scary engine noise-problem gone

[Werner R.]

for the few following this problem, my conga drum kncock turned out to be a bad rod bearing for the number 4 piston. the old bearing had definately turned and worn away. no stamp marks left on the outside. well, i mic'd out the crank pin to a max of 2.220 with a min of 2.216 [a little out of spec]. the plasticgauge showed a taper going from .001 to .004 [again slightly out of spec]. i emery clothed the crank pin to get rid of any burrs and replaced the old bearing with a new one, standard size. things seemed tight on assembly. i ran the car 40 this weekend without a knock. i am sure this is a temporary fix, and i plan to have the problem properly taken care of in the future, but i want to drive 750 gentle weekend miles before i have to do that.
best
werner

[Clem Z.]

Re: scary engine noise-problem gone

be careful because you could have the rod seize and break and destroy the engine

[Werner R.]

Re: scary engine noise-problem gone

how ?

[Mike McKown]

the short answer is

sooner or later you will spin the new bearing and the insert halves will jump on top of one another. When this happens it will wedge the crankpin to the rod and your engine will stop rather suddenly. Not a question of if it will happen, just when.

I pulled this same trick in 1962 on a 265 Chevy. The bearing spun and welded itself to the crank. Took a screwdriver and pried the bearing off the crank, filed the heavy and emeryed the rest. Dressed the rod cap parting face on a piece of sandpaper laying on plate glass and slapped it back together with a .001 under bearing. My smallest measuring instrument was a 12 inch rule so I had to "feel" the fit. Back on the road in two hours. It ran for about six months, 40 miles a day back and forth to work. A few drag races thrown in. About once a month, I would have to replace the bearing as it would loosen up and make a small noise. I would replace it before it made a big noise.

It finally siezed, as Clem noted, but by then I had saved my pennies and dimes and bought a new crate 327/340.

I don't recommend you follow my path unless you don't care about the possibility of destroying your engine.

[Clem Z.]

Re: the short answer is

if the orignal bearing insert spun in the rod the big end bearing crush that keeps the bearing from turning in the rod is gone and it is just a matter of time before the insert spins again. JMHO

[Mike Cobine]

And all the other bearings

You didn't mention it, but I'm guessing you checked the other bearings while you had the pan off. Pulling a used bearing out and putting it back in is a recipe for disaster. A new bearing has a crush fit when installed. It even keeps that crush while taking it on and off for Plastigage. But once you run the engine and the heat begins to work, the crush is set for good and they are never as tight if removed.

The moral of the story, if you ever remove an old bearing to check clearances, check for your own piece of mind, then throw the bearing away. Install a new bearing. Most times you can simply install new bearigns without polishing or turnign the crank.

In your case, the journal is messed up, going from .001 to .004 in clearance, this will make the bearing walk even sooner.

I would not do that 40 miles easy cruise UNLESS you had to get to a hospital, your father was dying, a meteor was aimed at your house, or some other emergency. If you were my brother, you could probably drive it until the body rusts off, but I doubt you have his kind of luck.

What Federal Mogul has to say:

http://www.federal-mogul.com/cda/content/front/0,2194,2442_2875_6752,00.html

Good article on bearings and crush fit:

http://www.stealth316.com/misc/clevite-eng-bearing-fund-p4.pdf

Good article on checking clearances:

http://www.jr333.com/pontiac/clearance.htm

Bearing failure analysis:
http://www.bobistheoilguy.com/bearin...aranalysis.htm

Ad /article on Plastigage

http://www.dana.com/perfectcircle/Plastigage.htm

[Werner R.]

Re: And all the other bearings

well, i appreciate the advice from the experts, and i will have to put on my thinking cap.
best to all
werner

[Mike Cobine]

Re: And all the other bearings

If there is no really good reason you have to have the car right now, I'd pull that crank, have it check and turned it necessary, and put the engine back right. Much more peace of mind.

The idea of any trip having to worry about "what if it quits here?" in the back of my mind would destroy any pleasure to the trip.

Get a couple friends, couple of local club members, or whoever, pull the engine out one evening, drop the crank at a local machine shop the next day, pick it up in a day or two, and put the engine back together.

Odds are the rod needs attention if it had been hammering, so pull it, too.

If it was an all-out performer, I'd say forget resizing the rod, since you'd be off in balance (a few thousands shorter after resizing) but in a street engine the way these old cars are normally driven, you could have it resized, the full set rebalanced, and then put it all back together.

A week in the machine shop would be worth the peace of mind definitely for all future trips. Face it, we are not 21 and crazy anymore.

And on Yahoo the other day was an article that the biggest contributor to heart attack was stress, followed by cholesterol and smoking.

[Werner R.]

Re: And all the other bearings

mike
i agree with everything you say except :"not crazy any more." i still am.
best
werner