6 replies to this topic

[Kilst]

Hey guys,

I've been having an issue with my 99' Impreza GF. Started to develop a slight tapping noise last week from the engine after a medium pull to 5K.

 

The tapping is most noticeable under load around 1500 - 2500 rpm, and heaps louder when the engine is cold. The tapping is related to rpm. It's more of a high pitched tap.

Went through all the basics, and have determined it's coming from around cylinders 2 & 4 by using a stethoscope. I had to give it a solid rev to hear the noise while stationary. The noise is most apparent a bit behind the valve cover gasket on the top of the engine.

My guess is valves need adjusting, but really, take that with a grain of salt. I haven't been working on cars for very long.

Any opinions?

Cheers

[El_Freddo]

Welcome to the forum.

A big end would be a dull knock rather than a tap sound. At start up a big end is most noticeable before full oil pressure has built up.

A single rev out to 5G wouldn't do a big end unless you're low on oil.

I'd say it's valve related, and from what I know of that era of EJ engine you'll have rollers instead of HLAs that could become probe to tapping at times.

Cheers

Bennie

[Kilst]

Haha thanks for the welcome.

I can't hear it on start up unless blip the throttle hard, or it's under load (taking off/accelerating). Definitely a tapping sound, not a dull knocking. Sounds a lot like injector tick, only way louder.

 

Wasn't low on oil at the time of the pull, but that's good to know.

Yeah, I'm pretty sure they're rollers from what I've read.

Guess I'll be pulling the valve cover and doing adjustments in the next few days then. Thanks for the input!

[El_Freddo]

Check your fan belts to make sure they're trensioned properly.

When was the last time you had your cam belt done?

Cheers

Bennie

[Kilst]

Timing belt was done at 170000kms. We're at 204000kms now, but I've looked at the belt, and it looks good.

Other belts were checked/tightened this morning. Ac needed adjusting.

Cheers

Edit: Actually, now that you've mentioned it, I should probably check the timing belt hasn't skipped before I pull the valve covers. I'm dreading sealing those suckers. I assume a timing belt slip could produce the symptoms?

[Kilst]

Okay, update.

Timing is all good.

Compression test was ~180psi across all cylinders (cylinder #4 being at 190psi)

I ended up putting the stethoscope on the fuel rail around cylinder #4, and low and behold, that seems to be the source of the noise. Pulled the injector connection from cylinder #4 and bam! Sound gone completely.

I'm not really sure what to make of all that.

I'll get a video up soon of the noise though.

[Kilst]

Video: https://youtu.be/Ld7mUgfh8XQ

Getting a mic on it really brought the sound out. Sounds pretty bad to me now

The sound is most apparent when you can see me pressing on the throttle cable assembly, and at around 10 seconds. I have the mic facing injector 4 at those points.