Q7 - Broken fragments of crankshaft shells - repair or scrap

[e4Audi]

Hi all

I have a 2016 Q7 TDI Quattro Diesel 2967cc, 120k miles on the clock. Always serviced by Audi specialist and been a great car.

Few weekends ago I was driving on the motorway and suddenly noticed a loss of power. ECU went berserk and told me to restart engine etc. No noise and no warming lights prior to this.

I managed to coast off the motorway and car would not restart. When hooked up to recovery guy's computer it came up with low oil pressure but oil tank was full. Got it towed to a garage and the engine does start but sounds awful and isn't working properly.

My mechanic drained the oil and a few metal fragments were in there which he thinks are remnants of crank shafts shell. He doesn't want to take the head off and thinks I should buy a new engine for him to fit or scrap (I wouldn't know where to start with either!)

Has this happened to anyone else in the past? And is it something that can possible fixed or a whole new engine replacement needed?

Any advice or guidance really appreciated

Thanks
Chris

[BlindedByTheLights]

Follow the advice of the mechanic you’re paying to give you advice?

[e4Audi]

He said he doesn't want to get involved in removing the head of the engine but it's possible it could be fixed. Just seeing if anyone else has experienced a similar issue and what they did

[stevemcs]

Sell it for spares, lets say go get an engine for 4k, then remove and swap over parts, refit probably 20 hours, then gaskets, bolts, probably a turbo - anywhere oil can get you wouldn't swap over, by the time your done you will be into 8k and all you have done is fit a used engine. Its not worth it.

[jfdi]

If it's crank bearings that are failing then there's not much point removing heads. It's the bottom end that needs removing which I would guess is an engine out job. Cost of rebuilding would depend on the amount of damage but if it's knocking loudly then it's going to be very pricey as likely the crank is scrap. A known good (that the tricky bit) second hand engine will probably be cheaper.

[stevieturbo]

e4Audi said:

Hi all

I have a 2016 Q7 TDI Quattro Diesel 2967cc, 120k miles on the clock. Always serviced by Audi specialist and been a great car.

Few weekends ago I was driving on the motorway and suddenly noticed a loss of power. ECU went berserk and told me to restart engine etc. No noise and no warming lights prior to this.

I managed to coast off the motorway and car would not restart. When hooked up to recovery guy's computer it came up with low oil pressure but oil tank was full. Got it towed to a garage and the engine does start but sounds awful and isn't working properly.

My mechanic drained the oil and a few metal fragments were in there which he thinks are remnants of crank shafts shell. He doesn't want to take the head off and thinks I should buy a new engine for him to fit or scrap (I wouldn't know where to start with either!)

Has this happened to anyone else in the past? And is it something that can possible fixed or a whole new engine replacement needed?

Any advice or guidance really appreciated

Thanks
Chris

Pictures.

Can't see why he'd want to take the head off though, when the bearing shells are in the bottom end of the engine.

If indeed you are getting large parts of bearing out though, then yes that is pretty bad.

Anything can of course be fixed, but pricing up options, time involved, and whatever then may have some sort of warranty....will take time. Up to you to decide what may seem best.
And never know might be worth pricing a short motor or bare engine from Audi. It probably will be mental....but you never know.

[HJG]

New (second hand) engine time. I wouldn't even entertain the idea of repairing it.
Ironically it would've been easier if the connecting rod punched a hole in the block because then you'd have no option!

[stevieturbo]

e4Audi said:

Hi all

My mechanic drained the oil and a few metal fragments were in there which he thinks are remnants of crank shafts shell.

We need pics.

One aspect of that concerns....he "thinks" they're remnants.

If they were parts of the bearing, it should be pretty obvious. So it should be a fairly certain diagnosis.

At this stage, and obvious first step should be to remove the sump. It looks pretty easy to do. Removing the heads would be idiotic, as is the suggestion.

https://www.youtube.com/watch?v=WsSAS1Lkr-0

[bearman68]

Compression test on a scope first thing. Save taking the sump off, and it will identify if the crank is damaged.

If there is doubt, remove the sump as said. Bet that's not an easy job on these.

If you like the car, might be worth putting an engine in. I often use a portal website called first choice spares, or even Ebay - but that's for common engines.
But you gotta like the car to change the engine - if you don't you'll be better off selling as spares or repairs. Changing the engine will probably cost ore than selling and buying again.

[journeymanpro]

bearman68 said:

Compression test on a scope first thing. Save taking the sump off, and it will identify if the crank is damaged.

If there is doubt, remove the sump as said. Bet that's not an easy job on these.

If you like the car, might be worth putting an engine in. I often use a portal website called first choice spares, or even Ebay - but that's for common engines.
But you gotta like the car to change the engine - if you don't you'll be better off selling as spares or repairs. Changing the engine will probably cost ore than selling and buying again.

How does a compression test show crank damage?

[TGCOTF-dewey]

If you want to see if it is bottom end, Flexible endoscope through the sump drain may show what's gone. It's a half hour job, so not spendy.

[fourstardan]

No idea on what you should do but what a situation but stripping down sounds expensive in the first place for something non repairable.

120k and full service history on a Q7 that I expect has cost you a fortune...is there any hope for owners now days!

[bearman68]

journeymanpro said:

bearman68 said:

Compression test on a scope first thing. Save taking the sump off, and it will identify if the crank is damaged.

If there is doubt, remove the sump as said. Bet that's not an easy job on these.

If you like the car, might be worth putting an engine in. I often use a portal website called first choice spares, or even Ebay - but that's for common engines.
But you gotta like the car to change the engine - if you don't you'll be better off selling as spares or repairs. Changing the engine will probably cost ore than selling and buying again.

How does a compression test show crank damage?

You see it as a discontinuous wave on the starter motor current.

[Polly Grigora]

journeymanpro said:

How does a compression test show crank damage?

It's a mystery and like you need to know all about this method

Have had plenty of engines knocking like fk due to crank bearing failure yet the majority of them passed a compression test

Someone will be along shortly to explain in detail how this works

It could be a case of the starter motor drawing less current for a few milliseconds when one or more crank journals are making no contact with a shell that is badly worn or disintegrated

I don't know

[finlo]

Or maybe the piston won't travel fully up the bore if the shell has parted company?

[STe_rsv4]

finlo said:

Or maybe the piston won't travel fully up the bore if the shell has parted company?

This was my thought.
Piston wont fully compress the gas in the cylinder due to the loss of travel from the bearing not being present.

[bearman68]

I repeat, you see it as a discontinuous wave on the starter motor current.

The starter motor current looks a saw tooth wave. A broken con rod bearing will show a marked step, and an instantaneous drop in current - I guess about 50 amps and about 1/00 of a second. About that I suppose. It can be usually be clearly seen on a scope.
Measuring starter current waveform is a very clever way of doing a compression test. It's very quick and easy - maybe takes 15 minutes, and shows all sorts of interesting things, that a conventional compression test won't.

[Matt_E_Mulsion]

Maybe the OP's mechanic doesn't want to get involved in taking the engine to bits to either identify the fault and/or repair it. It doesn't sound like a trivial issue or a cost effective repair, hence why he may be steering the OP into either sourcing a good second hand engine or getting shot of the car.

[stevieturbo]

Matt_E_Mulsion said:

Maybe the OP's mechanic doesn't want to get involved in taking the engine to bits to either identify the fault and/or repair it. It doesn't sound like a trivial issue or a cost effective repair, hence why he may be steering the OP into either sourcing a good second hand engine or getting shot of the car.

It sounds like he doesn't have the ability to fully diagnose, given he "thinks" what he has seen are bearings

If the bearings are fked that bad, the debris will be pretty obvious. Nor is his train of thought about removing heads....making any sense whatsoever under the circumstances.


Not sure if such failure is common on these engines or not. Hope not....I have one lol.

[tapkaJohnD]

e4Audi said:

Hi all

I have a 2016 Q7 TDI Quattro Diesel 2967cc, 120k miles on the clock. Always serviced by Audi specialist and been a great car.

Few weekends ago I was driving on the motorway and suddenly noticed a loss of power. ECU went berserk and told me to restart engine etc. No noise and no warming lights prior to this.

I managed to coast off the motorway and car would not restart. When hooked up to recovery guy's computer it came up with low oil pressure but oil tank was full. Got it towed to a garage and the engine does start but sounds awful and isn't working properly.

My mechanic drained the oil and a few metal fragments were in there which he thinks are remnants of crank shafts shell. He doesn't want to take the head off and thinks I should buy a new engine for him to fit or scrap (I wouldn't know where to start with either!)

Has this happened to anyone else in the past? And is it something that can possible fixed or a whole new engine replacement needed?

Any advice or guidance really appreciated

Thanks
Chris

You are whistling in the dark, trying to know the extent of damage without dismantling the engine.
OR, your 'mechanic' just happens to have a mate with a 'pristine' replacement engine, that he's going to tell you about. He doesn't work for A.Daley Associates, does he?