Working on my donor engine for my '74 Crew Cab tonight and when I pulled the front cover to replace the front seal and gasket I was dismayed to find the KDP was MIA.

And upon further inspection I found that it made a journey south, leaving behind a path of destruction.

The cracked case is easily seen in that pic. Oddly enough the engine didn't leak oil too badly.

 

What really has me concerned is the broken cam gear tooth.



This engine ran well and has no other issues. The IP was recently rebuilt before I bought it, no smoke, or odd noises. I do have a parts engine with, what I hope is a good case. Should I be concerned with the chipped cam gear or just let it ride?

 

You have to pull the gears off to change the case don't you?

 

It's not that simple. The IP and vac pump have to be removed. Cam gear is a press fit, so cam has to come out, and the timing pin is supposed to be checked against true TDC on number 1 cylinder when the gear case is changed.

 

Might as well change the gear then.

OR

Case really doesn't look like some of the other ones that had KDP damage. If it barely leaked I think I might try sealing it up and running it as is with same gear.

 

Cummins now pulls the gear off the cam rather than pulling the cam to change out timing cases. Then they heat the gear up and press it back on the cam.
You could do it either way.

Or just seal up the crack in the cover and run it as is.

 

Eh, if you have the engine out of the truck it isn't a big deal to pull the cam and fix it right.
Just keep engine upside down while cam is out or at the least on its side so tappets don't fall out.

 

that gear will run a long time like that it's most likely already run a long time. 3/4 or more is still there Ken

 

By the looks of the engine, it has been running quite a while like this. I can't see any marring on the crank or pump gear to warrant changing gears. I plan to attempt to dress it with a gear stone and reuse it.

 

I'd say the PO got VERY lucky that there wasn't more catastrophic damage.

 

I agree witht eh others....just clean it up and run it. I wouldn't bother with replacing the case. I would probably clean the cracked area really well, the smear some RTV or some similar product on the inside of the case over the crack...then maybe some JB weld, or two part epoxy on the outside?

 

If the case was holed or the crack was worse I'd replace it. But with what you have I'd patch it like TC said.

 

I agree. I've heard stories of the KDP going the other way and wiping out the entire gear train, bending push rods and valve, and other such nonsense.
After seeing this mess, every other 5.9BT I own or work on will get the KDP tabbed or at least the hole in the gear cover staked so the pin can't exit.

 

I thought about it, but that isn't my style. I despise oil leaks and cobbled up repairs. If I wasn't doing as much work on the rest of the truck I may consider it, but for me "good enough never is".

 

KDP was the first thing I did to my truck. I scared myself silly reading catastrophic failure stories on the net.