What can cause the turbo to leak oil into the intake

Check exhaust smoke color when engine hot. If there is white smoke, there may be oil in the pipes. Means the valve seal is leaking oil into the cylinder. Another way to check is to look at the spark plug tips. If is full of soot like burnt oil then the oil is leaking into the cylinders.

If yours is E60 turbo, check the presence of residue oil in both the exhaust and intake turbine. If there is, the oil seals in the turbo housing is leaking oil. They do sell service kits for turbos.

Do you have a external leak or does your engine oil drop but you can not see a leak. My S60 had a leak and it was from the return pipe from the turbo to the sump.You can remove the belly plate and look from the bottom at the back off the engine.You will see the return pipe at the bottom of the turbo. If it does not leak at the there the turbo might be worn and it is blowing the oil into the intake.To check remove the intake hose and check for excess oil in the intake system.

i own an Audi a6 2.7t i always see some oil in my intake its cause the car has a poor PVC system you could put a catch can on your car to eliminate this problem no big deal a blown turbo would be white smoke major and or blueish smoke or sounds like a dentist drill under boost.

Leaking of any fluid is not normal. The only time any fluid should expel from the car is if you have overfilled something. Your turbo could need replacing, you could have a hole in the intercooler. Have you noticed any lack of performance or extra smoke...

if the turbo is leaking oil into the engine then you have an internal engine problem. the turbo works off of the engines exhaust , therefore if oil is getting back into the intake from the turbo then it is coming from the exhaust. posible worn piston rings or bad valve seals. it also could be a bad turbo bearing and seals letting engine oil leak into the turbo from the turbo oil lines from the engine and blowing back into the intake.

It is part of the cause,

If oil is accumulting inside the inetercooler, it means that the turbo-shaft seal is leaking causing oil to by pass in to the intake system, then through to your intercooler. A quick check to see if this is a fault, remove the hose/piping from the turbo the intercooler and place a piece of white paper over the hole at the turbo where the air is dispelled. Run the engine for a few minutes and if you notice any oil occuring/building up on the white papaer, then it is the turbo seal. This method is used on everything from jetskis to dump trucks. If no oil is present then the oil leak will be coming from somewhere else on the engine, and being sucked in through to the top of the intercooler. May have to remove it to see where any other leaks are coming from.

There is a oil drain return from the turbo charger to the sump. If the sump oil level covers the outlet into the sump, oil will build excess pressure tin the turbo causing the sealing rings to leak oil in to the intake manifold. This would cause smokey exhaust and loss of oil. Try this. Drain the sump completely, refill with the exact quantity of oil to Mazda spec. Dip the oil and if the new oil level is lower than the full mark on the dipstick, you have found the cause of the problem. Mark this new level with a scriber or file and fill only to this new level. Hope this is the solution.

I assume it is a turbo diesel? Then:

Location of the sensor:
- in early cars is in the ECU, with vacuum pipe going from intake maniforld duct to the ECU
- later models on the air intake duct, with wiring going to the ECU.

The fault may often be caused by:

- air leaks in MAP sensor line to the ECU (early ones only) or any of the vacuum control line hoses. This normally due to perished/loose flexi pipes, etc).
- leaks in the air hoses going between turbo/engine/intercooler. Can be spotted by slight oil contamination at the point of leak.

Or it's variable vaine sticking (even intermittently) in the turbo due to contamination, preventing the turbo from performing according to the ECU demand, and hence being 'shut-off' by th ECU

So - check all vacum line for leaks, ensure turbo actuator is free to move, all air hoses are intact and secure, intercooler not leaking.

check to make sure the turbo oil return pipe is not clogged. if it is pressure will build up causing oil leak through seal causing it to smoke.