1.8T: Blown turbo or headgasket?

[poostA4]

I have a '03 A4 Cabriolet 1.8T, and I am experiencing issues. Some say it the turbo or the head gasket and I need a more justified answer. The cars mileage is climbing and is now at 170k, but now is garaged to prevent further damage and to justify what is exactly wrong. The car at idle blows whitish-blue smoke but not a lot of smoke by any means. But while driving it has a clouds of blue smoke, but a deceleration the car still has a more blue smoke, I checked the oil and oil cap, on the dipstick it one minor dot of a lighter color and the oil cap it's self had one dot (small-medium size) and also Touched around the turbo housing (not really knowing my way around I didn't take the chances taking anything off) and it had a huge amount of oil/grease but i don't know if that is normal? Which of the two do you possibly think it is? Thanks!

[B6ayfour]

what other issues besides smoke? could mean a lot of things. blue smoke sounds like turbo to me though.

[poostA4]

what other issues besides smoke? could mean a lot of things. blue smoke sounds like turbo to me though.

I mean the turbo still spools, and I believe there is a slight coolant leak but that have been happening prior from all this, and also the car feels more sluggish when floored (this might or might not be true, the car hasn't been driven in a while because I now have time to get to all of this) and besides a lot of grease/oil on the turbo housing I think that's it.


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[diagnosticator]

If there is coolant burning in the cylinders, that is almost always from a failed head gasket. The "whitish" appearance of the blue exhaust smoke is evidence of coolant burning from a head gasket leak.

Sudden development of blue smoking from gross oil burning is usually from an overfilled crankcase oil level provoking oil to escape through the turbo shaft dynamic labyrinth oil seals at either or both the turbo compressor or turbine. Or the turbo dynamic labyrinth shaft seals are fouled with carbon deposits causing excess oil flow through the dynamic shaft seals. Another cause of excessive oil burning with blue smoke is worn out heat aged valve guide seals. This typically develops more gradually compared to leaking carbon contaminated turbo shaft seals.

The evidence and symptoms of the separately caused problems occurring at the same time, the blue smoke oil burning and coolant burning in the cylinders are coincidences . There is no limitation to the separate different causes occurring one or the other.

[poostA4]

If there is coolant burning in the cylinders, that is almost always from a failed head gasket. The "whitish" appearance of the blue exhaust smoke is evidence of coolant burning from a head gasket leak.

Sudden development of blue smoking from gross oil burning is usually from an overfilled crankcase oil level provoking oil to escape through the turbo shaft dynamic labyrinth oil seals at either or both the turbo compressor or turbine. Or the turbo dynamic labyrinth shaft seals are fouled with carbon deposits causing excess oil flow through the dynamic shaft seals. Another cause of excessive oil burning with blue smoke is worn out heat aged valve guide seals. This typically develops more gradually compared to leaking carbon contaminated turbo shaft seals.

The evidence and symptoms of the separately caused problems occurring at the same time, the blue smoke oil burning and coolant burning in the cylinders are coincidences . There is no limitation to the separate different causes occurring one or the other.

So in the shortest manner there isn't answer, it's you pick a repair to do and hope you picked the right one.


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[Human Garbage]

Not quite man. Do a compression check. If you have a blown headgasket it will be readily apparent by the lack of compression in that/those cylinders. Its where I would start at least...

[diagnosticator]

So in the shortest manner there isn't answer, it's you pick a repair to do and hope you picked the right one.


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Blue smoke from burning to much oil, and symptoms of burning coolant, are separate issues with different causes. There are a couple of frequent causes of excess lube oil burning, but only one typical cause for burning coolant.

One reliable way to determine if the head gasket is leaking, is to get a sample of the coolant and have it tested by a lube oil analysis lab for the presence of dissolved combustion gasses in the coolant. Normally, there is zero detectable dissolved combustion gasses in the coolant. If dissolved combustion gasses are detected in the coolant, that is firm evidence the head gasket is leaking.

With regards to the excess lube oil burning and blue smoking, the two primary causes need to be checked to identify the cause for the blue smoking symptom. With this in mind, a high milage engine will have practically a 100 percent chance leaking valve guide seals are partially responsible for higher than normal lube oil consumption and oil burning with variable exhaust smoking under certain operating conditions. In severe cases, the oil lost through the valve guide seals is high enough to result in the accumulation of oily deposits around the turbo turbine housing, due to condensation of partially burned vaporized lube oil in the exhaust. Performing the relevant troubleshooting steps, will reveal the most likely cause for excessive lube oil burning, and the associated remedy required.

If the valve guide seals are not leaking excessively, then the turbo shaft oil seals need to be examined for defects allowing excess oil leakage into the turbo compressor or the turbine housing, either or both causing excess lube oil consumption and associated blue exhaust smoking symptoms.

It is a matter of experienced judgement concerning which troubleshooting procedures are performed before other tests as needed to determine the most likely cause for the existing symptoms.

In addition, if the crankcase ventilation plumbing is plugged up with sludgy deposits, will result in high crankcase pressures that will provoke oil burning from oil being forced past the valve guide and other engine seals. as well as higher than normal oil loss past the piston rings than will occur with normally slightly negative crankcase pressure. Normal crankcase pressure averages a few inches negative water column pressure, or about ~ -0.4 psig below ambient air pressure.

The above described possible causes for the symptoms occurring, assumes the compression test results are within the acceptable limits of the compression pressure specifications with any excessive compression pressure variation due to valve seat leakage compared to compression loss from excessive piston ring and cylinder wear.