1996 4.6 P38 - knocking sound on idle

[vougese39]

I can buy a new block from Land Rover for half that money, so my statement stands.

what and fit a substand block back in thats a sound aproach not!

block from land rover genuine bare or a short motor? shorts are going for nearly £1800+ vat then with all the aprts not getting much change out of 3k are you?

[Hybrid_From_Hell]

FWIW

I am having THL replaced into My 5.2 Block by J Eales @ £650 and I sqeked at that price

THL will sort issues a la dropping liners etc, get someone good and give them the pistons and they

will plateaux hone to suit so away you go

Nige

[argonaut]

It's back again!

After just over a month and maybe around 3,000 miles the dreaded noise has returned. Symptoms are identical to the first occurence of this problem and the noise is the same (refer my OP in this thread).

I spent a pleasant hour or so underneath the car yesterday evening, removed the inspection plate from the bell housing and checked all bolts for tightness - they all seem fine. The flywheel is new as is the drive plate. I checked as carefully as I could but I could not see any sign of cracking or other damage to the drive plate or flywheel. Reluctor ring is perfect, engine still running fine apart from the blasted knock sound on idle. So, is there anything else it could be? Or, if it is the driveplate failing again, this would the third time it's done so (the previous owner told me he'd had the plate and flywheel replaced) - three failures would definitely suggest to me that there's another problem causing this failure, could something be perhaps badly out of alignment to cause this failure(s)?

Cheers

[argonaut]

Right, something is definitely not right with my car, following my previous post I had the car checked again, this time by experts. They confirmed my diagnosis that the drive flex plate had failed again, they showed me the removed one, it was in bits. They replaced it, everything was fine. Now, one week later and after about 1500 the noise is back, klonk klonk klonk on idle! I am now at the stage where I'm tempted to push the car off a high cliff.

Has anyone heard of drive flex plates failing this quickly and is there a common cause? When it was replaced last week everything was checked and it all seems in order but something must be wrong.

[Range Rover Blues]

How much was the flex plate (flywheel) as I might need one if I ever scrape together enough for an Ashcroft's stage 2 hybrid auto box for my LSE. I don't know what model year I need though but it is to fit the larger torque converter of the early P38 4.6.

Though if a new one is £40 I might go that route.

[argonaut]

Well with many thanks to a kind donor I will hopefully soon have the bits and pieces I need to have a go at fixing my Rangie once and for all (ha ha). The problem with failed flexplate returned again and it seems there is probably an alignment problem (tip from Dave Ashcroft at Ashcroft Transmissions). I will be looking at renewing the torque convertor, flexplate and also making sure that the alignment dowels are correct and present.

I don't have the luxury of a 4 post lift so I will be doing things the old fashioned way - laying on my back underneath the car and struggling - any tips on the best choice of swear words needed here?

Seriously though, although I don't have a lift I do have a pair of jackable ramps that will raise up to about 18" so hopefully I will have enough clearance to be able to remove the gearbox and importantly, be able to move it sideways out from underneath the car.

I will be documenting the progress as I go and will try to put some pics and text up in this thread just in case it may be useful to others.

The first step has now been done - since I'm too old to enjoy laying under a car whilst it's outside in the cold surrounded by snow I've spent a few hours this afternoon and now have the car in the garage, in a day or so it will have dried out and hopefully warmed up to something approaching room temperature rather than the -2°C we're currently enjoying here.

Does anyone have experience of gearbox removal in this fashion (i.e. without a lift and using ramps/axle stands) - any pitfalls I need to be aware of going in?

Any tips or simple words of encouragement much appreciated.

Cheers

[argonaut]

How much was the flex plate (flywheel) as I might need one if I ever scrape together enough for an Ashcroft's stage 2 hybrid auto box for my LSE. I don't know what model year I need though but it is to fit the larger torque converter of the early P38 4.6.

Though if a new one is £40 I might go that route.

well I paid around GBP 470 for the flywheel and flexplate together but bear in mind those are Hungarian prices and parts for the RR are very expensive here, you can get much better deals in the UK.

Ashcroft list the flexplate for GBP 28 (I think plus VAT though)

[Bowie69]

argonaut, 

Do you *need* to remove the gearbox? Would it be possible to do it just by sliding it backwards for access?

Honestly interested, as I think it should be possible, could save a lot of work...?

[argonaut]

argonaut, 

Do you *need* to remove the gearbox? Would it be possible to do it just by sliding it backwards for access?

Honestly interested, as I think it should be possible, could save a lot of work...?

Good question to which my honest answer at this stage is "I don't know". If I can get away with just disconnecting it and sliding it back then I will but I doubt I'll be able to move it back enough to remove the Torque Convertor.

[Bowie69]

Will you need to remove the converter?

This ideally should stay with the gearbox, to save smashing the oil pump on reinstallation. I suppose it will be a case of if you can get enough access to remove the bolts holding the flex plate to the flywheel....?

[argonaut]

Will you need to remove the converter?

This ideally should stay with the gearbox, to save smashing the oil pump on reinstallation. I suppose it will be a case of if you can get enough access to remove the bolts holding the flex plate to the flywheel....?

Yes, I was aware of the issue with the oil pump - the thing is though that one of the suspected causes of the repeated flex plate failure is unbalanced torque convertor - if I was certain that the TC is OK then I wouldn't remove it but since I'm not sure and I'n going in there anyway to me it makes sense to replace the TC at the same time. I discussed this problem at length with RPI and one theory is the TC, the other theory (from Ashcroft) was possibly missing alignment dowels which I can only check once I've disconnected the gearbox and moved it back enough to check.

Have you any alternative theory that might account for the flexplate problems? It's now failed three times.

I'm grateful for any suggestions as I really want to fix this issue once and for all.

[Bowie69]

Ah, if you are removing the converter anyways, it is a big lump, I would say you will need to remove the box in that case...

It is odd it has failed 3 times, I suppose the only common component left is the TC, migth be worth swapping it out for a known good one? I suppose you could always ask a friendly tyre firm to balance it for you 

[argonaut]

Ah, if you are removing the converter anyways, it is a big lump, I would say you will need to remove the box in that case...

It is odd it has failed 3 times, I suppose the only common component left is the TC, migth be worth swapping it out for a known good one? I suppose you could always ask a friendly tyre firm to balance it for you 

Yes that's what I'm planning to do - swap it for a hopefully known good one. As an aside - would getting it balanced by a tyre firm actually work?

The flex plate has actually failed four times, three times during my ownership of one year (I bought the car last Christmas) and the previous owner told me he'd had it replaced shortly before I bought the car. I did send the PO an email asking if he'd any theory or if he knew what was the root cause but I didn't receive an answer from him.

I am however, becoming an expert on diagnosing failed flexplate from the sound :-)

[Bowie69]

I doubt balancing it at a tyre place would, I'm unsure how the very difficult to remove fluid would affect it, and there's nothing to clamp it to the machine with.... was more a tongue in cheek remark

[argonaut]

I doubt balancing it at a tyre place would, I'm unsure how the very difficult to remove fluid would affect it, and there's nothing to clamp it to the machine with.... was more a tongue in cheek remark

That's the spirit in which I understood it - I couldn't see how a tyre balancer would be able to do it anyway.

Well, let the games begin, Rangie is now sitting proudly on my ramps - access actually looks pretty decent. The ramps are jackable and at the moment with them on the lowest setting there's easy crawl access under the gearbox and I think that when the time comes to remove the gearbox from underneath the car, with the ramps raised a bit it should be straight forward.

Driving up on the ramps was a wee bit hairy - I'm here on my own with no-one to guide me so I used a couple of old mirrors so that I could see how lined up the car was as I was driving up - worked a treat.

[Bowie69]

Good luck then!

[argonaut]

Cheers!

[argonaut]

A brief status update: after a couple of days playing with the car I now have the gearbox removed, not too bad a job really.

Both alignment dowels are present, there does not appear to be anything wrong apart from the large split across half the diameter of the flexplate - this confirmed my diagnosis anyway.

I also discovered that 3 of the bellhousing bolts were loose and 3 of the flywheel bolts were loose too - that probably didn't help things.

Now I await the replacement parts but in the meantime I will be doing plenty of cleaning and fettling under the car - any good tips for a decent paint or sealant to use? I don't do very much offroading but I'd like something decent. I plan to remove all surface rust and treat/coat/paint the affected areas.

[argonaut]

Depending upon the vagaries of the weather and the delivery of the replacement items I will hopefully soon be getting ready to reassemble my gearbox etc.

I have a question regarding alignment of the torque converter / oil pump. RAVE shows that a special tool can be used for this but looking at the pictures of it (poor images) and also looking at my torque converter it seems that the "tool" can only be something that bolts into the TC using the flex plate mounts. That being the case I suppose that I could use a couple of longer bolts that also fit these holes so that I have in effect a couple of handles to manhandle the TC into position. That's all well and good but does anyone have any tips on how to make sure the TC aligns and engages correctly with the oil pump drive? My idea is to make sure that the oil pump drive is aligned at say 12 o'clock and that the TC slots also line up to this. I want to make 100% I get this right as otherwise I end up with a knackered oil pump / gearbox. Has anyone got a tip for me?

Cheers

[David Wright]

The torque convertor needs to be installed into the gearbox BEFORE you attempt to offer up the gearbox to the engine - check Ashcroft's website this gives the dimensions for the offset from the gearbox face to the face of the torque convertor. This procedure ensures that the oil pump is engaged into the torque convertor and allows the gearbox to be bolted up.

DO NOT force the gearbox onto the engine as you are almost certain to damage the oil pump and will need to start again.

[Bowie69]

The dimension is probably 51mm from TC mounting holes to face of bell housing, but as above, check for your code on Ashcrofts site.

To fit the TC I didn't use anything other than my hands, the handles for sure would make it easier, but not essential by any means... Actually fitting it, I did it a few times to make sure, it has 3 notches as it slides on, no need to line anything up before hand, it's not just the drive you need to line through, but there's 2 sets of splines as well, IIRC.

Basically, slot it on as square as possible, rotate slowly with a small amount of force pushing it home, eventually it will fine it's home and slide onto the first notch, repeat, and it will find it's second, and then the third. At this point measure the distance. then quadruple check everything. I would suggest as you will be man handling the box back into it's home, rig something to make sure once you arte happy with the position, it won't slip forward upon installation, a ratchet strap and some wood would probably do it OK.

[argonaut]

@ David - thanks for the tips, yes I was aware that the TC has to go on to the gearbox before offering it up to the engine, I was planning to do that anyway. Thanks for the Ashcroft tip - very good idea, I will check there.

@ Bowie69 - thanks for the tips, especially regarding aligning, very useful. I was also planning to make up some sort of strap to fix the TC whilst I get the gearbox up and aligned.

My replacement parts haven't arrived yet, I'm still hoping they turn up before the Christmas break but if not then I've still plenty of other stuff to do - I'm giving the underside of the car a good clean up. I also noticed that I have an oil leak from the sump gasket so I'll be tackling this too. As I will have to drop the sump to do this I will also check the crankshaft endfloat - it occured to me that if the crankshaft endfloat is out then this might potentially also cause excess flexing of the drive plate leading to premature failure. I've worked out that the interval (distance in miles) between flexplate failure is reducing so that would tend to suggest that whatever is causing this problem is gradually getting worse. Unfortunately I have not yet had an "Ah ha!" moment and I have not found anything wrong that would cause these failures. Changing the TC is following suggestions received here and it's worth a try. I will also try to get a dial gauge to measure run out of the flywheel flexplate mounting face just in case the crankshaft might be bent.

Since there's already mission creep on this job is there anything else I should do whilst I'm there? Gearbox filters and lower pan gasket maybe?

Cheers

[argonaut]

Well my replacement parts arrived today.

I have a question regarding various torque convertors and hopefully someone here can help out: the TC I removed from my car is marked "M19" whereas the replacement I now have is marked "T27". From what I have been able to find out it seems that the T27 flavour was used for the 4.0L and type 22 gearbox. Does anyone know if I can safely use this on my 4.6L with type 24 set-up? Externally the TC's look the same although I have not yet had a chance to measure the diameter to compare.

Many thanks in advance!

[argonaut]

I’ve now removed what was left of the flex plate – it was in 6 pieces and that’s after only around 2,000 miles. I found very clear signs that the flex plate has been in contact with the rivets on the flywheel that hold the reluctor ring in place – there are circular depressions worn into the flex plate (see pics) and some scoring on the flywheel itself that corresponds to worn/polished areas on the flex plate. To my understanding the only way that the flex plate could come into contact with the flywheel is if the torque convertor is pushing it too far – a worn TC can expand too far and maybe that’s the problem or as already suggested, if it’s badly out of balance it will wobble or follow an eccentric orbit causing the flex plate to twist? My money is on the entire TC pushing back too far as the rivet wear marks are evenly spaced and not elongated which suggests to me that the pressure on the flex plate was more or less constant and not intermittent.

So my question, has anyone ever seen such rivet contact wear signs on a flex plate? I now have a spare (used) plate that shows no such signs at all.

Cheers

[elbekko]

That's quite the breakage. If it has pressed against the flywheel, be sure to check if the crank doesn't have any excessive play in its bearings, I've heard of bad TCs putting so much pressure on there that they wear out very quickly.