What are the general symptomns?

That deep low down clunking sound, is it from cold or all the time?
I dont suppose there is any other way of finding out?

The reason i ask is that im a bit paranoid about my MY00 and engine failiure

 

Since it is usually terminal pretty quickly then if you don't know whether you have got it but it still goes, then you probably haven't. I would describe it as more of a machine gun noise than a clunking with a marked drop (ie tending towards zero) in oil pressure. If it wasn't too bad you would get a rattle when starting a warm engine until the oil got to the bearing. You could find out by connecting an oil pressure gauge but you would need to know what the right pressure is.

 

Ok, i definitely dont have that, just a bit of tappet/injector noise though. I just read a load of stories of people driving along and piston melt down / big end failiure (yes i know the 2 are different).

Thanks though

 

Big ends usually can be quite heavily worn, or down to the copper without giving much sign of pending failure in terms of noise. If your lucky you may momentarily get a bit of knock or rattle on startup, most people won't hear or notice it. By the time it does start knocking whilst running it is well and truely gone and you won't go far until it spins a bearing and ruins the crank and rod.

As said above, oil pressure is the best way of judging it. As the increased clearances caused by worn bearings will cause a drop in pressure as more oil is leaked from the gap between the bearing and journal, also starving oil to other bearings that are fed via the worn bearing. The oil pump usually has the capacity to maintain a good pressure despite bearing wear, but pressure drop would be more most noticeable at idle. Noisy tappets, are always a headache, they do rely on good oil pressure to operate quietly. But you can't rely on them to give indicatation of adequate oil pressure, as they so often become noisy for no apparent reason.

 

Hmm ok, well i want to invest in a set of guages anyway

 

Well now you have an excuse for the missus

 

Thanks, was trying to think of one

 

I've trashed two sets of big end bearings on my track day car (205 Mi 16) due to oil surge around the corners.
The things you would notice are, lower than normal oil pressure, a mechanical knocking sound when the engine was NOT under load i.e. going a constant speed (when accelerating or decelerating the noise goes away).

I drove 25 miles home both times, dropped the sump and fitted a new set of bearings. Good as new.

( i have since got the crank reground, new bearings, sump baffle, to solve the problem )

The problem is that the bearing area is smaller on a subaru crank, so they are more fragile.