Andy.F

There have been many reports of the dreaded 'big end failure' on the Subaru. There are also many theorys on the cause but to date, no conclusions have been drawn.
It may be that there are a number of contributing factors instead of one single reason ?

I believe that much information has been gathered on this subject in the past, although as far as I'm aware, the results were never published.

I have drawn up a simple 20 point questionaire. If anyone who has had a failure, or has first hand information on a failure could contribute their experiences.

If you can post answers against No's 1 - 20 or better, cut and paste the questions in to your reply (makes more sense for others to read this way)

I can pull together some statistical data which may benefit us all.

If anyone wishes not to publicise their data then it can be Emailed to me and I will post it anonymously on your behalf.

--------------------------------------------------------------

1 MODEL
2 YEAR
3 MILES
4 FAILURE DESCRIPTION
5 FAILURE DATE
6 MILES SINCE SERVICE
7 SERVICEB BY
8 OIL TYPE USED
9 FILTER TYPE USED
10 FILTER PRIMED PRIOR TO START
11 ENGINE PRIMED ON STARTER MOTOR
12 FUEL & ADDITIVES IN USE
13 AMBIENT CONDITIONS AT FAILURE
14 ENGINE MODIFICATIONS / POWER
15 BOOST PRESSURE MAX HELD
16 TYPE OF USE NORMALLY
17 TYPE OF USE PRE FAILURE
18 MAX RPM USED IN GEARS
19 MAX RPM HELD TOP GEAR
20 DURATION OF MAX HELD IN TOP GEAR

--------------------------------------------------------------

Hints re completion

1 eg WRX/Sti/UK/P1 etc
2 MY
3 at failure
4 eg No 3 big end knocking and piston cracked
5 approx
6 since last oil change
7 eg main dealer, local garage, self etc
8 make and type ie synthetic
9 eg subaru, fram, halfords ets
10 was filter filled with oil pre fitting
11 was the oil system primed by turning the engine on the starter motor for 20 - 30 seconds befor starting
12 eg shell optimax / bp sul / esso ul /millers oct booster/ nf etc
13 approx temperature / dry / rain
14 any modifications also engine power and torque if known
15 maximum held boost pressure if known
16 eg daily commuter, fast motorway, track days, weekend car etc
17 as above but include mph if possible
18 normal shift point when driving hard
19 for more than say 10 seconds
20 within 1000 miles of failure

thank you for your input

Andy

fivepint

bttt great idea...

carl

21. ALUMINIUM OR STEEL BONNET

Andy.F

Via Email
--------------------------------------------------------------

1 MODEL Sti v5
2 YEAR 99
3 MILES 33,000
4 FAILURE DESCRIPTION No 2 big end gone, knocking, crank u/s pistons not broken but bores 1 & 2 scored badly.
5 FAILURE DATE Jan 02
6 MILES SINCE SERVICE 800
7 SERVICEB BY Subaru Specialist
8 OIL TYPE USED Mobil 1 15/40
9 FILTER TYPE USED unknown
10 FILTER PRIMED PRIOR TO START unknown
11 ENGINE PRIMED ON STARTER MOTOR unknown
12 FUEL & ADDITIVES IN USE Optimax & Miller CVL
13 AMBIENT CONDITIONS AT FAILURE Cold and dry
14 ENGINE MODIFICATIONS / POWER SS backbox otherwise std 280 ?
15 BOOST PRESSURE MAX HELD unknown
16 TYPE OF USE NORMALLY Various, mainly weekend, no track days
17 TYPE OF USE PRE FAILURE 'Brisk' country drive, not thrash
18 MAX RPM USED IN GEARS 8000
19 MAX RPM HELD TOP GEAR 8000, once about 1 year ago
20 DURATION OF MAX HELD IN TOP GEAR few seconds only
--------------------------------------------------------------

Sheepsplitter

Andy, how about a couple of more points to request info on:-
21. Do you have an additional oil cooler?
22. Do you have water injection fitted?
23. Do you let the engine warm up before exceeding 3000rpm?
24. Do you have an intercooler protection shield fitted (to stop the fins getting damaged)?
25. How did you run the vehicle in (if owned from new)?

Andy.F

Good points Sheepsplitter, especially 23 !

For some reason I can't edit my original post (keeps saying wrong password but it's not)

Points 21 & 22 can be included in 'engine mods'

The other points raised can be added as comments if appropriate. It's not intended to be an exclusive list, I just tried to keep it simple and maintain some sort of structure.

thanks

Andy

Sheepsplitter

I think you are doing a smashing job starting this off.
If you want a hand compiling the results/spreadsheeting it up or something for presentation back at the end let me know.

Hopefully I will not be taking part in the survey :-)

Mr.Cookie

1 WRX
2 1995
3 89000
4 Big ends on 1 and 4 melted piston on 3 and a bit more
5 12th March 2002
6 3000
7 not saying sorry
8 Castrol GTX
9 Subaru one
10 not a clue
11 not a clue
12 Optimax/shell super
13 Damp and mild
14 K and N, HKS Hiper, Samco hoses
15 not a clue
16 I drive like a granny
17 140
18 6-6.5
19 6-6.5
20 All the way to the Ring cept when there were corners

Garage which used to service car had kinked one of the oil hoses they put on, considered part of reason [img]images/smilies/mad.gif[/img]

Si

Mr.Cookie

Ps car always run up to temp before heavy footedness creeps over me

stiscooby

Would you guys, who didn't want to mention the place who serviced your car, e-mail me........so I know where not to go.

Thanks.

Sheepsplitter

stiscooby: We should not assume that the last place to service the car caused the engine failure. All that we are gathering are histories of failure, it's possible engine failure may be down to a particular garage, but it would be dangerous to imply anything like that at this stage.

nichop

Sorry, totally off the subject but...great to find someone else in Woking Sheepsplitter !

Mr.Cookie

I'm woking too

ustolemyname??stevieturbo

iTrader: (1)

While the survey wwill reveal something, Im too lazy to read the long posts. The BIG question is, I think anyway, What can be done to prevent big end failure. Melted pistons, Broken pistons, scored/damaged bores ( related to pistons ), are all related in one way or another to abuse. ie increased boost, wrong fuel etc.
The big ends should be able to withstand massive increases in power before letting go, even then, they shouldnt really. I have seen big ends go, usually no 3, on several engines. They range from a reasonably fresh P1 to my own 130,000 mile legacy. From failure while cruisng and taking it easy on the motorway, to racing a TVR chimera 450 ( and doing quite well I was, til it started to rattle ). A friends failed even with full rebuild, with new bearings, new uprated pump ( graham goode, dont know what is uprated about it though ) in less than 2000 miles ( just like the engine before it ), but I think it was ultra lite billet flywheel related. No explanation why though. Oil, the latter engine used Mobil 1 motorsport, my legacy was on cheapie castrol gtx.. From one extreme to the other they fail. WHAT IS THE SOLUTION????? Bigger oilways? Proper oil cooler? Channel X' wonder lube 2050, yours for only £9.99 ????

ustolemyname??stevieturbo

iTrader: (1)

And i suppose i may add my little bit too
1 MODEL : 92 UK legacy estate
2 YEAR
3 MILES : 127000
4 FAILURE DESCRIPTION : Big end, assume no3, couldnt be bothered stripping it yet
5 FAILURE DATE : may 2002
6 MILES SINCE SERVICE : less than 1500
7 SERVICEB BY : stevieturbo?
8 OIL TYPE USED : castrol gtx skinflint
9 FILTER TYPE USED : blueprint jap stuff
10 FILTER PRIMED PRIOR TO START : always
11 ENGINE PRIMED ON STARTER MOTOR : No, oil lite goes off nearly instantly anyway
12 FUEL & ADDITIVES IN USE : SUL
13 AMBIENT CONDITIONS AT FAILURE : mild/sunny
14 ENGINE MODIFICATIONS / POWER : usual exhaust etc
15 BOOST PRESSURE MAX HELD : 14psi
16 TYPE OF USE NORMALLY : abuse/track/fun/fun
17 TYPE OF USE PRE FAILURE : Racing TVR Chimera 450 up motorway
18 MAX RPM USED IN GEARS : 7000
19 MAX RPM HELD TOP GEAR : when?
20 DURATION OF MAX HELD IN TOP GEAR : never very long, rarely do it.

nichop

sheepsplitter, what's your email ? Fancy meeting up in Woking some time guys ?

dowser

Andy - try emailing Bob Rawle. He collected lots of info around 12-18 months ago. The only common factor seemed to be it was mostly (always, Bob?) after a recent service...the why wasn't answerable.

At the very least, Bob will have a load of additional examples he can give you!

Richard

Sheepsplitter

nichop: You can get me on oc95@dial.pipex.com
A meet sounds like a good idea (as long as it doesn't clash with an England match of course ;-) )

TonyBurns

iTrader: (3)

I see that 3 out of 4 are jap imports and the other is a higher mileage UK car, is this telling you something????

Tony

Andy.F

Bit early Tony

Via Email

1. UK Turbo
2. 1999
3. 38K
4. No. 2 piston let go
5. Sept 01
6. 3K
7. Subaru dealer
8. Helix
9. Subaru
10. No idea
11. No idea
12. 97 RON no additives
13. 20c
14. ITG panel + SS backbox
15. 1.05 Bar
16. Normal road no trackdays
17. 140 MPH
18. 7K
19. 6.5K
20. A few seconds

ustolemyname??stevieturbo

iTrader: (1)

Again, would I be right to suggest that piston failure, in any guise, should not count as random engine failure, as generally they break or melt for a reason. Detonation doesnt happen on its own, and neither do weak mixtures. The cause of both are generally the users fault, or someone trying to modify/tune it.
The survey should be limited to engine failure, eg crank/rods/bearings, maybe belt failure too?Anyone agree?
I have also seen quite a few with the new style tensioner, with faulty tensioners when re-newing a belt.

EvilBevel

Stevie,

>>Detonation doesnt happen on its own, and neither do weak mixtures.

Not meant as a dig or anything, but it would happen on its own if for example the MAF goes haywire. (yes I know, pet peave of mine these days, but still)

I have seen a lot of reports in the three years that I follow this board about totally standard cars that let go. No tuning, normal servicing etc. Or safe PPP cars etc.

I is annoying though that after 2-3 years of constant reports, we are nowhere nearer understanding exactly what is happening

Could it be there are 2 or 3 prime reasons (or maybe more), and that we can't find them because we are looking for the "ultimate" reason ?

Oil, airflow over bonnet, STi versus UK (octane number), oil temp, servicing, high speed runs, all these things (and a few more ?) have been brought up as possible causes... but never proved beyond doubt. Maybe it's a combination of certain factors ? Or several independant factors ?

I am 100 % positive though that a number of cars (specifically MY99 plus) have let go because of a failing MAF. Just read about another 2 examples on a Dutch bbs

So you could well say: how many cars depending on MAF, and how many depending on MAP.

One thing seems to be sure: the big ends on our cars are not designed with a good margin in mind.

nichop

Blimey, all this talk about big ends going is making seriously question the longevity of my MY99 UK scoob and whether to buy it off the company after 3 years. I thought the engines were bullet proof. Seems not.

Andy.F

nichop

I'm sure if we started a Engine non-failure survey we would get thousands of posts !!!

With some 14k + scoobynetters 5 or 6 failures (so far) are reasonable odds I think

Andy.F

Steve/Evil

I know you can use statistics to prove almost anything but I thought if we gathered enough info it may be possible to see some trends forming.

Even if something unexpected like "There were 0% recorded failures on cars which do frequent track days" emerged, it may give a different direction to look in, such as carbon build up.

And of course I'd be much happier to do a track day

Andy

nichop

True. What kind of mileage are folks getting out of their scoobs ?

SMG

Good work lads, even if its a normaly asperated 200 hp screamer i run lead bearings as they will take more loading, and if they run low on oil there less lightly to nip up spin the bearing in the rod and weck everything. Lead bearings ars avalible for the scoob but are not fitted as std, although most production performance vehicles ive come across run a lead bearing including cosworths, bolts have just as important roll to play as well, a rod bolt has verious factors to its design and when you start overcoming these its a matter of when, not if. Example, 16v golf race car run for years no probs, regs change you can run webbers, so run twin 45s makes more power 2 b/end failures in a row third build ARP uprated
bolt set, problem solved and we pushed even harder still no probs.
Cossies etc have aircraft spec bolts from std, and you can get big power from stock internals. Pistons std scoob pistons not great, forged/cast pistons it does not end there, material spec, even some forged pistons are high silicon based and these can fail. Scoob std pistons do not even have steel expansion rings in the skirt, this stabilizes the rate of expasion and contraction. If a piston for what ever reason gets to hot 9 times out of ten when it cools it will be smaller, the piston is slightly oval, and the skirt is tappered only the bottom of the skirt is where your bore clearance is. Hense piston slap. Sorry i got a bit carried away there il shut up now.
Steve

ustolemyname??stevieturbo

iTrader: (1)

Well then, the weak mixture did not happen on its own, it was caused by a faulty MAF. The cause is known. Detonation due to poor fuel ( ie running a 100RON car on UK fuel ) again, cause known.

EvilBevel

Oh semantics time than.

Could you define "not on it's own" ?

I thought you meant it as "the owner did not take the utmost care of his standard/tuned car". I was wrong obviously.

scoootie5

1 MODEL : WRX RA Import
2 YEAR : 94
3 MILES : 52000
4 FAILURE DESCRIPTION : Big End No.3, Smashed Piston No.3 (different time), Bent Conrod No.1
5 FAILURE DATE : April 2002
6 MILES SINCE SERVICE : 2000ish miles
7 SERVICEB BY : Myself
8 OIL TYPE USED : 10/40w Magnatex
9 FILTER TYPE USED : Usually Subaru everytime but this time a Coopers (DOH)
10 FILTER PRIMED PRIOR TO START : Yep
11 ENGINE PRIMED ON STARTER MOTOR : No
12 FUEL & ADDITIVES IN USE : Optimax
13 AMBIENT CONDITIONS AT FAILURE : Sunny/Warm
14 ENGINE MODIFICATIONS / POWER : Turboback no cats exhaust, Blitz Airfilter, HKS Blow Off Valve, 270ish
15 BOOST PRESSURE MAX HELD : 1.1Bar
16 TYPE OF USE NORMALLY : Commute and Weekends
17 TYPE OF USE PRE FAILURE : 5up Dual Carriage Way 80ish
18 MAX RPM USED IN GEARS : 7000
19 MAX RPM HELD TOP GEAR : 5500
20 DURATION OF MAX HELD IN TOP GEAR : Rarely 5/10secs


Thanks
Scott