Sheridan

I have a new noise today, when starting up the engine and pulling off there is a dok, dok, dok (but not load enough to sound like a big end) it is in time with revs, the noise faded and vanished after about 2 or 3 miles and the car was back to quiet to as a rolex (not even a tick). I seem to remember something about this a while ago being the hydraulic valves or similar, but can't find it. The car is a 97 UK 5 door.
Thanks
Shez

Otis

Hello Sheridan,

I had an identical problem on start up with my last Sport and it resulted in an engine change. When I replaced the Sport with a MY98 Turbo I found that it made the same noise so I gave the bugger back and we went our seperate ways. I am now in an MY00 Turbo and crossing fingers and toes.

With the Sport I was told by the International Motors Technical chap that it was a problem with the short skirt pistons and No.3 cylinder (nearest passenger footwell?). However, when checking out the noise on the MY98 Turbo they told me it was not that problem but just a characteristic of the Turbo - a respnse I am not totally comfortable with or sure if I believe.

Hopefully your posting will prompt enough postings along the lines of 'yes mine does it' or 'never heard it' to give us both an idea of the occurence. A number of dealers have told me about 5% of Turbos do 'IT' but what is 'IT'?

Please, anybody out there with or without any experiences of this add your comments below.

AlexM

Hi,

My car (MY98 UK) also sounds a bit rough when it is very cold. It seems to be more from the valve gear than from the bottom end, So I've decided not to worry about it.

more of a ticking than a light knocking?.
Piston slap seems more common with Turbos than with NA engines - higher temperatures=greater expansion.

Rgds,

Alex

adge

iTrader: (22)

My MY98 is in the garage this week having 1 or more pistons replaced due to excessive rattling on starting from cold, which disappears when the engine warmed up. The garage said it was Piston slap and they would probably end up changing No 4 piston as they had with all the others. It appears to be a problem with the MY98 and is being done under warranty.

adge

iTrader: (22)

Rang the garage today to see when I might get my car back and it looks like it will be the middle of next week as the new block!!! and parts(pistons) don't arrive until monday, good job its under warranty, I just hope the new parts have been modified to eliminate the problem in future.

Otis

Hello Adge,

A new block (short motor) was exactly what I had with my previous Sport. I must admit I was a bit worried when you said it was only new pistons you were getting as this would hardly address the wear in the cylinder
bores.

As of quite recently my dealer did not think they had found a cure yet! However the problem did not come back after the rebuild. I've always wondered if that was anything to do with the fact it had 'real oil' in from the start.

Becareful running-in as the engine will obviously not have had any bench running like a normal new engine.

Otis.

Trout

iTrader: (1)

This may be naive - but when I was talking to Park Lane about replacing damaged pistons and sounding very worried about bore damage - they said it was no problem as only the liners needed replacing - is this unique to STis or Phase II engines or bollox?

I only ask as it seems to be in conflict with comments above.

David

MorayMackenzie

Rannoch,

My STI III doesn't have replaceable liners, consequently whould need to be either rebored or replaced if it were damaged/scored.

Moray

firefox

Howdy..

I didnt think any Scoob had liners...

I could be wrong.. I have been plenty of times before... lol

J.

Sheridan

Thanks you all for your replies, I have been listening very carefully every morning and the noise is worse when cold, then gets quieter as you get up to temp, but it dissappears completely after getting decent boost a couple of times. I assume this is because the boost generates even more heat.
Anyway I'm due a service in <1000 miles so I'll mention it to the chaps then, Mill Lane have been pretty good so far so hopefully they'll sort it for me.

adge

iTrader: (22)

Rang the garage today and they are going to fit a new short motor which has arrived today. With any luck I should get my scoob back by the end of the week.

SteveC

I've also had something very similar with my 96 4-door Turbo. When cold, the same kind of noise, like a light small-end, or piston slap, particularly noticeable if I just raised the fast-idle a fraction by moving the throttle by hand from under the bonnet.

The noise went off when the engine warmed, but came back when everything was very hot after a run, presumably when the oil was thinnest. I found decent oil (Castrol RS) helped the hot noise, but not the cold noise.

I spoke to IM techies, who said it was "lash adjuster" noise (tappets in old money!), and that my car had hydraulic adjusters which gave a few probs such as this. I'm afraid I didn't believe this (I know all about sticky hydraulic tappets - if you've also got a 20yr old Range Rover you certainly do!), the noise was much too solid.

I guessed the noise was caused by excessive clearance somewhere when cold, quietened down when expansion took place and oil was still reasonably meaty, and then came back when the oil was like hot tea after a run.

Anyway, after a few conversations, the result was a new short engine from my dealer Spring Park Motors (under warranty, very helpfully indeed, with no fuss at all, and a nice neat job). IM did however insist they stripped it down first, and they said they found some ovality in no:4. Car mileage at the time was about 16k only.

This is beginning to sound like a bit of a more widespread problem....?

Steve.

Mark Cole

Shez,

You've exactly described the cold start behaviour of my MY97, 20K miler.

It's been doing it for a while now and although I've been back to the dealer (Bell & Colvill) and described the noise, its always warmed up when I get there so they can't here it for themselves to comment.

Like you I've got a service coming up shortly so will leave it overnight so that they can have a listen.

I'd be very interested to here what your dealer does to cure your car.

Mark

Otis

Hello Don,

Thankyou very much for your guidance. This kind of professional/technical information is invaluable and an example of the Bulletin Board at its very best. I have been one of the 'genuinely caring motorists' to which you refer and have had a short motor in my last Subaru due to piston slap. I have now seen the error of my ways! However I sincerely hope, and suspect, driveway idling was not the sole cause of the problem I encountered.

Thanks again
Otis.

Sheridan

Thank you Don all valid points, however what is a reasonable warm up procedure, I probably am over gentle. I start the engine and leave it running for 15 - 30 seconds whilst I plug in my stereo etc at this point it is ticking over at about 1500 rpm on fastidle, I then reverse from the drive with the revs hardly getting to 2k, then proceed to drive keeping the revs between 2k - 3k until the temp guage has moved up to the middle then I am happy to nail it, am I being too gentle ?
Also I have noticed that between services I use no oil I'm aware that the oil consumption is the rings job, but doesn't the fact that it doesn't use any mean the bore must be in reasonable condition.
To move the thread to another topic, if people here are getting new pistons and blocks what are the views on running in ? I have been involved in motorcycle racing for too long and we run in new motors by getting them up to temp then nailing it, this means your motor will burn a little oil but will be more powerful, I did this with one of my road bikes after blueprinting and fitting 2 ring pistons, the power we ended up with was incredible but it does burn oil (about 1/2 pint every 2000 miles).
However I would never do that with a car as I need my car for longer distances, burning that much oil in a bike doesn't matter if you do 3k miles a year on it, but if you do 1k a month then it is a different matter. I would also be suspect of the longetivity on a car engine run in that way. Anyway what are your views on running in ?

Don Palmer

Good oil is a must - never ever put substandard oil in a good engine.
I wouldn't worry too much about a bit of piston slap on a cold morning - pistons need a bit of clearance to work properly - piston slap is only the movement of the piston across the bore - top and bottom of the piston can move in or out of phase with one another and the ensuing clatter is only a serious problem when the clearance is exccessive. - If the noise is significantly reduced when the engine is warm it is unlikely to be a terminal condition.
Loose engines are always a bit noisy when they are cold. If you ever heard a Caterpillar diesel start up from stone cold you'd never beleive there was nothing wrong with it.
The other great mistake made by the genuinely caring motorist is warming the engine at tickover. Oil flow is crucial to engine performance and durability. It is far better to drive the thing than leave it on tickover.
Mixture strength at tickover is far too rich for engine longevity and oil circulation is much reduced at low engine speed. Consequently the oil is washed from the bores at idle speed when rich mixtures are used and combustion is largely incomplete. Unburnt petrol dilutes the lubricant which is more than likely to be in short supply due to low oil pump efficiency at idle engine speed.
Get out and drive the thing at low (modest) load and modest engine speeds and all will be much happier and much longer lived.
When the oil temperature is normal and not before - thrash the living daylights out of it. It will continue to perform brilliantly provided you put the best oil in it.

adge

iTrader: (22)

Well its been in the garage for 2 weeks now, I hope I get it back this week - now waiting for manifold stud bolts to arrive. I'm getting fed up with the Legacy Auto.

AlexM

Hi,

Re Running in

Your motor won't last nearly as long if you don't follow a proper running in procedure. Don't forget that we're talking about a street car engine, not a racer. If your race engine isn't giving its best the first time you use it, you're disadvantaged. The reason you get the engine up to temp, and nail it is so the engine gets loosened up very quickly - it will deliver as much or slightly more than a carefully run in example, but its long term durability will be compromised. In this case, your cylinder bores were probably glazed hence the oil usage. Any oil usage on a road car that doesn't go away after a couple of thousand miles is bad news in the long term - My car doesn't use a drop between services.

True race engines are built to much higher tolerances than production car engines (blueprinting), so their running in procedure will be different as clearances will have been optimised during the build.

The running in process I use is:

0-500 miles - no more than 2/3rd max rpm, and 1/2 throttle (avoid coming on boost)
500-1000 2/3 - 3/4 throttle max, maintain rpm limit.

Don't run the engine at the same speed for long periods of time, vary speed and load as much as possible to avoid bore glazing.

Rebuilt engines have to be treated even more carefully in the first 500 miles as they haven't done any bench running. Factory cars will always have done some bench running prior to installation in the car.

Cheers,

Alex

Don Palmer

Sheridon that looks sensible to me. I agree with other comments on getting max power from a new engine but it would never happen to one of mine!
Well built engines love to be thrashed, in general hand built engines are 10% better performers than factory built jobs. It comes down to little details and these are important. Go to the best engine builders and they do the details and don't even tell you about them.

Sheridan

I opened up one of the engines a couple of years ago to replace second gear after a mishap going into paddock hill bend.
The crank webs were polished so well you could use as a shaving mirror, I was not allowed to touch the entire crank to piston assembly (my engine man said he would kill me if I did) but they are apparently all balanced, the way these engines rev is just incredible, they don't really have any mods I'm even running std cams, but everything is weighed and matched etc. Pity it costs so much or I would do it to all my engines

Jimmy M

I have a '94 UK Legacy Turbo thats done nearly a 100k miles. I have the same sort of noise, but mine definitely sounds like tappet noise.
It only used to occur when cold, but it now does it almost all the time (though much quiter when cold). It usually goes away at tickover.
I have spoken to many different garages and they nearly all say 'hydraulic lash adjusters, they do that'. Trouble is it's getting very severe now and something must be done so I'm stripping the heads down my self.
Interestingly one garage told me that the lash adjusters are susceptable to 'gunge' build up and it's always worst running flushing oil through the engine during an oil change. I've done this several time now and the noise does go away for a short while after the service, only to return. Anyone else go an opinion on flushing oils and tappet noise?