Still knocking, slipped liner question

[dragnet]

Just put back together the 4.6. New timing gears/chain, front cover, oil pump, water pump, thermostat, serp belt, plugs etc. When the motor was apart had a good look at the rod bearings and they looked fine. Fired motor back up and 'yippee'...still have a bad engine knock when the motor is cold under load. There does not seem to be anything amiss inside my block yet there is an insistent knock coming from the bottom end everytime I start it. If you've read my earlier posts I thought I had found the problem when I pulled out my oil pump and the outer gear was in three pieces, guess not.

Based on my searching slipped liners get worse as the engine warms up, not better. Is there any chance this is a slipped liner and as the engine gets warmer the metals expand and the knocking lets up?

My only other guess is piston slap, but man I can't believe piston slap could be so loud. I feel the knock though the whole truck when it's cold.

Thanks.

 

[crown14]

I saw a '03 4.6 the other day that had locked up the oil pump like you describe, and in the process had cracked the harmonic balancer. You check yours?

 

[dragnet]

Thanks I'll take a close look.

 

[p m]

IME - the broken down substrate in catalytic converters in two of my Rovers made sound just like rod knock at idle...

 

[pjkbrit]

Not to 'knock' you...but I would never throw old crank bearings back in a used motor....for the cost of the bearings I would always replace them while everything's apart...also, what about the camshaft and followers...any work there? I concur with the rattling cat comment also....could even be a exhaust manifold gasket blow.

 

[ptschram]

Not to 'knock' you...but I would never throw old crank bearings back in a used motor....for the cost of the bearings I would always replace them while everything's apart...also, what about the camshaft and followers...any work there? I concur with the rattling cat comment also....could even be a exhaust manifold gasket blow.

X a bazillion! There is no reason to "inspect" bearings. Either leave them alone or replace them. If you have good oil pressure, you have good bearings, period, end of discussion.

It the knock were due to oil starvation, you would likely have scrambled the bottom end long ago.

Did you check the oil pressure before disassembly?

Does the knock go away as engine speed is increased?

 

[gmookher]

my 04 knocks. I suspects liner slip, but it s a subtle knock. Whats the down fall of looking away, I mean its not broken the truck runs fine, and strong. its just when cold too.

 

[dragnet]

Oil pressure is fine. Knock dissappears around 2000rpm. Shouldn't say dissappears. Becomes too fast and too faint to hear well. If you really listen it's still there. It's really only bad when cold and under load. I hear it distinctly every morning due to a slightly uphill drive way. If I let the truck warm up for a while it is less noticable.

Truck is my families daily driver. Really don't want to have to worry about the motor grenading each time my wife and new born are in the truck. I have bad visions of the motor going at highway speeds and somehow taking the brakes, tranny or dirveshaft with it. I would be fine in that situation but my wife would panic and the result would not be good.

Never thought it would be possible to own a 5 year old vehicle that gives me more worries then my 69 MGB. Guess I've been proven wrong.

 

[dragnet]

By the way we didn't replace the rod bearings, just looked at them and replaced the torque to yield bolts. Perhaps I'll get a new set of bearings and go from there.

 

[dragnet]

Definitely not exhaust related. Checked all gaskets and put a stethiscope to both cats. This knock is more then just noise. When it's bad you can feel it vibrate through the truck.

 

[robertofollia]

My 99 D2 does the same noise, from new Once hot or after highway it's sweet as oiled spaghetti. No noise.

As I will pickt it up in the following days after a headgasket replace and ... YES! new ACE valve block modulator, will continue checking for the knock if it's still there.
BTW, oil pressure is perfect, as soon as the engine fires up the oil pressure light extinguishes.

 

[ptschram]

If you have good oil pressure, you do not need new bearings. It is foolish to replace bearings without the ability to measure the clearances.

IS the noise at the same frequency as the engine speed, or half that speed?

 

[dragnet]

ptschram,

I'm going to take a short video of the truck and post it. Maybe it will make some sense then. I'm starting to believe it's just a bad case of piston slap...real bad case. If that's what it is I'll just live with it until the motor packs it in and I can rebuild it properly.

 

[JohnB]

Not to 'knock' you...but I would never throw old crank bearings back in a used motor....for the cost of the bearings I would always replace them while everything's apart...also, what about the camshaft and followers...any work there? I concur with the rattling cat comment also....could even be a exhaust manifold gasket blow.

x2

Really a bad cam and lifter can sound like a knock at start up. Mine made that knock until the lifter comepletely failed and took the cam with it. Once fully warmed up though it just sounded like a bad lifter.

 

[Discotec]

My 2 cents worth.....If you had a slipped liner, that would have been blatantly obvious when you had the heads off the engine. You did have the heads off i presume.

My guess is piston slap....... from one who has been there.....

I've driven over 20,000 miles with pistons slapping away......

 

[gardrover]

This is a shot in the dark from someone unfamiliar with the issue, but could the
2003 oil pump failures sound like this? If it is cracked wouldnt it be slapping around in there?

http://www.discoweb.org/forums/showthread.php?t=55265&highlight=gerotor

good luck.. I heard an 03 drive by me the other day that sounded like a jackhammer
the thing was knocking so badly.....

 

[dragnet]

Just replaced the oil pump as it had broken in a few places. Did not improve sound.

I've actually recorded the sound and posted it here.

2003 Knocking sound

Take a listen if you have time.

Thanks.

 

[singingcamel]

My 2 cents worth.....If you had a slipped liner, that would have been blatantly obvious when you had the heads off the engine. You did have the heads off i presume.

My guess is piston slap....... from one who has been there.....

I've driven over 20,000 miles with pistons slapping away......

Ive been told that a slipped liner will sometimes move back into normal position once the engine is off. This info from a reputable source.