Hi i have a 1998 UK Impreza Turbo 2000. Its done 50k(fully documented) and is running standard. When i start it from cold it is quite tappy, sounds like bottom end noise which goes once it warm. Also once it is warm if you hold it at 1100rpm it has a slight tapping noise also. Its running on Mobil 1 oil. Any ideas other than bottom end problems.

 

sounds like piston slap, common problem on that year car

 

Yeah thats piston slap, wouldnt worry about it on bit mine has 90k on it now and is still going as strong as ever.

Andy

 

Cheers for the advice.

Will this get worse or is they anything i can do. Sorry to sound dumb but im lost with engines

 

Providing the piston slap is gone when the car is fully warmed up (20 mins driving+) then it'll be fine and shouldn't deteriorate, just look on it as an audible warning to take it easy when the car is cold.

The slight tapping noise just above idle speed could well be the boost solenoid, mine ('97) does that when reversing into a parking space. Does it come from the driver's side front suspension turret area ? Again, nothing to worry about.

 

It's not necessarily piston slap, that tends to manifest itself in a knocking noise. Many Scoobies produce a "ticking sound" when cold. As someone else has suggested could just be normal boost solenoid noise. Have you tried changing your Oil, I don't think Mobil 1 is particularly highly regarded on here. Motul or Silkolene Pro S seem to be the prefered choice. The grade is also critical, of course. I belive someone on here who knows much more about oil than I do has suggested that 10w 50 can help to silence the rwo when cold a bit.

Have a word with "Oilman" on here.

Regards,

 

Sounds to me like he is describing 2 different noises. If the noise when it's cold sounds quite heavy and a bit like big ends it probably is piston slap. Tappet noise is also quite common, and again not a concern, providing it goes away when warm, although it can take a LONG time to get it warm enough to get rid of tappet noise. I believe the Subaru test is something like "if the noise goes away after warming the engine up and then 20 minutes running at 3000 rpm it's O.K"

 

Thanks again. Gonna try changing the oil in the next week or so and see if thats any better.

 

If you're not going to take it to a specialist to have the oil changed, and with the greatest respect to you, do make sure you research and follow the correct procedure for oil changes in a scooby, or serious damage (and a BIG bill) might result.

Regards

 

Its been going to Monks Heath Subaru dealer and they have been putting Mobil One in it. If i take my own oil will they not advise against it?

 

They shouldn't as long it is fully synthetic and of the appropriate grade!!

Seriously mate, do a search on this: I think you'll find that the very knowledgeable on here sugest Motul or Silkolene Pro S. I use the latter in mine.

Regards

 

I have the same year same model and have exactly the same as you.

I'd more or less put it down to Piston Slap after reading various threads.

mine does go away when its warm and I find it an excellent indicator as to when I can start to push on a bit

 

Piston slap is silent from cold for the first 30 secs or so - then it starts making a knocking noise. If you blip the throttle at this point you can hear it clearly. It should disappear after about 5 mins of normal running. Both my STI3 and GTB have slap - the STI3 has done 45k and it's just noticeable. The GTB has done 96k and it's much more noticeable. I did find different oils made a big difference in general start up noise in the STI3 - currently on Silkolene 10w40.

 

I have a similer problem...that has only started up again..

The car was having a problem with Piston Slap, so was taken to Cheem Motors, who for some reson changed only 2 of the pistons for Modified Pistons, and left the other 2 standard..

Anyway..20,000 mile son i think the original 2 Pistons are causing an issue, though have not got £1000 to have it resolved, though not too bad at the moment...

Cheem Motors also advised that there was an issue with 98 cars, and the resolution was to change the Original Pistons with a Modified Set...



http://www.sidc.co.uk/faq.htm#3.14



--Sam

 

Thing is though, on the very great majority of cars it never develops any further than the noise when cold, doesn't cause any problems and doesn't use oil etc, so really, you are paying £1000 to get rid of a noise that is only there when the engine is cold. Personally, I can live with the noise at that price.
I've even seen it suggested that the cars that are slappy when cold are faster - the slight extra clearance equates to less friction once everything is warm and running smoothly.