[Hurricane106]

This posting is a follow on to 2 other posts regarding my ’08 Super Leggera catastrophic failure. In this episode of Bad Day in Lambo-land I cover some details of the engine disassembly, what I have uncovered regarding the failure and ask for input on potential causes. I will break this up into 6 submissions as there are a few pictures to share beyond the 5 per post limit.

I found disassembling the 5.0 liter V10 relatively straight forward to disassemble except for the one not so obvious part of disconnecting the cam chains. The specialty tools I used included a set of 12 point /triple square sockets (8,10,12 and 14mm), a set of torx bits and a set of female torx sockets. I also made the special tool for turning the crankshaft.

Disclaimer - I won’t go to the extent of saying anyone should approach taking their $54,000 engine apart with reckless abandon. I do have a bit of experience with such things and… mine is already a total loss so no real worries.

The first step in engine disassembly was to pull the intake system. Removing the intake cover revealed a mass of oil and debris that I presume was kicked up when the engine failed. See pic 1 and 2

Next step was removing the fuel rail, engine wiring and intake plenum. Below the plenum I found oil in the pockets on top of the engine. There is no feasible place for this oil to have come from and the source is yet to be ascertained. The oil filter and tubing did not suffer any leaks. See pic 3

Viewing into the intake ports revealed oil on top of several valves. The positive part of this was that it verified the valves for the 2 damaged cylinders had some degree of sealing. The bad part is that this raises the possibility of an issue with the PCV system. See pic 4 and 5

 

[Hurricane106]

2 of 6 Extra bits and cam chain

The engine disassembly continued with pulling the exhaust manifolds, clutch & flywheel, valve covers, water pump and AC pump. The next part of the process is to remove the cam timing chains. Prior to this I checked the cam timing and found that the left bank intake cam was out of time by around 10 degrees. I inserted some long studs into the cam timing fixture holes to show the problem. The studs should be parallel to one another. See pic 1 and 2

It is not clear if the cam timing issue was before or after the failure. I have yet to disassemble the VVT mechanism to check for damage. I can tell you that the timing issue did not result in any valves contacting pistons.

After a bit of contemplation I figured out the secret sauce for disconnecting the cam chains which is to remove the cam timing gears. To disconnect the timing chains, pull the cam chain covers, relieve the pressure on each tensioner by applying pressure against the mechanism that has the small hydraulic cylinder (use a screw driver as a lever), place a pin or piece of wire in the 2 holes that align when the tensioner is compressed to keep it from releasing. Following this you can loosen the bolts holding the gear and VVT mechanism to the cams. With the chain loose the cam gears pull off. There are 6 screws to remove on the cam chain tensioner which can then be lifted out. See pic 3 and 4

 

[Hurricane106]

3 of 6 head removal, broken rods and pistons

Removing the head is relatively easy at this point and requires removal of 4 perimeter bolts and the main head bolts. There are reliefs in each cam which allow you to get an extended torx socket on the head bolts without removing the cams.

Upon removing the heads the damage to 2 of the pistons and associated cylinders was very evident. Piston #3 was quite damaged and as the upper part of the rod was missing it came out with no effort. The piston did leave behind the oil ring which was fused to the cylinder. See pic 1 and 2

Piston #8 also came out with no effort as the lower ½ of the rod was gone. See pic 3 and 4

 

[Hurricane106]

4 of 6 timing drive chain and accessory chain removal

The main timing and drive chain cover is the next piece to be removed. There are several different length bolts to keep track of with the cover. The intermediate shaft for the front wheels is pressed into the cover so a little plastic mallet action is required to remove the cover. Pulling the cover exposes the 2 crankshaft drive chain assemblies.

I was fascinated by the design that went into this portion of the engine. The outermost chain drives the gear which drives the accessory shafts (AC pump, water pump, oil pumps). The inner most chain drives the slave gears which connects to the cam chains. See pic 1

Removing the assemblies is straight forward. The tensioner removal follows a similar procedure as with the cam chain tensioners. Compress the tensioner put in a pin, remove tensioner, remove pulley. The accessory drive gear assembly can be taken out as a unit by pulling the 5 longest screws. See pic 2

The accessory drive gear assembly does take a little bit of effort as the main output shaft section is sealed in place with black silicon gasket maker. I used gentle prying pressure under multiple points and rocked it back and forth slightly to get it to release. See pic 3 and 4

The last pieces to remove prior to flipping the engine is the harmonic balancer and pass through shaft for the front wheel drive. The locking portion on the driveshaft coupling nut needs to be ground down prior to removing the nut. Once the nut is removed the coupling slides off with little effort. See pic 5

 

[Hurricane106]

5 of 6 lower end disassembly, what a mess

After attaching the engine to an engine stand the block is flipped over which shows the extent of the damage. See pic 1 and 2

Removing the lower pan shows the next level of destruction. See pic 3

As the lower portion of the crankshaft is now exposed rod caps can now be removed and the piston / rod assemblies can be pushed out. At least those that are still intact.

The laid out pistons provide a good view of the carnage. See pic 4

I was relieved, but not surprised, that there were no obvious signs of an oil related failure.

Pulling the lower crank cradle required pulling the many small bolts from the periphery followed by the main journal bolts. This is where the female torx sockets come in to play. If this were a usable engine block the main bolts would be removed in a specific order with tension being released in a careful fashion. Since that wasn't the case an electric impact made quick work of the bolt removal. The block halves need a bit of a tap with the magic plastic mallet to get them to separate.

Rolling the crank allowed full view of the remaining part of the #3 rod. See pic 5

 

[Hurricane106]

6 of 6 - Just questions, no smoking gun

After putting in the effort to disassemble the engine and sifting through the many pieces the specific cause of the failure is not clear.
What is clear is that whatever that first key element was it definitely wreaked havoc on the whole system.

Questions:
-What caused the oil puddling and was that a factor?

-Is there any potential PCV issue which could have contributed to an oil based hydro lock? (Analysis says very unlikely but still has to be considered)

-Did the out of phase cam contribute in some way or is it collateral damage?

-Was the root cause a rod cap or rod cap bolt failure?

-Was a broken piston the initial failure?

-Has anyone seen similar failures which were traced back to a specific root cause?

-With the replacement engine do I put in aftermarket pistons and rods for peace of mind?

 

[Drew Zee]

Fascinating write up and details. Thanks for sharing and for keeping us all posted. I'm sure that we will all learn something new as you continue to troubleshoot and diagnose.

 

[wrex]

My initial, unprofessional, opinion would say it was most likely the wrist pin of piston #3, which then slingshotted and hammered around, making contact with connecting rod of cylinder 8. Also, would make sense that this caused the majority of the carnage to the block itself.

Hydro locking I suspect would leave more evidence up top and even have ruined the valves before the piston. Having said that, this could explain the mid-timed camshaft if it did push back greatly with fluid in the cylinder. I would just be shocked that the valves wouldn’t become the “fuse” in this scenario though, and be the first point of failure. Based on your pics, I would venture the guess that it started and ended with the bottom end.

You said you were jamming along at 7500 RPM, and to have sucked in that much fluid into one cylinder only seems absurd at that velocity.

What baffles me is what caused the bottom end to fail. Is there a chance it was grossly overfilled on oil, or were you the last one to touch that? If any old shop did it, they often get the fill really wrong.

The piston ring fusing itself to the cylinder sleeve makes sense as it would have been crazy hot and then would have stopped dead once it no longer had a failing wrist pin thrashing a connecting rod to it. It would have also super heated it at that rev-range as it likely was mis-aligned prior.

The oil up top is very easy to explain if the piston broken when you stopped as the many revolutions it would have had before grinding to a halt would have been enough to let oil be whipped up into the top of the cylinder and back through the intake valves, as there would no longer be vacuum on that cylinder. That would basically create an inner blow by with one outlet, which is the intake runners/manifold.

Again, all my enthusiast’s opinion based on the photos and story you provided. Thanks for sharing such awesome detailed photos. I find this fascinating!


Sent from my iPhone using Tapatalk

 

[CFI Designs]

have a few of those 5.0 blocks with the same failures. Good luck on the repairs.

 

[Hurricane106]

CFI - Was there any identifiable causes for the failures on those that you have?

Wrex - A broken piston releasing the wrist pin is one of the theories. Unfortunately the top half of that rod is missing so a big part of the analysis lies with it. I have many hours with a metal detector trying to find it.

Oil level was good and no anomalies detected prior to the failure. The hydro lock theory came into the discussion as that is a failure seen with some of the flat 6 Porsche engines. There was nothing to support that theory in this case.

The ring embedded in the cylinder appears to be mechanically driven into the cylinder wall. It is much easier to see from a different angle. The amount of damage in the cylinders is amazing.

Your explanation on the oil up top is consistent with feedback from a couple engine builders who have encountered failures with engines on a dyno.

Thank you for sharing your thoughts!

 

[Jason B]

Very cool pics and thanks for taking them. If you have a decent cell camera, you could always do a video too if it's easier.

To make ya feel better this can happen even on newer cars. Huracan engine blowing and no one knowing why.

http://www.huracantalk.com/forums/general-discussion/4240-engine-failure-questions.html

 

[CFI Designs]

Boosting a weak motor, surpised yours being naturally aspirated it failed but anything is possible.

 

[jackflash]

Pics look very similar to a 2004 Cadillac CTS-V car I bought at auction with an engine that had been hydrolocked. I realize the 5.0 Lambo is a completely different design from a modern American V8. In the V instance, the driver ran the car at high speed under a railroad trestle during a heavy rain and the resultant splash went into the intake filter mounted on the driver side wheel well. One rod was "bent" and there was a fist sized hole in the side of the block in the location of the piston/cylinder that ingested the water.The heads and valves were not hurt at all. Don't suppose it was raining during this failure?

 

[Hurricane106]

This is a complete stock setup so very surprised to encounter the failure. I am leaning towards aftermarket pistons and rods for the next engine. The few Lambo people I have spoken with assure me the stock internals are very good and that this is an anomaly.

The failure occurred on a beautiful sunny day. It did feel much darker after the failure.

I do have a few videos on the overall project including one on assembling the oil pump. Unfortunately I am on a very slow DSL connection so uploading the videos is painfully slow.

 

[LamboTT]

Great write up but without details on the event, I can’t guess what could have happened.

 

[Waz]

This may be relevant. I run an old 2008 Reiter GT3 5.0 Gallardo (an endurance race car) and a number of these cars broke rods and grenaded in the first year of racing in 2008/9 and a refit with new rods went into most of the 53 pre-LP cars made. I think the new rods are Carillos with their bolts. The engine is very reliable and it has been 3.5 years since last re-build. We normally run two 1 hour enduro races on a weekend plus practice and qualifying so quite a few hours run between 6500 and 8000 rpm and 6 or 7 meetings per year.

 

[Hurricane106]

Very relevant

Waz thank you for sharing as this is very relevant. Do you know if the GT3 engines are using the stock Mahle pistons?

 

[Kenny94945]

Thank you.
Great documentation

I can offer no insights into the failure

 

[EvanK]

Interesting post, of course sorry about what happened. Thank you for sharing all the information and pictures though, pretty neat to see things totally disassembled.

From the photos my guess is that the #3 piston failed where the wrist pin goes through. As it started to give way there the wrist pin and connecting rod were no longer pulling the piston perfectly straight back down the bore, but also forcing it to rotate some within the bore (out of plane from the cylinder head), leading to high friction force/temperature and the fusing of the piston ring to the cylinder wall. Eventually, perhaps even within a single stroke, it completely let go and debris wreaked havoc on the crank and #8 rod/piston assembly. I feel like all the other stuff was just a natural result of stopping an engine at high RPM with catastrophic force.

 

[Waz]

Waz thank you for sharing as this is very relevant. Do you know if the GT3 engines are using the stock Mahle pistons?

Sorry, but not sure about the pistons. I think they are standard.