HELP! She sounded like a diesel this morn!

[rbalach]

Hi guys,

Started her up this morning, and she sounded like a diesel engine ! Sounded like a metallic knocking sound, quite loud and quite fast (at cold idle). I reved the engine a little and the sound got faster. The sound went away after some time after she warmed up. Drove her last night with no probs, sounded like crap this morning ! Any ideas ? valves ? bad gas causing knocking ?
I started her up later this afternoon and there were no noises, smooth as ever.
Thanks

RB

[AutoTchr]

Typical Subaru telling you its time for her oil change. The engine in my car sounded terrible after I installed it. It had sat for two years without running. It took about 1-2 hours for all the valve noise to go away.

I've brought this up before, but you seem to be very knowledgable, so I wanna call it to your attention.

When my car is idleing, there is a deep knocking sound coming from the engine. Very quiet... I didnt even notice it till my mechanic called it to my attention, and he said it is too quiet for him to diagnose. It is like a 'thud thud thud thud' it increses with the rpms if you rev it a little bit, but higher than 1800 rpms, the engine noise becomes louder than the "thud" sound. I dont think it has gotten any worse, and I have no idea how long it's been doing it. It is just something that is always in the back of my mind when I'm driving my car.

-Mike

[rbalach]

AutoTchr,

I just had the oil changed less than 500 miles ago at the dealership ! I checked the oil level,and thats ok too. Oil looks like new oil, not the really dark used oil color.

RB

[AutoTchr]

Hmmm, how long has the sat? If it has sat a long time, then let it run for awhile. If you have been driving it regularly then the noise is something else. This is all I know without actually hearing it!

Hope this helps.

Mike

[DavieGravy]

This threads increadibly old, but If you read this, I would suggest starting your car up every day you don't drive it. Let it run for a few. I have this problem, and this seems to help. On another note, I'm not sure if oil type would make a difference, but consider this also.
Dave.

[kuoh]

I think this could be a symptom of one or more of the valve lash adjusters going bad. Mine has had this knocking for over 4 years now, but still seems to run fine. It started as a barely perceptible knocking only after being parked for several days, progressing to knocking on cold mornings till the engine warmed up, to now with knocking almost constantly. The good news for me is that it sounds like there is only one bad lash adjuster judging by the frequency of the knocking. The bad news is I don't know whether it's the intake or exhaust or even which side of the engine it's on.

KuoH

[Beav]

The cause could be a weak lifter (follower) or an oil filter draining back. If the problem spans more than one oil filter (especially different mfg.) you might try using something such as 'Lifter Medic' or similar.

[DavieGravy]

Originally posted by Beav
The cause could be a weak lifter (follower) or an oil filter draining back. If the problem spans more than one oil filter (especially different mfg.) you might try using something such as 'Lifter Medic' or similar.

What's a lifter and what's a lifter medic?
Dave

[Beav]

'Lifter' loosely equals the same function as the 'cam follower' or 'lash adjuster'. Typically the piece that contacts the cam lobe and transfers motion to the remaining valve train.

'Lifter Medic' is a brand name of an oil detergent specifically formulated for clearing deposits from noisy hydraulic lifters/followers. Depending on the cause of the lifter's noise naturally, one would normally have a 50-50 chance of it working. Since it can possibly help, most likely won't hurt (never say never ) and only costs a few coconuts, it's worth giving a try.

[DavieGravy]

Think I will. Thanks.