P38A P38 4.6 Buying Advice

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sz00

New Member
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Hi all,

I am going to have a look at a RR P38 4.6 (Thor engine) this weekend and I was wondering whether you could give me some advice on what to look for and more specifically what checks can I do to ensure no cooling/engine block issues? The RR has covered about 150k miles and it has been with the last owner for more than 10 years. He told me that the head gaskets have been done couple of years ago and that it has been OK since that (never overheated previously- just loosing coolant slowly). He sounds genuine but still are there any simple checks I can make to ensure no cooling issues?

Thanks in advance,

John
 
There are quite a few places for the V8/P38 to leak coolant..

#1 The heater matrix O rings are an issue with all p38's this will soak the carpet with OAT, chances are you'll smell it and feel it, the carpet gets sodden..
#2 The front cover can leak, along with the waterpump
#3 Headgaskets
#4 Valley Gasket

It is imperative to get it up to temp, take it for a nice long test drive, when you return lift the bonnet and listen to the motor, it should be whisper quiet..
The Rover V8 can have a tick attributed to a good few issues.
#1 Tappets, usually crap which blocks the oil feed hole and NRV in the tappet the easy way to know whether it is tappets or liners, is the tappet will particularly be audible from cold start and continue until hot, if bad..
Another issue is the tappets and cam themselves are worn and can no longer take up the slack..

#2 cylinder liners can slip in the block, this noise ONLY manifests when hot, due to a design flaw in the casting the water jackets are offset in the block and the coolant galley sidewall is quite thin towards some bores and can crack if overheated, this causes the aluminium block to shrink away from the steel liner, and you get a very audible "clack clack clack" noise when hot, this the the liner moving with the piston..

#3 Worn timing chain, which again makes a tap noise,

"cooling system"

The p38's cooling system is marginal at best,

Worn Viscous fans and knackered water pumps plus clogged rads are but a few of the issues that can plague the P38..

The Rover V8 is an all aluminium V8 and it is all too tempting when having leaks to fill it with just plain water, which over time will cause the block to corrode, which blocks the rad with silt and causes the engine to run hot, which exaggerates the liner issue

The VC in the fan can also cause issue, give it a spin with you hand when cold, it shouldn't spin like a top, it should turn but not freely.
There is a documented "newspaper method" but i doubt the owner would let you shred a news paper with his fan ;)

Water pumps can also fail, the indicator is (1) a pretty evident noise (2) a leak from the weep hole on the bottom of the pump, this indicates water has got past the grease seals on the bearing and its ****ed. to be frank ;)

The Front cover can also leak, this usually can be rectified when the water pump is done, an involved job as the sump has to be dropped, but not too bad..

Next up in the Valvetrain..

The V8 is a quick beast, not so much in standing 0-60 but the mid range pull should be pretty good for something with 407nm all available at 2400rpm if it is sluggish expect the cam to be worn, which is common on neglected engines this is usually accompanied with the valve-train tap from above ;)

More to add on that front if required..

AUTO BOX..

The 4.6 is fitted with the ZF4hp24 the shifts should be almost unnoticeable if the gearbox has a shunt or slurrs between gears, expect neglected oil changes to be to blame..
under light acceleration it should change at around 1700rpm, make sure sport works too!!

Check Low range works too, as this is seldom used, the grease in the servo motor turns to concrete and stops the motor working..

Regarding transmissions, the transferbox VCU can seize which causes the front wheels to skip on tight turns try and do some tight turns in a carpark and make sure the front wheels don't skip..
Also on that note..

Check the tyres, they should be a matched set, tread patterns most important as dissimilar treads will cause the VCU to burn out..
The VCU detects a "really" rather than "quite" difference in wheel rotation and grip... ;)

Also listen out of a "chirrup" sound coming from the passengers footwell on overrun this is a sigh the morse chain in the transfer box is slapping the casing and will eventually cause it to snap, with bad results.
especially prevalent on badly maintained or abused examples..

"brakes"

Check the brake fluid, colour should be clear, if it is black that is a sign seals are breaking down..
When the ignition is cycled a Humm should come from under the bonnet, this is the pump pressurising the accumulator, this should stop after 10secs if it continues for a good while then you either have a leak or the accumulator is shot..
Latter is more common..

Worth noting the brake fluid level too, it should be on the full mark or above after standing, if it drops significantly after the pump primes, this is a sign the accumulator has worn. the gas has escaped the accumulator sphere and the space it used to occupy is being taken up by the brake fluid, the butyl seal in the sphere usually fails..

More to come when i can think! ;)
 
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Get a diesel.......
SMirC-thumbsup.svg.png

:p
 
Answering this question is always hard. It's a common occurrence here in the States that someone will have enough money to buy a good reliable Civic. That's also just enough to buy the cheapest Rover for sale on Craigslist... and the bastards then treat it like a Civic. You are going to look at a 20 year old P38 with 150k miles which most certainly has had several owners already. 150k miles is where issues really start to crop up so I'd want to see a folder with 10 years worth of receipts in it. If you buy that vehicle regardless you are agreeing to become a mechanic. We all think we won't be 'that guy' and we trust our instincts but he is selling it for a reason!
- Ask to have the vehicle cold when you look at it so you can see and hear what it does upon cold start and as it warms up. Bonnet open.
- Slip liners already mentioned but they're no joke.
- Old fuel pumps on these fail, and with no warning. Number one P38 issue is a failed fuel pump. So when was it replaced last? It very well could be original.
- The heater core o-rings are a pain to replace and thus neglected. You can't tell they're leaking just by looking at it but they're dripping into the carpet foam. It will never dry out. UK P38's may route these differently but a quick way to tell recent leaks is stick your hand in where the carpeting meets the center console in the driver's foot well and feel for the foam underneath the carpeting. Coolant has a bitter taste... :( Remove the floor mats and check there as well.
- Related to heater core is the Book symbol on the HEVAC. That means blend motors are toast or a bunch of other things. Fixing requires pulling the entire dash out of your car. Worst 3 days of my life. Pulling the entire dash (one does not just pull the dash off a P38!) just to repair the heater flaps is soul crushing. https://www.landyzone.co.uk/land-rover/p38-hvac-self-diagnosis-book-symbol.151245/ Even if not present you'll want to test every heat position and the AC because he could have cleared it before you arrived.
- In the engine bay on the driver's side there's a large square fuse box. Pull off the cover and you'll see yellow and green cube relays. Check for burn marks on the relays and in the sockets. The yellow one's can look toasted but also can look new yet still be failed. If you buy that P38 just replace this and all the relays together. It's quite cheap and will side step so many issues later. This is root cause of most intermittent, hard to isolate electric shorts but is also an easy fix. Those relays control the fuel pump, brake system, EAS, ABS, heater blower motors, lighting, everything. And they're probably original. :)

- Working on a P38 is never as straight forward as you expect it to be.

People buy Rovers because they are charming and nice to drive but some of those owners also try to fix the issues piece meal or half-assed, or treat it like a Civic, just so they can save money and it never works out. The previous owner might be one of them.
 
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- Does the cruise control work? He has to prove it.
- You'll want to push every button, open and close every door, windows and sun roof open and closed. Does every speaker and sub have sound?
- Is there water where the extra tire lives?
- Do the heated seats work? Electric seat buttons all work?
- There are electronics behind each door card that are linked to the security system. If they fail they'll disable the engine. Parts are no longer available and must be rebuilt.
- There's a unique code (for US P38's anyway) to re-enable the engine. Ask for it.
- Key fobs will have unique serial numbers on the back which often wear off. Each fob is linked only to that car's security system.
 
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- P38s are sensitive and want a good battery in the 900 - 1100 CCA range. A failing battery is the other common source of random, non-related electrical errors. The battery is in the driver front corner under a big plastic cover. You'll need a coin or a screw driver to remove it.
- There's a coolant return line that snakes over the top of the engine, the heat from which will make it brittle. This line runs to a throttle body heater plate brilliantly mounted upside down. That plate often leaks down on to the rocker cover. Common but easy fix.
- The rocker covers will always leak. Tighten them down every oil change to stay ahead of it.
- Sit in the drivers seat, at idle, and feel for intermittent vibrations coming up through the seat. Won't be tied to engine RPMs. Repeat for front passenger seat. Could be a misfire, or just worn UJs.

You guys have all that required MOT maintenance which we most certainly don't have so all the things I mention might not be as relevant.

Alright, I'm going to stop now. Please take pictures!
 
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