what is this on my piston rod? - ClassicOldsmobile.com

Go Back  ClassicOldsmobile.com > Repair & Restoration > Engine > Big Blocks
what is this on my piston rod? >

what is this on my piston rod?

what is this on my piston rod?

Reply

 
 
 
Old November 2nd, 2018, 07:27 PM
  #1  
Registered User
Thread Starter
 
Join Date: Sep 2017
Location: Oak Island NC
Posts: 17
what is this on my piston rod?

Got my engine back from the machine shop and noticed this carbon looking stuff on the number 3 piston. It is very hard and does not flack off or scrape off. When I returned it to the machine shop he told me he did not know what is was. He said it could be from the original casting of the rod and recommended I leave it alone. I do not know if I should try to wire brush it off or take his advice and leave it alone. Has anyone see this before or Know what it is.



Docs72 is offline  
Reply With Quote
Old November 2nd, 2018, 08:11 PM
  #2  
Registered User
 
BackInTheGame's Avatar
 
Join Date: Jul 2009
Location: Colorado - Front Range
Posts: 615
Pure-D Guess here:

The bottom saddle of the rod looks like it had too much material removed at some point in the past. Note the digits on the side are cut off. Then, after that PO made it too light, perhaps they JB Welded a weight of some sort. The weight went bye-bye some where along the way, leaving the "JB Weld." The outer edges look like they've been hitting the inner wall of the block, thus the "JB Weld" starting coming off. That material sure looks like worn/damaged JB Weld to me.

As I said, Pure-D Guess. But it looks plausible...

I'm surprised the mechanic said to leave it alone. I think I'd want to get to the bottom (get it! ) of the situation.
BackInTheGame is offline  
Reply With Quote
Old November 2nd, 2018, 08:44 PM
  #3  
Registered User
 
Join Date: Sep 2013
Posts: 2,613
You need a better machine shop! They should have noticed that and pointed it out. Jmo
wr1970 is offline  
Reply With Quote
Old November 3rd, 2018, 04:44 AM
  #4  
Registered User
Thread Starter
 
Join Date: Sep 2017
Location: Oak Island NC
Posts: 17
rod

Thanks for the replies. I agree finding a good machine shop that knows what they are doing is getting hard to find. I think I may need to find another rod and replace this one.
Docs72 is offline  
Reply With Quote
Old November 3rd, 2018, 07:10 AM
  #5  
Registered User
 
Join Date: Nov 2008
Location: Central Fl
Posts: 5,086
Originally Posted by Docs72 View Post
Thanks for the replies. I agree finding a good machine shop that knows what they are doing is getting hard to find. I think I may need to find another rod and replace this one.
And then have them re-balanced as they won't be the same.
cutlassefi is offline  
Reply With Quote
Old November 3rd, 2018, 04:35 PM
  #6  
Registered User
 
Join Date: Dec 2016
Posts: 186
Doc,
Have you tried to scrape it off ?? I have seen some pretty crappy OEM castings that look very similar. Not necessarily Oldsmobile but it really does not matter. If it scrapes off easily then you need to remove it so it wont come off in operation. Could be baked on oil if that bearing got real hot. As far as re-balancing, I doubt that taking it off would make more than a gram of difference. Was your assembly balanced ? Does not look like it so there is probably more difference than that in the rods anyway.
BillK is offline  
Reply With Quote
Old November 3rd, 2018, 09:14 PM
  #7  
Registered User
Thread Starter
 
Join Date: Sep 2017
Location: Oak Island NC
Posts: 17
rod

cutlassefi and BillK thank you very much for your help. Bill this doesn't scrape off easily it is very hard. I think I will weigh it and then try to remove it with a wire brush on the bench grinder, If it is baked on oil it should comes off without much effort. If it is JB weld as backinthegame mentioned it will not come off easily. Thank you all for your time and advice it is greatly appreciated.
Docs72 is offline  
Reply With Quote
Old November 4th, 2018, 06:27 PM
  #8  
Registered User
Thread Starter
 
Join Date: Sep 2017
Location: Oak Island NC
Posts: 17
Well I tried to remove it with a wire wheel today and all it did was polish it!!!!!! I hit it on the grinding wheel and it did grind some off. I think that backinthegame is correct and this is JB Weld. I think new rods are in my future.
Docs72 is offline  
Reply With Quote
Old November 5th, 2018, 06:48 AM
  #9  
Registered User
 
Join Date: Nov 2009
Location: Red Oak, Texas
Posts: 1,474
Doesn't look like JB, looks more metallic. Could possibly be flame sprayed metal from the looks of the discoloration on the side of the cap. Possibly to add weight to the rod for a previous balance.
edzolz is offline  
Reply With Quote
Old November 5th, 2018, 08:12 AM
  #10  
Registered User
 
Join Date: Dec 2016
Posts: 186
I think you are worrying way to much about it. Whatever it is has probably been there since the engine was new and isnt going anywhere.

By the way, was the engine supposedly balanced this time ? Does not look like it.
BillK is offline  
Reply With Quote
Old November 5th, 2018, 09:48 AM
  #11  
Registered User
 
Join Date: Feb 2009
Location: Pittsburgh Pa.
Posts: 940
I have used a bernzomatic propane torch to remove JB Weld. If you don't mind putting some heat to it you will know weather or not it is JB. It doesn't take much. A few moments with the tip of the flame on a corner will tell. If it is JB it will crumble off easy after heating. I think JB is good to about 6 or 7 hundred degrees. Anything over that will cause it to deteriorate. If you want you can use a vise or other heat sink to keep the heat from heating the rest of the rod.

Last edited by stellar; November 5th, 2018 at 09:50 AM.
stellar is offline  
Reply With Quote
Old November 5th, 2018, 08:05 PM
  #12  
Registered User
Thread Starter
 
Join Date: Sep 2017
Location: Oak Island NC
Posts: 17
No the engine was not balanced this time. I am probably worrying about nothing. The engine was running with this rod in it and seems to have no problems . Maybe I should just put it back together and let it ride. Thanks for all your replies
Docs72 is offline  
Reply With Quote
Old November 5th, 2018, 08:48 PM
  #13  
Motorhead
 
11971four4two's Avatar
 
Join Date: Feb 2011
Location: minnesota USA
Posts: 3,613
HEY THERE
All the best

IF
you are going to run that engine leave that material on the rod end. Chances are it (the material) was added to balance the engine.
Button it up and enjoy the ride
11971four4two is online now  
Reply With Quote
 
 
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
shamusj
Brakes/Hydraulic Systems
6
November 25th, 2016 05:42 PM
Octania
Parts Wanted
0
May 11th, 2013 09:02 AM
marlar98
Big Blocks
8
January 20th, 2013 01:42 AM
defiant1
Brakes/Hydraulic Systems
1
March 30th, 2011 07:30 AM
geckonz08
Big Blocks
3
August 15th, 2009 10:29 PM


Thread Tools
Search this Thread
Quick Reply: what is this on my piston rod?


Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.