Big End Bearing gone at 75k??
 

was driving along and my car spat a bearing, was just wondering if its normal for this to happen at 75000k miles,.
and is it worth going down the forged route, ie pistons and rods, or should i just put standard ones back in
?? cheers in advance

i guess no one knows anything about this then!!!!!!

probably confused by the title, not to worry though,

no it's not normal, but there are a quite few who have had a big end go at relatively low mileage with a decently serviced car,....................i have a personal theory on this though as there's a couple of scoobs that drive past my house regularly, (i live on a long steep hill) the one scoob driven by a lady a few streets over from my drives up the hill daily, in the wrong gear, i.e. barely moving, but in 2nd, you can hear the car really struggling, this puts immense strain on the bigends as the load is massive coupled with low RPM, resulting in low oil flow and pressure, the bigends on a scoob are relatively small too, so this exacerbates this type of driving.

The same thing would happen if you floored it whilst in too low a gear, i.e. 3rd at 1000rpm, again, a massive load on the bigends, with low flow and oil pressure, do this enough times and the big ends will eventually fail.

that's my theory anyway.

sounds like a good theory,

was just serviced, although i hadnt serviced it for 10k prior to that which is probably to long for a car running the power it is.

What are your views on putting forged pistons in now the engine is in bits, im replacing the bearings with race bearings so no worries there. my thinkin is that it would be stupid to not change the pistons now that they are easily assesable. as they could very well go in another 10k as there known for it!?

either way its gonna be big money :(

Price in a new crank, as it cannot be reground on a scoob, as for a forged build, you'd need to weight up cost vs power requirement.

Feel for you, I've got a hawkeye wrx with similar mileage and a few mods, with more planned.
I'm fully expecting/prepared for something "big" to go at some point but have the philiosophy that when something goes I'll just replace it with something better, whether it be brakes, suspension or the engine.

Cant see me ever getting rid of the car as I've had it from new and love it to bits but probably most things will end up being replaced one day, especially the way I use it :D

If it's run a bearing, you'll need a new crank.
At 75,000 you are bound to have some kind of bore wear, so it makes sense to do it once do it right. I appreciate the cost implications!
You have a number of choices of piston, but don't be tempted to do a "drop in". It'll need reboring and hone to suit the new pistons.

Ive seen the same on cars with as little as 26K on them, the majority of big end failures I see tend to be 70-80K. UK sub 250 bhp cars will last much longer. There are many reasons why they suffer with this problem but the bottom line is the big end bearings are narrower than 'in-line' engines and don't last as long. Yes a set of forged pistons is a good idea.

Im getting a new crank and race bearings fitted, scoobyclinic is just waiting on the go ahead on the pistons, 650 quid, plus 150 for machining costs for the forged set up!

i fully expected the engine to go at some stage, as running 340bhp and 360 torques on standard internals was bound to cause problems at some stage!

with the new pistons, bearings and crank im thinking the engine wud be good for 400+ so may throw in a re-map as well,

wud there be any danger of the top end of the engine going with the extra power? or are they fairly reliable up top!

Arent the gearboxes suspect past the 350 mark?

some say that, but others ahve told me there good for 400, so i dunno, only one way to find out haha

It's a WRX, not an STi

JohnD

Good observation lol, so your saying it won't handle much more power then??

forged pistons are going in, havent decided wether to up the power or not, might leave it as is, engine will be more reliable then and the gearbox will be safe :)

You say it had just been serviced. Theres s few about that have spun bearings shortly after a service. It seem that often in these cases the filter wasnt pre filled causing starvation to the bearings on start up

just wanted to add. The two cars ive personally seen were both knocking at around 30/40 miles after an oil change and both had dry filters fitted

its the torque that kills the gearbox on wrx's, if you push power to far , factor in another £2.5k for a new 6 speed box.
Big grin factor involved though :lol1:

Don't think the people that serviced it wud make a mistake like that! They are very experienced and I fully trust them! However it could very well have been the reason! But I have no way of finding out :-|!