Leon FR TDI Mk 1 - Smoke on start-up

[BenG]

My (2004) car has the ARL engine, and doesn't see much use so often sits around for a week or more between trips.

The problem is that, when starting the car from cold, I get a puff of what looks like white or bluish smoke from the exhaust (can't tell for sure from the drivers seat) and the car runs a bit rough for a second or two before idling normally. No other symptoms or problems and the problem does not recur if the car is started again later in the same day.

Still seems to be happening now the weather's warmed up, e.g: if starting when it's 7-8°C outside. Initially I thought maybe a dodgy glow plug or plugs, but now not so sure.

My friend had a similar issue with his old Golf Mk 4 TDI and his local garage stated that valve stem seals needed replacing, but my car has only done 62k miles so surely these would not be worn out yet? Someone somewhere else has suggested injector seals. If these were leaking could oil get into the cylinders?

Any suggestions or experience is welcome.

Cheers,

Ben

 

[BenG]

Bump.

Any ideas folks?

Not many peeps in the diesel section??

 

[dgjdrummer]

Mine does this and has done every morning for the last 6 months. even at around 7-8 degrees there will be some condensation build up, the metal exhaust will hold some for starters.

Also these cars pump oil from the PCV system back through the intake and this is supposed to be burned off during normal combustion. Some of this could build up and give you a bluey puff of smoke at times.

Unless there's other symptoms I wouldn't worry too much.

 

[Nath.]

The smoke is probably from partially burned oil. Diesel is an oil, if the glow plugs don't work properly you can get a puff of partially burned diesel for a few seconds until there is enough heat to burn properly.

Have 3-4 goes on the glow plugs and see if this helps.

Injector seals, could be.

valve stem seals, could be

PVC system clogged up, could be.

 

[BenG]

Cheers for the replies. Some ideas there but I need to narrow down...

I gather the glow plugs are not actually used above a certain minimum temperature so if the problem occurs at say 7-8°C I think perhaps that indicates it's not a glow plug issue(?)

Is the PCV system the roundish thing on top of the cam cover, behind the oil filler? If so, I might have a go at cleaning it out.

Any way to test if leaky injector seals or valve stem seals are the issue?

Would injector seals allow engine oil or diesel to seep into the cylinders?

Would valve stem seals leaking cause oil smoke or increased oil consumption?

Thanks,

Ben

 

[BenG]

P.S. It's definitely not just water vapour, more like white smoke.

 

[Nath.]

Cheers for the replies. Some ideas there but I need to narrow down...

I gather the glow plugs are not actually used above a certain minimum temperature so if the problem occurs at say 7-8°C I think perhaps that indicates it's not a glow plug issue(?)

Is the PCV system the roundish thing on top of the cam cover, behind the oil filler? If so, I might have a go at cleaning it out.

Any way to test if leaky injector seals or valve stem seals are the issue?

Would injector seals allow engine oil or diesel to seep into the cylinders?

Would valve stem seals leaking cause oil smoke or increased oil consumption?

Thanks,

Ben

My understanding is:-

PD Injector seals would cause engine oil to seep in, the injectors are mechanically driven off of the cam. The seal separates the injector nozzle from the oily mechanical bits. Normally the poor seals also cause poor running from a cold start too. Very similar to faulty glow plugs.



Valve stem oil seals would cause both smoke on startup and increased oil consumption. The oil seeps into the cylinders, gets partially burned and turns into smoke then disappears out of your tail pipe. In bad cases of valve stem oil seal failure you get smoke on over run and long periods of tick over too.

When I say over run I mean when you're coasting down hill in gear with the clutch engaged. (when the wheels are turning the engine as apposed to the engine turning the wheels)

 

[BenG]

Thanks for the replies.

I'm leaning towards injector seals possibly needing doing, but might get the glow plugs checked out as well.

It can wait 'til the next service though as the car is otherwise running fine and we seem to finally be out of the endless Winter

 

[dgjdrummer]

I had my glow plugs replaced last August (nearly 10k ago) and I also get this problem only without rough running, just normal cold start kind of running.

 

[BenG]

I get slightly rough running for a couple of seconds after cold starting, coinciding with the white smoke, which is quite subtle really.

I'm guessing there's a build-up of either diesel or engine oil in the cylinders which is clearing itself.

Looks like I've got possible injector or valve stem seal issues. Both sound involved and expensive to fix so I'm going to have to ignore them for now unless they cause a running issue with the car....

Thanks everyone for the input.

 

[G4reth]

My 2004 TDI does this every morning and has done for the last 18 months, not had any problems with mine. Hopefully nothing serious going to happen.

 

[HedleyNEUK]

Yeah mine does this every now and then, moreso when i havent used the car daily...
also had a naughty diesely stink for a minute too...
everything else seems absolutely fine..

 

[BenG]

Just had a dodgy glow plug replaced but has not made any difference to the smoking when cold.

The smoke looks blueish to me so I think I've got either leaking injector seals or valve stem seals.

 

[Nam-uk]

your better off changing all the glow plugs if one goes

 

[BenG]

Funnily enough the garage told me the same & I thought they were just drumming up buisness

Looks like a job I can do myself though if any more plugs start playing up.

 

[Andrewcupra TDI]

did you get to the bottome of this after

mine is a rite bitch to start if left for a week or soo it will take ages of constant trying to hold key on

 

[BenG]

Not really. Decided to live with it as the car starts fine, just smokes for a couple of seconds. I guess either valve stem seals or injector seals are leaking a little oil into the cylinders overnight, from what's been suggested so far.

If your car is hard to start it suggests a different problem. Glow plugs shouldn't be needde in this weather, so maybe you have an air leak allowing fuel to drain out of the pipework overnight, so the fuel system has to re-prime before the engine will start?

Just one possibility. Low compression (bore/ring wear) could also require more cranking to start the engine (but takes a high mileage to wear out these engines if they've had proper oil changes!), or if the cranking speed is low (tired starter and/or battery) then the engine will take longer to start as it is relying on heat generated by compressing air in the cylinders fast enough to ignite it.

 

[Masterkm]

Had this problem on my MK2 1.9TDI after the turbo blew, has been doing it for 12months now. Had injector seals replaced and still kind of occurs but better than first thought. Decided to live with it as car runs fine.

There is a small amount of oil consumption but nothing to worry about as I have been told. Still a rough idle for a few seconds as your getting too. I suggest its valve stem seals but as Midland VW said, its not common on these engines tbh.

 

[BenG]

I find it odd the valve steam seals would be worn out after only 64k miles, or perhaps they just dry out / shrink (are they rubber?).

There is no noticeable oil consumption by my car, but it just runs rough for a few sec. as you say as though it's clearing the crap / oil out of the cylinders. Still starts quickly though so I'm tempted to ignore it.

Won't look great when selling the car though. Someone might assume the turbo's knackered...