DodgeIntrepid.Net Forums banner

1 - 20 of 22 Posts

·
Registered
Joined
·
413 Posts
Discussion Starter #1
Its a very light and rhythmic knock. Tell me what all it could be? I recently started driving about 80 freeway miles per day whereas before I did a mix of city/highway and about 20 miles a day...guess the 2.7 is going on me? I have a code 0303 and a 0406 to go with the knocking...car has also overheated a couple of times due to one of the fans going out (for the second time)... :cussing:
 

·
Registered
Joined
·
4,388 Posts
Code 0303 is a misfire on cylinder #3. Code 0406 is for the egr valve. I periodically get that 0406 code every now and again but it goes away after I restart the car a few times. That knocking could be because of that misfire. Check out the spark plug, coil and wiring for the #3 cylinder. Fuel injector is another possibility. Sooner or later someone will suggest a leaking intake manifold. Its a possibility but there'd also be a lean condition also and the O2 sensor would pick up on that and set a CEL for it also. Those are the basics and easiest to check. The condition of the spark plug can tell you a lot.
 

·
Registered
Joined
·
224 Posts
If the knock is all the time, I bet it is mechanical. A ticking noise is probably the valve train, the knock maybe a rod (spun bearing).

Easyest is to do what froggy did first, then the sh*t starts to hit the fan if that is not it.
 

·
Registered
Joined
·
4,388 Posts
WhiteHawk said:
If the knock is all the time, I bet it is mechanical. A ticking noise is probably the valve train, the knock maybe a rod (spun bearing).
.
Spun bearing is the final end to a rod knocking, and once the bearing is "spun" the motor isn't going to turn over. Been there done that on a 2.3L Ford twice.

Misfiring will cause some unusual noises. If you can pin down what's causing the misfiring and fix it so you're running on all cylinders again, then if the noise persists, you can start looking further. Start with the "usual suspects" I mentioned and from there it starts to get deeper, mechanical problems. If there's actual mechanical issues with that cylinder that could lead to both noises and misfiring like valvetrain problems. A rod and/or piston problem U wouldn't think as a likely candidate to create both noise and misfiring unless the rod were broken so there wouldn't be combustion in that cylinder at all.
 

·
Registered
Joined
·
224 Posts
My car I turned it over just fine, by hand actually. I have two spun rod bearings that I found so far, maybe more.

I think you spin the bearing first then the rod knocks.

A rod knocks because of the excessive clearance between the connecting rod "large" end and the crank pin. The excessive clearance is caused by a spun bearing (O.D. decreases from wear). The spun bearing is caused by improper lubrication, metal to metal, bearing grabbing the crank pin journal.

Yikes, a broken rod would be a catastrophic failure! Rods are very strong, it is unlikely you broke one or will break one. Forged Powdered Metal Rods with Cracked Caps, that is High Performance chit.
 

·
Registered
Joined
·
4,388 Posts
WhiteHawk said:
My car I turned it over just fine, by hand actually. I have two spun rod bearings that I found so far, maybe more.

I think you spin the bearing first then the rod knocks.

A rod knocks because of the excessive clearance between the connecting rod "large" end and the crank pin. The excessive clearance is caused by a spun bearing (O.D. decreases from wear). The spun bearing is caused by improper lubrication, metal to metal, bearing grabbing the crank pin journal.

Yikes, a broken rod would be a catastrophic failure! Rods are very strong, it is unlikely you broke one or will break one. Forged Powdered Metal Rods with Cracked Caps, that is High Performance chit.
Got it backwards, first the rod knocks because of the exess clearance then the bearing spins when the clearance is so much that one half of the bearing ends up overlapping the other half. Happened to me twice and both times, the starter couldn't turn the crank at all. Knocking can also be caused by a loose or worn pin but that won't cause a spun bearing. Different ends of the rod involved.
 

·
Registered
Joined
·
1,992 Posts
Let's not forget piston slap,either, resulting from worn wrist pin (small end of the connecting rod) journals in the rod or the piston...
That'l make interesting noises..
There's "spun bearing" info on this site somewhere with pictures...
 

·
Registered
Joined
·
224 Posts
froggy81500 said:
Got it backwards, first the rod knocks because of the exess clearance then the bearing spins when the clearance is so much that one half of the bearing ends up overlapping the other half. Happened to me twice and both times, the starter couldn't turn the crank at all. Knocking can also be caused by a loose or worn pin but that won't cause a spun bearing. Different ends of the rod involved.

Ok, I see what you are saying about the overlap action stopping the crank from turning. I wouldn't think a lower mileage engine would get slap...I have pulled a running 350 out of my suburban with 140,000, no slapping or weird noises, just did it to stroke it...anyways, two of the bores were larger then .060 oversized and the rest I had to bore to .060 to clean them up...then again its a chevy :bgtup:

Back to the spun bearing, I think with the consistant oiling related problems with the 2.7, I think a premature failure is at cause and not so much wear related or just plain old age.
 

·
Registered
Joined
·
3,552 Posts
So, here's my .02:

Rod knock is a hollow sounding echo from the oil pan area. It is at crankshaft revolution speed (duh!) and has a "tock, tock" kind of sound.

A valve train knock has more of a "tick" sound and occurs at twice crankshaft speed.


A spun rod bearing is a result of loss of lubrication to the bearing crank journal face. This loss of lubrication can be caused by lubrication system failure or by excessive clearances in the bearing allowing loss of pressure. When the pressure is lost, the protective film that the crank runs on is lost, and the crank contacts the bearing shell in the rod end. The bearing seizes to the crank journal immediately on contact, ruining the bearing and usually the crank journal surface. You may or may not be able to spin the crank depending on what happens after the bearing shell welds itself to the journal. If the shell spins in the rod end a few times, the clearances open up enough to allow the crank to rotate.
When the bearing spins (It spins in the rod end, both halves of the shell) it ruins the crank and very often the rod itself.

It's called a spun bearing because the bearing shell spin in the rod itself instead the crank rotating on the insulating oil film between the crank and bearing.

The knock you hear is the clearances opening up between the crank journal faces and the bearing shells, resulting in the oil film thinning out and eventually it will allow contact with the shells resulting in a "spun bearing".

If it is rod knock you have, it is always terminal to the engine.

To help localize and trouble shoot it, perform the stethoscope test. Either purchase an automotive 'scope, or get a long screwdriver. If using the screwdriver method place the handle on the bone of your skull just behind your ear.
Start the engine, ensure you have no loose or dangling clothing and stay clear of rotating assemblies, and place either screwdriver or scope on different parts of the engine. If it is rod knock it will be louder lower in the engine (oil pan area). If it is loader towards the top (valve cover area) you likely have a valve train noise.

Many problems can be diagnosed with a little experience and practice.

Piston slap is usually found in higher mileage engines or ones that have been overheated.

Piston wrist pin knock is a possibility but unlikely. Again, characteristic of high mileage engines.

Also, I may have missed it but what engine are we talking about here and mileage?

Froggy, if your bearing shells slipped one over the other, you had on heck of alot of clearance before hand. I find it hard to believe the engine would even run with the clearances opened up enough to be even close to allowing this to happen. More likely, one shell was forced over the other after the seizure and resulting "spin". I just have a hard time believing that one shell could be forced over the other if the engine was running at all before hand, but I've seen stranger things after taking a failed engine apart, I guess. If true, that engine must have been one heck of a mess inside.

Good luck

BJ
 

·
Registered
Joined
·
4,388 Posts
Great White said:
Froggy, if your bearing shells slipped one over the other, you had on heck of alot of clearance before hand. I find it hard to believe the engine would even run with the clearances opened up enough to be even close to allowing this to happen. More likely, one shell was forced over the other after the seizure and resulting "spin". I just have a hard time believing that one shell could be forced over the other if the engine was running at all before hand, but I've seen stranger things after taking a failed engine apart, I guess. If true, that engine must have been one heck of a mess inside.

Good luck

BJ
It was a Ford. Enough said. But worse than that, it was a Ford 2.3L 4 cylinder. It spun the second time no more than a month later. I had all kinds of oil problems on that motor. the intake lobe for the #4 cylinder was almost completely round from oil issues. I bought it used from some chick, and the whole car was really not taken care of. I was young at the time and I'm stating my dad's observation of what he found when he took it apart the first time. He was a mech for many years, so I'm sure he's seen his share of crazy stuff. And when it happened again, he didn't even bother, we yanked to motor and got another one. Once it happened again, it was pretty clear the crank was shot. Oh and I forgot to mention the approx. 5lbs of sugar we drained out of that tank that came with the car!
 

·
Registered
Joined
·
413 Posts
Discussion Starter #11
Great White said:
Also, I may have missed it but what engine are we talking about here and mileage?BJ
Its a 2.7 with bout 95,000 on it. The noise is more "breathy" than knocking or ticking. Piece of crap, I really cant afford this right now.... :mad:
 

·
Registered
Joined
·
413 Posts
Discussion Starter #12
got a mechanic to listen to it...he said I have some lifter noise up high but the other noise is coming from down low but isnt a rod...says it may be the torque converter but didnt really know just by listening..told me to keep the oil topped off and leave it alone (he knows how poor I am), any thoughts?
 

·
Registered
Joined
·
4,388 Posts
willjones4 said:
got a mechanic to listen to it...he said I have some lifter noise up high but the other noise is coming from down low but isnt a rod...says it may be the torque converter but didnt really know just by listening..told me to keep the oil topped off and leave it alone (he knows how poor I am), any thoughts?
check the a/c and alternator belts. I just went thru this recently where the a/c belt was going and was making a thumping noise at a low idle. I replaced my a/c tensioner pulley and kept the old belt on, not realizing that the tensioner was still set at the "new" position and it made one hell of a thump, thump noise.
 

·
Registered
Joined
·
413 Posts
Discussion Starter #14
OK, thanks. I'll check those. I asked the guy if it could be an exhaust leak but he said no. It sure sounds like one to me as it keeps up with engine speed. Its very embarassing driving around with it sounding like it does...
 

·
Registered
Joined
·
400 Posts
Is it a ticking noise? Mine sounds like if you stuck a playing card into a spingin fan and it kept hitting it... and i drove it around for about two weeks and yes it was loud enough to be embarrassing as well..

One dude who said he had experience with cars listened and said it might be a bent rod like others are saying here... i didnt think it was much and kept driving it until the coming weekend i was going to take it in...

On the way home from work one fine day doing about 75mph on the express way..... WHOOOMP WHHOOOMP WHOOOMP... my car started sputtering big time... it would still go if i hit the gas but it was acting very bad so i immediately pulled off the expressway and got to the first side street i could and parked.

Come to find out all that bullshiet I've got threads concerning now... just sounds similar to my ordeal... sorry if im a lost cause stressing my problem! Thought it might help... cause i drove my car for too long and now im screwed with no car and little money to fix it right now!

I just dont want what happened to me to happen to anyone else! ... and to think this could have all been 'mostly' avoided for me with the 100k maintenance....
 

·
Registered
Joined
·
982 Posts
ThaArtist said:
Is it a ticking noise? Mine sounds like if you stuck a playing card into a spingin fan and it kept hitting it... and i drove it around for about two weeks and yes it was loud enough to be embarrassing as well..


I just dont want what happened to me to happen to anyone else! ... and to think this could have all been 'mostly' avoided for me with the 100k maintenance....
A playing card in a spinning fan is similar to what it sounds like when the chain tensioner wear pad breaks or the chain gets loose and rubs against the front engine castings. the Chain spins and the end of the tensioner rubs up against the back of the chain or the bask of thr chain starts eating into the metal fins on the front of engine.

And don't feel bad because the owners manual never mentions doing anything to the timing chain, even at 100K.. :icon_frow Because a timing chain normally last longer.
 

·
Registered
Joined
·
400 Posts
Ahhh... mucho gusto...

not sure what that means but i remember it from spanish class... maybe "thank you very much" ?? haha i forget...

thanks for clearin that up tho...
 

·
Registered
Joined
·
413 Posts
Discussion Starter #18
I think Froggy may have hit it. :grinyes: I just went out there with a spotlight and peered down in there and the belt (at least the part I can see) looks pretty thrashed-we may have a winner! It is more of a "flub flub" type noise than he described at idle and turns into a breathy/airy type noise that matches engine speed-jeez I hope that's all it is-I am so broke right now... :notify: what am I saying-"right now"-Im always broke :rolleyes:
 

·
Registered
Joined
·
3,552 Posts
ThaArtist said:
One dude who said he had experience with cars listened and said it might be a bent rod like others are saying here...
if this "dude" actually said the words "bent rod", I'd stop listening to what he has too say as he doesn't know what he's talking about.
Rods that are "bent" are found lying on the ground next to the block, not still in it.

I'm thinking he's not as "experienced" as he thinks.

Pretty much check any rotating component, belts pulleys and accessories included.

Cheers

BJ.
 

·
Registered
Joined
·
1,992 Posts
Great White said:
if this "dude" actually said the words "bent rod", I'd stop listening to what he has too say as he doesn't know what he's talking about.
Rods that are "bent" are found lying on the ground next to the block, not still in it.
PRICELESS!!
 
1 - 20 of 22 Posts
Top