Hi guys, can i ask for some info off you on this topic, opinions, experiences etc etc.....i have a 55 plate wrx, pretty much standard. Recently i had the pleasure of replacing my big end bearings.. OUCH!! I was told by the company that did the work, the reason behind the bearing failure was the fact i had a bleed valve installed?? i have a boost gauge so i know it was maxing out at 1.2 bar which i didnt think was too high. Obviously i know mappin it on a rollin road is the best solution but i just wondered what you guys think as i dont believe a bleed valve knocked my big ends out at 1.2 bar? Any thoughts on this?? In fact...is it even possible to destroy your big ends through this? A melted piston i would buy but big ends?? Any thoughts? Cheers guys.

 

1.2bar boost with no fuelling or timing adjustments probably along with a cone filter and decat, you bet it would have caused it.

 

Yeah think that would have done it, as would have been leaning out.

Get a 3 port on there and remap.

 

bleed valves = bin please

 

Ok, any explanations on how that would be the prob? As far as i know oil starvation is the usual suspect on big ends?

 

There was a problem with 05 cars due to welds cracking on pickup pipes etc,the problem with bleed valves the power comes in like a train without control quite low down rpm.Bleed valves are like a virgins wedding night,she knows she going to get it but not sure how much

 

Piston failure burnt valves yes, crank no, lack of lube over reved lack of warm up time,pressure relief valve stuck open,poor oil.A visual on the ends will tell exactly what went wrong

 

Lol greg! Yeah ive heard all these horror stories about big ends on scoobys just pizzzed off i had to join the club!! I understand all the dangers of running too lean without the correct fueling and wastegate creep with bleed valves but i still dont understand how it could banjo me big ends? one explanation ive heard is heat transfer through con rod burning up the oil but i wasnt running 2bar!! Just need a logical explanation cos am still confused lol, cheers guys.

 

you sure about that? a good dose of det would would knock a weak bottom end out very easily.

 

Has the engine been put back together yet? if not get them to replace pickup pipe with new one Scooby brought out a revision,if you dont when engine fails again which is likely the bleed valve will be their way out,

 

You are right but over quite a long period,no different than blowing nos,the failure is piston not crank,unless you squirt under 2k then its bent rods

 

Its all together and home mate so i cant check bearings. They checked pick up pipes and no probs. personally i think they were after me forking out for a remap as they have a rolling road and all the equipment. Just wondered if there was summet i was missing

 

A good engineer can pull an engine apart and tell 99% why it failed,smell of the oil was my way,state of ouside block,state of pistons,crank etc,the big picture.I never rebuilt an engine unless I could find why it failed

 

I had a classic shape terzo b4 this and ran 1.3 through an in car digital boost controller for 2 years with no probs. Sold car in perfect running order so another reason i doubt this. obviously every car is diff but am still not convinced this was the prob.

 

Had a guy come in with a blown cossie rebuilt engine balanced light piston performance bearings new up rated oil pump etc,less than 2k engine blew up same fault as first time pistons,while I had it in my workshop took ecu out found it had a f--kin star chip.The car and bootfull of engine parts was pushed out the workshop for him to tow away,never heard another word,

 

So whats yr opinion on boost levels then on a standard fueled wrx engine? Ive heard 1.2 is fine (obviously too much tooling around is bad lol) i want a remap but still pondering where to take it.

 

if the ecu has'nt got control of the boost ie: bleed valve instead then it does'nt know for sure how much fuel is needed, i reckon it ran lean and detonated putting too much pressure on the crank bearings, it does happen! bleed valves are evil things and should be left well alone trust me i have learnt that lesson the hard way.

 

i agree blead valves are like a lucky dip u dont no what youre gonna get