Guys,

I know there are loads of posts about this, and I have looked at most of them. A few questions:

1) Was it only MY97 & MY98's that were affected or did the problem exist in MY99 cars as well?
2) I understand that Subaru made modifications to their engines following the piston slap problems. I have an RB5 WR Sport. It is a 1999 car. Just want to know if the engines fitted to these were modified to eliminate piston slap.

Information on this topic seems to be very subjective, so an answer from anyone with definate knowledge would be much appreciated.

Cheers

 

Can someone explain how this happens? (Besides fitting too thin head gaskets!)
I've headr it loads, but don't really know specifically what 'piston slap' means.

 

Huw,

Piston slap occurs when the piston skirt or bores wear slightly allowing it to rock in the bore under power. As the engine heats up the slack is taken up by thermal expansion and the noise cannot be heard anymore.

The problem occured because Subaru fitted pistons with too small crowns/skirts.

 

not sure this is 100%, but this is what i've learnt ...

it WAS only the 97/98 design that caused the problem.
it was resolved by a new design piston, which i assume was used in 99 onwards engine.

the fix to 97/98's was to
a) replace piston (usually no 4 (nearest turbo)
b) replace complete short block

the reason it does it is due to the design / materials of the crowns / skitks etc.

it is very evident when cold, and should dissapear when warmed up.
on mine (MY97) its evident when you dab the gas when cold. after driving down the road, for 2 mins, its gone.
saying that, i neva take it above 2500rpm until its fully warm & no boost obviously!

Not sure that it DOESNT occur in other years .

not sure its a real problem, as some cars, like cossies etc are REALLY REALLY bad cold. and some forged rods& pistons sound like that (although I wouldnt be able to dive a car like that!)

hope that helps some.
Steve


[Edited by ScoobyDuck - 1/12/2004 9:47:31 PM]

 

i think ull find all scoobs suffer ...well from what ive read anyway..mines a my 96 and slaps like a goodun when cold [sounds like its well knacked]but is ok when warm i think its a drawback with a horizontaly opposed engine[u cant stop gravity]

 

Recently seen an STi 7 with the familar slapping sound.....

 

So could my oil consumption be associated with the tapping noise first few minutes at iddle?
I changed belt tensioner and oil in my last service and noise dissapeared for two days, now is back, I don't know if this is due to fresh oil that prevents temporarily slaping sound, due to new tensioner that failed again or something else!
Subaru claims that new age cars don't suffer from such problems,
but the service can't find it as it's present only below 1350-1400 rpms for few minutes, only when car is full cold and more pronounced from the turbo down side of engine.
JIM

 

Oil consumption can be attributed to piston slap, but not always. Does it smoke??

 

No it doesn't smoke except the first few minutes until the car reaches working temp which is normal with the cold weather I believe!
JIM

 

Depends what colour it is. If it is white and wispy then it is water vapour which is totally normal. If it has a blue tinge then that means there is oil in there too and this is not so good.

 

Steve,

If no.4 is nearest the turbo then your engine is in the wrong way around

I believe it was no.3 they changed on my car.

Andrew...

 

Cheers for the explaination Spatch.

 

Mine's a MY99 and it's just been diagnosed with the Slap

Dave

 

yep had it annoyed the f*ck out of me when to subaru and they fixed it MY98 proven warrenty so its a used car.slap can happen on any age of impreza it depends on how the engine is run in and luck. but my 98's did have a design fault with the pitons being to small

 

Story of my life

 

My USDM 2002 WRX has piston slap so I do not think that it is just those years. It my be just those years that subaru is fixxing.

 

Hmmm, new ones can have the problem too. It seems to me that the problem was worse with MY97/MY98 but it can affect other years to.

The next question is, 'does the slap stabilize (can it be stabilized) or does it progressively get worse? Any comments?

Mark.

 

It can gradually ovalise your cylinder, but as long as it goes when warm then i dont think its a major issue.

 

NO your car just sounds like a tractor in the morning :O

 

I've had slap on an MY97 JDM since 45,000 miles. Its now done 90,000 miles. The noise at start up is horrendous and is still audible when warm (up to 2,500 rpm) but oil consumption is still what it was back at 24,000 when first bought.
I still give it some welly after 15 mins and it still puts out 260 bhp and pulls very well.
The downside is trying to sell it. No one wants a car that sounds like a tractor and to get rid of it would cost £2000 - hence why it is being despatched back to the HP company.

Nick

 

Nick,

Has it got worse over the years or has it stayed pretty much the same? It doesn't appear to ge affecting your performance?

Mark

 

Mark,
It got a lot noisier this winter.
Its far more audible in winter with lower temps but fades in summer.
This winter it came back with a vengence and I decided it was too embarrassing to drive so its going.

Nick

 

Sure I read in another thread that Scoobysport will sort the usual slap problem (replace no 3 piston) for about £600 for the whole job.

Kevin - STI3, and yes it slaps a bit too...

 

Nick,

What oil are you using? - just out of interest.

Has anyone tried Slick 50 in their engines to help reduce slap or stopping it from getting any worse??

Mark.

 

i kicked up a fuss with subaru when they told me they would not fix it. managed to only pay £250 for half the labour charges after loads of ranting from me. car sounds fine now and everything seams ok after about 7 months with it done. its so nice to get rid of that horrid sound it made.

 

Mark,
I use whatever Subaru put in at service time plus top ups with Mobile 1 motorsport. Top up has never been more than 0.5 litres in 7,500 miles.
Don't think slick 50 will help at all. You need more metal in the bore to take up the slack. Only an overbore plus bigger pistons/rings will help.

Nick

 

mine is a 97 wrx and it might sound a bit slappy, specialist said it was the lash adjusters, but tbh im not that botherd

its gone when warm so i dont care, the car is tickled about till its wram anyways so there isnt really a problem IMO
my mates uk car with less miles then mine has a simmiler sound from cold (but not as bad)

ill "fix" it if it blows up but im not expecting it to happen, ive heard a lot of cars now with noisey engines

 

Andrew , woops ! ok , so i cant count !

3 4
1 2

(front of car)

and fires 1,3,4,2 : left left, right right ? hence to boxer note. or something like that! Im getting there.. honest!

Steve