What Killed this motor? Side seals wore out after 1k miles.
 

We tore this down today, there was a LOT of oil comming from the front main seal at it started to lose compression really badly.
It had a total of about 1,000 HARD miles on it.
What we saw is burnt side iorns, scored up housings near the exhaust, scored rotors a broken oil control o ring, and side seals that looked like they had a million miles on them.

All of the bearings looked decent
None of the seals were broken... confusing.
Someone said that maybe the spacer in the front wasn't correct and led to too much play in the E-shaft.
I believe this was a "throw down" motor (so says Scott)
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Scott said the thrust bearings didn't show heat stress or wearing so I don't think it was a end play issue.

You forgot to say this engine was run in enduro racing with 16-24 hours (per race)of hard full turbo power running.

The mileage is way over 1000 miles but it still died early. This motor was build with alot of tired parts.

Feb race 225laps = 535.5 miles
Apr race 280laps = 700 miles
Jun race 267laps = 635.5 miles
Oct race 229laps = 545 miles
Dec race 223laps = 557.5 miles
Figuring the track run time at 70:40:58 almost 71 hours
Total = 2973.5 + a test-an-tune day that Scott bet it to death and it over heated when it blew the turbo water feed line.

The motor began leaking out the front main seal just prior to the last race - but only when under full load. Not sure if this is related to the failure.

Whatever happened when the motor finally failed was sudden. I had just exited a turn and was powering into the straight when it felt like the rear end of the car locked up. Of course after disassembly it seems that was feeling of the rotor sides grinding on the irons. This was combined with LOTS of oil smoke out the exhaust. Didn't feel like an apex seal letting go and I was right - all apex seals intact.

Afterwards, the engine was spuriting lots of out the front seal. So much I think we could have drained the entire oil system in two laps if we had kept on.

Still, I find it unusual that the front stack seems problem free and the bearings are in place and in relatively good shape.

the heat witness marks on the plate show no oil supply
this may be effect from the leaking front main and resulting very low oil level and low oil pressure
or maybe issue with oil pump pickup sucking air
or may indicate the crank jets where blocked

The front seal was only leaking after you let off from full power, I think I have a video


This isn't of the leaking but it was where we started to see the leak

http://www.youtube.com/watch?v=w3DZUxu_LfA

This can not be ruled out...... The oil pressure gauge failed from over pressure (shimmed FD pressure reg) and it was a 100psi gauge

I'm going to go with this since the evidence supports it.

Front seal was leaking a lot. At some point the front seal started leaking a hell of a lot.

With a low oil level, the oil pickup started to suck air when we had the car in the turns. Engine started to digest itself and eventually some of the side seals ended up welded in their grooves. In this way we lost compression. Sucks - but that engine had a hell of a run!

agreed.

something like that happened to one of my customers but engine had 3k miles. i figured was low oil on the engine. he was using a different dip stick so he was running very low on oil
i had same marks on rotors and plates

lack of lubrication. likely was picking up air during cornering or ran low on oil at times, pump could also have been worn or oil filter/cooler semi clogged.

whenever you see a scorched iron like that, it's due to no oil on the oil seal scrapers.

Add to list of things to do:

NEW OIL PRESSURE GAUGE. :D

What was the condition of the o-rings under the rotor's oil control seals?

Were you using synthetic oil?

One a similar postmortem engine disassembly the above o-rings had reacted badly with Mobil 1. This caused a bad oil leak to the side seals causing them to carbon-up and stick. The combustion then starts flaming down the sides of the rotor, carbon is like grinding compound, and.... what you have.

How much oil was in the pan at shut down? The level can go down quickly in this scenario.

Barry

Castrol 20w-50 Dino oil

I think it was just on the bottom (barely) of the dip stick.

The oil was running out of the front cover when he brought it into the pits.

On top of a new oil pressure gauge I am installing a oil temp gauge, and a low oil pressure light

It could have been a oil cooler problem too, maybe the t-stat quit working

replace all that. just to be safe :)

well i have yet to really see any of the oil thermostats fail in one of these engines but that doesn't mean they can't.

i would eliminate the e-shaft thermal pellet and the oil cooler thermostat, neither are really necessary on a track dedicated car.

also be sure the oil pickup was tight and not clogged with silicone or debris from lazy assembly or silicone happy builders, and on track dedicated cars it doesn't hurt to overfill the crankcase a tad, about .3 quarts to prevent starvation on hard cornering or an oil pan baffle to keep the oil in the pan.

Running a baffle plate?

The e-shaft thermo pellet had been deleted, there is a oil pan baffle in there I think?? (Scott can u confirm), I am unsure how to delete the oil cooler thermo pellet

There was no silicone used on the oil pickup, fresh gasket.

Atkins thermal pellet installed.

No aftermarket baffle installed. Not really sure if this would have helped.

Oil pickup installed with a new gasket. A few strings of silicone found on the screen, but nothing unusual. I do think our builder is a little silicone happy sometime but don't think this is the cause of failure. :)

I still think the engine bled out through the front cover seal. It was bad and then it went to worse. There is oil EVERYWHERE.

Need an S5 turbo rotor housing to build a new engine before February. Anyone have a good one hangin around?

if it was an FD a pan baffle wouldn't really help but seeing as it is an FC it would definitely help keep the oil where it needs to be.

it could have been the front main seal that caused the string of events but you can't stop to add oil so the pan baffle and a little extra oil likely could have saved it, possibly.

the front mains usually leak due to the hub surface being pitted, resurfacing the hub or replacing it will get rid of the issue. DO NOT put it on a wire wheel to clean it. i chuck them to the lathe and run over the surface with 200 grit to clean up the surface and that seems to work well with used hubs, had a few initially that leaked with the wire wheel method so i pitched that process. you could also have a crankcase breather issue which is pushing oil out of the front, which built up over time as the engine became more worn and was sealing combustion gasses less. make sure the crankcase has adequate breathing.

You know, I didn't SEE a whole lot of oil come out of that motor when we pulled it apart... It looked like maybe a quart to me. It didn't occur to me at the time because I though it was inconceivable that both chuck and scott didn't watch the oil press gauge, and I didn't realize it was broken.
I think there was more oil outside the engine than inside it.
Also, there were a LOT of looser than hand-tight bolts on that car... but the oil pickup wasn't one of them.... And the screen looked pretty good.

well for whatever reason, the engine was pushing oil out and likely got too low during race and starved the motor of oil at random times which is the only reason the engine was able to keep going.

i've learned over the years that drivers NEVER look at gauges. the ONLY way is to call them on the radio, and ask and even that gets mixed results.

the car MUST be built so that it'll run without gauges, because nobody is looking at them anyways

I new the gauge was broken, but it still worked a little. It told if you had some oil pressure.

I look at the gauges during every stright, no questions.

When I was driving there was no problem so I didn't need to come in.