Strange (ominous) engine behaviour. Not sure what to make of it

Hi all

I've been fairly convinced that the head gasket is slowly 'going' on my TD5 for a while now due to the following reasons:

Slow but continual coolant loss
Pressure remaining in the system long after the engine has cooled fully (unscrew the rad cap even a day after driving the car and it hisses a lot and coolant bubbles up into the header tank
Top rad hose pressurises a lot leading to leak from bleed screw. I think this is a 'result' from gasket going rather than being the cause where the coolant is simply leaking out of this, (but is there any way to tell what's normal or not?).

New top hose is on order anyway to try the cheapest thing first, in case the coolant loss is just faulty sealing on the bleed screw/o-ring etc.

So I've been topping up once each week or two and it's been fine generally. No bad overheating at all. It's never got close to the top of the gauge when it has moved above normal temp, so hopefully the head is ok in terms of whether or not it'll be warped, but I don't know just how susceptible they are to that.

But the other day the engine began behaving slightly worse and I'm not sure what to make of it. Plenty of coolant in there btw.

I noticed while driving the car that I could feel a slight vibration through the pedals and the floor. Seems to only really occur when the engine is under load/on boost, and I noticed also when under load a really odd noise I can only describe as 'twittering' or 'chirruping' faintly. It doesn't do this all the time however.
It's not a normal turbo noise at all, and I'm absolutely definite on this. Had lots of turbo cars over the years and I'm familiar with the range of noises they tend to make. Thankfully I've only ever had one full on failure with a turbo while running too.

Seemed to still pull ok though, and despite the strange vibration I would say the engine didn't really seem to be 'rough' as such, but then I'm not used to the characteristics of a 5 pot engine when it's not going well.

Additionally, there's some element of smoke for the first 0.5-1 mile or so now as well, and this is a new thing as it wasn't doing it until the last few days that I have ever noticed. Not an enormous amount but noticeable. It's either white like steam or possibly with a little blue in there - hard to tell.

I'm a bit concerned that I possibly have a combination of failing head gasket, AND failing turbo, but now I've started to fret about it in my head I'm not thinking properly about the obvious things to try first to rule out or confirm any of these issues.

I removed the pipe to the turbo inlet for a look yesterday and to check for play. There is some visible play in the shaft but it's hard to tell if its any more than it should be as they should normally have some I would expect.
There was however some oil in the turbo inlet, which is worrying, but is this coming from elsewhere since it's at the inlet?


Sorry the vibration/noise thing sounds a bit peculiar and strange but I can't describe it better than this, and with it only happening under load, I can't of course reproduce the symptoms with the car on the drive and me looking under the bonnet etc.

Appreciate help since it's currently our only family transport and I'll be a bit stuck if something fails suddenly and it's off the road. Happy enough to change the head gasket myself if need be as that doesn't really phase me if it needs doing, but not sure about all the diagnostics I can try out first to help identify the issue.

Nanocom has not showed any errors that aren't usually there.
The car has an allard intercooler, and dastek chip, and runs at 20psi on the turbo side (not the manifold side).
EGR is removed.

Manifold is ok (not sheared studs or anything like that).

If the head gasket does need doing, it's a 1 hole one I believe (car is a 1999 manual btw). Are there any real nasty surprises doing the head gasket or difficulties needing special tools etc? Was going to buy a locking pin kit if nothing else. And is it worth doing say injector seals at the same time?

Many thanks
Grateful for any suggestions

Jim

hi i also have oil and play in turbo dont think its worth the paranoia
vibration may be the rear prop donught check it for cracks n splits
the expansion bottle on mine always sits a low level no point in filling as it always runs low and has leakage at temp sender have you checked the thermostat as it may be fawlty shurly if the head gasket is away it would run rough or show water in oil or oil in water check thermo first

Cheers for the reply mate!

Will check that propshaft donut thing tonight if I get a chance. Is it quite obvious to see when they need doing?

Saying that, if that was knackered would it not make it vibrate all the time? Worth a look anyway I suppose, but this only happens some of the time, and only then when engine is under load or on boost which is why I thought maybe the turbo was going. Not sure that I could have an intermittent vibration if it was something on the propshaft but who knows?

It's very noticeable though when it does it - even the mrs complained about it!

No mayonaise in the oil cap etc, or oil emulsion in expansion tank.
Car is using coolant but is definitely leaking from bleed screw so it may possibly just be that. Like I say I wasn't sure if that leak is because it's running too much pressure in coolant system from a failing HG, or if the top hose or bleed screw seal are just weak. New top hose and header cap on the way anyway.

You reckon it's worth replacing the stat as well then? If that was failing wouldn't the car just overheat?

Also there's this thing going on where it still has pressure in the system even a day or so after it was last run. Surely that's not normal is it?
Heater blows cold sometimes but presume that's just cos the coolant drops a bit at times and it gets airlocked or whatever. I replaced the rad not too long ago as the old one had a leak.

Cheers anyway - all info/suggestions are welcome as I'll be in the kaka a bit if something goes badly wrong, and I don't have the money to just hand it to a garage and tell them to have it sorted and ready by teatime!

the stat if shut reduces water flow giving u build up in pressure the water will still flow the temp needle should sit around centre of gage

Ahh, fair enough cheers.

Needle is almost always (once eventually warm anyway!) bang centre on the gauge.
The only time it's ever gone higher (and never to the top) is when the coolant is a bit on the low side, but that's only happened a couple of times since I keep it topped up.

When it has happened I've just either stopped a few minutes then carried on with as little boost and load as possible so the temp drops back to normal til I can get home and top up after it's cooled a bit.

I will order a stat then tonight as a precaution.
£15 on ebay and I rang my local motorfactor today just to enquire and want £60 for one which won't even be a proper LR part ffs!!

Right - just popped out to have a scan under the car to check out the rubber donut since it's been suggested it might be the cause of the vibration and matching drone noise.

It's not good and is full of cracks but isn't actually splitting apart or anything yet.
Needs replacing from the look of it (see for yourself below), but what sort of state are they usually in to start causing vibrations?

It's started happening fairly suddenly over the last few days, and only does the vibrate thing some of the time, but it does seem to kick in around 50mph mostly, and often has a deep drone sound with it, which seems to match what other people have said with theirs.

Here's what we're looking at on mine - looks ropey but no idea what these are like when others have had this problem:

I hate to be the agent of doom but my diagnosis would be a cracked head. Quite common on these, and the white smoke is a tell tale - sniff it and see if it smells of coolant. If you have been topping up with water only this will make it worse as the engine needs a strong antifreeze solution to inhibit corrosion. The juddering could be from uneven compression as a result either of cracked head or blown gasket. The most likely place for it to go is no 5 exhaust valve.
Sorry - hope I'm wrong.

Thanks - have worried about that myself but am hoping it's not going to be the case. I know it's common though and a possibility. It's actually only a little bit at startup, and today I barely noticed anything at all so not sure why there was what seemed like a fair bit the other day, but it was after an a couple of days solid of rain/drizzle/mist if that makes a difference - am guessing it may well do.

Will keep an eye on it.

If it was a cracked head causing steam wouldn't it be constant? When I top up I do it alternately with water then antifreeze to make sure it's not running diluted down compared to normal.

Re' the vibration (not juddering as such), the symptoms match what others describe for knackered rubber propshaft donut going bad, and mine has indeed got a lot of cracks in the rubber.

The mystery squeaky noise has been suggested as bad UJ(s). I took a sound clip of it today but it's iffy quality just from my phone. You can make out the squeak about 9-11 seconds into the sound clip.

Usually happens at mainly low speeds moving off through the gears after traffic lights, and is linked to vehicle speed.
The vibration and drone usually rears it's head around 50mph or thereabouts and under load.

Sound clip of squeak:
http://dl.dropbox.com/u/10616601/2012-02-14 17_31.wav

Cheers!

steam will happen at startup because there will be a cylinder full of coolant (forced through the crack or blown gasket by the residual pressure when the engine stops). Once going, there is less likelihood of coolant being able to get in. I've had two cracked heads (only one on a TD5) and in my experience they can keep going for a long time, gradually getting worse.

Right - that makes sense I suppose.

Well I obviously hope that's not the case but am not going to pretend it's not a reasonable possibility.
My only particular hope to make me think I might be lucky is that the car has never full on overheated its nuts off as it were. Each time the coolant has run low I've spotted the needle moving up and acted accordingly so I'm hoping that will have reduced the likeliness of cracked head. Might be wishful thinking but no way of knowing unless the head comes off.

Known facts though at present:
Coolant IS being lost via the bleed screw (new hose coming)
Pressure stays in the system after cooling (noticed when releasing header tank cap)

So once the new bits come (new stat, new top hose, new header cap) I'll see if it resolves anything, and if not then head gasket really has to be the next thing to try I think.

Anyone know the part number or a supplier for the steel dowels (that won't try charging £15 postage or something as well!!) for if/when I have to do the head gasket?

Time to start swotting up on the job details and looking for How Tos. Saw one last night and it didn't look a horrific job (assuming you don't find cracks that is).
Any special tools needed for TD5 HG replacement?

Cheers!

where are you?
bradford engine units are good for advise / parts / testing / gaskets.

had the same thing on mine, early past year.
Is your disco 2 one of the first series, year 2000,2001,2002? If so the head has plastic guides which, with time, move the head, hence a cracked joint. My car had analysis plenty without apparent fault but in fine it was the joint. Cost me the best part of 4000€ in Belgium!

Yes, it's essential to use metal dowels when refitting the head.

Am on the Isle of Man so not much scope here for parts apart for online!

Anyone know part number for the metal dowels or who keeps them in stock etc?
Presume they're only a few quid.

New top hose came today and hopefully other bits will come by weekend so I can get things on and start testing on Sunday with a bit of luck.

New top hose came yesterday so will get that lashed on ASAP and hopefully that will at least stop the coolant leak so I have a better idea of what else is really going on...

This morning there were a good few clouds out of the exhaust for approx the first mile or so. It's not fuel, but I'm not sure if this is coolant or something else. Mostly white but definitely with a bit of blue in there.

So I'm not sure what the cause is.

It was mentioned on previous page that if it's a crack in the head that coolant can seep in overnight causing clouds on morning start up, which then clear quickly, but there's oil in there from the blue tint I'd say.
OR, I wondered that the turbo might be starting to get a bit worn hence the blue
OR, could it just be doing this from a head gasket?

Can't think of any particular way to try and tell without either removing the head or bolting on another turbo. Would rather try and find out what's wrong of course before buying parts for a problem that might not actually exist!

OK - updates:

Today I replaced the thermostat (what a pain in the hoop to undo the clamps as they're spring ones, not jubilee type!), the top rad hose, the header tank cap, and the propshaft donut.
Not been able to do a proper test jet as there's been alsorts of stuff going on today. Hopefully can get out again shortly though.

Found a few things that rather surprised me.
First was in the EGR replacement pipe from IC to manifold. It had emulsion in it. Nice grey layer of sludge, which was also present in the hose coming to it from the outlet of the intercooler:

Yuck!


Now this made me think "Yeah, definitely got a head gasket problem then", but then I thought about it and I'm a bit puzzled how it could have emulsion here. Basically the turbo sucks in fresh air, it gets compressed, goes through the intercooler, then goes through these pipes before going in the engine. So how can this muck be present here when there shouldn't be any water/moisture, and no link to the coolant system?!!! The oil filler cap had no emulsion and dipstick was ok too. Inside the entrance of the manifold it was just like black tarry oil coating the inside surfaces, like last time it was apart.

The next thing was that there was a pressure leak in the EGR replacement pipe. It has a welded on boss on it, and I found this was leaking and fixed it. Is it possible that moisture has been drawn in through this somehow (condensation after the car is used?), mixes with oily fumes or something, hence then giving some of the clouds I've intermittently had out of the exhaust recently when a bit of the sludge gets burnt??? :?:
Can't really see how else there'd be sufficient moisture there to mingle with whatever oil type stuff is mixing and emulsifying.

So I'm still not sure if there is a head gasket issue or not. I haven't yet got the full amount of coolant in yet, and the heater is still blowing cold so I need to bleed the system I think to sort that, then I can monitor coolant levels over the next week or something.

Next issue:
Swapped out the propshaft donut and that was easy enough. I think the bearing in the middle of the donut needs replacing and a new one came with it but I ran out of time and had to get the car back together. What's the easiest means of changing the bearing? Do I need a slide hammer or something to remove the old one?

Lastly - one of the UJs is really shafted and I'm worried about using the car so I need to replace it as quickly as I possibly can. This is obviously where the mystery squeak has appeared from, as others suggested!

Are all the UJs the same part number along the front & rear propshafts? The broken one is the front one of the pair just in front of the transfer box:


If anyone has the part number for this UJ on TD5 Disco I'd be grateful, but I'm sure I can find it without too much hassle online or on Rave or something.

That's all for now folks!

One extra possible to worry about - you really need to sniff that smoke and see what it is. It's probably NOT oil, as the engine won't be hot enough to be burning it. It is likely to be coolant. However, white smoke on start up can also be unburnt diesel - smells, not surprisingly, of diesel. Various causes: some engines just do it when cold; or it may be because your glow plugs aren't working; or it may be that the injector timing is out. This happened on my 200TDi because of a worn keyway in the crankshaft pulley, but I don't know if it's possible on the TD5 motor. Whichever it is, it will be easy to smell the difference.

jgs- 4x4 sell a front prop repair kit on ebay. comes with 3 uj joints & the bearing for the Double Kardon joint. Works out about £71 but cheaper than a replacement prop

Also there is a guide on this forum on how to change them

Thanks for the tips chaps.

Strangely (in a good way) there didn't appear to be any clouds from it today. Not sure why. I will continue to observe and monitor it though and try to get a healthy lungful to see how it smells.

Can diesel really burn as white smoke? I always thought than unburnt fuel (whether petrol or diesel) came out as black smoke, water vapor came out as white, and anything with oil involved would be varying strength of blue.

Interesting mention of glowplugs though. There's been a few occasions in the last month or two when first thing in the morning it's not been so keen on firing up cleanly and quickly. 9 times out of 10 it fires up instantly and without fuss, but just once in a while it needs to be cranked a few turns round before it catches properly.