TDV8 starts but dies instantly

[Ed Poore]

5 minutes ago, Escape said:

Now it starts, tries to settle at idle, very lumpy and usually dies within a second or so.

This strikes me as the crucial bit.

Obviously when it's starting nothing's moving so the ECM has to assume everything is functional and just "hope for the best". Once it's started up then it's detecting a fault and shutting things down. If no fault codes are being logged then perhaps it is a mechanical issue like a jumped timing chain.

I don't know how easy it would be to rule that out - I'm sure if you faff around for ages checking connections etc., and then eventually get around to checking it out and find it's jumped (same thing happened on my 300Tdi) you'll be kicking yourself.

Never had cause to delve that deep into the engine but depending on how genned up you are on electronics perhaps you can hook up the crank and cam shaft sensors to a scope and turn the engine over by hand to see if they line up as expected? Or pull an injector in No1 etc.

[L19MUD]

9 minutes ago, Ed Poore said:

 

Obviously when it's starting nothing's moving so the ECM has to assume everything is functional and just "hope for the best". Once it's started up then it's detecting a fault and shutting things down. If no fault codes are being logged then perhaps it is a mechanical issue like a jumped timing chain.

I

Sadly I think you may be on to something here. Not heard of TDV8s skipping chains though but it is certainly possible

[Escape]

I have to agree with you both. The engine starts with a set of default values, once turning the problem manifests itself. It doesn't feel like the ECU is shutting down deliberately though, more like desperately clinging to idle but failing.

Quote

At the moment we're leaning towards a mechanical problem, like skipped timing chain or something else causing loss of compression.

We came to the same dreaded conclusion it's beginning to look like a mechanical issue... Which might well mean the end of the road for this car, considering it's got around 250k miles and pretty poor bodywork. It was de facto replaced by a newer RRS 3.0 last year, but kept around for occasional use.

[Ed Poore]

Depends on how much time / effort you want but maybe breaking for parts might be the most economical sense?

If you strategically remove stuff to check timing etc., first you might find a "quick fix".

Don't know how easy it is but maybe a quick compression test. Don't know if you can do Dad's trick he did with his Shogun which was a pressure transducer up the exhaust and he could see one cylinder in particular misbehaving.

Maybe something simple like a microphone and record and then look in something like audacity at the amplitude of the peaks.

[Ed Poore]

At 250k could the chain simply have stretched a bit?

[elbekko]

10 minutes ago, Ed Poore said:

Maybe something simple like a microphone and record and then look in something like audacity at the amplitude of the peaks.

That sounds pretty ingenious! Although not sure how well that would work with a V8, since there would be overlap. And especially not if it's not even starting.

 

[Ed Poore]

The pressure transducer would probably work because there'd still be the pulses (hopefully) from the cylinders.

If you could get it into each exhaust manifold you could narrow it down. Up the exhaust it might provide an indication of an issue which you could narrow down.

[FridgeFreezer]

Megasquirt does that by looking at the VR (crank) sensor waveform and timing how long each tooth takes to go past, you can in theory record the same with an audio recorder as VR sensors like most crank/cam sensors are just a large magnet so look a lot like a microphone electrically.

Just be careful as when it's running they can generate quite high voltages an oscilloscope, even a very old rubbish one, would show you a fair bit - DSO138 clones all over ebay for super cheap will also suffice.

Picoscope/Hantek use to have a whole library of good & bad automotive waveforms on their website that was very informative for troubleshooting sensors like this - ABS sensors are the same (variable reluctance) too.

[Escape]

We finally managed to identify the problem.

Yesterday I got my hands on a scope so we tried the relative compression test. It took us a while to interpret the data but there didn't seem to be any evidence of compression loss on one or more cilinders. While cranking over the engine, we noticed it didn't really make a difference if the electric fuel supply pump was running or unplugged. Even unplugged the engine would fire a few times before dying. So the high pressure pump must be good enough to get the fuel from the tank.

Then we started hearing bubbling noises from the intake, surely that can't be normal and they weren't there before! Some more investigation showed oil in one of the hoses from the airfilter to the LHS turbo. And a noticeable drop in engine oil level. So there we have it, one of the turbo's has had it, spewing oil into the intake and possibly blocking the exhaust. 

I was surprised to see the turbo's are not too expensive (£200ish) and if I read the workshop manual correctly should be just accessible without a body-off. So we'll probably give that a go.

Thanks all for the suggestions and support! Even though it's not the easy fix we hoped for, we're very glad to have found a cause.

Filip

[Anderzander]

Well done 👏🏻 

[missingsid]

Geez was that a lucky escape? I rember the video of the diesel engine running away due to burning its own engine oil.

[Escape]

15 hours ago, missingsid said:

Geez was that a lucky escape? I rember the video of the diesel engine running away due to burning its own engine oil.

Very true! Especially as it's an automatic so once it starts running on oil there's not much you can do to stall it, except pull off the intake hoses. And I wouldn't want to be the one undoing the hose clamps while the V8 just behind it is revving towards an explosion!

Next question, any tips to replace the turbos?

Filip

[Ed Poore]

2 hours ago, Escape said:

Next question, any tips to replace the turbos?

Remove the old ones and install the new ones? 🤷‍♂️

[Escape]

You make it sound real easy! Want to come over and show me? 😁

[Ed Poore]

Oh I'm an expert at removing stuff. So I can definitely help on that front! 

[Ed Poore]

Genuinely though I have heard that the sport is much more of a pain than the proper Range Rover so most people remove the body.

Apart from that I don't know much. There might be a write up over on fullfatrr.com or the equivalent for the sport. If not then it would be nice to have one.

[Escape]

From what I've heard and seen, the TDV8 seems a bit easier to work on than the TDV6. The manual claims it can be done without removing the body and I've seen estimates of 8-9 hours to replace 1 turbo. So should be doable. I'll get someone to take some pictures and will try to do a write up.

[missingsid]

22 hours ago, Ed Poore said:

Genuinely though I have heard that the sport is much more of a pain than the proper Range Rover so most people remove the body.

Apart from that I don't know much. There might be a write up over on fullfatrr.com or the equivalent for the sport. If not then it would be nice to have one.

The is a full thread on Disco3.co.uk  about fitting a TDV8 in to a D3 that will have loads of body off pics that might help with the geographyof the engine?

[Escape]

Some progress, finally. On Friday I got the RRS up on the ramp and started disassembling things. I had decided not to take off the body. And sure enough, instruction 8 in the workshop manual, a single line 'remove bodywork from chassis'. Musth have missed that when I first browsed the workshop manual... It is like so many manuals, for some things every nu and bolt is described in detail, even with a separate full set of instructions for the left and right hand turbo despite being pretty much identical, and then something major is just casually mentioned! Determined not to give up without a fight I soldiered on. After about 5 hours I had the right hand turbo out, having come at it from 3 sides: exhaust and intake side is easiest from below, the bolts holding the heatshields can (just) be removed through the wheelarch and the turbo to manifold was easiest from above (after removing the battery tray etc). A lot of hard to reach bolts, but I'm not convinced it would have been that much easiers without the body. You would have a better view of what you're trying to do, but a lot of clearance issues are with the chassis and suspension mounts, not the body itself. So IMHO definitely not worth it, I'm sure I wouldn't have been able to get one turbo out had I started with the body. 5 hours didn't seem to bad (I took it fairly easy), I had found one reference stating 8.5 hours for replacing one side.

The left hand side looked like it would put up even more of a fight. There's a propshaft there, and extra engine mount and on a LHD car the steering shaft... To get the prop and downpipe out of the way I needed to take out the crossmember holding the gearbox. Luckily that came out easily, the only problem was thet I found myself holding the crossmember in one hand, unable to put it down because I couldn't get a clip from the wiring loom off, and balancing the downpipe in the other hand. 🏋️‍♂️

As I feared, several bolt were a lot harder to get too because of the steering shaft. Luckily not were too tight, so with an assorted collection of extensions, joints and flexible ratchet spannes I got everything out. Final battle was the hose from the turbo to the intercooler, impossible to actually reach so I tried losening it with a prybar and then gave to turbo a good pull to get it to come off. Getting it back on will be interesting!

What I found, mainly lots of oil in both turbos, I managed to catch about a liter and probably spilled as much as well!
The right hand one seems to spin freely and without play, so hopefully just the seals that failed (the car has almost 400k km) and no real harm doen.
The left hand one is a different story: the exhaust turbine is jammed solid, even with some force applied it wont spin. The intake turbine was jammed to the side, but could be freed. So the shaft must me broken! Some damage to the turbine blades as well. I'm hoping the oil in the intercooler worked as an oil bath filter and kept the debris from reaching the engine. I'm gonna rig the oil feed and return pipes from the turbos so I can try and fire up the engine without the turbos, just to see if it will start and run. If it runs and doesn't sound like a bag of nails I'll order 2 new turbos and prepare myself for another challenge.

I took a few pictures, showing the oil out of the turbohoses (after the first big splash was aimed at the drain pain) and access from the front, side and rear with the right hand turbo already removed.

Filip

PS: no idea why the last picture is upside down. It shows correctly if I open it directly??

[Blanco]

It'll be a great achievement  when you get sorted, .... just have to bear in mind how many things you didn't get distracted by if you had taken the body off route!😉

[FridgeFreezer]

Give that you own a 2-post lift why not take the body off? They're designed to come off fairly quickly and easily for jobs like this after all

[Escape]

From what I've found so far, it's not that easy to take the body off. Plenty of connectors, brake lines, steering, loads of plastic trim, fuel lines, coolant, aircon ... And then the turbos would still be wedged between the chassis/ suspension and engine so not that much gained unless you take the engine out as well. I'm sure that would have taken me longer than just fight my way to all the bolts. Only real advantage would be access to the intercooler hoses.

Also, my 2-poster isn't free at the moment and it was much easier to get the RRS from the trailer to the 4-poster. 😉

[L19MUD]

On 7/14/2021 at 8:55 PM, FridgeFreezer said:

Give that you own a 2-post lift why not take the body off? They're designed to come off fairly quickly and easily for jobs like this after all

From speaking to a mate who has done a few now - 4 hours off and 4 hours on once you know what you are doing. He said it took double that the first time he did one

[Escape]

19 hours ago, L19MUD said:

From speaking to a mate who has done a few now - 4 hours off and 4 hours on once you know what you are doing. He said it took double that the first time he did one

8 hours each way is about what I'd expect, a lot of extra work and still hard to get to the turbos because of the chassis. Plus the risks of things going wrong on an older car (threads stripping, clips and connectors breaking... I stand by my decision to attack from the trenches. 😉

The decision to fit new turbos or not is still pending. I rigged the oil feeds and we tried starting the engine without turbos just to check for signs of other damage. But it wouldn't fire. Sounded OK, but no real sign of life. Not sure if this is because of other/related problems, or just because the engine management can't cope with the open exhausts. This does make the decision more difficult, would have been nice if it hard started before continuing the work...

[Simon_CSK]

Filip

I blew the turbo on one of mine and currently breaking it as there is too much to do that needs the body off. I.E. need to do the Ace roll bars and the turbos and the car jist isn't worth it. Anyway my car seized up and I was talking to a trader from Wales and he advised me to take the oil cap off and rock the engine back and forth on the crank shaft until it turns and then try to start it. Sure enough it fired and ran.

He did tell me what you have done is possible without taking the body off but he quoted 10 hours.

ANyway the point of my ranbling on is that he stated the TDV8 is fairly bullet proof and has had many in with seized engines which then turned out to be blown turbo's. On that basis I am assured that the engine on yours will be fine. Mine is.