joz8968

iTrader: (13)

Was it a case of that, at the time, you weren't aware of det, harsh environment, etc... Or was it simply a case of that you thought everything would be okay, regardless?

silent running

It hadn't ever done that before.

I wanted a rolling road run and that's what I got. I've done a lot of runs (with other cars and different rollers) with no problems, but then I've also had one where a 100 shot of nitrous running off a progressive controller was fine on the road and drag strip, but on the rollers it blew the entire inlet tract apart and lifted the bonnet off its hinges. You win some you lose some LOL

Sonic74f

David,
Have you for any reason had an engine apart that had no big end or piston related issues that had 40/50k miles done? If so what was the general condition of it, generally is there a lot of wear on the internals even if running quiet at this sort of mileage or do things just go suddenly?
Thanks.

merlin24

iTrader: (1)

You will always find some sort of bearing wear on an engine with no noise/knocking that has done that sort of mileage.
Normally find that the upper rod bearing has wear,due to the loading from the turbo.

Mick

Sonic74f

Hiya Mick, what I meant and should have said was excessive wear, its obvious there will be some wear but what I was asking was would there be excessive wear at the mileage in the sense that what sounds like a health engine could less healthy that it sounds or do they go from normal wear to blowing up?

merlin24

iTrader: (1)

That's the Million Dollar Question !!
Its a fine line between having some wear and "coppering" the bearings leading to bearing failure.
Average oil clearance on the big ends is in the region of 0.0015" ~ 0.002", so it wont take much for "excessive" wear to occur due to whatever reason ( as mentioned in other reply's to the thread).
As the oil clearance increases ,the bearing halfs start to hammer on the big end journal,the bearings spread out and form a knife edge - scraping any remaining oil from the journal and eventually spinning in the rod.

When you do an oil change,you can have the engine oil analysed by various company's to see what metallic contamination is suspended in the oil.
This would be an early warning/preventive maintenance of impending engine failure.
A lot of people use Magnetic sump plugs, but seeing as most of the bearing material is non-magnetic - bit of a waste of time IMHO.

Mick

merlin24

iTrader: (1)

There should be no signs of metallic contamination/copper/"gold" in the oil when changed on a healthy engine.
You can also cut the old oil filter open to see whats lurking inside.


Mick

Sonic74f

Thanks Mick, that answers my question perfectly. Would any signs of copper bit in the oil when drain off give you an indication that its going to go at some stage. Should there be zero contanimation of copeer bits in the oil on a healthy engine?

APIDavid

iTrader: (4)

Difficult one that, Ideally there should not be any metallic deposits in oil drainings for obvious reasons. But we have had a car/engine here with a silvery coppery sheen in the oil that is still track daying etc. fine after two years like that.

We are all waiting for the bang, including the owner, who knows the score. So far no bang.

We also take used STi / WRX engines to bits that come in from Japan. The mileage is recorded on our paperwork from over there.

62,000 km's copper big end bearings
141,000 kms like new.

As the yanks say; Go figure!

There is no hard and fast rule that you can rely upon in my opinion.

David APi

Sonic74f

Thanks for your reply David, its a bit of a lottery in one sense I suppose. I suppose all one can do is do the normal checks before you buy and follow rules after that.