Need engine Help! Rod knock??..spun bearing??

cosmo · Post by **cosmo** » November 21, 2011, 10:12 pm

I'm not an engine expert, but my engine started making a loud hammering noise while cruising and deceling for the last traffic light on my way home. It was louder than any ticking I have ever heard. I slipped it out of gear and the hammering decreased with rpm. It would barely idle at the traffic light unless revved it. It felt like it lacked power when when the light turned green, so i took it easy ....and then the noise stopped, power came. back. At home, I shut it down and restarted it ..no noise. I restarted it 2 hours later..no noise.
What does this sound like to you?
Can something that sounds so bad just go away? Anyone had a similar experience?

slick4x4 · Post by **slick4x4** » November 21, 2011, 10:32 pm

did you lose oil pressure ?
have you checked the oil for silvery metal flakes ?
.......
maybe you just had a spark quit on 1 cylinder... but that shouldnt make a loud knock

banjopicker66 · Post by **banjopicker66** » November 22, 2011, 6:36 am

Do not drive it any more than you must to get it safely out of the way. Tow it home if you must.
Hammering is a definite sign of a rod problem.
Check your dipstick for oil.
1. For metal flakes
2. for a sharp burned smell.
Either one will indicate serious problems.
If you do not find anything, then let the truck sit overnight on a level spot.
Drain a little oil into a clear container, about half a coke can full. Check it for metal. Again, metal flakes are bad.
You may find it worthwhile to pull the pan to check for metal and the rotating assembly.

Best of luck. Not a pleasant spot to be in, and many of us have been there. I threw a rod on the interstate once.

supersmitty · Post by **supersmitty** » November 22, 2011, 7:14 am

Was it a knock or a did it sound like a ping. You could have been detnating if your fuel mixture went real lean causeing loss of power and a load noise as you loaded the engine. Usually when I see an engine with a rod knock it doesnt go away, it only gets worse and or the rod breaks loose and creates havoc. Good luck.

cooter · Post by **cooter** » November 22, 2011, 8:03 am

if the noise came from a bearing then the noise will not go away and the engine doesnt loose power normally when a bearing failure happens. Im thinking you have a valvetrain problem, remove valvecovers and start there

cosmo · Post by **cosmo** » November 22, 2011, 8:49 am

Looks like a busy thanksgiving weekend for me

Understand looking for metal in the oil.
What am I looking for in the valve train? Should it obvious or subtle?

cooter · Post by **cooter** » November 22, 2011, 9:58 am

look for a rocker arm loose, a pushrod which may have come out or bent, wiggle each rocker arm and check for something loose. If everything is runninggood now it may be a mystery. Make sure to check oil pressure just to make sure it is ok

HiBoy63 · Post by **HiBoy63** » November 22, 2011, 10:48 am

A piston wrisp pin could be making a knocking sound. I dont think it stops once it starts. A collapsed piston skirt may make a knocking sound on startup but sometimes will quite down as the engine warms up. I dont think either or these would cause a poor idle. Maybe a valve or two sticking could cause the rough or poor idle. Im not sure what a broken valve spring might cause as I have never experienced that before.
Another possability is that you may be loosing spark in a few of the plugs due to cross fire. Making you think it is a loud banging noise. Check for a crossfire or problem say with the distributor cap mabey cracked or carbon arced bad plug wires. Loose or broken wires at the coil.

Tech · Post by **Tech** » November 22, 2011, 11:34 am

Sounds like a hydraulic lifter went flat to me. It is the only part that I know of that can go flat /get pounded down and stuck in the old sludge then pump back up and start working again. (but usually not without some help)
It definitely makes lots of noise and power loss.
It also happens at half the crank speed but it takes a good ear to distinguish this. find another noise like an exhaust leak and see if they happen at the same frequency or doubletime.

I am beginning to think that some brand of oil is killing oil passages. Yours is the third case that I have heard of this month. 1 Mazda, 1 BMW and now a ford.
My son saved the other two engines with two cans of Seafoam.
Pull the valve cover, start the engine, add both cans of seafoam to the engine.
Pour them all over anything that moves.
Note how well the engine is oiling.
Watch for improved oiling.
let it run for up to 1/2 hr.
Dump the oil and filter.
Check the drain pan for flaky silver bearing material.
Replace the valve cover and add oil and filter.
See if it lives.

The BMW guy was really happy with a $12 fix, the dealer wanted to rebuild the engine.

R Pope · Post by **R Pope** » November 22, 2011, 2:06 pm

Two possibilities...
A chunk of carbon or a part of the carb or something fell in to a cylinder and rattled around for a while, then spit out the exhaust.
Or, you spun a bearing in the bottom end. The knock starts when the bearing goes out, and when it stops knocking the bearings have stacked up on each other, taking up the slack (for a little while!)

cosmo · Post by **cosmo** » November 22, 2011, 9:40 pm

I got lucky and the guy who built the engine came over and we checked the valve train. Everything looked good no loose rockers , bent pushrods, plugs looked good. Compression looked good. oil pressure good.
His thought maybe a collapsed lifter. I'll look at the oil tomorrow

bunchoftrucks · Post by **bunchoftrucks** » November 24, 2011, 12:14 am

Don't forget that sometimes the eccentric on the cam that runs the fuel pump can make a pretty scary sound too. It happened to me and for the cost of a fuel pump my "rod knock" went away. To test it I clamped off the fuel line to the card and pumped the pump off. Started the truck, no noise and I was definately relieved.

Need engine Help! Rod knock??..spun bearing??

Need engine Help! Rod knock??..spun bearing??

Thanks for the advice

Verdict is still out