Engine Knocking

[SVXMAN2001]

So my 96 lsi has developed a rather noticeable engine knock. About a year ago I changed from conventional to synthetic oil. The car has approximately 95k miles.

The "knock" as I am describing it, is coming from the rear driver's side of the engine. I researched the svx manuals and it appears that it may be something valve related (worn/broken lash adjuster; worn valve; worn cam journal). Suggestions for diagnosing the problem, according to the manual, are to disconnect each spark plug connector to determine to isolate the problematic bank.

The knock is most noticeable while at idle. During city/highway driving the car seems fine. The car isn't throwing any codes.

I took the car to a subaru dealership and they stated that I should get all the seals done (front seals; valve covers and rear main seal). The knock that i described to them is normal, to me this completely discredits their diagnosis. Oh estimated cost to do the suggested work is $1,800.

I will try and get an audio of the sound to help with diagnosising this issue. Suggestions or advice would be greatly appreciated. thanks in advance. Chris

[SVXMAN2001]

Anyone? Bueler?

[Joe]

Perhaps you have a collapsed lifter. Hard to diag without vehicle present. Try to add seafoam to engine oil, following directions. If noise goes away, great. If noise remains, it should be isolated to a single component, quite likely a lifter and replaced.

[Cam]

Not sure if this helps...but sometimes our cars can have the lash adjusters collapse (empty of oil and start ticking). I have read that you can get rid of this by revving the engine aggressively. Not sure if this is your problem or not, but thought it would be interesting to know and possibly help.

[Cam]

I normally dont take shots in the dark like this, but I have heard "lifter tick" referred to as common, or "normal", on subarus.

[TomsSVX]

Subaru solid tappet engines are notoriously noisey little buggers. Their clearances are large esp when they are not adjusted. A dead lifter on the other hand can be quite loud and obnoxious when there is no other noise...

Tom

[michael]

What type of fuel do you use and when was your last oil change? I find that an oil change usually clears up any ticking or knocking that occurs.

[SVXMAN2001]

Just changed oil and 91/93 octane fuel is used. Seems we are all of the consensus that a faulty valve or lash adjuster is a likely culprit. The noise is just very unsettling, owning svxi for over 10 years now you develop an ear for what a properly running svx should sound like. This sound is something like a hammer hitting metal (not so much as a "tick"), completely overtakes all other engine noises going on (noisey p/s pump, alternator, ticking fuel injectors, intake manifold hissing...)

Tom, solid tappets? I thought the stock engine used hydraulic lashes thereby negating any adjustment...

[TomsSVX]

Yes we use hydraulic lifters. I was just speaking of people calling suby engine noise common.

Is you oil light ever coming? Could have lost a big end to a bearing

Tom

[SVXMAN2001]

No, that's just it. If oiling levels were running low, the light would come on and would explain why perhaps there is a spun bearing or inoperative lash...but light hasn't ever come on. I did however notice, from the recent oil change, that only about 5 quarts came out...usually holds 6.

[Green1995SVX]

Chris-

I sound recording of the noise would certainly make diagnoses much easier. My 95 made a "knocking" sound that the Subaru dealer told me was normal, but I was never comfortable with it. It wasn't very loud, though.

Mike

[TomsSVX]

A bearing making that kind of noise would drop the oil pressure. Does the light come on when you have the key on, engine off?

Tom

[Trevor]

The oil pressure switch opens to extinguish the trouble light after pressure rises above 2.1 psi and is for good reason, what many term an idiot light. The closing point could well be less than the operating point, but this differential is not specified.

With the no trouble light, one can only assume that there is 2.1 psi oil pressure at idle, which is when the noise is most apparent. The specified normal pressure at 600 rpm is 14 psi. A proper pressure test would surely be worthwhile in view of the possible repair bill involved.

[dcarrb]

Once my '90 Legacy developed a sudden, awful sounding tap-tap-tap from the left-front cylinder. I just knew it was bad.

But it dawned on me that I'd recently replaced the spark plugs. Apparently I didn't get one properly snug, and it had begun backing out. (Great mechanic that I am.) Perhaps something to consider before resorting to drastic measures.

dcb