!?$!?$?! Vibration!

[ashyers]

You guys are probably right, fix it as opposed to cross fingers.

It looks like I need to decide if it's time to build the spare motor or band-aid the one in the truck.

If I start pulling parts on the one in the truck it may make sense to just pull the motor, flip it and do the bearings. We've been contemplating swapping the bearings in the truck vs. on a stand. I'm not sure it would save any time/aggravation to do it in the truck. It would be interesting to see if bearings sorts the vibration issue.

As usual, these decisions are driven by time and $.

Of course there's the transmission we just tore down to contend with and that $!@$! reverse fork shaft. I'm worried I'm going to break the case!

I'll update with "progress".

Andy

[ashyers]

Today the students and I pulled the pan, the thrust bearing, and #6 rod bearing.

Looks OK

TrustGoodSide.JPG (98.4 KiB) Viewed 2494 times

Ouch! There's the .007" + wear.

ThrustBadSide.JPG (81.28 KiB) Viewed 2494 times

[ashyers]

Here's #6 rod bearing and the lower thrust bearing again. The upper/lower rod bearings looked identical. Looks like I achieved maximum life on 'em! Though worn, they are smooth and the wear is even. We have not rolled out the upper thrust bearing yet.

The thrust brg. is .010". The rod brg. is .020" and was dated 11/77. I suspect it's been in there for a bit. The wear on the main is weird. It's very smooth & consistent, and about the color of JB weld.

Thrust,#6RodLower.JPG (89.35 KiB) Viewed 2493 times

Not beautiful, but likely functional. I had 25-30 psi at a hot idle with 10w-30 VR1, 55 psi at 2500 RPM

Journals.JPG (93.98 KiB) Viewed 2493 times

This is the kind of stuff you find in an Auto Shop that's been around as long as the M37! Works well with the crank in the block.

OldTool.JPG (125.51 KiB) Viewed 2493 times

[ashyers]

Here's our tool for rolling in new mains. We tested it in the spare motor and it seems to work fine.

BrgRoller.JPG (119.69 KiB) Viewed 2492 times

BrgRoller2.JPG (122.41 KiB) Viewed 2492 times

[w30bob]

HI Andy,

Wow.......looks like you caught it just in Time! Did the other rod bearings look the same?

Regards,
Bob

[ashyers]

Bob,
We have not pulled them yet. I just needed one to get the size. I'll post photos when we remove 'em.

To me it looks like something was chemically nibbling at the bearing material, areas look sponge like under magnification. Anyplace the overlay was touching the crankshaft it was that dark gray color you see on the thrust brg.I suspect it sat with crappy oil for some time.

I'm curious to see if swapping the bearings out has any effect on the vibration or oil pressure.

Andy

[w30bob]

Hi Andy,

Great info.........thanks for sharing. The fact that your engine was running pretty good (except for the vibe) will have us up at night worrying about the condition of our bearings now. Thanks for that! Just kidding. It's more of a testament to how robust these engines are. I would think both your vibe and oil pressure will be better with new bearings...........they sure won't be any worse!

thanks,
bob

[w30bob]

Ok Andy...........times up! We're all on the edge of our seats waiting to hear what you found. So how bad is bad?



regards,
bob

[ashyers]

Jeeze, it's Bob the taskmaster!

Well Bob,
I was going to wait until we have pulled all of the bearings and take some photos, but... and then there's the transmission that I was going to post photos of the new vs. old syncros... and then there was that darn meeting this afternoon...

Here's what we know now:
#1, #5, #6 rod bearings have been swapped and plastigaged. All showed around .002" clearance with the new bearings installed. #1 showed some babbit remaining, but very little. #5 & #6 looked nearly identical. In the weird department we plastigaged the old #6 and the clearance was nearly the same as the new #6. I realize plastigage has it's limitations, but I was surprised there was not a larger difference. It was less than .0005".

I'll post photos and info when we yank 'em all out or if we find something weird, I promise Bob !

Andy

[52PLOWERWAGON]

when I did my engine the used ones were about .002

and my new ones were .016 and .014

so the old ones stayed

and I have 25 lbs 0il pressure at idle when hot with a used oil pump

I do plan on getting a new high flo oil pump some day

[ashyers]

Bob,
These are for you ! We don't have the mains out yet, but here are the rods.

#1 showed the most overlay, but something took a trip around at some point. Fortunately the bearing did it's job and it didn't groove the crank.

1,2,3 Upper On Left.JPG (120.92 KiB) Viewed 2421 times

As you can see they look pretty darn similar.

4,5,6 Upper On Left.JPG (129.71 KiB) Viewed 2421 times

[w30bob]

Awesome! Thanks Andy!! Now I can get some SLEEP!!



bob

[ashyers]

Here's the same bearings at a slightly different angle.

You can see the overlay that remained in these photos. On the opposite side of the bearings there was none to be seen.

1,2,3 View2.JPG (114.62 KiB) Viewed 2420 times

I expected #5 to be the worst from what I've heard about these engines, but it looks pretty much like its buddies.

4,5,6 View2.JPG (110.98 KiB) Viewed 2420 times

The new bearings all had very similar clearances of .002"+. We're going to do the mains now and then button things up. It should be interesting to see the result.

Andy

ps. Bob, the next photo is for you too, just because...

Syncro, Old, New.JPG (103.27 KiB) Viewed 2420 times

[Kaegi]

you might be able to find .001 under bearings if you want a tighter clearance. the old bearings look like fairly normal wear. are you going to check the wrist pin bushings?

[ashyers]

Kaegi,
I was happy to find .020" undersize! You think there's still .001" under for that size available? Either way, I'm not too worried about the clearance, I'm more concerned about the surface finish of the crankshaft. At this point in the engine's life I have a feeling bearings on the "less tight" end of the spectrum may be just the ticket. The oil pressure was OK with our copper coated wonders.

As far as wrist pin bushings, we did not intend to check them. We planned to do the mains, button the engine up, break it in for a bit, and assuming no disasters continue to enjoy it. We will eventually rebuild the spare motor and pluck this one for a proper tear down and rebuild in the future. We may start on the spare motor this year, it depends on finances. These old 230's are a bit pricey and I need to check with the local machine shop and see if they are willing to take on the work. I need to space things out or I can't afford gas for the old truck!

Andy