GeorgeNZ

It was a public holiday in NZ today, so I decided to strip down my engine that failed while racing in December.

This fell out when we got the car on the hoist



Failure was 8 laps into a 1 lap race while changing from 5th to 6th. There was no warning; I'd just done a PB the lap before. Oil level was checked immmediately before the race and is always run at full and has never been run low while I've run the car. I use Redline 15W50 and it is changes frequently. Oil pressure is logged on the MXL and starts off at 5bar (warm) dropping to 3.5bar when running hard and the oils hot. Pressure does spike down half a bar through some corners.

In September I had a couple of occurrences with bolts coming loose, on the alternator and the power steering pump at which point I had the balance shaft timing checked and they were found to be 180degrees out. In hindsight, I should have dropped the bottom off the engine and replaced the oil pickup.

The engine did a further 500 race miles before this failure.

View thru the sump - #2's not looking good



Sumps off - its not getting any better



At least it stopped on the down stroke - no apparent piston/ valve contact



Closer inspection of the oil pick-up - just a wee crack



I'm hopeful that the head is OK since there doesn't appear top be any piston/ valve contact - I'll get it checked out and freshened then plonk it on the replacement motor.

The replacement motor has been re-bearing'd and ringed, sump baffled and a new pickup with suction ring. I've put an oil temp channel in and the MXL data shows its right up there at 260F (3.5bar), so more cooling is called for.

Dave in Chicago

Wow! That woke me up...

George, sorry for your misfortune here. I'm very grateful for the detailed pictures and the added analysis. Thank you.

RajDatta

Ouch!! Misaligned lower balance shaft sprocket has done this to too many people. Its amazing how many shops get it wrong.

Good luck.
Raj

MichelleJD

sasilverbullet

I understand how the balance shaft 180 out can cause vibration that will loosen bolts, but I didn't see any 'loosened' bolts on that #2 rod end cap.

Please explain...

Techno Duck

Im speculating here, but the balance shaft out of alignment caused excess vibration which cracked the oil pickup tube, this caused oiling issues which led to the eventual explosion of the #2 rod bearing.

Seems probable as the #2 is generally the one that goes first with oiling issues.

Makes me want to double check my balance shafts...

RajDatta

Maybe I should have been more clear in my statement. I was referring to the cracked oil pickup tube. As explained earlier, the excessive vibrations, which are worse than having no balance shaft belt at all cause the oil pickup tube to crack.
Regards.
Raj

Jason Judd

Sorry for your loss George...

Just terrible.

Jason

333pg333

From an Aussie to a Kiwi, I feel for you mate/bro. What's your plan of action?

GeorgeNZ

Yeah - thats racing - already up and running on a replacement motor. Unfortunately, I didn't have time in the build to get the crank drilled and the RSBarn windage tray didn't arrive in time - will have to wait until the end of the season. It did get Carrillo rods and a Lindsey sump baffle kit though.

Most enlightening was the oil temperature and the effect on oil pressure. I'm still getting a half bar pressure drop on some corners when hot, so the main focus right now is getting the oil temperature down.

333pg333

George, what sort of racing are you doing? Looks like Targa type events in your avatar? What mods are you running in your car? Looks stockish suspension, is it a straight CS?

GeorgeNZ

Targa and Bridgestone series. Suspension is custom Koni 2 way's with 425lb King progressives up front and 28mm TB's with 185lb helpers on custom Koni singles at the back. Elephant Racing bushes in the rear and TSV Hard Urethane bushes up front Sways are stock (non-CS) and 20mm adj in the rear in delrin bushes. Its not a CS - still got the small brakes but does have a factory lsd and short ratio gears 2nd to 6th. No other mods to the engine but running an MXL dash/ logger - Empty she's 1260kg - the custom headlights saved quite a few kilos.

rpm's S2

Ouch! Pictures like than can keep you up at night.