306 1.9TD Diesel Knock Revving From Idle.

Post by **CitroJim** » 26 Jan 2008, 22:00

One of my pals has a 306 DTurbo owned from nearly new and now on 108,000 miles. In his ownership it has been driven to Greece towing a caravan, lived in Greece for four years and was driven back here two years ago.

Generally it runs as sweet as a nut and has been very trouble-free but recently, a very strange problem has developed. If it sits idling for a long time (say 3 or 4 minutes) and then revved, the engine will race away with a very pronounced diesel knock, as if it is runnning far too advanced. This lasts only for a second or two and then everything returns to normal.

It is hard to reproduce and today we got it to do this just the once so I could hear it. It has the Lucas pump.

The fuel in the fuel line from the filter head looked a bit airy (some big bubbles every now and again). I asked the question of when the fuel filter was last changed. This met with a blank look and it was presumed some time in the past six years in Greece

We changed it and the old one was very near black

The fuel supply now looks a lot less airy.

I am hopeful this and a dose of Redex fuel additive has cured this strange behaviour but in case it has not, any thoughts?

I checked the leakoff pipes and they're fine..

caveman_si · Post by **caveman_si** » 26 Jan 2008, 23:46

If the fuel has sign of air in it then that is probabaly the reason for the idle being off.
Air in lucas pumps does funny things. The leak off pipes have no effect on a lucas running or starting. Start off by checking the fuel filter for leaks and then check the piping back to the fuel tank to make sure the joints are all tight.
If the fuel is still airy then put some grease on all the joints to try and elimate that at the cause.

It possibly the fuel filter houseing itself is leaking if its not any of the fuel hose/joints. If its the black round fuel filter housing located above the thermostat then the o ring underneath is known to perish. Also the water drain off screw is know to leak as is the white thing located round the back.

Hope that helps as a starting point?

Post by **CitroJim** » 27 Jan 2008, 21:12

Thanks Si,

So far, so good. He's given me no reports of it happening today so fingers crossed the filter has done the trick.

Post by **CitroJim** » 28 Jan 2008, 21:34

Alas, all is far from well with this engine

It became clear today that the engine is smoking badly when under power, when revving and even when idling for an extended time. The smoke is blue and it's consuming oil in rather large quantities, hence the knock and race when coming off idle.

Diagnosis blown turbo

It's really the only thing left aftrer excluding the synthetic 5W oil (changed for good old mineral 15W/40 as a test) and the PCV/breather valve for correct operation.

Apart from this, the car runs like a clock and is in no way down on power.

The intercooler is not excessively oil contaminated but the turbo housing is soaked in oil and produces a haze as it burns off. I checked the turbo oil feed and return lines in case they were responsible for the oily turbo and they're sound. Besides if they were leaking, it would not cause oil burning.

The cat was replaced 4 months ago by one of our local fast-fits and they apparantly "had difficulty". The upshot is they have bodged terribly the manifold to downpipe joint and there appears to be no articulation left in it. I reckon because of this, the turbo has fractured.

Another worrying sign is a tinkling noise heard at the exhaust tailpipe as the turbo spools up and a general rough sound from the turbo itself with a sort of cross between a squeal and a whistle at 3000rpm. It does not sound good.

Please confirm my diagnosis or perhaps suggest any other causes. I did think of valve stem oil seals but thought that was a real long-shot in an XUD.

Also, is it possible to replace a turbo on a 306 with the engine in-situ? It looks jolly tight. It's bad enough in a Xantia where there is a deal more room

philipte · Post by **philipte** » 29 Jan 2008, 08:29

Jim, it does sound like the turbo is dead/dying The tinkling noise and rough sound could well be the turbine or compressor blades rubbing on the housing, and this combined with the oil loss makes me think the the root cause is bearing/seal failure.
I'd be very wary of running the engine at present, I once saw a Rover 220D destroy itself when the turbo oil seal failed completely. Huge clouds of smoke billowed out of the tailpipe as the engine revved wildly. The panicking owner turned off the ignition but of course it made no difference, and the engine only stopped when it had burned the contents of the sump...it wasn't a pretty sight.

XantiaMan · Post by **XantiaMan** » 29 Jan 2008, 08:52

If there is access to one, get a diesel compression tester and confirm all is well with the bottom end. In my experience with petrol cars the symtoms of a blown turbo are almost identical to that of a cracked piston ring or ringland, only a small performance drop is noticed also.

If it all turns up good, then apart from blocked breathers i would say its the turbo. Blocked breathers could also be a cause, and the seals failed as a result.

Gareth

Post by **CitroJim** » 29 Jan 2008, 12:39

XantiaMan583 wrote:If there is access to one, get a diesel compression tester and confirm all is well with the bottom end. In my experience with petrol cars the symtoms of a blown turbo are almost identical to that of a cracked piston ring or ringland, only a small performance drop is noticed also.

If it all turns up good, then apart from blocked breathers i would say its the turbo. Blocked breathers could also be a cause, and the seals failed as a result.

Gareth

Thanks Gareth,

A compression test is a good thought. It did cross my mind it might be a bottom end problem but there is nothing in the way of crankcase pressurisation to be noticed when the oil filler unscrewed and absolutely no sign of excessive blow-by or fumes rising from the filler. If there was as bottom end problem, I would expect plenty of blow-by to be evident. Am I right?

philipte wrote: The panicking owner turned off the ignition but of course it made no difference, and the engine only stopped when it had burned the contents of the sump...it wasn't a pretty sight.

Oh err, nasty

I hear an XUD goes pretty spectacularly as well. Rumour has it the head melts before the bottom end throws in the towel

It may explain why a head Xac and I spent two hours removing in a scrappy looked like the combustion chambers had been eaten by moths

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uncle buck · Post by **uncle buck** » 29 Jan 2008, 17:47

philipte wrote:....I once saw a Rover 220D destroy itself when the turbo oil seal failed completely. Huge clouds of smoke billowed out of the tailpipe as the engine revved wildly. The panicking owner turned off the ignition but of course it made no difference, and the engine only stopped when it had burned the contents of the sump...it wasn't a pretty sight.

I have had this happen to me a few times a few years ago with freight rover normally aspirated diesel vans (Company Vehicles)....anyone who drives a diesel engined vehicle should be ready just in case this ever happens to you.

Just brake & bring the vehicle to a stop & let it stall....obviously you want to get into a high gear (Top) if your not already.
let the engine cool down for 5 minutes or so & then try restarting, if it immediately starts to rev up again stall it again & let it cool down more.
Once you can start it up without the revving off you go.

pug_owner2002 · Post by **pug_owner2002** » 29 Jan 2008, 20:43

Hi Jim,

The turbo went an my old 306 DTurbo, it actually sounded like a police car siren!
I managed to remove it with the engine in place, it was very tight though, I got it out by undoing the battery tray so that i could slightly move it and then bring the turbo out that way.
One point to mention was the plastic filter that was at the inlet to the turbo oil feed pipe from the engine had disintergrated and bits were in the oil feed pipe and had probably gone through the turbo's oil chamber (if that is the correct term?

), i was told by my local pug dealer that the filter was only required whilst the engine was new and not to bother with a replacement as it was no longer required.
I had my turbo reconditioned by a company called turbo techniques as I couldn't get a second had one at the time (mine was a garret), the service etc i received from this company was very good.

I hope this helps.

uncle buck · Post by **uncle buck** » 29 Jan 2008, 23:49

pug_owner2002 wrote:....One point to mention was the plastic filter that was at the inlet to the turbo oil feed pipe from the engine had disintergrated and bits were in the oil feed pipe and had probably gone through the turbo's oil chamber (if that is the correct term? ), i was told by my local pug dealer that the filter was only required whilst the engine was new and not to bother with a replacement as it was no longer required....

I was told much the same by a Pug dealer....that the plastic filter was supposed to be removed at the first service (500 mile?)

pug_owner2002 · Post by **pug_owner2002** » 30 Jan 2008, 21:41

I was told much the same by a Pug dealer....that the plastic filter was supposed to be removed at the first service (500 mile?)

I acctually did wonder if it had contributed to the turbo dying, so much for dealer service history.

Post by **CitroJim** » 02 Feb 2008, 18:55

A small update.

The owner took it to an Indie for a second opinion today who dignosed duff valve stem oil seals

Possible but I've never heard of them giving any trouble in any XUD but a specialist has diagnosed so who am I to argue

The bit that caused me to fall off my stool was the cost quoted to have the head off, skim, renew said seals and replace head.

They want £700 for this work....

I'm in the wrong job...

XantiaMan · Post by **XantiaMan** » 02 Feb 2008, 19:35

Apart from age which kills stem seals, i cannot see them failing to the extent it would cause a smoke screen, mine uses no oil and has alot more mileage than 108k, my old Monty engine is at 210k still on original head etc..

I would still have done a compression check.

AndersDK · Post by **AndersDK** » 02 Feb 2008, 19:39

Well - the job is rather involving ...

Removing cambelt
(meaning new cambelt & timing bits when refitting, unless a guarantee can be issued that these parts are in near off the shelf condition)
Removing diesel pump
Removing head
Disassemble head in further bits
Test and possibly renew jets
test and skim the head
Reassemble head
Refit head
Refit pump and timing bits
Fine tune the diesel pump

Even with a moderate labour rate, it quickly sums up. I'd say it should be possible to do at some £4-500ish

You can get a rather long way in first assuring the diesel coldstart system is in good condition. Then do a fine tune of the diesel pump at hot (only !)engine.
Upgrade to a high quality diesel engine oil (not too low viscosity : at least 10w40 or 15W40) and finally drive a couple of tankfuls with jet cleaner added.
That will most likely revert this engine to something quite acceptable in daily use.

It may well pay a miracle using one of these tephlone based snake oils added to the engine oil.

Post by **CitroJim** » 02 Feb 2008, 20:22

XantiaMan583 wrote:I would still have done a compression check.

Too right Gareth

Anders, yes, when you break the job down into what has to be done just to reach the head it is easy to see why it costs as much as it does. I forget that my time to do such jobs is free but for others it's how they put food on the table...

I'll suggest to the owner that a can of snake oil is worth a go. After all, it cannot do any harm and as you say, it might just do some good!!