Bearing question

[Ed K.]

Re: Bearing question

Yes, knocks after sitting 6 -8 hours as leaving work. Next AM in home garage it's fine. That eve, 8 hours later knocks again.

[Ed K.]

Re: Bearing question

All journals look and feel OK

[Domenic T.]

Re: Bearing question

Ed,
had a similar problem on a entirely different kind of engine. The oil pump would loose it's prime. Another was oil siphoning down from the bearings.
There is/can be a lag in mechanical oil pressure readings. Your description sounds just like a new filter without oil in it at start up. Save me the time of going back and reading, but do you show oil pressure when it makes the noise, or is there time to look?
The pump is under oil so it shouldn't loose it's prime. That was the problem I found in a engine with a oil pump that was not under oil. Maybe someone will remember something about that.
I had bearings out almost every day when I did this a Chevy and I don't see a wear problem that would make noise on those old bearings, then go away. I would change bearings as advised, but it seems like there is something else wrong in the oil system that starves the oil to the main bearings. The main bearings get their oil 1st then go's thru the rod bearings. Any metalic in the oil?

Dom

[Domenic T.]

Re: Bearing question

Ed,
I found the oil siphon to the oil pan problem, and the oil pump (that was not in the pan), lack of oil pressure on start up problem, by pressurizing the system after the engine was not started for days. It's just like removing the distributor and priming the oil system on your engine. I have a accumulator that I pressurize aircraft engines with before the first start. If you did that and the clunk was gone on start up then you could look else where. My set up only take a few to do because I have all the fittings for what I work on. Also it is not impossible for the oil filter and oil in the pan to seek the same level which would cause a clunk on start up. There is a oil bypass valve on the oil filter mount that may have a broken spring or something silly like that.

Dom

[Ed K.]

Re: Bearing question

Pressure climbs as the 4-5 knocks occur. Very fine particles found after oil and filter were changed after 50 miles.

[Steven B.]

Re: Bearing question

Some of your rod bearings look pretty suspect based on your photos. The mains don't look all that good either. If your journals are good, you can probably get away with replacing the bearings. I would think it would be a good idea to mic the crank if you can. Hope everything works out in your favor.

Steve

[Michael F.]

Re: Bearing question

back in day just reinstalled bearing after checking, so if crush lost how does that affect bearing if reinstalled after checking for damage and potential issues???

[Domenic T.]

Re: Bearing question

When the bearing is bad it shows on one side if the rod is bent, if not the wear pattern is in the center or all the way around into the meat of the bearing. There are multiple holes drilled in bearings to get the oil to other places like the cam or to squirt the oil under the pistons. Some bearings have a center groove cut right down the middle for oil. Some a circular groove spiraling around cross ways. There is a chart some where to read possible problems like bent rods or out of round cranks. Pits will only hold oil, yours look like corrosion. A bad bearing doesn't get quiet in a few seconds, it only gets louder. In the old days they made bearings out of leather to get home. Actually they used their belts in a pinch.
I have used foil under bearings to get the proper clearance, then blocked the edges with a hone to get .0005.
All is good advice and I am sharing what worked for me the last 58 years.

Dom

[Duke W.]

Re: Bearing question

back in day just reinstalled bearing after checking, so if crush lost how does that affect bearing if reinstalled after checking for damage and potential issues???

As I said previously, as long as you don't remove the bearing half from the cap or crank/rod saddle, it's not an issue.

Duke

[Domenic T.]

Re: Bearing question

Duke,
I'll bet the bearing crush syndrome was invented when they made leather bearings! That was done back before we were born and carried out thru the 50's by old timers. They soaked the leather in oil, laid it on the rod and tightened the cap. Then removed the cap and trimmed the leather that CRUSHED out. Then did that over and over till the fit was done.
That's why they wore leather belts in those days when they went on a long trip. I doubt that was done at any factory, but was a field repair that lasted a long time.

Dom

[Dick W.]

Re: Bearing question

As I said previously, as long as you don't remove the bearing half from the cap or crank/rod saddle, it's not an issue.

Duke

Been many bearing removed and reinstalled. Old indian trick was to place the ends of the bearing on a wooden block and give them a light tap with a rubber hammer to "recrush" the bearing.

[Ed K.]

Re: Bearing question

First, thanks to all for jumping in. Very much appreciated.

I'm concluding that the safest way to proceed would be to remove motor for a rebuild. But that may not be necessary. Plus, I would like to avoid timely engine removal, costly rebuild and avoid possible body damage during removal/install of a rebuild unless absolutely necessary.

Therefore I'm leaning towards installing new bearings and oil pump. Do a 50 mile test with a few sit-for-8 hour knock tests. Drop oil and filter and check for particles.

My only concern is possible engine damage from a bad rod during the 50 miles - damage that may kill the numbers matching motor. OR am I being overly cautious about rod related danger?

[Duke W.]

Re: Bearing question

First thing to do is remove, disassemble, and inspect the oil pump gears and housing for damage. Clearly, something in the engine is disintegrating and causing abnormal particle contamination, and unless you find the source and correct, it's likely to continue.

Given the bearing condition I would expect the crank journals have some damage. They should be carefully inspected for damage and dimensional conformity. Also, pull the inlet manifold so you can remove the lifters and inspect the heels for damage, and check the cam lobes. Using a dial indicator to measure lobe lift and compare to OE specs is best.

Check the particles for magnetic attraction to determine if they are ferrous or non-ferrous. If they're non-ferrous it could be an indication of bearing disintegration, like mains or cam bearings, which are non-ferrous.

Duke

[Ed K.]

Re: Bearing question

Pulled oil pump - All OK. Journals OK. Now need to get magnet to check particles

[Ed K.]

Re: Bearing question

Pulled oil pump - All OK. Journals OK. Now need to get magnet to check particles

Particles magnetic. Cannot find anything elsewhere. Pulling motor.

Much thanks to all for jumping in. Will post eventual findings