I know this has been discussed at length in various threads, but I'm a little confused about a few things.

Some say the EGR valve(s) failing can cause turbo failure, but I can't see how this can happen, considering the exhaust recirculates back to the induction system after the compressor of the turbo (so any soot doesn't pass through the compressor possibly causing inbalance).

I've also been told (by a Landie mechanic) that EGR coolers can leak coolant into the gas side and cause turbo failure, but again, I can't see how this can happen. Surely the water would enter the engine via the exhaust recirc into the air side, so not really getting anywhere near the gas side of the turbo charger, from which it came. Unless maybe, the leakage drains back down to the turbo whilst the engine is off, causing the damage when the engine is restarted.

What damage can be caused by EGR failure, in either the open or closed position.

Could someone explain, please.

Are turbos failing due to operator error? Not idling long enough etc, before shutting down the engine. Some say the turbo drain pipe blocks up, but I'm not sure I subscribe to this one. I couldn't find any posts where someone has identified this specifically causing turbo failure.

White metal bearings (should) have an infinite life span...............

Anyhoo, just bi curious

In my experience, they fail due to:

Blocked oil FEED pipe, restricting oil flow to the turbos
Turbo overspeed, due to split turbo hose/s
Lack of mechanical sympathy, not warming up and cooling down correctly

I'd suggest the oil feed pipe is a serviceable item every 50k or so, to prevent blockages. An Engine Flush before an oil change would likely clear any build up inside the pipe, but not everyone is a fan of this option...

Turbo hoses should be replaced ASAP after splitting

The last point is just common sense

Thanks mikey

Words I can understand

So failed egrs cause what......

Just a lumpy engine and a massive debt in the purse?

Lack of power and an EML on the dash

There are reports (on here) that EGR parts end up in the engine doing serious damage................ MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

http://www.fullfatrr.com/forum/topic32262....p;start=30

Interesting reading that Craig.

Can you explain how egr failure causes the turbo to overspeed?

I would've thought that overspeeding would be prevented by the variable vanes on the turbo reducing flow of exhaust, thereby reducing speed of the turbine

Self preservation by the ECU??

cheezels wrote:

Interesting reading that Craig.

Can you explain how egr failure causes the turbo to overspeed?

No i cannot sir I’m afraid... I have had conversations with the top guys at Midland Turbo’s and they have tried to explain it but to be fair its not my speciality! BUT... They have researched this phenomenon and their advice (which i recommend to my customers) is to have ANY EGR issue addressed immediately rather than turning off & on the ignition to reset the MIL during journeys! Day after day, week after week etc etc etc

No worries.

Can you recall a trend of which turbo fails the most often.

I think, from what I remember, it is the driver side one??

Gday Steve
I'm glad you're turning your engineering mind to this problem. Clearly from the WSM the crank case vapour CCV enters the turbo with air from the filter. I couldn't work out from the WSM how exhaust gases enter the system. The WSM shows the EGR feeder pipe finishing at the back of the turbo above the exhaust pipe. Are you saying there is a mixing chamber post turbo? All I can see is the from the engine bay is a pipe going directly from the turbo to the intercooler.

I've read a couple of accounts of a EGR leaking coolant causing engine failure. The last account suggested the leak had been occurring for a long time to the point where a lot of coolant was found in the turbo & intercooler.

There had been a couple of fatigue type EGR failures where bits of metal fall into the induction system. ______________________________
Vogue tdv8 08MY poverty pack - wow

Hey Pete,

Yeah, can't help myself., although I'm no expert.

The exhaust gas flows from the turbo charger inlet up to the cooler, through the EGR, and into the charge air after the throttles (well, I'm fairly sure that is it). Times two, for both banks. It is difficult to make out on the drawings.

I'm not sure how coolant leaking from the cooler would flow against the exhaust stream, back down to the turbo and somehow pass to the air side and into the charge air cooler. Not really possible.

Coolant would pass into the engine, through the EGRs, into the air system after the throttles. Or maybe drip back down to the turbo, when the engine is off, possibly pooling in the turbo (gas side) and causing blade (and imbalancing) damage to the turbine blades when the engine is then restarted. Vibration caused by the imbalance will wreck the turbo quickly.

The reports of water in the charge air cooler could just be natural condensation, depending on ambient conditions. To be sure, the water should be tested for nitrates to see if it is actually coolant.

The EGR causing turbo overspeeding is a bit difficult to swallow as well. The ECU would see a turbo overspeed and compensate with adjusting the vanes. Also the flow is from the turbo, not to it.

Overspeeding (as Mikey suggested) caused by a turbo hose split after the air cooler would make sense. The engine doesn't know it is losing charge air pressure from the split, so adjusts the vanes to compensate, thereby speeding up the turbo.

I'm also with Mickey and oil restriction caused by overheating of oil supply/return. The exhaust temperatures are extremely hot (turbo is rated for 800 degrees) and the oil would be working in a difficult environment.

I'll be flushing the engine (using the Cost Effective Maintenance kit), each time I service it.

Also, I'm wondering if the crankcase mist seperator plays a part in the driver side turbo failing. I'm pretty sure it is maintenance free and should seperate the vapour, but the system works by 'vacuum' caused by the turbo (air side). Any liquid should drain to the sump, but any carry over will enter the turbo compressor. Maybe stalling it, or knacking it in some way.

The revive you mentioned should clean the turbo, anyways, but I'm probably gonna have a look a bit more at this.

Whilst I'm not convinced the EGRs cause turbo failure, I will be buying the emulators just to be on the safe side and enjoy the benefits of not having them. As has been mentioned, bits fall off and enter the engine (air inlet plenum) and cause damage.

Just my 2 cents..........

Thanks, that makes things a bit clearer. ______________________________
Vogue tdv8 08MY poverty pack - wow

I'll post a drawing laters.

Just struggling with excel

Here is a drawing of the system.

Happy to be corrected