Turbo Charger Failures

[Guest Stephen345]

Hello,

 

I was driving along the road when, without warning, the car just lost power. I pulled over and noticed some "smoke" coming from the rear of the car.

 

The dealer told me that the turbo charger had broken and that the smoke was unburned diesel but the chap who towed me home said the engine was low in oil and this was becasue the oil had be burned. The dealer later said that there was oil in the turbo and they had to leave the engine idling for a long time to burn all this out, so was it oil or was it diesel, I don't know?

 

The dealer either repaired or replaced the turbo, I'm not sure which, but when I drove home I noticed the engine "whistle" every time I touched the accelerator pedal. I was going to take the car back the next day, but I only got to the end of my road. The car suffered from the same loss of power but without the smoke this time.

 

The car was towed again to the dealer who said it was a software fault; the turbo was not sending signals to the computer but this was now fixed.

 

The problem is that that whistle is still there. Should I be worried?

 

Thanks.

[raveydavey]

Sorry I can't help with the whistle (although to be fair, I've never heard a C3 whistle, so I'm guessing it shouldn't be doing it...)

 

It will have been oil in the turbo - probably a slip of the tounge at the dealer, or someone on service reception getting confused.

 

It is vitally important to let any car with a turbocharged engine tickover at idle for 30 seconds or so before switching the engien off to allow oil pressures to settle down and equalise in the turbo or it will cause premature wear which will give the white-ish "smoke" you saw and ultimately lead to a replacement turbo.

The absolute worst thing you can do is to rev the engine as you switch it off.

[Stephen3452]

It is vitally important to let any car with a turbocharged engine tickover at idle for 30 seconds or so before switching the engien off to allow oil pressures to settle down and equalise in the turbo or it will cause premature wear which will give the white-ish "smoke" you saw and ultimately lead to a replacement turbo.

The absolute worst thing you can do is to rev the engine as you switch it off.

 

Hello,

 

I am the original poster. Sorry for the delay, first I went on holiday, then I had computer problems, but now I am back. I cannot get the forums to log me in so I have had to re-register.

 

It seems my local franchise kept trying to repair the turbo. I got fed up with breaking down and being towed in (four times so far) that I lost confidence with them and phoned another franchise for a second opinion. They booked the car in and replaced the turbo. They told me that they never repair turbos; they always replace. The whistle was the bearings in the turbo.

 

I know about not revving turbos when you switch off, but I don't know how I know this. I am sure that Citroen did not tell me. They ought to put it in big letters in the handbook or a big stickre on the steering wheel when you buy the car.

 

Anyway, I am sure I have not revved it when I switch it off, as I drive on to my drive I slow down so as not to hit the garage wall and then switch off when I am at a standstill.

 

What's inside a turbo? Is it just a fan that forces air into the engine under pressure? Is it mechanically driven by the engine? Why does revving it wear it out?

[paul.h]

Letting the engine idle for some time before switching off is to allow the turbo to slow down from 1000's of rpm before you stop the engine and oil pump which is feeding oil to the turbo fan bearings. If not, the oil film goes and the bearings wear out early. When they wear, the fan can go off central and cause the oil seals to wear allowing oil into the engine to be burnt, hence the white smoke as they fail - had this on a Saab 9-5 (petrol), the car was surrounded by a cloud of white smoke when it went. Early signs of turbo wear are smoke on start up. Also when a turbo fails, parts of it can end up in the air intake to aftercooler and the engine so these should also be cleaned out and the engine oil/filter changed. There may also be a need to replace the exhaust catalyst and lambda probes if the oil has contaminated these.

[stimulator]

What's inside a turbo? Is it just a fan that forces air into the engine under pressure? Is it mechanically driven by the engine? Why does revving it wear it out?

 

A turbo is a dual unit. on one end of the shaft is a turbine and on the other end is a compressor. The turbine is in the exhaust outlet from the engine and is contained in one chamber. The compressor is contained in another separate chamber and is in the air inlet path to the engine cylinders. The turbine drives the compressor. The compressor is an axial flow fan it starts off with the air in a large volume and compresses it into a smaller volumethis allows more air into the engine, However there is a problem with this method and that is HEAT. The exhaust gas is HOT and when you compress air it to gets HOT infact very hot. If it was put into the engine at that temp it would pre ignite the fuel so it has to go thru a intercooler which is simply a air blast heat exchanger.

The turbo on a C3 is also further complicated by being variable volume this allows the internal compression to be changed to prevent turbo lag. This is achieved by a small vacumn device on the side of the unit.

 

The need to all the turbo to idle before shutting off the engine is to ensure that he engine oil is circulated thru the bearibgs to COOL them down. The oil system on the C3 also has a oil cooler which is mounted below the oil filter.

 

I run my two C3s HDI 1.4/1.6 16V 92 BHP on fully synthetic oil a sits cooling and lubricant qualities last laonger.

[Stephen3452]

Letting the engine idle for some time before switching off is to allow the turbo to slow down from 1000's of rpm before you stop the engine and oil pump which is feeding oil to the turbo fan bearings. If not, the oil film goes and the bearings wear out early. When they wear, the fan can go off central and cause the oil seals to wear allowing oil into the engine to be burnt, hence the white smoke as they fail

 

Thanks for the replies they have helped explain a lot.

 

I certainly had some white smoke as it failed, so that must be what happened.