Con rod wear pattern ok?

[ebinmaine 67,464]

Here's a few pics of the connecting rod from the 1975 K341 going on the C160 Automatic.  

 

Very smooth.  

No lines I can catch a fingernail on.  

No blueing. 

No aluminum visible on the crankshaft. 

No up/down  play is felt by the hand but I have no plastigauge. 

 

Note the color change near the bolts.  

 

 

Rod appears newer than the rest of the engine interior but I do realize it's also a different material.  

I believe the PO had it apart many moons ago.  

 

It'll go back together for now but should I put it in line for a rebuilt engine or is this normal?

 

 

[squonk 41,098]

I'm thinking the crank is out of round. Get some green plastigage and check it. Cheap insurance. You don't have to get it running by tomorrow. @richmondred01

Edited January 8, 2023 by squonk

[John2189 452]

I would think the dark spots is where it is not touching the crank journal.
If it was mine, id run it 

[ebinmaine 67,464]

Just now, John2189 said:

I would think the dark spots is where it is not touching the crank journal.
 

That's my thought too

[squonk 41,098]

If the surface of the rod journal isn't touching the crank, that's a problem. It's how good engines get ruined.

[ebinmaine 67,464]

5 minutes ago, squonk said:

If the surface of the rod journal isn't touching the crank, that's a problem. It's how good engines get ruined.

That was my thought. 

Mahle website shows different though.   

According to the screenshot below, 2/3 of the surface should touch... BUT...

That's on a separable larger engine bearing. 

 

I wasn't sure if a small engine with splash oil is the same spec.   

 

[squonk 41,098]

The key word in that description is "uniformly" There is nothing "uniform" about the wear on your rod.

[pacer 3,169]

I dont recall ever seeing one like that??? I would be leery.... and at least get a measurement on it, plasti or a mic. The crank does look good, not giving a clue to what is going on with the con rod. Again, I'd get a measurement.... if nothing else, I'd replace that rod, theyre certainly cheap enough on the bay.

[ri702bill 8,318]

58 minutes ago, squonk said:

I'm thinking the crank is out of round. Get some green plastigage and check it. Cheap insurance. You don't have to get it running by tomorrow

I too agree - BUT to verify the different clearances, you need to use the green Plastigage at 90 degree intervals on the crank. Best thing with using the squish gage - it WILL show if there is a taper on the journal - the used plastigage will not be even across. Last time I used that stuff was about 1995.....

[ri702bill 8,318]

1 hour ago, squonk said:

You don't have to get it running by tomorrow

I thought that comment was reserved for the Collosus Project.....  

[lynnmor 7,305]

I would measure the crank at a number of locations, if it checks out, then I would polish the journal.

 

Also, take a good look at these lines to see if something is going on there:

[ebinmaine 67,464]

45 minutes ago, lynnmor said:

take a good look at these lines

Good eye!

 

I believe those are casting flash but I'll double check with better lighting.   

 

[Achto 27,570]

6 hours ago, ebinmaine said:

It'll go back together for now but should I put it in line for a rebuilt engine

 

If you pulled the piston out of the cylinder. Are you goin to run a ball hone through the cylinder and put some new rings in? Once you pull a piston out, the rings will not seat again.

 

When I was a Harley mechanic I changed a lot of cylinder base gasket on Evo engines. I would pull the cylinder up until I could access the wrist pin. If I could remove the wrist pin with out letting the rings come out the bottom of the cylinder then it only got new gaskets. If the rings came out or the bottom of the cylinder then it had to be re-scuffed and new rings installed. I did way more than 100 of these jobs, most of the time I did not have to put new rings in. 

[ebinmaine 67,464]

6 minutes ago, Achto said:

 

If you pulled the piston out of the cylinder. Are you goin to run a ball hone through the cylinder and put some new rings in? Once you pull a piston out, the rings will not seat again.

 

 

 

 

I did not pull the piston past TDC at any point for the very reason of not wanting to get new rings and hone the bore.  

 

 

 

[WHX?? 48,815]

Just now, ebinmaine said:

 

 

I did not pull the piston past TDC at any point for the very reason of not wanting to get new rings and hone the bore.  

 

 

 

OK that's wise but I would still measure the bore just to compare it with specs. See if it's oval-shaped. Plastigage isn't the worst idea on the big end. 'Course I have been known to run it like ya stole it EB.

[8ntruck 6,999]

Got any dye check?  That would give you a definite answer on the suspicious marks on the rod.

[ebinmaine 67,464]

3 minutes ago, WHX?? said:

measure the bore

I have no way to measure the bore. 

 

[ebinmaine 67,464]

Just now, 8ntruck said:

Got any dye check?  That would give you a definite answer on the suspicious marks on the rod.

What's that and how's it work? 

[8ntruck 6,999]

Dye check is a 3 part crack detection system.  Comes in 3 spray cans - cleaner, dye, and developer.

 

Step 1 - clean the part with the spray cleaner.

Step 2 - spray dye onto the suspect area of the part.  Let set for a couple of minutes to let the dye wick into any cracks that are present.

Step 3 - wipe the dye off of the surface of the part with a rag or paper towel.  Spray cleaner onto another rag or paper rowel and wipe down the surface of the part.

Step 4 - spray the suspect area with the developer.  The developer is a very fine white powder in a thinner.  When it dries, the powder wise draw some of the dye out of any cracks, making them visible as a red line.

 

Might be available at an industrial supply house or maybe NAPA.  We used it at work to look for cracks at the specified inspection intervals when we were testing wheels.

[David Blanchard 9]

Run it not a high rpm race motor

[WHX?? 48,815]

You gonna fly it at 33,000  ft EB? ... didn't think so... run it...

[ebinmaine 67,464]

4 minutes ago, WHX?? said:

You gonna fly it at 33,000  ft EB? ... didn't think so... run it...

32000 Max

[WHX?? 48,815]

20 minutes ago, ebinmaine said:

32000 Max

Attaboy... worse thing you develop a knock  but then there the pleasure of a full rebuild. 

I says to Dan I got this 161 that's starts and runs good. Smokes like a bandito tho. You gonna take care of that he says? Nope I says run her. Maybe it will clear up maybe not. Worry about that bridge when we cross it. 

Benefits when having parts tractors.  

[SylvanLakeWH 25,553]

8 hours ago, WHX?? said:

 

Smokes like a bandito tho. You gonna take care of that he says? Nope I says run her. Maybe it will clear up maybe not. Worry about that bridge when we cross it. 

Benefits when having parts tractors.  

 

This just in from our Wisconsin affiliate:

 

True source of global warming, continental drift, and the round earth theory identified..."!!! 

 

[Achto 27,570]

10 hours ago, ebinmaine said:

I have no way to measure the bore. 

 

Some thing to add to your arsenal one day. Maybe not the best quality sets if you are a machinist, but they will be good enough to let you know what's going on & what you need for parts.

 

https://www.harborfreight.com/search?q=telescoping bore gauge

 

https://www.vevor.com/outside-micrometers-c_10820/vevor-outside-micrometer-premium-precision-carbide-tips-machinist-tool-0-4--p_010689764898?utm_source=google&utm_campaign=18457895227&utm_term=&gclid=EAIaIQobChMI1OuP8bG6_AIVhxfUAR0I8gmzEAQYBSABEgLkV_D_BwE&v_tag=7ec532d0-9011-11ed-ac31-9daacb9ce42b.1

Edited January 9, 2023 by Achto