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6.5L Vibrations, any ideas what it can be?

Allfritz123 said:
Does that mean the 6.5 crank end is different than the 6.2 that I took a picture of? I could hardly see how you could ever misalign the dowel! While the FP might bolt on an angle, I think the bolts would be too short to catch and it should be obvious that you are not installing it in correct position - especially if you took it apart! Are you suggesting the dowel pin gets ejected back with incorrect position as FP metal knocks it back and so was missed for location? I guess you could hammer the pin in and or take a cutting wheel and cut it off. I wouldn't think anyone would do that as you would be a pretty crude engine rebuilder! I could hardly fathom someone would use this as a solution without realizing they have a problem.

I will look at a 6.5 that I have on a pallet and see if it has a dowel. I thought 6.5 and 6.2 were the same cranks others than the rear seal makeup.
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You are misunderstanding.
I went out to my shop, set the flexplate on the correct way took a picture. Turned the flexplate the wrong way and took a picture.
The locating pin is at the 9:00 position in both pictures- I did not move the crank.
Look wt the locating pin, and look at the counter weight.

Go try the dame thing with your 6.2. ANYONE can put the flexplate on backwards with the locating pin in place.
6EDB6ABA-A336-410F-8BAF-F14F5BB7DC5E.jpeg9B37B8FE-1DC9-4386-8A47-863732ED50FB.jpeg
 
So look at this picture. Sorry my photo drawing skills sux. But notice the center line I drew in red. The majority of counter weight is above the pin height.
Now flip the flexplate over so the pin and the bolt holes line up.
The majority of the counter weight will be below the pin.

There is also the problem the tc bolts don’t fit in properly but it has been done many times- it will go together backwards.

But the flexplate instead of helping correct the balance issue will make it worse.

Just incase someone doesn’t understand what the counter weight is- the thing I circled in blue.

87A854A8-1272-455C-91F2-D2D450C657CF.jpeg5458FFBC-6C58-46E2-AC29-FCD9B884084D.jpeg
 
The vast majority of us on here knew what "put on backwards" meant. Not putting it on 180° off (the dowel pin prevents that) but "wrong side out". It would be like if you put your underwear on with the fly to the rear, @Allfritz123, your dowel pin would prevent that, but if you put them on inside side out, they'd go on just fine and fit over your dowel pin, but your fly would now open to the wrong side - just like the counterweight on the flex plate is now on the wrong side in relationship to the dowel pin. That clear it up for you?
 
Hello, just wanted to follow up with my findings with the extreme vibrations I was experiencing with my 6.5. Thank you Will and everyone else for all of the help and suggestions. Sorry it took so long, March was very busy for me and I couldn't find the time to tear into it. I finally did and replaced the flex plate with a new one, It was the flex plate! It was warped a lot! I could see it slightly move away from the crank on a few of the bolts when removing it! I finally got it back together this weekend and fired it up, immediately I noticed a big difference, the serpentine belt was smooth and not jumping all over the place. I let it warm up a little and bumped it to 2K in park and it didn't want to vibrate the dash off the truck.

Took it for a drive and it was great, it does vibrate a little more than I remember but I also installed neoprene motor mounts and I think the dash did loosen a bit from previous tests but its not much more than what I remember over a year ago when I started this entire re-build.

Lesson learned, if you buy an engine from a yard and its good, replace the flex plate! It was installed properly, just warped. Maybe the flex plate was damaged when the engine was pulled from the other vehicle, or when they shipped it?

Thanks again everyone for all of the support and suggestions, this forum is amazing. Hopefully this helps someone else in the future
 
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@Scott_2255 just for insurance and peace of mind. replace the harmonic balancer too. not knowing the history of the engine coming from a junkyard. when that HB goes, so does the crank!!! if you have the extra funds, invest into the fluidamper. it's a fluid filled harmonic balancer that will last you a lifetime. the standard ones off the shelf at any auto parts store you can only trust them for a MAX of 30,000 miles. IF and only IF you can get your hands on an AC DELCO one. only trust it for a MAX of 100,000 miles.
 
Thanks for the suggestion it does have a Fluiddamper installed and the Leroy Diesel one piece assy pulley.

Hopefully I can enjoy this thing a little now. Timing seems a little bit off still but I'll check it again this weekend. I have all the tools necessary to do it properly, just need the time 😂
 
Thanks for the suggestion it does have a Fluiddamper installed and the Leroy Diesel one piece assy pulley.

Hopefully I can enjoy this thing a little now. Timing seems a little bit off still but I'll check it again this weekend. I have all the tools necessary to do it properly, just need the time
Will L. said:
Glad you’re dialed in.
When ya have time to kill, even couple minutes at a time, read through the stickys.
It can save you a ton of money and headaches.
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Thanks, I definitely will check them out and brush up on my 6.5 reading. Been without this thing for nearly a year! Was about ready to sell it and move on.
 
Glad to see your new posts! Several of us thought you might have given up in disgust, got rid of the beast and then fell off the edge of the Earth!🤣🤣🤣 Happy for you that you discovered the problem and that it was indeed something as simple as a bent flywheel. Yeah, no telling how the parts yard gorilla pulled that motor or if it was set down on the edge of the flywheel first after pulling it. Glad you got it figured out, hope some of our 'what ifs' helped point you in the right direction.
 
Thank you. Yeah, I was thinking about it for a bit but I like the 6.5 and the truck and have so much invested in a new engine I couldn't.🤣.

The help was great, thanks to everyone for the advice and ideas.

Hopefully my issues will help someone else in the future. It was a painful lesson for me.

Still thinking the injection pump is temperamental as it stumbles on a cold start. Funny thing is the worn out inj pump that had 220k was working better than the "refurbished new"SS diesel one. Should have not turned that one in as I got no core refund either...


Going to try and re time it again as a check engine light came on this morning.

Thanks again for the help. At least one issue is resolved 🙂
 
dbrannon79 said:
@Scott_2255 what year is your truck again? just curious if you are using a tech2 or something to set the IP timing. getting the TDC offset within spec is sometimes a hair pulling affair.
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It's a 97, I have a tech 2 clone. Even with the proper tools it's very challenging. I set it once but it was on the edge of being too advanced so I'm guessing it's out of tolerance slightly
 
Scott_2255 said:
It's a 97, I have a tech 2 clone. Even with the proper tools it's very challenging. I set it once but it was on the edge of being too advanced so I'm guessing it's out of tolerance slightly
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Rotate towards the RH side of the truck. But not very much. A little is a lot.
After reading IIRC, Alaska Diesel Drivers comments, I too ordered in reversible, with the lever switch, ratcheting 15mm 12 point box end wrench.
After it arrived, did some configuring, cut off the ratcheting head end and welded together a wrench that reaches all 3 of them pesky IP hold down nuts.
 
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