What's wrong with my 996?
Discussion
Hey guys,
My 996, a late 98 3.4, started to exhibit a strong knocking sound coming from the driver's side of the engine. It's the dreaded "sounds like a lifter" type of knock. Very audible at idle, gets faster & louder as revs increase (haven't revved it past 2.5k).
I can't put a link to a video due to being a new member so you'll have to use imagination I'm afraid.
What's weird is that the sound came all of a sudden. I did push the car fairly hard a few hours earlier (up to >> 150mph) for a short period of time (3-4 minutes of fast driving, car fully warmed up). The car was running fine coming home, the noise appeared within 500 yards of starting it again a few hours later. I didn't do anything to do car in between save for a mod on the PSE relay (cutout delete) which seems unrelated. Tried running the car without the exhaust relay wishfully thinking it could be "just" that, but it obviously doesn't make a difference.
What's even weirder is that the car just spent 3 weeks in the shop for a new IMS / clutch, and cylinder #6 was bore checked, with no evidence of scoring found. One of the chain tensioners was also swapped for a good used unit.
The oil is brand new (<150 miles), and the car still has oil & oil pressure. The tailpipes are a bit black on the inside but there's no oily residue in them, nor is there any on the bumper. Not a single code on the ECU.
Also the car has a full history, low miles (45k), and "only" four prior owners in 25 years. Very clean inside and out.
At this point, I'm really hoping it's "just" a bad exhaust leak, but will take any advice (and am checking the price of full rebuilds..). Really a shame as this is a dream car I just purchased less than 200 miles ago, and on which I thought I'd done my due diligence
.
My 996, a late 98 3.4, started to exhibit a strong knocking sound coming from the driver's side of the engine. It's the dreaded "sounds like a lifter" type of knock. Very audible at idle, gets faster & louder as revs increase (haven't revved it past 2.5k).
I can't put a link to a video due to being a new member so you'll have to use imagination I'm afraid.
What's weird is that the sound came all of a sudden. I did push the car fairly hard a few hours earlier (up to >> 150mph) for a short period of time (3-4 minutes of fast driving, car fully warmed up). The car was running fine coming home, the noise appeared within 500 yards of starting it again a few hours later. I didn't do anything to do car in between save for a mod on the PSE relay (cutout delete) which seems unrelated. Tried running the car without the exhaust relay wishfully thinking it could be "just" that, but it obviously doesn't make a difference.
What's even weirder is that the car just spent 3 weeks in the shop for a new IMS / clutch, and cylinder #6 was bore checked, with no evidence of scoring found. One of the chain tensioners was also swapped for a good used unit.
The oil is brand new (<150 miles), and the car still has oil & oil pressure. The tailpipes are a bit black on the inside but there's no oily residue in them, nor is there any on the bumper. Not a single code on the ECU.
Also the car has a full history, low miles (45k), and "only" four prior owners in 25 years. Very clean inside and out.
At this point, I'm really hoping it's "just" a bad exhaust leak, but will take any advice (and am checking the price of full rebuilds..). Really a shame as this is a dream car I just purchased less than 200 miles ago, and on which I thought I'd done my due diligence
. Planning to do that - the shop's 45 miles away so I'll have to arrange for a tow. Was hoping to get some feedback in the meantime.
What surprises me is I've never heard of bore score or failed rod bearing showing up all of a sudden, without codes or anything.
Also, YouTube vid. f7d7so9CBgw sounds very much like my noise, this way I can get around the no-links-for-new-members limitation
What surprises me is I've never heard of bore score or failed rod bearing showing up all of a sudden, without codes or anything.
Also, YouTube vid. f7d7so9CBgw sounds very much like my noise, this way I can get around the no-links-for-new-members limitation
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