CDR Valve

[Trevtron]

After installing a new cowl to hood seal I Pulled off my air cleaner assembly to have a look at the CDR valve.

There was no evidence of water in the oil and the air cleaner isn't caked in oil either. Although there is a slight bit of oil on the air cleaner bolt.

Is this what they're supposed to look like if they're still serviceable?

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[Trevtron]

Parts cheap, gonna replace it with a Motorcraft one.

 

[idiTravelAll]

I'd imagine that's normal but I'm all to new to these engines

 

[Trevtron]

I've read a lot about them but haven't seen to many pictures showing what a good used one looks like. Wasn't sure if I was being to over cautious by replacing that one. Small investment to make considering the consequences of a faulty CDR.

 

[Thewespaul]

That looks about normal, they way you can tell they are bad is if you can start the truck and pull the oil fill cap off. If there is a significant amount of blow by and it doesn't go away when you increase the rpm manually then your cdr is not functioning properly

Of course assuming you have a healthy engine

 

[Trevtron]

Engine is strong and hasn't given me any issues. Earlier I tried that and their wasn't any blow by at idle through the oil fill neck, I'll try it while increasing the rpm manually tomorrow. Thanks!!

 

[Thewespaul]

If you have no blowby and there isn't a ton of oil in the intake I wouldn't replace it

 

[Trevtron]

Sounds good and makes sense, thanks

 

[Garbage_Mechan]

Here I go starting a controversy........But I can't stand it any longer.

The CDR valve 99.99% of the time does nothing except perform as a connector from the intake manifold to the crankcase.

CDR is short for Crankcase Depression Regulator.

I have the dealer release documents someplace from the introduction of the 6.9. It is laid out there as to it's single function. That is IF the engine is operated with and extremely plugged air filter the valve is designed to regulate the depressed air pressure (Vacuum) in the crankcase and cut off the air flow from the crankcase to the intake manifold. It is a safety feature so that the high vacuum in the intake manifold in the case of an extremely plugged air filter or intake tube will not draw the oil out of the crankcase and result in a runaway.

The valve has only 3 moving parts. Diaphragm, spring, and the metal part that seals the exit of the valve when vacuum against the diaphragm and spring has drawn it closed. I have been around these since they were new, used to have a fleet of them and have never seen this happen.

The CDR valve cannot effect blowby or oil consumption during normal operation unless it is somehow plugged or has been activated and got stuck shut. Either of these you could see immediately after you remove it. Normally you can see right through the air flow path, nothing tricky here.

 

[franklin2]

Here I go starting a controversy........But I can't stand it any longer.

The CDR valve 99.99% of the time does nothing except perform as a connector from the intake manifold to the crankcase.

CDR is short for Crankcase Depression Regulator.

I have the dealer release documents someplace from the introduction of the 6.9. It is laid out there as to it's single function. That is IF the engine is operated with and extremely plugged air filter the valve is designed to regulate the depressed air pressure (Vacuum) in the crankcase and cut off the air flow from the crankcase to the intake manifold. It is a safety feature so that the high vacuum in the intake manifold in the case of an extremely plugged air filter or intake tube will not draw the oil out of the crankcase and result in a runaway.

The valve has only 3 moving parts. Diaphragm, spring, and the metal part that seals the exit of the valve when vacuum against the diaphragm and spring has drawn it closed. I have been around these since they were new, used to have a fleet of them and have never seen this happen.

The CDR valve cannot effect blowby or oil consumption during normal operation unless it is somehow plugged or has been activated and got stuck shut. Either of these you could see immediately after you remove it. Normally you can see right through the air flow path, nothing tricky here.

Never heard that before, makes sense. Thanks for the complete explanation of the reason it was installed, how it works, and your information source.

 

[Garbage_Mechan]

There is a way to observe / test the operation of the vacuum cut off valve portion (Depression Regulator). A strong shop vac connected to draw air in the normal flow direction should cause the valve to close which will be obvious since air flow will stop.

The 3 reasons to replace the CDR. 1 Parts are loose inside or diaphragm stuck shut.2) A pesky oil "sweat" around the OD of the valve at the crimp caused by the aging of the rubber diaphragm. 3 A ruptured diaphragm causing oil to leak out of one of the holes that vents the area of the tuna can behind the diaphragm. Vaporized oil condenses inside the CDR valve and can cause the illusion it somehow controls oil consumption related to blowby. The condensed oil flows (drips) back to the crankcase. Only #1 would effect operation

 

[Thewespaul]

How can a cdr not affect blow by? It releases crankcase pressure into the intake... Regardless of if there is a cdr there or a plug there the same amount of blowby is produced since it is a factor of ring sealing but a good cdr will direct it into the intake. A bad cdr will not meter the amount of pressure going into the intake and will not separate the oil and vapor and cause oil consumption.

 

[Garbage_Mechan]

Doing emission retrofits on L-10 and M-11 Cummins we installed a Donaldson Spiricle closed crankcase vent system. Must have been involved with 50 of those. They have a CDR (though called something else) Mann ProVent retrofit crankcase vent systems have a "CDR regulator"
A Mann Provent would be a great idea for these trucks especially turbo equipped. I just installed a Mann on our 7.3 Powerstroke. Works great to keep IC clear of oil mist and boots oil free

 

[Garbage_Mechan]

How can a cdr not affect blow by? It releases crankcase pressure into the intake... Regardless of if there is a cdr there or a plug there the same amount of blowby is produced since it is a factor of ring sealing but a good cdr will direct it into the intake. A bad cdr will not meter the amount of pressure going into the intake and will not separate the oil and vapor and cause oil consumption.

Not trying to an a__ but did you read my post?

It doesn't regulate a darn thing unless intake manifold vacuum gets super high from a plugged filter, I think it was 22 inches of vacuum. Other wise it does nothing to regulate blow by. Try it. The valve will not move without high air flow and vacuum.

 

[DaveBen]

You Can't make a vacuum with these engines. This is why they have vacuum pumps that are belt driven. No throttle plate = no vacuum.