Matt_H

Hi,
Along with many others I often get a bit paranoid over the old piston slap problem... when cold my engine does sound quite chattery/rattly/tickety etc etc but I think this is different than the piston slap noise(?).

Anyway found this on the web and wondered if anyone had any comments on whether this is a good way of diagnosing piston slap more conclusivly..

(from a VW site)
"Piston Slap
It occurs at every power stroke, so it sounds off in time with the valve train. Piston slap is a dull, hollow sound. It's difficult to hear over the normally loud VW engine components and not easy to isolate. In fact, there is a better chance of hearing it while driving than when stationary. If you think you hear piston slap, remove and replace the spark plug wire to each cylinder one at a time. When you get to the affected cylinder, the noise will greatly diminish. Disabling the cylinder will reduce piston slap because combustion loads no longer exist. Reconnecting the plug lead will restore the noise. Remember to ground the plug lead when disabling a cylinder."

cheers ,
Matt.

p.s Next time car is serviced I will ask them to check... if I do have piston slap how much roughly to fix? (with slightly bigger piston I presume?)

WREXY

This should make it easier for ya!

http://homepage.ntlworld.com/alan.le...p%20(cold).mp3

Cheers,

Wrexy.

Matt_H

Cheers Wrexy but I've already listened to that...a lot..and still can't make up my mind!! I think its hard unless you really know what part of the noise you are listening for...if that makes sense?!
...I dunno - will have to get the people at Park Lane to have a listen. Any idea of price to fix?

cheers ,
Matt.

WREXY

Well then, this is what it should sound like when normal. Maybe if you listen out for the differences you will distinquish it. This is a recording, (provided by Alan leslie), of when that same engine has warmed up and piston slap has dissapeared.

With the first recording, try and listen to the engine as it is being revved. you will here the roughness, (ggrrrriiing), like a diesel engine makes. that is the piston slapping.

With this second recording you will here that it sounds smooth as it's being revved and that the rough noise has dissapeared.

http://homepage.ntlworld.com/alan.le...p%20(warm).mp3


Hope this helps.

Cheers,

Wrexy.








[Edited by WREXY - 6/14/2002 10:57:53 AM]

Matt_H

Thanks again Wrexy... mine sounds nice and smooth when warmed up too. oh dear...not looking good. Normally I like slappers but not in this case!
So just to be clear...the rattly almost diesel engine sound when the engine is cold is not just a characteristic of the scoob engine?
Also - do you reckon the disconnecting one HT lead at a time idea is a good one?

cheers
Matt.

p.s Any recommendations for places to get fixed anyone? Take to Park Lane for servicing - presume they can sort?

Charlie H

Mine seems to be very rattly as well when cold (MY93 WRX) Had the car for about 20 months but never noticed it before. (maybe just paranoia due to all the talk of engine failure. I spent a couple of hours last night surfing the web trying to find info on scooby engine failure but it looks like there isn't much info about so I take that as a good sign.

Where is your rattle? Mine seems to be from the cylinder head area on the passenger side and it gets a lot quieter when warm, although is is still there.

Am I just paranoid or should I be worried?

Matt_H

Hi,
yeah I think mine is loudest on the passenger side. I've read that no.4 piston is the one that is usually 'the slapper'(!). Is no.4 on the passenger side? Can't remember the cylinder numbering on the scoob - anyone?
Not really sure how noisy it should be when warm...I'm not really a guru so I'm in the same boat as you really...

cheers,
Matt.

WREXY

Matt,

The diesel like sound is not a characteristic of the engine. I haven't heard one live, making that noise yet. I remember Pete Croney once posted that disconnecting the injector lead was a way of checking.

As for where to get it fixed, I know dealers fix them, but someone from the UK will have to answer, where else you can get it sorted.

Cheers,

Wrexy.

Matt_H

Wrexy - cheers I've only just realised you aren't from the UK!! doh!.... I'll get me coat!

So any guys from over here know recommended places?? (its a 97WRX so
will have to be specialist rather than uk subaru dealer I imagine)

cheers,
Matt.

rjben

So what happens if you leave it? Mine sometimes has slap when cold and I never 'rev' it until it's been running for at least 10 - 15 mins. Will it fail or something?

Cheers,

Rob