My wife's Legacy 2 litre GLS has developed a really loud bang, bang, bang (metallic sounding noise) from the left hand bank. The car sounds like a really noisey London taxi. The noise appears to be coming from the l/h rocker cover area. The problem is that it is intermitent, when the noise is not there the engine runs as sweet as a bird. Sometimes it happens when the engine is cold and sometimes when it is hot. One time it was knocking really badly that she pulled over and phoned me up to listern to it. I told her to turn the engine off for a couple of minutes then restart it. When she did it was running sweet as a bird again. Has anyone any ideas, it's doing my head in. Trouble is that I can't take it to anyone to listern to cause it might not do it once I get there. HEEELLLP!!!!!!!!

 

sounds like the oil may not be getting up there , give it an engine flush and put some 10/40 semi oil back in it that mat do it , otherwise your oil pump may be on its last legs either way stop running it until its been flushed as it will naff the head up then its money time,.

 

also pop an oil filter on it to eliminate that being clogged,.

 

That was the first thing I tried. Flushed engine out with good quality engine flush, then changed oil and filter. Ran alright for a day then back to London taxi.
Could it be something on the rocker assembly, ie arms or shaft (blocked oil port!). Thought about taking the rocker cover off this weekend to see if I can shed any light on it. Its got me baffled.

 

Just had a thought, if it was the pump wouldn't I get the noise on both banks of cylinders, this only comes on the left hand bank.

 

as its an on and off rattle it isnt a worn bearing so that rules out pretty much every thing , if some tappits dont get enough oil they make a good old noise so thats why i sugested the flush to clear everything out so it would get the oil up there, flush it for a good 20 mins with some good bursts of the throttle if thet fails i would pretty much gamble on swapping the tappits(lifters), but first check your oil pressure to rule out the pump,.

 

What year is the car, my legacy turbo suffered with a sticking lifter, all the flushing and oil changes didnt sort it out. replace the offending lifter if it is that, not a job for the faint hearted though.

 

quick thought take the sump off and check the pickup for blockages, it may be starving the top end ie tappits ie bang bang rattle rattle,. if all else fails a new head is only around £35 of flea bay and its a 5 hour job to swap it ,

 

its not too bad a job swapping a lifter , cam belt off , rocker off and your pretty much there . the engine can be lifted out of its mounts and moved to one side to do it so you have more room , only 2 16mm nuts,.

 

Check the sparkplugs

 

Spark plugs were the first items I replaced.

 

I meant, check them to make sure they are done up tight. I had a loose one on my prezza & it sounded like a noisey tappet.

 

its an intermittent rattle so its nothing loose or worn so it must be a dogey oil flow causing the rattle i reckon