Started to get a very fast 'Tap, Tap, Tap' when starting if the car has been left standing for a couple of days.
My thoughts are that this could be Hydraulic tappets loosing pressure/leaking or maybe an injector.

It's a very fast Tap... and not the distinct piston slap Knock, which I had plenty of on my Cosworth.

Do these MY have Hydraulics, if so how much are they ?

 

Or are they called 'Lash Adjusters' ???

 

yes hydraulic.

wouldn't want to have to change them, but it should be possible with engine in car if all else is removed.

Dunno about cost, but my legacy has awful tappets, which use design similar to pinto engine, uurgh. I have put some "Wynns hydralic follower additive" in mine, so we will see. Seems to work, as I think the noise is slowly reducing.

The problem with mine, is as the oils thins slightly when warm they make more noise. But it comes and goes of it's own accord, hence the nickname "voodoo tappets".

They can be modified to be solid with under bucket shims if you're so inclined. Legacy ones are about £28 each plus fitted etc, so not cheap for 16.

Are you using a 15/50 oil?

Honestly, if it's only when cold, I wouldn't worry.

Paul

 

My MY94 WRX started doing this as well. I was told you can replace the top followers with the engine in, but you really need it out to do all of them, and you really need to do all of them if any are noisy. My mechanic only charges an hours labour to drop the engine, so it aint that bad. I was told the hydraulic followers would be 16 each roughly (so £256 to do the lot, plus labour, so about £400-£500 all in) I decided to bite the bullet and fit some STiV heads (with solid lifters). There were some for sale on here recently for £200 I think.

 

My mechanic said that he has had quite a few apart but has yet to find any Hydraulics. The only place he has seen Hydraulic is on the 2.2

But he was unsure about early Impreza and will be getting back to me tommorrow, aa he has only done later and STi variants.

The Job will be done at the same time as a Cam Belt, as the cams need to be removed to get to the Tappets.

He also mentioned that the collets can drop out fairly easily and has seen this happen on one occasion, causing a similar sympton.

 

deffo hydraulic 93-96. solid on 97-98, but again, various sizes and configurations. Sti tend to have larger followers with under bucket shims, otherwise shimmed on top.

not sure about phase 2, possibly a mix again.

Paul