostat first @ £27 but the cooling system was over pressurizing very quickly and then over heating. I now have a choice; scrap the car or spend £2000 on a second hand block or £3000 on a new block(all in prices). The car is a very good example. spot on all round and I love driving it. I've opted for the new since hopefully I'll get another 85,000 miles out of it. My advice to anyone with a P38 is replace the thermostat every 10,000 miles. It won't stop the inevitable but it might buy you some time.

The thermostat is quit reliable. Replaced mine thinking it needed doing. Went back as I thought it was not opening. Not the case it was air in the systyem from the O rings in the heater matrix, also the top bleed off the rad was blocked. Dont rush into the conclusion of BLOCK BLOCK BLOCK. Head gaskets and cracked heads may be the case. There are plenty of folk will give you the doom gloom and ask for the £4k for an engine . Easy money when it can be a lot of other problems

Off the top off my head can't think of any 4.0s that needed a new block due to cracking or leaking. I mean they've overheated and needed gaskets, water pump, rad, fan etc etc but not a new block. Probably asking for trouble as I write this but that kind of failure does seem to be more an issue with the 4.6.

rasheed said:

Off the top off my head can't think of any 4.0s that needed a new block due to cracking or leaking. I mean they've overheated and needed gaskets, water pump, rad, fan etc etc but not a new block. Probably asking for trouble as I write this but that kind of failure does seem to be more an issue with the 4.6.

Click to expand...

i wish you would have told, my 4.0 engine that. the 3.9 4.0 4.6 are all the same block, and all will [can] fail..

Even if you buy a coscast block this can still have the same problems as the Rover blocks, this is because they are sand cast blocks, and can suffer with core shift. The top hat liners have been used in racing, check JE engineering. RPI are good but look around at other companies and see whats what. In 97 and on the better blocks were graded red. These can be great engines (TVR used them) and can produce plenty of hp. Mines done 150k and i'm still tuning it for more hp.

Dig deep in this forum. overheating can be due to a load of problems.
Firstly get a block tester from fleebay £32. When the engines cold take the cap off and warm engine up. When at temp do the block test (big test tube with rubber bung and a bellow at the other end. If the liquid turns orange you have exhaust in your water, so you can go from here. Take out all the plugs and take a good look at them and this will give you an indication where the water is getting in. If the colour in the tube stays blue start looking at pump , rad, hoses, heater o rings , thermostat. Its not a lot to change the whole lot and if its overheated then they've all been under pressure. RPI are good but they can frighten you into spending a small fortune. When they do a LPG conversion they want to chop your spare wheel well off, fit 2 tanks and a stainless exhaust. Not needed and way OTT. Advise offered on here is free without financial gain. I read a thread on here where a new block was fitted and still overheated. Turned out to be a blocked rad ! Turned out to be block rad tiny hose, turned out to be fan.
It may be your block, but get your hands dirty first. At £50/ hour a few threads on here could save you £1500 easy

Excellent advice, Willos.

There be an old sayin

If ye dont put in lad
Dont expect anything out