St3mpy

Update: See end of thread for findings.

I've attached a YouTube video. The engine is making a knocking noise. At first I thought it was a lifter. I pulled the camtower and found 2 soft lifters and one that seemed stiff in the bore. I replaced the 2 that were soft and put a used one in the deformed bore that seemed to slide better. It did t help, the noise is still there, unchanged.

I'm afraid its a rod bearing, but what do Y'all think?

http://www.youtube.com/watch?v=0cHTevu3hFg&sns=em

dirtyTurbo

I'm afraid it sounds just like it to me my friend. Stop running the engine and take it apart before you kill your crank forever

KuHL 951

Sounds just like an exhaust leak or another lifter, my rod knocking was much much deeper sounding. Have you checked for cracks at the exhaust flange or a bad gasket? What do you mean by deformed bore? A deformed bore will bind on any lifter and still make the lifter not operate correctly.

pnbell

Yea, well good news; That is not Rod Knock..

I am interested because for like a year and a half i have had a strange knocking noise from that same area... Right at the back of the engine.. Mine is not nearly pronouced as yours though. (I will take/post a video of mine later)

Anyway I hear mine the most at 2-3k rpm. Seems to be louder some days.
I have Replaced all the lifters with INA lifters (the ones i took out were INA too) No Change in noise..
*Valve Springs seemed fine, though i didn't really test them in any way...*
I have Replaced all the Rod Bearings; No Change in noise...
I have replaced all Exhaust Gaskets; No change in noise... (Though i am sure i do have an exhaust leak)

Anyway I hope you find what is causing this noise, as it might be my issue too... Keep Us Posted, and hopefully someone helpful can chime in..

Question for anyone:
Could a weak Valve Spring cause the a Valve to stay slightly open, then bang close: causing a sound like this?

AScholtes

Sounds like a rod knock to me....

aj986s

It does sorta sound like an exhaust leak. As long as the electric fan doesn't kick on, you can try blowing some smoke around the exhaust flange/header. Or if smokers aren't available, maybe you can spray some water and look for bubbling, before the exhaust gets too hot. Does it change when engine is warmed up. My Suburban has a small exhaust manifold leak that disappears when the engine is warm.

Doesn't sound as loud as rod knock I've heard on a couple of cars. In each of those cases, the oil PSI dropped dramatically when a rod bearing was going/gone.

AScholtes

I spun 7 out of the 8 rod bearings in one of my old mustangs. They were wiped and 2 were fused to the crank. It would only knock above 3K rpm...

whalebird

I had a similar noise - car ran fine like this for a couple of years. My diagnosis is piston wear. My car sat for a couple of years and when I revived it as a daily driver, I discovered I had all 4 injectors leaking badly after I had driven the car like this for a while. This washed the cylinders down with oil, and now all the iron coating is gone from the pistons (#3 in particular) and they are below spec from wear.
This may be increasingly more popular as our cars get older. Your car may do this for a long time with no problems. Pistons will slap for a long time.
Take a stethoscope and listen inside the oil filler, then at points where all the lifters are in the cam housing, and certainly around the exhaust manifold.
Rod bearings, and said piston slap will be dramatically effected by pulling each injector plug in order to identify which of the cylinders is the worst.

Indy Rev

Mine sounded exactly like that when I had a stuck lifter. Easy test is to drain a bit of oil and add some Lucas oil for 10 bucks and let it run for about 20 min. If it is a lifter you will hear it quiet down while its running.

I'm not trying to start a debate on whether or not to use additives, but I do know first hand that this will answer you question on lifter knock or not.

AScholtes

I had an old 4 banger car that tapped like that... i swore it was in the head, but it was a rod that eventually let loose and came out of the side of the block...

My point is, it can be just about anything to be honest. I have heard them just tap and then I have heard them so bad you swore that the rod was banging around inside the motor. I would suggest dropping the pan and checking them out... they need to be replaced anyway

V2Rocket

sounds like a lifter or your injectors are getting old...944 injectors sound like a tractor and just get louder

get a thin (1/4" square or 1/2" or so) stick of wood and put it to your ear and on each injector and on the cam tower at each lifter location and see where the noise is the loudest...that will tell you what the problem is

St3mpy

Thank for the help guys.
The number 4 exhaust lifter bore is tight. The lifter won't just drop down into the bore, you have to push it. The lifter I pulled out had a longitudinal tiger stripe pattern on it. The lifter I replaced it with must have been worn more because it slid more freely in the bore.

I forgot an important fact: a couple of the lifter bores were scored, one fairly deep. It didn't affect the lifters sliding in the bore though, and none of the lifters were scratched. The lifters I pulled out were INA aftermarket, not INA originals. The lifters I replaced with (3 in total) were INA original. All lifters are hard now. As I said before, even after all the lifter swapping, the sound hasn't changed at all in frequency or pitch.


I pulled each injector plug one by one and the sound was still there. I also used a PCV tube to listen in the injector. Their tapping was much softer than the one in question.

I put a bottle of Marvel Mystery Oil in about 1000 miles ago. No change. For a timeline reference I replaced the lifters a few days ago.

The thought of piston slap crossed my mind, but my old Cherokee had it, and from what I remember it sound more like a diesel. That may be because it was a larger engine.




Thanks for the help again. I'll take everyone's suggestions and try them if it hasn't already been done.

St3mpy

A quick update: I used a metronome to try and "time" the tick. I ended up with about 400 beats per....errr, taps per minute at idle. The tachometer shows an idle of about 925 rpm. So basically the tap is occurring once every other revolution.

So, to me it can either be:

-- A Lifter Problem
-- Bent Valve
-- Broken valve spring/Floating Valve
-- Broken valve seat
-- Rod bearing that only knocks on detonation
-- Exhaust leak (haven't checked into this one yet)

-- Am I missing something?

Another fact that could be an issue: When I pulled the plugs to check for any tell-tale signs, I noticed they looked a little hot. I checked the plug number, and they were 7's instead of 5's . I replaced the plugs with NKG's, but it didn't seem to help, although the car is running smoother now. (this was done a couple of days ago). For the record, I bought the car thinking it was a bad lifter almost 2 months ago.

944Ross

It sounds like something may be restricting oil flow to the cam area - new lifters need oil too. The wear you saw is a positive indication of insufficient oil.

Rod knock would be at twice the frequency of your noise. It would also vary significantly in noise level with load.

St3mpy

Thanks Ross. Yeah, fast or slow, up hill or standstill, the intensity is the same. My oil pressure is 2.5 to 3 bar at idle and 5+ reving. I'm running Shell Rotella T6 10w40 synthetic here in Alabama. Napa gold oil filter which has the check valve.