Cummins B3.9-P; hole in block from balancer weight

agreed rondig!. Funny thing is that the owner said it was still running when they found it like this. they thought it had pitched a rod.

After seeing that hole, more than ever, I would recommend that you magna-flux to see if any cracks go up, toward that closest bolts, above the hole!

I've patched blocks before and welding was not successful the entire edge of the patch. Very few individuals can successfully braze anymore. I'd be tempted to clean the paint off around the hole with paint stripper and form a metal patch. Metal surfaces need to be surgically clean. Then use 3M body panel adhesive to glue the patch on. Same thing the OEMs use to glue on car door hinges. Good stuff! Still may have a nuisance oil seep, but more cost effective than block replacement.

I think he takes his time and manufactures a cover for that window in the block using some epoxy as sealer it will work just fine.

Truck Shop said:

I think he takes his time and manufactures a cover for that window in the block using some epoxy as sealer it will work just fine.

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That is my intention. I was thinking of acquiring some Devcon or the like and either sandwiching the block between two plates with screws and sealer or the other screw and patch methods others have mentioned. It appears to be a very clean breakout between structural webs and I would be afraid of trying to do a heat and fuse based repair as the integrity of the block seems fine. If it doesn't work, the project would still go back to the original plan of a longblock or running unit so not much to loose.

I've seen and used Belzona for that purpose. It used to be an approved fix for marine engines. I've been out of that industry forever but if it worked then it should work now.

Set it up in a trade school to show how things work in a diesel.....charge admission and get your client a free engine...

Am figuring you don't have the missing piece.....but if you did:
There is a company that mfg's stitching "contrivances", has a hooked thread and a smooth finish to the bored hole, pretty trick.

Lock n Stitch out of Turlock, California.

http://www.locknstitch.com/index.html

oceanobob; sadly no. If it were mine, I would have looked for the pieces but alas, his crew didn't have the forethought to find them for a patch. The call went; 'Hey Wes, I've got an irrigation skid that needs a new engine as it threw a rod and has a hole in the block.'

What a **** poor design for a counter balance set-up. That engineer should be standing in front of a firing squad.

I finally have an update on this hunk of junk. A service tech at Dallas Cummins was kind enough to find a parts breakdown of the offending balancer. With all our rain, I am getting some backlog and stale projects out and I made a call to see about parts. The balancer needs a shaft, 2 flyweights, and several needle bearings for a rebuild. NO ONE I talked to had EVER seen or dealt with one of these! Here is the kicker; the shaft is $1,100 and no availability. Best the parts man could tell me is it would be a build to order item! At this point, I decided to see if it could run without it as a Shibaura engine I just put a crankshaft in could, I was told, be run without the same style balancer. To verify my idea, I got through to a Service Tech out of the Ft Worth shop who also had never heard of or seen one. He said it would likely throw a rod as this engine is externally balanced (balancer unit) instead of a crank snout harmonic balancer and internal crank balancing.

So... now on his concurence to mounting and drive parts interchanging with a 4BT, I am now in search of a complete running 75HP non turbo engine to drop in and be done with it.

wrwtexan said:

So... now on his concurence to mounting and drive parts interchanging with a 4BT, I am now in search of a complete running 75HP non turbo engine to drop in and be done with it.

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If in fact your water pump will mount up to a 4BT that would sound like a good option. Just doing a quick Google search shows rebuilt units going from $3,000 to $5,000 so if you could find a running take out of something your pump would mount to I would think you would have a much better setup than a patched together B3.9. Only dealt with a few 4Bt's and but those gave almost zero problems. Think that was the engine in a 1989 Case skid steer at work that was still going strong in 2015 when I retired with no real repairs!

Almost every 4b I ever fooled with did not have the balancer. They usually only came in automotive applications like ups and bread trucks. With harded mounts in industrial applications the 2up 2down vibration was not as noticable. Watch out for those Chinese "Cummins" out there, they are not the same

partsandservice said:

Watch out for those Chinese "Cummins" out there, they are not the same

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Is there any obvious visible difference that would help us avoid these?

The engines look the same and parts are interchangable. They are actually Cummins engines manufactured in China. The parts have Cummins parts numbers. When you see a new long block 3.9 5.9 or 8.3 for a good deal , that is what they are selling. I have a customer that runs 7 or 8 old machines with the 5.9. He wants these engines because of the price. When the cam or crank breaks he just gets another one. As long as you go into knowing what you got , it works for some.

I just looked through the first page , so just clear things up a little . The 4b is 3.9 liters. The 6b is 5.9 liters.
4b naturally asperated
4bt turbo
4bta turbo , after cooler

Not that it matters...

Example
All that changes when you get into the QSB and ISB s.

Then a 4B is what I need. I have seen several on facebook marketplace for 1500 to 3K running.
What I understand is a B3.9 is the ugly stepcousin to the 4B (3.9L) series.
The 4's with no harmonic balancer must be drilled and counterweigthed internally.

Again, not that it matters, but for the sake of conversation; I have believe the step cousin is the B3.3 Cummins. It is identfied by the single rocker box. May have also been a B3.9 , just never run up on one.

The B3.3 is Japanese through and through and appears to have nothing to do with the 3.9. I would like more info on the 3.3 but I only have ever seen maybe 3 of them. With Stanadyne pumps, very strange for a Japanese engine.