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Old 10-09-2016, 09:37 PM   #26
dmann
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OK, car has now gone a total of 1200 miles since I put in the new parts, 700 miles since audible knock started. Knock always seems to be heard from coast down. The car has to be going fairly slow to hear the noise because it's not insanely loud. Less than 20 MPH on coast down probably. Noise is always louder if car is well warmed. Not noticeable when cold.

I drove it about 240 miles yesterday and it was pretty exciting because I wondered if it was going to give up. RPMs were up to about 3000 for many of those miles. Noise seems about the same to me, not any worse from what I can tell.

I feel like a circus caller: Step right up, guess how many miles it has left before it blows up!
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Old 10-09-2016, 10:00 PM   #27
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Oh by the way, I found this old General Motors training video about engine noises and found it pretty interesting. Especially the part starting at 13:11:

https://youtu.be/okmcF8nXdW4?t=13m11s

Basically I got 3 things from the video:

1. The main bearing clearance they talk about is .0008 - .0011
2. They said that some customers could actually hear knock at .002 clearance
3. That the crank doesn't rotate in a perfect circle inside the bearing; the rotation is influenced by belts and by the power stroke. On the power stroke, the clearance between the crank and the bearing can drop to 40 millionths of an inch.

This gives me more perspective regarding how important the tolerances are. It's an interesting video.
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Old 10-09-2016, 11:00 PM   #28
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Originally Posted by linuxman51 View Post
500 miles is a while to go if you think a rod is out of round enough to cause premature wear. we had one that we rolled a crank, new mains and new rod bearings into a few years ago, ran quietly for about 20 minutes, started ticking, then tapping, and after maybe a total of 50 miles was hammering worse than it was initially. They just don't last long when things are that out of spec.
Have you ever swapped a crank and one rod into a block that had otherwise good compression and pistons?


If the crank isn't scored ad mics ok going at least 2 directions and is probably "good", you have to catch a rod knock really pretty fast before you need to swap a rod (at minimum).
Don't ask me how I know this...unfortunately I've had this trial more than once...but learned rapidly to check as much as I can in a reasonable amount of time thereafter with the tools I have.

It's actually faster to tap a piston out and swap a rod than whole engine though.

So, didn't swap out the offending rod though amirite? But crank and bearings, yes?
I totally had this experience, minus swapping the crank. Crank mic'd out ok, and wasn't scored or torn up, but the rod bearing was pounded on one side. Neglected to take into account the egged out rod. Light tap became as bad or worse in short order exactly as you describe.

Did another one, but that time just swapped 1 rod with one I dug out of a JY motor I had laying around along with bottom halves only used rod bearing shells mixed around (not pounded by the power stroke) (no comment) used rods and it's still running today 100K later! Totally backwards and wrong, but if no major wear and the crank is fine, eh, it has a pounded/egged out rod and needs a bearing shell or two...shortest path home...
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Old 10-10-2016, 02:00 AM   #29
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The only thing I ended up swapping was the rod bearings - I did measure them with plastigauge and they were within spec, but I don't know if the rods were out of spec in other dimensions.

I never identified which rod was actually making the noise. None of the old bearings were out of spec.

At this point in time I wish I would have pulled the pistons and rods and had the machine shop check them




Quote:
Originally Posted by Kjets On a Plane View Post
Have you ever swapped a crank and one rod into a block that had otherwise good compression and pistons?


If the crank isn't scored ad mics ok going at least 2 directions and is probably "good", you have to catch a rod knock really pretty fast before you need to swap a rod (at minimum).
Don't ask me how I know this...unfortunately I've had this trial more than once...but learned rapidly to check as much as I can in a reasonable amount of time thereafter with the tools I have.

It's actually faster to tap a piston out and swap a rod than whole engine though.

So, didn't swap out the offending rod though amirite? But crank and bearings, yes?
I totally had this experience, minus swapping the crank. Crank mic'd out ok, and wasn't scored or torn up, but the rod bearing was pounded on one side. Neglected to take into account the egged out rod. Light tap became as bad or worse in short order exactly as you describe.

Did another one, but that time just swapped 1 rod with one I dug out of a JY motor I had laying around along with bottom halves only used rod bearing shells mixed around (not pounded by the power stroke) (no comment) used rods and it's still running today 100K later! Totally backwards and wrong, but if no major wear and the crank is fine, eh, it has a pounded/egged out rod and needs a bearing shell or two...shortest path home...
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Old 11-13-2017, 01:26 AM   #30
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Quick update - car has gone 21,000 miles since I swapped the rod bearings. Still making noise.

I drove the car loaded with 5 people and a trunk full of luggage through the mountains at full throttle and 4500 RPMs. Didn't seem to matter.
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Old 11-13-2017, 01:45 AM   #31
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Originally Posted by coalminer View Post
The rear main usually tells the tale.
er uuuuhhhm the lower shell farthest from the oil pump MIGHT be a better hint..

Where is the pump???? towards the rear.

Where is farthest away??????
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Old 11-13-2017, 01:49 AM   #32
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OP 192,000 or what miles..Ever think that maybe its not rod bearing..Volvo crank and oil pump are quite good..can go LOTS of miles and be fine..

But some things wear out as a function of cycles--up and down cycles..Things that goe up and down...
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Old 11-13-2017, 05:33 AM   #33
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If a crank or rod bearing is making noise on a b21/23/230, it won't be making noise for a long time.
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