Engine rebuild- third time lucky?

IMG_20151017_112739

The workshop was a sad place for a while, and then a big box of engine parts arrived from Minispares.

The engine has had its bores honed and every part scrubbed with hot soapy water until gleaming. New rings and bearings are fitted, the cam and followers reground, the gearbox completely disassembled and cleaned.

We’ve also taken the opportunity to fit a centre oil pickup, better needles in the carburettors, alloy rocker cover, and revised the engine breathing (it now has two breathers and an MPI-style breather manifold, feeding into breather ports on the carbs).

IMG_20151022_111334

IMG_20151022_111217

It looks good (again) but will it run?

IMG_20151025_103940

Yes. Yes it does. And rather well this time around- it’s far quieter than the first time and seems to have more power. We’ll see how it goes. While keeping an eye out for a replacement engine, just in case.

Time to come clean.

So. Engine reassembled, runs ok, oil cooler bursts.

Engine doesn’t run ok any more. 60psi oil pressure at idle, which drops linearly to 20psi at 4500rpm. There’s some kind of rattle. The oil, which was new 14km ago, looks like Deepwater Horizon had a glitter rave.

Out it comes again.

IMG_2040

Here’s the damage:

IMG_2041

Those bearings are toast. One, in particular, but the others aren’t looking too flash either.

We took all the bits to Henry at Auckland Camshafts, who consults as an engine failure analyst when not creating bespoke cams. His diagnosis: The obvious bearing failure is probably due to oil pressure loss, but started by particulate damage throughout the engine (almost like the engine block wasn’t cleaned properly before assembly. D’oh). The cam had been damaged, piston rings overly worn, and the whole lot is full of bearing shrapnel.

So here we are: the block is off at the engine reconditioners again to have the bores honed ready for new rings, and hopefully the crank can be saved with a polish. The cam has been reground (fairly severe damage) and the followers lightly refaced. Gaskets, bearings etc. are en route from Minispares in the UK.

Might not make it to the Mini Nationals this year.