Mojo

Most of the problems above appear to be on MY98 Scoobies.
Have Subaru sorted these problems out in the MY00 cars, or are they problems that seem to happen after two years to all cars?

millband

Are these bearing failures anything to do with oil starvation during the *huge* G's you're pulling on the track???!!

AlexM

Warren,

A 'short motor' is generally everything below the cylinder heads, excluding cetain ancilliary components.

i.e. New Block, crankshaft, pistons, rods, and probably an oil pump.

Cheers,

Alex
Worried MY98 owner....

Ron H

Mine has got this ticking sound too.
I guess this must be the waste gate solenoid?
I really would'nt know what the difference was. I presumed it was a tappet?-not very technically sound.
I hope it is only that. How would I tell if thats the sound?

Ron

Paulie

there definitely seems to be two schools of tapping... I'm going to have a stab at recording mine as a wav... it's a crazy plan...

Stef

I would definitely recco that everyone at least fits oil pressure gauges, they're the first things going in my car when it's back.

Stef.

Paulie

right now I'm thinking of fitting a musical bell and installing an ice cream machine

bobn3

Hi,

Is this issue only on turbos? or does it effect all version, because when cold my 97' sport sounds like a deisel.

Cheers

WAL

Thanks for the info, think I'd probably invest in a new oil pump if and when an answer/engine arrives.
The Sports allegedly suffer from exactly the same problem but the fix is only to change one piston.
The piston slap noise is NOT a metallic ticking noise, that is your wastegate solenoid. The solenoid will tick away all the time , lift the bonnet and look at the drivers side suspension mount area, rev the car using the linkage and all will be self evident.
Piston Slap (on my car anyway) only occurs from cold and lasts until the car properly warms up. Again lift the bonnet rev up and you'll hear the noise coming from the block. You can't miss it if your car has got it, trust me!!!
Hope this helps

Warren

[This message has been edited by WAL (edited 07-06-2000).]

scoobysnacks

Hi all,
Been reading the posts for a while now, and thought it was time I joined in. I've got an MY98 WRX (standard)with 39k miles on the clock. It exhibits a light(ish) knocking sound for the first 5 mins or so of driving. I guess this must be piston slap because it fits with everything I've read. I've heard it's more common on WRX's (more clearance because they're more powerful or something)Any truth in this? Also, what is the main downside if there is no performance loss and no oil burning? Is it really a big deal and does it always continue to get worse and eventually lead to serious engine damage?

firefox

Hello Peeps...

I'm not gonna say too much.

Piston slap is caused by a too large a clearance between the piston and bore.

Initially the performance will remain the same and everything will be ok. The rings will still seal.

But what is happening is the piston side skirt is impacting with the bore (Piston is twisting/tilting). Even the sides of the crownn might impact and wear. This will cause damage to the bore and the side skirt. The clearance will grow and grow. The bores will become scored and the rings wont seal correctly.

The noise is a donk-donk sort of noise.

The higher pitch tapping noise are your valves. Or possibly the wastegate solenoid. Although this doesnt tick at idle.

Any car can suffer from slap.

Turbo cars run bigger bore clearances due to the heat/expansion of the pistons.

Forged pistons run even larger clearances. Hence why they can be noiser at idle from cold.

The solution is to either fit a new engine. Or have your cylinders bored/honed and fit oversize pistons.

Subaru can actually supply 0.25 and 0.5mm oversize pistons via the dealers. But I have never heard of anyone using them.

I doubt the materials are that good anyway.

You can also get two Grades of Piston from Subaru Grade A and B. There is a stamp ontop of the engine stating which cylinder has which grade.

A good way of telling is to use a long shafted screw driver or stethoscope and put it on the heads, then the block.

Most tuners when doing a rebuild will fit a new pump, or at least strip and rebuild it, fitting new seals and checking on clearances.

J.

WAL

Thanks for the text book explanation of piston slap, I should have made my explanation of the wastegate solenoid noise clearer!!
My dealer certainly didn't mention you could get oversize pistons etc when I asked him, basically saying short engine is the only answer.
I think IM are really trying to play down this obvious defect and hoping peoples cars go out of warranty before they notice, cynical me..never.Witness the "internet scaremongering" story a lot of people have been fed.I think Firefox has quite clearly spellled out the end result of ignoring it and hoping it will go away!

Warren

scoobysnacks

Thanks J. for that explaination.
One more thing though. You said:
'Piston slap is caused by a too large a clearance between the piston and bore' and
'Turbo cars run bigger bore clearances due to the heat/expansion of the pistons'.
Does this mean it is normal for my MY98 WRX to exhibit some piston slap (light knocking sound) from cold, or should you never be able to hear it?

bob

Problems problems thank god I just sold my MY98.

DJB

My MY98 is just fine - I hope.

D.

Moz

why was there no low oil pressure warning if this seems to be the route cause of these bearing failures? and if the low oil pressure warning light is not coming on, then there must be sufficient pressure, if only in parts of the system which means that fitting an oil pressure guage might not show low pressure?

AndyMc

Hi all

Scoobysnacks,if cold piston-slap was normal I would have thought all the turbo models would do it from new.Also it shouldn't get significantly worse in just 10-15k miles like mine has.

Something that I don't understand is how some people with my98's have managed to do over 60k miles without trouble.
The fact that the relatively unstressed engines in the sports also suffer suggests the problem is more down to miles travelled rather than the owner having a lead foot.

Maybe it only deteriates so far then stabilises!

Andy

Steve Lawson

Probably likely to get lynched by you guys but here goes.We as a dealer have replaced a number of short engines on turbos,the NA engines are also suffering from slap on No 4 bore as well.The fix from IM is a short engine on Turbo models and a replacement piston on NA models.They have advised that when carrying out piston replacements you check for scoring and ovality is either present you replace the short motor.On the turbo models the bore is way out of tolerance to have it rebored hence a new
short motor.
The easy way to diagnose the fault is to disconnect the injector multiplug on the suspect cylinder whilst the engine is running,if it stops the racket you have piston slap.
IM's stance on the problem is if it goes away when warm no action is required.My advice is try to find a sympathetic dealer.

Steve Lawson

scoobysnacks

Can anyone tell me if the mechanical differences (to withstand more power) of the MY98 WRX compared to the MY98 UK version mean that a light knocking noise from cold is more common/normal(ish). Also, how much is a new short motor for a UK or WRX Impreza? Thanks.

Nico van Steen

If the light comes on, oil pressure has dropped to a very low level. With an oil pressure meter you can see the actual oil pressure. Once you've worked out the normal pressure, you will notice when the level drops gradually and use it as an early warning. Damage due to a sudden and sharp drop of pressure can't be forseen with an O.P. meter.

Only problem is to monitor oil pressure, when trying to round the Nurnburgring in 10 min. time:-)

Nico van Steen