Operation IDIocracy: CDR Turnaround Bracket


So after the turbos themselves were installed, I was staring down doing all the grunge work… the auxiliary systems that make the whole thing happen. Not going to lie, solving the geometric positioning problem was far more satisfying, because this is the “nickel and dime” stage of the project where I’ll have to buy this fitting and that hose and this fancy washer, and so on, over and over as I figure out more of what has to be installed.

The subsystems that had to become existent consist mostly of the crankcase ventilation system and the oil return system. Those are the critical ones; I was also planning on adding some gauges and other pointering-devices so I knew what was imminently going to explode

This post will be about the former, usually called positive crankcase ventilation. In dieselworld, this part is apparently called a “Crankcase Depression Regulator”, which presumably helps get the engine out of hiding in bed and takes it on a walk down the unusually scenic river promenade, having a ponderous conversation about what fulfillment means in life.

Seemingly called the “tuna can”, this big valve sits right behind the Intake Cave. My understanding of how it works is that because diesel engines do not pull meaningful vacuum (unlike gasoline engines which pull a strong vacuum), it just lets the crankcase pressure evacuate constantly unless the vacuum becomes too high, upon which it will start closing.

“High” vacuum is relative, as we’re talking inches-of-water territory (tenths of a PSI or less); apparently you don’t want the crankcase to be under atmospheric pressure by much, as it will start sucking in contaminants from outside through seals and gaskets.

The back of the canister is vented to atmospheric pressure to allow it to open and close, and the very weak vacuum pressure differential is why the can is so large compared to thumb-sized gasoline engine PCV valves.

Well, in any case, the problem here is that I’ll soon be shooting above-atmospheric pressure into the thing, and it has no backflow prevention (unlike a PCV valve) so I’ll be pressurizing the entire engine to 8-10 PSI! That sounds not fun.

First, let’s remove it to see what I have to deal with. It just unbolts from the two flange screws holding it on, and pulls upwards out of the (extremely stiff and dry-rotted) fitting. There’s a rubber washer that is the interface between it and the intake manifold.

So all the kits available for these engines have you move this canister somewhere else. Makes sense, since it has to be attached to a source of intake air at a slight vacuum relative to atmospheric pressure. The part I found troublesome is they all had you move it either deeper into the Engine Cave, or hanging awkwardly off a hose somewhere (like Spool Bus has).

I noticed that maybe I could just turn the can around and seal off the intake manifold hole with a plug. That will point the “outlet” backwards, allowing me to run a hose down over the transmission and into one of the air filters. Presumably in the final Vantruck integration I’ll tee off an intake hose in the same general location.

Well it turns out it’s not QUITE symmetric. I’ll have to space it outwards about 1/2″ or so, so I can’t use this OEM riser bushing. It’ll be an interesting little challenge to make an adapter for the thing.

Oh, in removing the CDR valve, I had to unbolt the OEM glow plug controller and that’s when I found the horrifying secret it was hiding this whole time.

Snekvan has always had this congealed goo that ran down the side of the engine block and transmission. It wasn’t oil; degreaser wouldn’t touch it. It wasn’t congealed coolant, as I couldn’t wash it off with water either. It seemed to be some kind of resin that had melted and flowed all over the place.

Well I found out where that resin came from: The entire underside of the glow plug module, seemingly made out of some kind of potting compound, had disintegrated and was EVERYWHERE. It seemed to be filled with some kind of particulate stuffing, too, which is the little yellow kernels.

Whatever it was, it had mixed with all the oil grunge and other …. substances and formed this cured cake of OH GOD. I had to take some terrifying solvents, a scraper, and a wire brush to it before I was willing to get any closer.

Much better. At least the problem is now hidden from view (The underside of the intake manifold will be cleaned in the future and is surely a horror show).

While I was in this area, I was also searching for places to deposit the oil that will be returning from the turbo bilge pumps. I noticed a little drain plug of sorts back here… what could it be?

Out it comes! I was hoping this was some other access to the crankcase, since right in front of it was the CDR exhaust port.

Imagine my surprise when I found that this plug is hollow, and it was just a “pan drain” to let liquid run down the side of the block from the central valley. Well, the more you know.

Check out this impressive difference between a generic automotive 7/8″ coolant hose and this 7/8″ McMaster-Carr sourced coolant hose!

Okay, it’s a bit of an unfair comparison. The automotive world sells these by the outer diameter, and McMaster seems to sell by the inner diameter. Still, the difference in wall thickness and reinforcement fiber count was staggering.

Here’s my battle plan. I’ll be using the thick-wall industrial coolant hose pressed over the CDR inlets and outlets as a hose “collet” of sorts. The CDR valve does not have an outlet nipple, so I hatched a plan to flare the hose over the port and capture it with a bracket.

Similar products do have a proper outlet hose nipple, like these for the 6.5L GM engines found in Humvees – I may get one to see if they can serve the same purpose.

This is what the “Hose Collet” looks like in the end, after I slit the hose segment with the bandsaw. It will be on both the inlet (pictured) and outlet.

The capture bracket for the outlet hose, which also doubles as the mounting bracket for the outlet side, is made from a regular ol’ chunk of 3/16″ thick steel barstock I had hanging around.

The native hose outer diameter is right around 1-3/8″, which made for a somewhat difficult slip fit using a regular 1-3/8″ step drill. Once flared over the outlet fitting, it’ll be trapped by this plate.

This is what the hose collet looks like once it’s been flared over the outlet and the capture bracket’s installed. It doesn’t stay on by itself too well, but that’s what the bracket is for!

The installation proceeds! I ordered a rubber plug of the right diameter from McMaster. It has a flange, which I generously rubbed with silicone (my friend for this project, the copper-filled silicone) and stuffed in.

This little pinhole on the CDR is how it access atmospheric pressure, so it shouldn’t be blocked. I made sure the plug top allowed it to breathe still – if it were blocked, I’d have had to space it out with a washer or something similar. Luckily, it was outside the flat part of the plug’s dome.

Foiled, part 1: The passenger side of the intake manifold sticks out a lot. I had to cut a corner off the capture bracket to clear it.

Here is everything in place. The new grommet going into the engine is made from a “poke it yourself” rubber grommet which I cut an offset 7/8″ hole into, such that it was able to connect with the new centerline of the turned-around CDR.

A short length of the 7/8″ Autozone coolant hose bridged this gap; the hose clamp on the bottom closes the “collet” hose, and the rubber grommet provides the sealing.

For the other end, I just drilled a hole into one of the air filter cans and just stuffed the 7/8″ OD hose in.

This hose runs up from the passenger side, following the transmission fluid dipstick.

And this is what it looks like on the bottom. The CDR’s outlet port now feeds directly into the right side turbo intake. Like I said, for the final Vantruck integration, I’ll probably try to tap an intake hose somewhere as it runs forward. I just wanted to prove the concept for now.

Next up and last before firing everything up, how I routed the oil return from the turbos!

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