school me on the cdr valve

I feel I understand it's basic principle and how the work but would rather have one of the experts clear it all up. Thanks.

From the Manual:

The CDR valve is very similar to a PCV valve on gas engine vehicles. It stands for Crankcase Depression Regulator. It's purpose is to recycle the exhaust gases that manage to get past the piston rings and into the crankcase.

If you're using a quart of oil every 1K miles you might want to take a look at their CDR valve.

The Crankcase Depression Regulator (CDR) Valve maintains crankcase pressure. Pressure must be regulated to prevent oil consumption through the intake system, and to prevent oil leaks due to excessive buildup of pressure. Control is accomplished by regulating the blow-by gases into the intake system to be reburned. Inside the CDR valve, a spring holds open a valve plate that connects to the CDR valve body with a flexible diaphragm. The valve plate is capable of restricting the outlet passage to the turbocharger air inlet duct when airflow pulls it closed against the force of the spring.

Specifications
Crankcase pressure at idle . . . . . . . . . . . . . . . . . 0-1 inch H 2 O
Crankcase pressure at 2000 RPM . . . . . . . . . . . 2-5 inch H 2 O

Crankcase Pressure Check
1. Bring the engine to operating temperature.
2. Obtain a water manometer (J23951)
3. Remove the oil dipstick and attach the hose of the water
manometer, to the dipstick tube.
4. Start the engine and observe the manometer at idle:
b" If the reading indicates that the crankcase pressure is 1
inch or H 2 O or less go to step 5.
b" If the reading indicates that crankcase pressure is highest
than 1 inch H 2 O inspect the CDR valve and recheck
crankcase pressure. (if the CDR valve is good check engine
compression).
5. Run the engine at 2,000 RPM, observing the manometer.
b" If the reading indicates crankcase pressure is in a negative
state (-4 to -5 inch H 2 O), the system is OK.
b" If the reading indicates crankcase pressure is in a negative
state greater then -5 inches of H 2 O replace the CDR
valve and retest.
b" If the reading indicates crankcase pressure is in a positive
state, review test and results of step 4."

Actually, you can make a water manometer easily. Get a few feet of some clear plastic tubing. Mount it to a board so you have a 'U' about 1.5 feet high on each side and about 3" wide. Fill it about 1/3 with water and mark the water level. Hook one side up to whatever you are testing and measure how many inches of water the level has changed.

AMG part number is 5714132 and it costs around $84
GM#25097699 Crankcase depression regulator valve $44.98 at www.alldiscountparts.com
ACDelco# CV910

The CDR valve is responsible for controlling the pressure/vacuum in the engine crankcase, and separating the oil mist from the air and returning the oil to the crankcase. When the pressure builds up because the CDR is stuck closed the crankcase pressure will increase, and could force oil past some gaskets and seals that could result in leakage.

If the CDR is stuck open oil mist from the crankcase will be sucked into the engine and burned as fuel, however, it is heavier and thicker than diesel fuel and, having greater BTU output, causes excessive heat in the cylinder. After a period of time, cylinder and head temperatures will reach unacceptably high levels causing the head bolts to stretch and the head gasket to fail.

A quick way to inspect your CDR valve is to remove the air cleaner assembly and look into the air intake with a flashlight. If you see engine oil mist in the intake manifold, test it out per the instruction above or get a new one.


link for the above: http://flashoffroad.com/Diesel/CDR/cdrvalve.htm

oldblue05 said:

I feel I understand it's basic principle and how the work but would rather have one of the experts clear it all up. Thanks.

Click to expand...

An EXPERT is a person 50 miles from his office/home carrying a brief case.

Don't claim to be one.

A CDR is to relieve the crankcase blowby pressure. The CDR has a diaphram internally that acts like a check valve. When the pistons are on there "suction stroke" they suck, along with the CC pressure to relieve the CC pressure thru the intake manifold, and turbo if you have one.

Edit: Hell'va write up above. That explains it all.

No experts here.... An expert is someone that knows a lot about one thing... That doesn't fit anyone here... In a very short statement they suck... When they go bad they blow.... Can they suck and blow at the same time... Nope.. They need to be replaced once in a while too. Never wash them in gasolene. That will ruin the rubber diaphram... Then the stop sucking and start blowing. Figure around 100,000 miles and replace them....At least remove them and test them for proper function at that mileage.....

Well since I have smoke coming out of my cowl hood... and there's is oil everywhere in my intake... and I never realized they wear out...Might be time to replace.

icanfizall: yeah seems that most of us know a little about alot.BUT THATS A GOOD THING!

Now that I just got chased by a 200 lbs hog walkin back from the duck blind I'm gonna pass on wrenchin tonight... the AR-15 might come out.

oldblue05 said:

Now that I just got chased by a 200 lbs hog walkin back from the duck blind I'm gonna pass on wrenchin tonight... the AR-15 might come out.

Click to expand...

build one of these and carry it with you next time you go to the duck blind.

how do you test the CDR exactly?

try to blow through the side that goes into the intake, shouldnt be able to, could even use REGULATED compressed air regulate to whatever boost pressure you run and see. then just try to blow through the side that goes into the grommet, should be able to freely pass air from that direction. Just a check valve is all it honestly is

or just check it the way 91 dirty diesel posted

I beilieve you cover small hole on back, blow/suck into the bigger hole and place finger in other side, you should be able to feel diaphram move. To clean it yiu can put it in a can of gasoline swirl it around abit then let it air dry. Do not blow compressed air into it

could of swore that you couldnt put it in gasoline because gasoline eats the rubber. why couldnt you blow compressed air through it as long as it was regulated?

Just what I've read in the past, I've used gasoline to clean it every other oil change for 2 years and no problems yet ?

91dirtydiesel said:

Just what I've read in the past, I've used gasoline to clean it every other oil change for 2 years and no problems yet ?

Click to expand...

just because you don't see the problem yet, that doesn't mean there isn't.
look at the pics from one that has been cleaned by gas.
if this doesn't convince you, I don't know what will.

How would you suggest to clean it then?

Dont? just replace it every 10 years or install a RDT

Were can you get a new CDR. i know mine is original due to the fact that it is grey like the valve covers.