Hi all,

It's a while since I've been on here, the P38 has had a few bits done here and there, like blend motors, but in general for the last couple of years it's all be fine.

A couple of weeks ago I noticed a new ticking noise. It seems to be from the passenger side, it's not there when you first start the engine from cold, but starts after a couple of minutes, once it warms up.

A few years ago I partly stripped the engine down, to replace head gaskets, camshaft, lifters, etc and installed reconditioned heads from V8 developments, since then other than a noise that I've posted on here about before and seems to be somewhat common, it's been smooth and quiet.
Yesterday I did an oil change, as it is almost a year since the last one, despite only doing a couple of thousand miles since the last one. I hoped that fresh oil might have been all that way needed and the ticking would disappear, however unfortunately not.

Like most, I always have slipped liners in the back of my mind whenever I hear a noise that shouldn't be there. So to be sure, I did a quick coolant exhaust gases test with the coloured dye (was fine) and also checked all the spark plugs on the passenger side, but all were the same, no signs of water getting in. Plus when I had head gasket issues previously, I had coolant loss from over pressurising, a misfire and things, which I guess you'd expect if the issue was liner related.
At the moment other than the ticking noise everything seems to be okay, it runs fine and not using any coolant or oil.
Today I took the rocker cover off and then removed the rocker shaft, as I thought maybe it had a crack or damage, but I couldn't see anything wrong with it.

So I don't really know what to try next, the lifters were all new when I rebuilt it with the new camshaft, so I'd hope it wasn't a lifter, but I guess it could be. It could also still be the rocker arms or shaft too I guess. Worst case it could be a slipped liner, slapping up and down?

Here is a video of the noise, when warmed up, and with a gentle few revs - https://youtu.be/rVi6JLTqwg4?si=xwTyQqunoY5GN4s7

Any ideas what I should try next or anyone had similar?

What oil are you using? There' was a batch of rockers with pads that weren't properly hardened but that would be more of a single tap from one cylinder. The reconditioned heads would almost certainly have been skimmed so the lifter pre-load could be at the limit and you need shims under the rocker pedestals. But if that was the case I would expect it to have always been there unless it was right on the limit and now a little wear somewhere means they are now at the limit. See https://www.v8developments.co.uk/preload.htm and https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://rimmerbros.com/ItemFiles/Manuals/Rover%2520V8%2520Cam%2520Follower%2520Preload.pdf&ved=2ahUKEwixvpmhrNeTAxVbWUEAHdUxDyEQFnoECDQQAQ&usg=AOvVaw3mLg0YlXpGfbKlDj4rHFNf

Thanks Richard!

Well I use 10w-40, to be honest I always have and it's been fine, then I bought a couple of bottles earlier in the year in preparation for the next oil change as usual. Since the tapping started I've been reading about 10w-60, which if I didn't already have the 10w-40, I'd have given it a go this time.

When I rebuilt it, I stupidly decided not to test the preload and therefore didn't use any shims. I guess once I put everything back together and everything was running fine and quiet, I thought I'd not need to bother with shims. Since the rebuild which was I think about 3 years ago now, everything has been fine, no ticking, no coolant or oil use etc. The other noise that I've posted about before is lower down and I asked a Land Rover independent specialist (reluctantly had my ball joints done there, as I didn't have the time last year or tools to do them myself) and at first they said what noise, which is reassuring that it's a common thing with these V8s and then when I pointed it out, they reckon it is more likely from the gearbox and nothing to worry about, just a typical noise that some have.

I've been searching around online this morning and seen a few different people that had issues with the cups in the rockers being loose or excessively worn. Yesterday I was more focused on the pads and rockers themselves than the cups where the push rods sit.

I think I need to take the rocker cover back off and look deeper at the cups of the rockers and the rocker shaft.
Seen as most other things have been replaced over the last few years, maybe it's time to go for new rocker arms and shafts, as well as new push rods. Then I can at least rule them out and test the preload and install shims if needed.
Should I choose to go down the route of new rockers, what rockers have others opted for? Not so keen on the idea of Britpart ones, but looks like there aren't many options...

Your car should be too late to be affected by the rocker cup problem, but after 25 years who knows what bits are inside an engine. This TSB shows which ones had the problem.

To be honest I won't fit Britpart if it is something that is 'mission critical' so would be wary of using their rockers. Turners list alloy rockers but show them as out of stock but they also list steel ones described as aftermarket but with no mention of who made them. I'd also be inclined to take the rocker shaft off and closely inspect the shaft and rockers. Before unbolting it, check to see if any of the pushrods will rotate easily. If they do, that is a pre-load problem.

I agree that some always have a slight knock, my car has always had one and I've noticed it on others to a greater or lesser degree. Mine was still there after the engine was rebuilt by V8 Developments and more noticeable from under the car which made me also think gearbox or torque converter. However, after 454,185 miles my original gearbox died on me (actually it was the torque converter internals that had broken up) and it was replaced with a 4HP24 from a low mileage 4.6 and the noise is still there. So the only thing in that area that hasn't been replaced or rebuilt is the flywheel and I don't feel inclined to remove the gearbox or move the engine forward to replace it when it may make no difference.

Yeah that's the thing, at some point the car had a replacement engine, a number of years before I owned it. There is a receipt for engine replacement and labour, but no details on what it actually truly included or age/mileage of it. So no idea what the age is of the rockers.

When I stripped it down the other year I was pleasantly surprised by how clean it was under the valley cover and since the reconditioned heads and new camshaft went in, overall it's a really clean engine on the inside. In fact when I took the rocker cover off yesterday the heads look brand new still. I've only done probably 6k miles since the rebuild work and I run 90% on LPG and keep oil changes strictly to yearly.
That said the rocker arms and shafts are probably the most used looking parts now internally, at least top end side of things.

Yeah the other noise I've really stopped worrying about, I'm not fully convinced it's the gearbox to be honest, I always feel like the noise comes from further forward, so really not sure what the cause is and not too bothered anymore.
This new noise is more concerning, as it can be heard clearly with the bonnet shut and pretty loudly.

I shall take the rockers back out and inspect more closely over the next few days and decide where to go from there.

I suppose I worry too much about liners whenever I hear any noise :/

Do Thors have the same purge canister valve that GEMS ones do? Because that makes a fast tapping sound that is worryingly like a dropped liner, once the engine warms up and only at idle.

My P38 had a ticking noise for at least ten years. It was cured by having V8 Developments completely recondition the engine,

Good timing on this post. My 4.6 V8 has been ticking over the last 12k miles I've owned it. Sitting at 207k, it was rebuilt at 165k and has always had 20w50 fed. This could be either the camshaft or exhaust manifold (it ticks the second the engine starts), but I'd like to play with the oil as it's due for a change.

Will 10w40 suffice? I'm on the brink of ordering it, but would like some input.

Going thinner will only make it worse if it is oil related. If it was exhaust manifold, chances are it would get quieter as it heated the manifold up and go away once hot.

Gilbertd wrote:

Going thinner will only make it worse if it is oil related. If it was exhaust manifold, chances are it would get quieter as it heated the manifold up and go away once hot.

This is the sound - https://youtu.be/7DsdQQsvo9k

The second part, which is recorded from the footwell. The microphone does not pick it up well, but there is a subtle rattle as I accelerate. I've got myself booked in a few weeks to get this investigated. I do hope it's the exhaust gaskets.

Definitely doesn't sound like an exhaust leak. Sounds more mechanical.

Hmm, so an update to mine, I bought another rocker assembly set, so that I had spares of everything before I disassembled the rocker cover again. I found that one of the push rods spins freely on one rocker. When I look at the rocker it's not easily visible any damage really, but I suspect the ball head is slightly recessed. I swapped over to a full new shaft and rockers, as well as all new rods. All the rods are now firm and feel secure.

I started it up and it had an awful misfire. I plugged the nanocom in and it's misfiring on both cylinder 1 and 4, plus a few random misfires on other cylinders. It was fine before... I've just taken the rocker cover back off and run the engine with it off to check everything over. It seems okay, oil is pumping nicely and although it's not had chance to warm up there is no noticable tick. However the misfires are a new issue. It seems it can't be directly related, as cylinder 4 is on the opposite bank that I've not touched. I'm wondering if I damaged a wiring loom or what now... Any ideas where to start?

I would suspect it's something you've disturbed while doing the other work. So have a good look at wiring to the coils and HT leads, I appreciate you've only been working on one bank, but 1 and 4 are off the same ignition coil pack (but not the same coil) so will be next to each other.

Thanks Richard, I've been working through the wiring to the injectors, coils etc today. It's been a long process of carefully removing old insulation tape and messy wiring from whoever fitted the LPG conversion years ago.

Does anyone know the pin out for the connectors into the sides of the coil packs? (The 3 pin connections into the main engine loom). I'm trying to trace these now, but struggling to find the details in rave. I've found the connector (C0156) for coil pack 1, but I can't find which pin leads to where in the loom.

Edit:
Should the coil pack be grounded via the connectors or is the grounding purely from the screws to the inlet manifold?

Yesterday after the initial start, it really struggled to start again, it was running so roughly and would barely turn over. It smells of unburned petrol. So today I focused on the injector wiring, knowing these had been cut previously for the LPG install. I found one break in the insulation on one of the negative wires to the injector for cylinder 8, which may have been able to touch the air inlet manifold and short to ground.
Other than that I couldn't find any problems, so put the inlet manifold, maf and intake pipes etc back on and started it again. It turned over better than yesterday but was rough, initially the Nanocom wasn't showing any misfires, but you could feel and hear the misfires through the vibration from the engine. Shortly after it was showing misfires again on cylinders 1 and 4.

Yesterday I'd cleared the errors on the ecu, so today it was a fresh start. I got error P0300 for misfires and weirdly P1303 for cylinder 3 misfires... Yesterday it was errors for cylinder 1 and 4.
Along with the random misfires on all cylinders yesterday, it's making me think it's not specifically only 1 and 4, it's just they seem to be worse.
It must be wiring related, but I just don't know what or where, all the wiring around the injectors and the manifold that has been removed looks okay and from testing continuity from various places like the LPG install connectors back to injectors etc seems to be okay. The 12v feed to all injectors appears okay too, running back to the engine ecu connection block. The injectors themselves are all showing around 14ohms of resistance, when tested individually.

Hopefully still relevant as you edited and added to your post while I was typing this reply. Hopefully, the cylinder 3 misfire is a red herring, although P1303 isn't listed on my list but P1313 is a catalyst damaging misfire on bank 1. A cylinder 3 misfire would be a P0303 code.

On C0156, the ignition coils have an ignition switched live on a white wire on pin 2, a red wire on pin 1 which goes to pin 8 on C0638 (small 9 way black connector) at the engine ECU while pin 3 has a Blue wire which goes to pin 2 on C0638 at the engine ECU. To fire the spark plugs, the ECU grounds the relevant pin and interrupts that ground, just the same is in the old days of points (if you are old enough to remember points), which causes a spark.

However, C0156 is connected to coil pack 1 where the red wire fires cylinders 5 & 8 while the blue wire fires cylinders 2 & 3. As you have a problem at cylinders 1 and 4, you need to be looking at coil pack 2 and C0052. That has the same ignition switched live on a White wire on pin 2, a White/Blue wire on pin 1 (which feeds cylinders 1 and 6 and is connected to pin 7 at C0638 at the engine ECU) and a Pink/Black wire on pin 3 (which feeds cylinders 4 and 7 and is connected to pin 6 at the engine ECU).

C0052 is at the other side of the coils (on the RH side as you look at it from the usual position of laying over the top of the engine, but LH side by standard convention of as seen from sitting the in the driver's seat)). The wiring in both these connectors is screened with a braided screen that is grounded.

The Thor engine has another 3 pin connector directly above coil pack 2 which has a grey connector that should go to the idle air valve and I have heard of people getting that mixed up with the black connector that should go to the ignition coils. Do that and you will get misfires on the cylinders that are fed from coil pack 2. As this will have been unplugged to remove the upper inlet manifold to get to the LH bank rocker cover, check that the two connectors haven't been swapped.

The LPG system cut wiring will almost certainly be pairs of coloured wires, a solid colour and the same colour but with a black stripe. The petrol injectors have another ignition switched live on one side (on a Brown/Orange wire) while the other wire, the one between the ECU and injector is the one that will be cut. The wiring can vary between different LPG systems but usually the solid colour wire connects to the cut end from the ECU while the back striped wire goes to the injector.

There will also be an ignition switched supply for the LPG controller which would normally be taken from either the Brown/Orange supply to the injectors or the white wire to the ignition coils and quite probably an rpm signal which is often taken from one of the wires to the ignition coils or it may have been taken from the camshaft sensor.

Thanks, really appreciate all your knowledge!

You're right it was actually P0303 for cylinder 3. I think P1313 was amongst the previous days errors, but I stupidly forgot to save or note the error codes before I cleared them! P0300, P0301 and P0304 were definitely there the day before.

Ahh, okay that makes sense now, the ground is used on the coils to switch the spark and 12v is live at all times (well with ignition on). That explains why there was no continuity between any of the 3 pins and the metal plate that holds the coil packs. I was for some reason expecting there to be a constant ground and the other 2 pins would be +12v for switching the coils to control the spark.
There has only ever been one bolt holding the coil pack plate to the inlet manifold and even that isn't the correct bolt... I really need to find what size they are so I can secure the coil pack plate properly.

Yes, there is a grey 3 pin connector to the idle air valve, that comes from a smaller branch of the loom that has this, the throttle body sensor connector and one to the purge valve.
I cheated when I removed the inlet manifold and didn't actually disconnect the coil packs. I didn't fully remove the manifold, I just disconnected enough to be able to move it up slightly and give enough clearance to get the passenger side rocker cover off. That meant the coil packs stayed connected just pushed back enough to not prevent the manifold from lifting up.

Also correct with the LPG wiring, there is a wire spliced into the +12v at petrol injector 1 that is used for the ignition 12v to the LPG ECU. I'm not sure where the RPM wire is, I didn't pay attention to that to be honest today.
All the injectors negative feeds have been cut and go via 2 connection plugs to the LPG ECU. To make it extra annoying, the wiring hasn't been crimped directly into these plugs, but soldered on to pre-crimped wires in the plugs, which use different colour wires! So the wire colours change multiple times!

It's a mystery, I convinced myself it was an injector wiring issue, with something shorting, but apparently not.
All the ignition leads were new when I did the head gaskets and rebuild the other year. The coil packs I don't know how old they are, as I've never replaced them, but have always been okay.
The MAF I've also replaced with a new Bosch one a few years ago. What's so annoying is other than the new tick noise, it's been running really nicely. No misfires on LPG or petrol, decent MPG (about 20mpg on LPG on a longer run) and idled smoothly on both LPG and petrol too.
So frustrating :( Something relatively simple has turned into this!

You need to identify if it is an injector or ignition problem causing the misfire. To check the injectors, you need a noid light. You can buy them but they are easy to make. All you need is an LED with a 470 - 1000 Ohm resistor in series to limit the current. Identify which way round it needs to be connected to make it light up and poke the wires into the back of the plug to the injector. As an LED is fast acting, you will see it flash when the ECU pulses the injector. As you have a problem with 1 and 4, connect it to a working one (cylinder 2 should be easy to get access to) and you will see the LED flash every time that cylinder fires. Then move it to cylinder 4 and see if it still flashes. If it doesn't, you know the problem is on the wiring to the injector, if it does and that cylinder isn't firing, it is sparks.

Oh that's a good idea! I do have some 3mm LEDs and resistors, so can try this on the injectors!
I can wedge one in both injectors 1 and 3 at the same time and compare.

I've also just found my spark plug tester, just one of those cheap inline ones, but at least I can check these too now.

Will have a look at it all later and see what I can find.

Thanks Richard!

1 and 3 might be awkward to get to on a Thor with the big bunch of bananas on top of the engine which is why I suggested 2 and 4. But the principle is the same. Combine that with a inline spark tester and you should be able to identify the source of the problem. Then you just have to find the cause.....

Finally had chance to do some testing today. I lifted the intake manifold again, as I couldn't get into the injectors on either side to get a reliable connection. I put an led on 1 and 3, then put the spark tester inline on cylinder 1.

Before I started it up, I reset the errors and adaptive values (decided that the adaptive values would be a mess after last week's testing).

It fired up, but was immediately rough. I checked the LEDs and both were blinking as I'd expect. The spark tester was also blinking. I checked the nanocom and the roughness timing was extremely high for cylinder 1, plus not good on 4 and 6 (but not quite as high numbers). 7 was also not great. Occasionally 8 would show a little roughness, but not anything like the others and I'm not sure how the nanocom measures the roughness on each cylinder exactly, so maybe an anomaly?

I then moved the spark tester to cylinder 3 and started it up again. The tested looked similar?! I'm not sure, the red light is pretty dim on both, so not really great for testing.

However cylinders 1, 4, 6, 7 are all on the same coil pack side...
I tested the 3 pin connector again for continuity back to the ECU. The 2 outer pins, are fine, both go to the same connector block on the ECU (but different pins of course and there is no short across the pins). Where does the center pin go to?

Either way, it's something coil pack related, maybe the coil pack is failing? It's doing something for the spark tester to light up, but it surely has to be related to this, based on the cylinder numbers with issues. It doesn't sound nice at all when it's running.

The nanocom shows errors P0300 and P0301, the live misfire input aligns with that as there are a lot of misfires on cylinder 1 and occasionally a couple on cylinder 4, but seems to be not enough to trigger the fault code.

Can the coil packs become weak? Looks like it's time for new coil packs... Any way to test them, if I remove them?