1998 Xantia 1.9TD Engine Runaway

acrowot · Post by **acrowot** » 06 Aug 2006, 22:23

I have just replaced the Head and Headgasket Timing Belt and Tensioner spring and plunger and Aux. Belt on this engine ( I bought the car with engine problems , it had overheated twice , on the first occasion the previous owner had relaced the Headgasket but not had it skimmed). I bought a second hand head that I was told had been skimmed and pressure tested, I also fitted one on the newer steel head gaskets. On starting the engine after rebuild it did start relatively easily and does tickover very sweetly. When I increased the engine revs. with the throttle there was a horrible noise akin to a big end that was about to disintigrate, I switched off but the engine ran on for a second or two and the revs increased to about 2000rpm before the engine stopped. There were clouds of blue smoke out of the exhaust at his point. I then gave up as it was rather late, next day started up again, started instantly and ticked over really nice, after about 15 minutes I decided to take the plunge and started to gently blip the accelerato, after 2 or 3 blips the engine hit maximum revs., I swithed off but the engine carried on at max. for about 5secs then died ( I expected it would destroy itself but it did not) this time the smoke out of the exhaust was white and there was a pile of black oily gunge on the floor at the back of the car. When I stripped it down and disconnected the pump ECU therev was quite a bit of corrosion on the ECU terminals which I cleaned off, on the second attempt at running the engine I had used a spare ECU that did not have corroded terminals. I can only think that the engine is running on the sump oil when this problem occurs although the oil on the dipstick is between high and low and is new oil, I do not remember exactly were it was when I filled it. I uaually fill under the full mark under these circumstances and then top up when I have finished the job. Is it likely that this problem could be caused by the Turbo seals failing, is there any other way that the engine oil could cause this problem or am I way off the mark with my assumption. I have removed the pipe from the Turbo to the inlet manifold and intend to start the engine again to see if the Tubo is the culprit, but not until tomorrow after my nerves have settled a little. Also there is evidence of oil in the water, I do not know if this oil is from the previous failures or not, there was no water in the car when I obtaind it.

AndersDK · Post by **AndersDK** » 07 Aug 2006, 01:20

If the turbo oil seal fails - it nearly always do so on the exhaust side as this is the side under most strain. Meaning any engine oil from here can NOT participate in the combustion.
Instead it will instantly evapourate by the hot exhaust and show up as white smoke from the exhaust. Any condensation from exhaust pipe will be gresay and smell like engine oil.

Note that unburnt diesel fuel will as well often be seen as white smoke from the exhaust - as it evapourates like the engine oil. If however the engine is over-fuelled - the exhaust smoke will always be black. Condensed fuel from exhaust will smell like diesel.

Engine oil can only get in via the intake - or from a serious piston/ring problem. If you are certain that the engine is in fact burning engine oil - then the exhaust smoke must clearly have a blue tint - and the wellknown un-pleasant sour smell of burnt engine oil.

You can test for serious blow-by in any cylinder by pulling the fume hose from the sump. There will be large pressure here possibly with spurting drops of oil when engine is running - if there is any significant blow-by.
We are talking serious pressure here like an extra exhaust - not the common small pressure puffing from the normal combustion leakage.

I tend to believe you have a problem with the rotary diesel injector pump. If this is filled up with air-mixed fuel - the fuel volume control goes haywock - and the engine will behave strange and scaring by the uncontrolled fuel volume. Be sure to have a piece of clear fuel hosing directly on the rotary pump's intake - to visually check for any air getting in.

Note : if the engine was in fact running on its engine oil - you will NEVER be able to stop it using the key. It will keep on running - and do so at maximum rpm it can do at all. Only thing that can stop it is to strangle the air intake.
Dont do that by hand ! (it can break your hand !)
Neither use rags ! (they can get sucked into the cylinders !)
Have a piece of wood handy to blank off the intake.

X-ing my fingers for you - it may not be as bad as you fear

Post by **Peter.N.** » 07 Aug 2006, 09:56

To eliminate turbo and lubricating oil causing the problem, disconnect the air intake to the engine, probably at the intercooler would be the most convenient place. I it still happens, it must be as Anders says, something to do with the pump.

(Sorry, I didn't read your post properly, but that's the way forward)

acrowot · Post by **acrowot** » 07 Aug 2006, 20:14

Thanks for your replies Anders and Peter, I have been unable to go in my garage today as one of my bosses has been in charge of me, my 8 month old Great Grandson, he goes home tomorrow so maybe. Anders do I read you right that air in the pump could cause this problem even though the engine is switched off, stop valve shut. The engine did hit max revs. for about 5secs in this state, I have started the engine since and it starts and ticks over OK. You have an interesting way of stopping the engine under these conditions and I will certainly have my piece of wood handy when I do battle with this engine again.

AndersDK · Post by **AndersDK** » 08 Aug 2006, 00:09

Yes -

You certainly DO read me correct. Air in dieslfuel causes the mechanical volumetric mechanisms in the rotary distributor pump to screw up.
Its wellknown - and one of the most common diesel problems discussed over & over again on this forum.

I can not give you an exact answer to why the engine starts and tickover fine - and then do its run-away stunt when accelerated.
Whenever you get the time - note all the indications there are right before your eyes :

colour & smell of exhaust
air bubbles seen in (your newly added) clear fuel hose
sump fume/vent hose pressure
running engine with/without turbo air ducting connected.
The diesel "clatter" or "note" or "sound" when the engine is running :
Is it a rough metallic tapping sound, a smooth quiet tapping sound - or even a violent knocking ?
- when the engine are performing under various conditions

You could very well have a mix of several problems.

acrowot · Post by **acrowot** » 08 Aug 2006, 07:31

Thanks very much for your comments Anders, I will let you know how I get on when I get the time to have another look at it.

weety · Post by **weety** » 08 Aug 2006, 18:36

had a rover 218 diesel do the old engine running on engine oil trick (the owner had just put cold water into an overheating engine)......my mate managed to chuck the car in gear and stall it before the engine exploded....that might be easier that trying to block the air intake.....

acrowot · Post by **acrowot** » 08 Aug 2006, 19:59

Thanks for your reply weety, I did think about putting it in gear to try to stall it but doing those sort of revs.I wondered if it would work, anyway I will bear it in mind. How would you say that thev engine oil was sucked into the engine to cause it to run on it in your friends car.

weety · Post by **weety** » 08 Aug 2006, 20:12

acrowot wrote:Thanks for your reply weety, I did think about putting it in gear to try to stall it but doing those sort of revs.I wondered if it would work, anyway I will bear it in mind. How would you say that thev engine oil was sucked into the engine to cause it to run on it in your friends car.

i think the head cracked allowing engine oil into the cylinders.....never actually took anything apart though.....oh and make sure you have your foot on the brake when you stall it

jeremy · Post by **jeremy** » 08 Aug 2006, 21:49

Head cracked allowing oil into cylinders - intersting BUT - where is it cracked?

XU's have a problem with the oil gallery or pipe feed to the camshaft which can fail where it passes through the head gasket. - Could this cause the problem - NO - it would only affect No 4 cylinder (next to camshaft)

Oil drains down fron the camshaft to the block. If the head was cracked - where could it get through? - Think about it - there is either a waterway or very thick metal in the way - and would it enter more than one cylinder? - again unlikely.

Oil draining back could get drawn in through a faulty head gasket. It would have to be really faulty - and if it was this bad there wouldn't be enough compression to ignite anything. Would it affect more than one cylinder with the drains at the ends of the head - unlikely.

Discuss!

AndersDK · Post by **AndersDK** » 08 Aug 2006, 22:51

Yeah its an interesting subject Jeremy

- but until a really huge pile of clean napkins & ready mixed powder milk supply are build-up - there will be too much guessing - and too little feedback facts

acrowot · Post by **acrowot** » 08 Aug 2006, 23:02

I have had a quick look tonight ( my boss is still with me so it is difficult he does not allow me much time off). I disconnected the Turbo at the manifold and the boost pipe, I ran the engine and air bubbles are present in the clear pipe feeding the pump, I stopped the engine and rebled to the pump until no more bubbles (I must say I also prior to all this I did clean the contacts on the pump ECU, these contacts had green crap on them that somtimes seems to grow on electric contacts.) I restarted and the engine behaved itself, no more doing its own thing. When reving the engine there was a small ammount of oil coming out of the Turbo, but I think this is normal. I reconnected the Turbo and boost and the engine worked fine once again. There are now more bubbles in the clear pipe feeding the pump but at the moment the engine is working properly. When this fault origionally manifested itself it was accompanied by a really loud knocking, I thought it had thrown a big end, I thought the engine was goosed, remember I bought this car with an engine that had its Headgasket fail on two occasions, the second time because a new radiator had been fitted by a mobile mechanic and the bottom hose had come adrift shedding all the water. My next job is to eliminate the air bubbles.

acrowot · Post by **acrowot** » 09 Aug 2006, 23:18

Managed to spend 3 hours on it tonight, fitted clear pipe between filter and primer pump, when engine started there were a few tiny bubbles in this pipe but quite a few large bubbles in the much smaller diameter pipe from the filter to the pump, I decided to change the filter assembly and small diameter pipe to the pump, this made no difference to the bubbles, they were still there. Before and after changing these parts the engine ran without fault. I decided at this point to take the car for a test drive, the car drove without problem, the engine was smooth, quiet and powerful, when I returned I checked for bubbles there were none, I will check again tomorrow. I now do not believe that the Turbo was responsible for my problem, also I do not think that the engine was running on engine oil. I woder if the contaminated contacts on the ECU could have caused the runaway, or was it indeed air in the diesel supply. I will be a little worried for sometime now when driving this car incase this returns. It really is a very nice car to drive even the aircon works, it has some minor faults (rev counter reading full scale, unable to reset trip) but I will leave these for another time. Also there is no excessive sump pressure.

caveman_si · Post by **caveman_si** » 10 Aug 2006, 11:23

fitted clear pipe between filter and primer pump, when engine started there were a few tiny bubbles in this pipe but quite a few large bubbles in the much smaller diameter pipe from the filter to the pump

From what you said no/few bubbles before filter and lots after sounds as if the filter is sucking in air causing the problems you have experienced. Dont quote me but i think there are 2 types of fuel filter for this car. One filter is a screw in canister with a plunger on top which rarely sucks air. The other fuel filter is mounted on top of the thermostat, it has 4 allen screws holding the top down and a water drain tap. This second type are known for sucking air.
The 3 main places it sucks from are the drain tap, the lid as either the seal on the filter is rubbish or not done up correctly or the seal between the filter houseing itself and the metal underneath can go and let air in.
All fairly easy things to fix though the last one requires a coolant drain.

hth Simon

jeremy · Post by **jeremy** » 10 Aug 2006, 12:17

The black bowl type fuel filter is in fact also a water/fuel heat exchanger and has a thermostatic control valve.

Many happy hours have been spent tracing air leaks in these things - only to find that its the thermostat seals which have hardened and are leaking. The thermostat is I think the strange bolt-like thing that can be seen on the rear of the filter housing at the bottom - and it may need removing and its seals replacing.

There were photos on this site but I couldn't find them last time I looked.