Sounds like a glow plug tip went through the engine at one time or another.

If the pits are not close to the edge of the piston and you see no cracks, you will probably be OK.

The stock hypereutectic pistons can be a bit brittle from the silica content.

 

Hey guys what's a CDR? just reading along and was wondering. Thanks

 

Crankcase depression regulator. Kinda looks like a tuna can, usually mounted on the intake right behind the air inlet

 

Thanks for the info. How do you service it. What do you have to do.

 

Some of the guys say that it should be pulled off every couple of oil changes and soaked in some gas and then allowed to air dry before reinstalling. As of yet except when I do an overhaul and replace it I have never needed to clean one, so maybe someone else can give you some insight. I do know that if it does not function properly it can lead to oil consumption.

 

The CDR regulates the flow of crank case vapor into the intake.

One functioning correctly will close off the vent as vacuum raises in the intake manifold at higher RPM's.

The oil vapor condenses inside the CDR, gets baked to a tar like gunk, which does not let the diaphram move.

So when the engine is at high RPM, it starts sucking oil out of the rocker cover, which the engine them burns for more fuel.

Take it off and throw it in a small pan of gasoline with enough in the pan to fill the CDR.
Let it soak while you grease the chassis.
Now aggitate the gas inside the CDR by shaking.
Now go drain the oil.
Aggitate again.
Replace drain plug and filter, fill with oil.
Aggitate again and drain.

You are looking for a clean inner surface, when you have it lay it aside to dry.
If you rinse out chunks of thin black rubber, the diaphram is torn, you need to replace it.

You can not see the diaphram, but never blow air into the CDR, diaphram damage will result.

Once nice and clean and dry, reinstall.

CDR should be serviced every other oil change.

If you do it often, the soak and aggitate turns into a one time deal before you dump it out and let it dry.

If it is extremely dirty, you may be soaking and shaking for several hours to disolve the tar.

 

Thanks, one more thing I learned here.

 

What would the engine do without the CDR valve? just curious.

 

You could run a draft tube down underneath the engine to siphon the excess crankcase gases off. If your engine has any blowby, you will get some fumes and smoke from it, especially under load. If it has alot of blowby, you will get the fumes and smoke constantly. You may also get some oil leakage from it.

Jason

 

Without the CDR, given the high compression of a diesel, the gaskets would all be leaking oil out in very short order.

 

Dave, you know that piston we were talking about earlier with the pits...well what if I wanted to replace only that piston, can i do that or would i have to replace them all?

 

You mean if it was just plugged off completely, right?

Jason

 

You can replace one piston just make sure it's exactly the same as the one you took out. You don't want to change the compression ratio or the weight.
Obviously replace the rings.
You should hone the cylinder so the new piston rings can break-in properly.

This is one of those "where do I STOP" deals.

You're going to have the crank out to hone the cylinder, so maybe you should replace the bearings?
Maybe turn the crank and THEN put in new bearings?
Should you replace the freeze plugs too?
Well if your doing that maybe you should have the block hot-tanked?
I'm not telling you to do ANY of the above things I just know what you're going through.



I'm having the same problem deciding what to do with my '94.
It needs some new gaskets as it's leaking oil.
Do I pull it and change all of the gaskets or do it in-chassis? (I know the ups and downs of both ways)
I KNOW if I pull the motor I'm going to end up finding a 6.9L donor and building a hybrid with 7.3L parts.
So for now I'm just trying to minimize the leaks.
The worst part is my Dad owns a machine shop so it's really had to resist the temptation.
I'm building a 454 (almost done) and a 440 (just started) right now so I don't NEED another engine build until these are done.

 

so in order to get the two pistons, the old and the new, at the same weight, can i just take them to a machine shop and have them balence them for me?

 

The pistons from the factory apparently where not weight matched. If your piston wasn't beat up bad especially near the edges i would just clean it up and run it with out pulling it out of the bore. Before you decide anything else you might want to check the piston to cylinder clearance and see if you are near or at the max. If you are it would be a good time to replace all the pistons and bore it oversize. Can you provide a close up picture of the piston. As stated previously you will need to pull the crank to properly hone for new rings anyways, at that point you are just a step away from a complete overhaul.