knocking when cold

[ard.core]

can anyone help with this one?

i have a 1990 single turbo ej20. when cold it knocks quite loud.
but after it has warmed up it seems to either go away or quietens down. a mechanic mentioned piston slap but not sure.

any ideas?

[Legacy777]

Can you explain a little more what the knock sounds like? Does it do it while just idling? Or is it only under load?

[scottzg]

my totally uninformed guess is that you are low on oil.

[ard.core]

its a bit hard to describe the knock. it definetly knocks on idle and under load like i say until it warms up a bit. it recently has gotten alot louder, and can be heard in the cab. the only way i can descibe it is when i rev the motor it knocks away the same as the normal subaru rumble.

had a lube done as mechanic suggested to see if that helps but just the same.

only worried my big end is on its last legs!!!

someone also suggested a loud injector?!

[Bheinen74]

bad piston most likely. probably where it connects to the rod.

[wiscon_mark]

sounds like you need to use a different weight oil. If the oil weight is too high intially, it won't protect very well when cold, because it isn't getting into the engine fast enough.

[badbasser98]

The type sound you are describing is like what I had in my car.... It ended up being piston slap as one of the cylinder walls was out of round. But the noise never completly went away, it was still noticable with the radio off and under acceleration even at full engine temp. Luckily, the car was still under warrenty and SOA gave me a new short block. I would have to say that if the noise goes completely away, that it is normal. Boxers are loud anyway, amplified when cold, in cold weather. I also tried what you have at first, it helped slightly, but the knock never went away. I would try a few of the other suggestions though before taking it to a mechanic and having them pull the engine to measure the cylinders...

good luck
-BB98

[Busdriver]

I just did an oil change, used Castro High Mileage this time.
At idle I hear a knock it appears for a few seconds then goes away for a few more.
What could this be?

Is there a correlation between RPMs and HLA noise?
I noticed that the morning after driving a little "spirited" winding up around 3.5k and 4.25k RPMs the HLA's are really loud until the engine is about a quarter warm on the temp gauge...
Could this really be? by only going up to 4k??

This happend before the oilchange too...

Is Castrol High Mileage 10W30 a good oil for an engine with over 175k?

[biggreen96]

well my 2.5 had a clicking/ticking that was around during cold months and which went away after a long drive. or after I put in new oil (for like 2 days it went away) I was told HLA's or piston slap. it never affected anything.

Knocking and pinging I think should be reserved terms.

[Busdriver]

Drove the soobster easy yesterday, so no HLA clicking this morning, BUT the knocking or clunking at idle was a lot more pronounced and louder, AND it was so bad that it made my acceleration buck during first and second gear almost lunging and surging...

Any clues? This stopped after driving on the freeway for 15 min....

My total daily commute is 11mi and I usually don't drive more during the week..

This really has me worried now!!!!

[Busdriver]

update to this clunking and bucking:
one of the sparkplug wires and the coil was grounding out, we have dewey mornings here so the arcing was most pronounced in the dewey mornings. new sparkplug wires and coil solved the problem.
Just wonder how it got started.
My idea is that a grounding kit I recently installed with one grounding point right next to the wire and coil might have killed them....