Pug 405td 168000mls 1997, 99% sure my valve stem seals need replacing, every now and then i get blue smoke on start up and car sounds like its running on 3 cyl for about 5-10sec, when the car is running no problems the thing flies for a diesel anyway, recently change glow pugs helped slightly but no fix, anyway what i was going to ask has anyone changed the seals without removing cylinder head? must be a way of holding the valve up through injector hole whilst removing spring and seal? anyone?
Duggie
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Duggie
Shouldn't worry about valve stem-seals on a diesel. Any slight leakage just gets burned along with the fuel.
The blue smoke is unburnt diesel and that will be down to low compression, anti-freeze ingress, [has it had it's second replacement head yet?] or possibly an injector fault.
Pop the glow-plugs out and do a compression test hot and stone cold. You're looking for one odd cylinder.
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Blue smoke is oil being burnt,if it was engine it would be white(injection timing,low compression or h/g),or black(excess fuel,as in blocked air filter,worn injectors).
Can you find out the clearance between valve and piston at TDC?It might only drop a few mil.I have done them on a CVH this way.Main thing is being able to compress the springs,make sure you block oilways so that collets don't go down them.
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See if you can hire a valve stem seal replacement tool. This works by using compressed air to force up valves against their seats enabling the other part of the tool to compress valve springs. Adapters normally come with the kit so the compressed air supply can fit either diesl engine via glowplug/injector hole or on a pterol engine via the spark plug hole.
Had similar symptoms on my 155,000 mile 309 normal aspirated diesel. Also getting slight oil/coolant mixing in header tank but not in engine and no 'mayonaise' either. I decided to remove head anyway as I wanted to decoke and re lap valves and repalce head gasket and stem oil seals which were rock hard and crumbling. Even at 155,000 miles there was a slight wear lip at piston TDC and the honing was still in evidence. The head gasket hadn't blown but was allowing oil and water to mix via water gallery. (Car always started on the button before) PSA diesels never cease to amaze me.
Incidentally, the valves were badly contaminated with carbon and were sticking in the guides. After a good clean up and new seals, and a valve lapping, the car really flew which amazed its new owner on a test drive.
If your car is in good nick, maybe go down the route I did. If not Sealey sell the special tools to help change oil seals or you may be able to hire one.
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I have used a technique where nylon cord is fed down the cylinder so that when piston is moved up, it traps cord and jams valves shut. It depends if you can get cord down glow plug hole via pre combustion chamber (these engines are Indirect Injection)
Its a lot of messing about and you still will need to investigate cylinder head and valves to see if any of them are sticking and/or burnt, which can still happen on a diesel.
If you plan to keep the car, remove the head and have a good look at the head gasket. If not, get a cylinder leakage test/compression test carried out to determine if valves or rings/bores are to blame.
Does car settle and run normally once it is warmed up?
Is there any knocking sounds from injectors?
White smoke on start up is fuel that hs not reached correct vapourisation point either due to low engine compression or poor glowplug performance. Black smoke on start up and/or running can be down to incomplete combustion caused by; blocked air filter, incorrect timing, and white smoke or steam vapour once engine is warmed up can be sign of coolant being sucked into cylinders via head gasket failure/cylinder head cracks etc.
Also poor starting is often caused by air being drawn into fuel lines via leaking primer pump, fuel filter, leak off pipes or perished fuel supply or return pipework. Always check the simplest things first as I had a Citroen XM TD that was a pig to start and run badly until a new filter housing was fitted.
Andrew
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What is you oil consumption. 1000 miles per litre or what. Regards Peter
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Only very late XUD engines actually had valve stem oil seals. As yours is in a 405, I think it unlikely it has any - the valves just run in bronze guides, and since the engine is not under significant negative pressure (unlike a petrol engine) no oil is sucked by.
More likely to be a duff injector, air leak, injection pump wear... or any other afflication on a high mileage engine. If it only does it occasionally, I'd just ignore it for now.
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RichardW
Is it illogical? It must be Citroen....
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A normally aspirated diesel although it doesn't generate same manifold vacuum as in a petrol engine, still relies on a pressure differential between outside atmospheric pressure (14.7psi at sea level) and negative pressure within the cylinder as piston moves down on induction stroke. As air flows from high to low pressure, the cylinder fills with air assuming pumping/frictional/fluid dynamic losses. Any wear in valve stem/guides or ineffectual seals will allow oil to be sucked through inlet valve and into the charge where it will be burnt with the fuel vapour. In extreme circumstances a diesel can continue to suck sump oil through guides and continue to burn it as a fuel source until the engine is stalled deliberately or it self destructs when all lubricating oil is used up. It has been reported in certain Renault and Japanese diesels.
In your case, unless oil consumption is high or it starts running like a dog, then just put up with it. It depends on how handy you are with a toolkit and whether the cost of investigating/rebuilding head and/or engine is a lot less than what the car is worth.
Also, a worn turbo can cause increase in oil consumption. If the seals are worn on either compressor stage or turbine stage, oil will be forced into induction side of engine or through exhaust Gas Recirculator valve and pipework. You will find out if you remove pipework from intercooler or EGR pipe where it passes into inlet manifold. If there is a mixture of oily wet deposits in either inlet or EGR pipework, then the engine is losing or burning oil.
Hope this helps.
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Cheers for the replies, ive carried out 2 head gasket replacements on previous 405tds, although not a difficult job i just dont have the time to do it plus its cold outside! the car isnt that difficult to start just sounds rough and with cloud of blue smoke until engine clears and runs on all cylinders, as i said earlier this isnt all the time, it doesnt burn a great deal of oil very rarely top up between changes (every 4000mls) i replaced all the leak off pipes when i replaced the glow plugs so for now i think i will leave things be or maybe have the injectors cleaned. Regards.
Duggie
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