Silly question (but that's just me ), but I assume the oil level is set correctly? Easy to check and it may affect the lifters if they can't get enough oil or if the oil is cavitated by the crank.

 

MY98 .. is using shim wit bucket. No hydro. stuff in it.

Problem might be on the mechanical part .. and I think it is the PISTON giving away.

Have ur dealer to do Compression test on the engine.

As for clearance of the cam and shim ......
In. 20
Ex. 25

Do double check wit the Dealer.

Good Luck.

 

Ok, I'm game - I'll have a go at the "what lifters are" thing and allow others to shoot me down....

A lifter is the interface between the cam and the valve. The cam rotates and the lifter follows the profile of the cam lobes and transfers this to the valve thus opening and closing the valve.

Lifters can be either hydraulic or solid. Basically a solid lifter is essentially a tube of material whereas a hydraulic lifter is effectively a piston using engine oil to pressurise it. This has the effect of extending or compressing the piston which means that the gap between cam and valve is more closely controlled. Solid lifters can mean that as the cam wears, because the lifter can't extend (cos it's solid) a small gap can develop requiring adjustment. If you don't adjust the gap, you can get premature valve and cam wear.

If your hydraulic lifter was sticking, this could mean that it wasn't getting fully pressurised with oil which would allow a small gap to be maintained. The noise you heard could be the lifter striking the valve as the cam rotates.

I think that's it but maybe someone can point where I'm talking total @rse. The final point is that lifters are pretty expensive (a set on my old Astra cost about 230 quid). Apparently, there can also be problems running hydraulic lifters on high revving engines because they can't pressurise quick enough because of the speed of the engine meaning again, premature engine wear. Dunno if STi's might suffer from this though.

Corrections on the back of a postcard to...

 

Had same problem with My MY98 at 40K. A bolt securing the Cam Belt cover to the block had come undone behind the Cam pulley. It sounds exactly like a ball bearing being thrown around. Try pulling the cover away from the block towards the front of the car, there should be no play.

 

Hi All,

I have been experiencing a problem with the engine of my Scooby (98MY UK turbo, 36k miles, unmodified) and am looking for some explanations and what to get Subaru to look at to try to cure the problem. Sorry for the long post...

On the Saturday before last I was enjoying a very spirited drive in my Scooby which involved using a lot of high revs a lot of the time. When I came across some traffic lights I noticed a strange "clacking" sound coming from the engine bay so I pulled off the road, opened the bonnet and listened.

Standing in front of the car looking at the engine, the noise was coming from the vicinity of the right side and front area of the engine, roughly where I would imagine the front right piston to be. The sound was a 'clack clack clack' sound at the rate of 3 or 4 clacks a second, and the clacks got faster in line with the idle speed when I pushed on the throttle. I would describe the clack sound as similar to a little ball bearing being thrown up inside the engine and hitting the metal wall or roof of the engine.

After letting the engine cool down sufficiently I stopped it, waited about 3 or 4 minutes and started the engine again. Now the clack had disappeared! I figured I would rather experience further problems there and then on Saturday in the late afternoon rather than on my way to work on Monday so I continued driving in the same spirited manner as before and the car drove just fine. After a short time I came across some traffic and while crawling along the road I could hear that the clacking was back exactly as before. I pulled over again, but this time it was not cured by stopping and restarting the engine.

I stopped for a while at a pub and then made my way back home. Although the car seemed to be producing about the usual amount of power I drove the car carefully because the strange noise was still there. The clack was there when I stopped for petrol along the way but by the time I got home it had disappeared!

I took the car out for a short drive on Sunday (no traffic) giving it a bit of stick and all seemed fine.

I phoned Subaru on Monday morning, explained about the noise and the guy said he didn't have any idea what it was, and he'd have to hear it to be any help.

On Monday on the way home from work I was waiting at some traffic lights and I noticed that the car was noticeably shaking -- the idle was rather lumpy. It was like this all last week and I booked the car into my local Subaru dealer for them to take a look at it today.

Last week I asked both Bob Rawle and David Power via email for their opinions on my problem, giving them the above description (hadn't experienced the lumpy idle at the time). Independently, they both thought that a problem with a hydraulic valve lifter was most likely, with it sticking or collapsing.

Today Subaru spent over an hour trying to find the cause of the lumpy idle, but with no success. I mentioned the noise from the engine before I got the lumpy idle and that a couple of people who know these cars very well thought a lifter could be to blame. I don't think they took much notice. The car is now booked in for all day Thursday for them to investigate further.

Since I don't want to consume any more of Bob or David's time, I thought it would be useful to get some input from all your engine bods out there. I would like to know what I can tell Subaru on Thursday that might make them take more notice of the engine noise in relation to this idle problem. It seems too much of a coincidence that a lumpy idle comes straight after a strange engine noise that has disappeared.

Also any help in explaining valve lifters to me and them getting stuck or collapsing would be helpful to make me sound more convincing to the technicians at Subaru!

All help greatly appreciated. Cheers,

Paul

 

DYNT,

Welcome back.

Does the bucket and shim arrangement only apply to the STI IV and '98 WRX (EJ20K?) engines, or the MY98 UK export cars (EJ20G?) as well?.

Thanks,

Alex

 

Hi Alex,

MY97 onwards r using shim(ontop) wit bucket
- Valve is longer and thinner

STI - Bucket ontop and shim below the bucket.
-Valve is shorter and thicker.

MY96 below ... Hydraulic lifter.

Info : There is 2 type of cylinder block for Subaru.
1. Open deck ... very common on STI and WRX
2. Close deck ... strong and wat factory rally team and race team r using.

Have u seen it before Alex???

 

Moray, the car certainly wasn't low on oil but might have been a bit high -- I added around 600ml 8 days (600 miles) before the engine sound (note: the car had a long hard high speed run in that time). After the engine noise I wasn't entirely sure that I had originally checked the oil while the car was exactly level so I rechecked it and it was exactly right (just below the Full hole).

LScott, I've just been out and checked the cam belt cover and it is secure.

If anyone would care to explain shim and buckets, I'm all ears!

Also, how long would it take a dealer to do a compression test on the engine (so I know whether I'm asking for a big check or not)?

Thanks for the replies so far,
Paul

 

Paul,

On most cars a compression test, or cylinder leak-down test is easy and quick to perform. I suspect it is a bit more tricky on an Impreza because it is time consuming to get the plugs out.

It would be unusual to get piston slap when the engine is hot without it having been noticable earlier on when the car is cold.
As DYNT says, if you have a mechanical problem it is most likely to be a piston problem, or possibly the valve train.

Either way, the dealer should be able to diagnose it easily by listening carefully. If it is a piston problem, you will be looking at a new short engine .

Let us know what happens.... I have an interest because my car sounds a bit rough until it is properly warmed up - I hope I'm not experiencing the first signs of piston slap....

Cheers,

Alex

 

The mystery has now been solved.

Subaru had the car all day Thursday and by the end had discovered that the problem is exactly the same as LScott's above -- a bolt flying around the cambelt area!

Apparently there is a plate which is bolted to the engine which I assume the cambelt cover then bolts on to. A bolt holding this plate to the engine came out, flew around the cambelt area, knocked out the cam timing on the offside bank but miraculously didn't significantly damage the cambelt.

When Subaru took off the cambelt cover they found two halves of a bolt resting at the bottom of the cover.

They still have the car because they are replacing a sprocket which they have to order in. The cambelt is also being changed. All covered under warranty. I should get the car back Monday evening, until then the Justy is proving err.....interesting.

This has now happened to two cars at similar mileage on the same model year. Does anyone know what locking mechanism Subaru use on important bolts like these?

Paul