[jacekowski]

Quite common on a lot of cars (i'm not sure if this is the case here) is strainer in oil drain pipe - this can get blocked with metal filings from previous turbo or hardened oil if you do not replace it with turbo, next one is going to be starved of oil and die very quickly.

 

[cj romeo]

Oil and filter changed every 7k miles, level checked every week and I can only recall stalling the engine once (when my wet shoe slipped off the side of the clutch pedal) in the last couple of years.

I don't mean user related !

I meant the oil volume delivered to the bearing, and compressor stall.

i.e. something else wrong.

 

[RomeoRaiderZ]

I don't mean user related !

I meant the oil volume delivered to the bearing, and compressor stall.

i.e. something else wrong.

I'll let you off this time, :lol:.

Just wanted to clarify in case anyone thought I was being clumsy clod with no mechanical sympathy.

To my dismay the car has now had to be taken to the main dealer, otherwise I'd be facing the full cost of the repair. At the main dealer, the parts will be covered by Alfa's warranty and the labour will be covered by the dealer themselves, but if the job was left to the indie garage the parts warranty wouldn't be honoured and there would be nobody to claim the labour charges from as my aftermarket warranty from WarrantyWise doesn't cover the same repair being required within 12 months of a previous attempt.

.

 

[RomeoRaiderZ]

I went into Western this morning to collect a few personal items that I'd abandoned along with the car and was pleasantly surprised. The service manager of the past couple of years (with whom I've had more than a few 'run-ins' over the issues with the 159) has 'retired' and the chap now running the department is one of the 'good guys', :thumbs:. I remember him from before the new regime took over, when he was the best spanner-wielder they had - a real Alfa expert and an enthusiast of the marque to boot, so there might yet be hope of finally resolving this recurring nightmare, .

 

[TheGrimJeeper]

Funny how staff attitude can aid in the overall perception of service, eh?

 

[RomeoRaiderZ]

There's been a bit of good news, , but several bits of bad news to negate it, .

The good news is that there is nothing wrong with the oil system in the car with the pump delivering a healthy level of pressure and all the oilways are clear, so it won't need a new engine which might have been on the cards had the pump proved to be at fault.

The bad news is that there is nothing wrong with the oil system in the car so they haven't a clue why the turbo failed. It would appear to be a similar failure to the previous instances, with the shaft connecting the turbine to the compressor snapped and the bearings seized solid, which you would think would point to lubrication issues, .

Also in the bad news camp, despite there being a good number of these failures around the country, the necessary parts are not held in stock anywhere in the UK so there will be a delay of a week or so awaiting their arrival from Italy. Additionally, there is no courtesy car available at Western until 4th February so with only one car between the 2 of us and an overlap of shifts making car sharing a logistical nightmare (as was my attempt at using public transport - 3 hours to cover what takes me 20 minutes in the car, ), I've had to waste some of my annual leave entitlement and start redecorating the house, , which is the subject of a whole new rant, :rant:, - http://www.alfaowner.com/Forum/rant-room/782906-builders-this-is-aimed-at-you.html#post11553650

.

 

[filomix]

Hi,

Sad to hear that they haven't found an undeniable cause for the several turbo failures...
I'm no expert in TBI engines but I've heard a lot about the wrong oil specification delivered by AR on early new TBIs and on scheduled maintenance on AR dealers, that caused a wave of turbo failures on Giulieta QVs...
Something similar to the well known situation of steering oil (GI/E vs GI/R), that cause a lot of steering issues on early 159s.

I've read that AR has already changed oil specs for the TBIs, so this could be a non issue for your case but, just my 2 cents...

 

[sussexa]

cant remember if we brought this up in the older thread a year or so ago but what or how does this engine releave boost pressure when full throttle then lift off and butterfly shuts ?
what sort of layout is the blow off valve ? mechanical ? electronic valve etc ?
has this been checked out, im sure ive seen mentions of compressor stall breaking shafts on the net(not alfa or tbi related).
heres a description off garret site
Q. What is compressor surge?

A. The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side. Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. Common conditions that result in compressor surge on turbocharger gasoline engines are:

-A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
-The outlet plumbing for the bypass valve is too small or restrictive
-The turbo is too big for the application

Q. What is the difference between a BOV and a Bypass Valve? How do they work, and are they necessary?

A. A Blow Off Valve (BOV) is a valve that is mounted on the intake pipe after the turbo but before the throttle body. A BOV's purpose is to prevent compressor surge. When the throttle valve is closed, the vacuum generated in the intake manifold acts on the actuator to open the valve, venting boost pressure in order to keep the compressor out of surge. Bypass valves are also referred to as compressor bypass valves, anti-surge valves, or recirculating valves. The bypass valve serves the same function as a BOV, but recirculates the vented air back to the compressor inlet, rather than to the atmosphere as with a BOV.

Q. What is causing my turbo to sound like a sewing machine's whistle?

A. The "sewing machine whistle" is a distinct cyclic noise cause by unstable compressor operating conditions known as compressor surge. This aerodynamic instability is the most noticeable during a rapid lift of the throttle, following operation at full boost.

 

[RomeoRaiderZ]

Hi,

Sad to hear that they haven't found an undeniable cause for the several turbo failures...
I'm no expert in TBI engines but I've heard a lot about the wrong oil specification delivered by AR on early new TBIs and on scheduled maintenance on AR dealers, that caused a wave of turbo failures on Giulieta QVs...
Something similar to the well known situation of steering oil (GI/E vs GI/R), that cause a lot of steering issues on early 159s.

I've read that AR has already changed oil specs for the TBIs, so this could be a non issue for your case but, just my 2 cents...

Yep - the change in oil specification was discussed at length in a thread started by myself about 2 years back : http://www.alfaowner.com/Forum/engines-ts-jts-jtd-and-v6/375295-oil-for-the-1750tbi.html

cant remember if we brought this up in the older thread a year or so ago but what or how does this engine releave boost pressure when full throttle then lift off and butterfly shuts ?
what sort of layout is the blow off valve ? mechanical ? electronic valve etc ?
has this been checked out, im sure ive seen mentions of compressor stall breaking shafts on the net(not alfa or tbi related).
heres a description off garret site
Q. What is compressor surge?

A. The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side. Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. Common conditions that result in compressor surge on turbocharger gasoline engines are:

-A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
-The outlet plumbing for the bypass valve is too small or restrictive
-The turbo is too big for the application

Q. What is the difference between a BOV and a Bypass Valve? How do they work, and are they necessary?

A. A Blow Off Valve (BOV) is a valve that is mounted on the intake pipe after the turbo but before the throttle body. A BOV's purpose is to prevent compressor surge. When the throttle valve is closed, the vacuum generated in the intake manifold acts on the actuator to open the valve, venting boost pressure in order to keep the compressor out of surge. Bypass valves are also referred to as compressor bypass valves, anti-surge valves, or recirculating valves. The bypass valve serves the same function as a BOV, but recirculates the vented air back to the compressor inlet, rather than to the atmosphere as with a BOV.

Q. What is causing my turbo to sound like a sewing machine's whistle?

A. The "sewing machine whistle" is a distinct cyclic noise cause by unstable compressor operating conditions known as compressor surge. This aerodynamic instability is the most noticeable during a rapid lift of the throttle, following operation at full boost.

That makes interesting, albeit disturbing, reading. That 'whistle' described in the last section is all too familiar, .

Prior to the original failure back in 2013, the car suffered from an intermittent loss of boost (you'd be on full throttle in mid-overtake and at around 3500rpm when it would suddenly drop the boost to 0) which was blamed at the time on a wiring issue at the lambda sensor. This sudden change in boost pressure probably had something to do with the subsequent turbo failure although at the time the finger of blame was pointed at the oil specification (see my reply to filomix above). Since then, although it's never again lost boost completely, it has suffered on occasions form a hesitancy under throttle with the boost gauge fluctuating by about 0.3-0.4 bar and only achieving a maximum reading of around 0.9 bar - if you lifted off momentarily then reapplied the throttle, it would then deliver the full 1.3-1.4 bar and not happen again for quite a time, .

Something else to bounce off the dealer methinks, :thumbs:.

 

[jacekowski]

Compressor surge is not always dangerous - it very much depends on operating conditions and when it happens.
On diesel engines it happens all the time - when exhaust flow disappears when you lift off but compressor is still spinning and delivering air - however here engine is still consuming air so surge does not happen until compressor slows down.

 

[RomeoRaiderZ]

Compressor surge is not always dangerous - it very much depends on operating conditions and when it happens.
On diesel engines it happens all the time - when exhaust flow disappears when you lift off but compressor is still spinning and delivering air - however here engine is still consuming air so surge does not happen until compressor slows down.

I think I'm just clutching at straws trying to get my head around what could be the cause. When it drops the boost under acceleration, it's so dramatic it's like you've hit a brick wall - you literally get thrown forward against the seatbelt, so something somewhere in the mechanicals must eventually take an extreme dislike to this sort of treatment. When it does its hesitancy thing, it's almost feels like a misfire with a very jerky power delivery,

At the end of the day though, I suppose, it's most likely not going to be my problem (if that doesn't sound totally selfish, ) as I'm pretty certain the "For Sale" signs will be displayed in the not too distant future, . On Thursday, I'm going to look at a likely contender for the practical replacement role, a Honda Accord Tourer 2.4 Type S and Sunday will see me testing a couple of Evoras for the 'something for the weekend sir?' requirement, .

 

[TheGrimJeeper]

I think the Evora is just the ticket.

I'd say look at the 4C, but seeing as though it's totally impractical and has basically the same engine.....

 

[RomeoRaiderZ]

I think the Evora is just the ticket.

I'd say look at the 4C, but seeing as though it's totally impractical and has basically the same engine.....

That's the killer blow for me, certainly when compared to the reliability of the Toyota-derived 3.5 litre V6 in my first choice.

 

[JabawokJayUK]

What about a GT86? A company in Cambridge does a turbo conversion for them that makes it a 2 seated RWD Scooby :thumbs:

 

[cj romeo]

As before, either the turbo isn't getting oil under all circumstances, or that turbo is constantly stalling due to air flow issues.

It's quite a bit smaller than the turbos I deal with though.

 

[RomeoRaiderZ]

What about a GT86? A company in Cambridge does a turbo conversion for them that makes it a 2 seated RWD Scooby :thumbs:

Why did I get a cold shiver down my spine when I read your comment? It's made me reconsider any form of forced induction and so I'm looking at the standard normally breathing Evora (with some performance-enhancing tweaks) over the supercharged S model, despite the 'blower' being a completely different beast in terms of operation.

As before, either the turbo isn't getting oil under all circumstances, or that turbo is constantly stalling due to air flow issues.

It's quite a bit smaller than the turbos I deal with though.

I'm not convinced that a definitive answer will ever be settled upon for this particular installation. I'm sure that there's now a much better chance of it being put back together again correctly with the guy who's now in charge of the service department at Western overseeing things, but I don't think they'll identify the root cause, hence "it was fun while it lasted, but bye bye 159", .

 

[John Sahl]

A turbo isnt supposed to get alot of oil, so if it gets too uch/too high pressure, that can also lead to failure. I dont know on these standard cars, but when we modify cars with bigger turbos, we also put in a restrictor in the oil feed to the turbo!

 

[cj romeo]

I'd doesn't need a lot of oil pressure (40psi or so) but it does need a steady volume.

 

[bembo449]

is it a bad batch of turbo's maybe ?

 

[cue2]

I think the Evora is just the ticket.

I'd say look at the 4C, but seeing as though it's totally impractical and has basically the same engine.....

But have their been similar failures with the same engine in its Giulietta installation ?
What differs from the 159 application , I wonder.
Hope you get it sorted soon.