Mazda 6 – Overruning – Turbo damage?

henrik1971

I don’t post on here too often, but I posted back in June about looking to buy a few years old Mazda 6 2.2 diesel, and people were cautioning about oil dilution and ‘dieseling’ which had been known to happen with these cars. Knowing this and being slightly paranoid, when I did buy one, I kept my eye on the oil level like a hawk!

However, I need some advice on the following timeline:

• Bought car in June. Newly serviced and MOTd. Drove it for 3 months circa 3k miles. All fine.
• 18th Sept oil change at Kwik Fit – they filled it exactly to the ‘Full’ mark
• Drove the car for about 4 or 5 weeks. Checked oil weekly. All okay, level crept up by a millimetre or two.
• Mid October car recalled by Mazda for software updates. All good.
• Three days later, driving in France , warning message flashes up on the dash in amber writing “ Vehicle System Inspection Required”. Car still driving fine. Phoned Mazda next day, they said, nothing to worry about. Drop the car in after we get back home and they will do a quick check.
• Drove home from France. Checked the oil level. All still good and just slightly above the Full mark and considerably below the ‘X ‘mark. Two days later dropped it in to Mazda.
• They checked and said the error code they’d pulled from the system indicated an ‘engine overrun’. The car shouldn’t be driven and they needed to strip the car down to see what damage may have been caused to the turbo.

Obviously I’ve left the car with them and wait to hear the diagnosis early next week. However I have two questions:

1. How could the overrun have occurred if oil level barely rose at all? When I asked them, they said it could “just happen” and there was no way to guard against it, regardless of the oil level in the sump. Any dilution can be an issue. Sounds a bit unbelievable to me. Are we supposed to change oil monthly?
2. When the error appeared the car was driving perfectly. All the way home from France it drove perfectly when I dropped it at Mazda it was driving perfectly. It was just the error message that I wanted clearing/checking. Why do they need to strip down a car to look for damage to a turbo/engine, that to me, is working perfectly?

Any advice on this welcome!

forgotmyname

Leaky oil seal in the turbo is the usual cause.

henrik1971

Thanks forgotmyname.


Now you've said that and I've googled further, I can see that leaking oils seals on the turbo is the more common cause of overrunning than an overfilled crank case.



I suppose inspecting the condition of the seals to establish if they have been leaking and if so, how badly is the next step - and whether it is repairable or needs replacing.... The guy said 2014 was the changeover year between two types of turbos - those that can be repaired and those that can't...

henrik1971

Just to close this thread, thought I'd report back that the turbo has found to have an internal fault - but they haven't said what it is. Needs replacing at £900+VAT + labour, so as you can guess I'm faced with a big bill, well over £1500. Just what you want before Christmas.


The interesting thing for me was talking to Mazda UK, very nice people. I'd been trying to get some goodwill from them to lessen the blow, but at 4.5 years and 114k miles it was more of a hope than anything else. However, Mazda claimed that if the car had been serviced on time, they would have considered something. It did have a full dealer history before I bought it, but when she read out the service record, every single service from 12,500 miles up to 100,000 miles had been carried out late - say 14-15k instead of 12500.
Based on that, I had to agree with them, that 'fairs fair'.
Life lesson though when buying a car. If the service history has any significance to you, check carefully the length of every servicing interval. If they exceed the manufacturers instructions, then you can forget the manufacturer honouring their side of the deal too.

The service overruns on mine weren't huge, but every single one was over, and combine that with many people's sceptisism about recommended service intervals being far too long already.

forgotmyname

Plenty of places will supply a turbo for half that.

chrisw

henrik1971 wrote: »

If the service history has any significance to you, check carefully the length of every servicing interval. If they exceed the manufacturers instructions, then you can forget the manufacturer honouring their side of the deal too.
.

I would echo this.

I've just had a new engine fitted in my 2014 Volvo due to cylinder leakage. Volvo agreed to contribute 90% due to the complete Volvo service history.

Mercdriver

On my Cx-5 which uses the same engine as the 6, I wait for the trip meter to reach 9500 and then I book a service meaning it gets done around the 10,000 mile mark - for me that is twice yearly.

Londoner_1

In my opinion mazda6 diesels are a joke, one of the worst ones out there, the petrols on the other hand are fantastic.

henry24

Londoner_1 wrote: »

In my opinion mazda6 diesels are a joke, one of the worst ones out there, the petrols on the other hand are fantastic.

Why what's wrong with them?

henrik1971

Well, another 24 hours and I've not been able to quite close out this issue after all.

After phoning round a couple of turbo specialists and asking for a verbal opinion over the phone, I am left in a bit of a quandry.
As stated above, turbos can be bought for less than the £900 mentioned above- and fitted at a lower cost.They also tell me that this twin turbo set up has two common faults: (1) the changeover switch failing or (2) the internal bearings failing - both of which would lead to symptoms when driving the car either in terms of exhaust smoke or engine power. Neither of which I experienced at all.


My conundrum is this. The warning message "Vechicle System Inspection Required" came up on the dash whilst I was abroad. Phoned Mazda who said not to worry and bring it in when I got home. I drove home from France. No perceptible symptoms of overrun at all.
When I took the car in, they plugged it in and told me the error code is 'engine overrun' and not to drive it any further. They postulate the problem is with the turbo but there are no visible symptoms when looking at the engine/turbo itself.

So I am faced with a large bill to fix a car that was driving perfectly fine and the diagnosis (turbo failure, replace turbo) is based just on an error code and an assumption of an internal failure within the turbo.

I of course am thinking, what if they are wrong? Its too expensive a repair to be made on assumptions.

• Is there anything else it could be?
• Is there a way of definitively diagnosing the fault so that I can have confidence that the expensive turbo replacement is the right thing to do?

In my last call with the dealer I raised this with them - along the lines of "if this repair turns out not to be the actual issue, will you refund, or will you keep going and fix it properly for no additional charge?" There was a pause on the other end of the phone and I have another call with the the dealer and the main mechanic there tomorrow. Was it a reasonable question for me to be asking them?

Any advice would be appreciated. I've considered having the car taken somewhere else in the area who might be better at diagnostics, but not sure what more they may or may not be able to do. Plus of course, in the meantime the cost (labour, etc.) keeps mounting.

xzibit

There's no guarantee it's the turbo. Plenty of people have an issue diagnosed only for the fault to remain when they get the car back.

The Mazda diesels really are a engine to steer clear of. With an engine with problems like that I really wouldn't take it to Kwik Fit either, although I wouldn't take any car to them, but that's just up to me.

It may be worth getting a second opinion from another Mazda dealer. If it is the turbo then it may be possible to repair it rather than replace completely, however you'd need to find a specialist, garages will just want to replace.

Once it's fixed, sell it. The Mazda 6 is a great car, I've owned one from new 2016-2018 but it was a petrol and I'm a lover of diesel engines, but point blank refused to buy a Mazda diesel.