Crankcase depression regulator valve
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Crankcase depression regulator valve
Hi. I'm new to this site, and new to diesels. I've read through most of this forum, at least the old engine posts, and I've learned tons. Just replaced my thermostat, and my truck suddenly runs in the normal operating temp. for the first time. 
Question: The Haynes Diesel Tech book tells how to change the crankcase depression regulator valve on my 6.9L. So far, all the parts guys I've talked to have said, "What's that?" Including the local Ford guy. I can see the thing bolted to my intake manifold, but I don't want to pull it off until I know I can get a new one. Does this thing have another name in the Ford shop manual (which, by the way, is unavailable at helminc.com
)? Or better yet, got a part number for it?
Paul Brassey
1986 F-350 Crew Cab 6.9L
Question: The Haynes Diesel Tech book tells how to change the crankcase depression regulator valve on my 6.9L. So far, all the parts guys I've talked to have said, "What's that?" Including the local Ford guy. I can see the thing bolted to my intake manifold, but I don't want to pull it off until I know I can get a new one. Does this thing have another name in the Ford shop manual (which, by the way, is unavailable at helminc.com
)? Or better yet, got a part number for it?Paul Brassey
1986 F-350 Crew Cab 6.9L
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From: Indianapolis
Crankcase depression regulator valve
The CDR valve is the diesel equivalent of a gas engine's PCV valve but unlike a PCV valve (as far as I know) doesn't need to be replaced periodically unless it is leaking. It is bolted with 2 screws to the rear of the intake manifold and has a hose or tube that connects it to the intake cover/gasket (it has a turkey tray type gasket like a big block Chrysler engine to seal the valley from the atmosphere). Probably the reason nobody knows what you are talking about is because they've never had to replace one (if I'm wrong about that I trust somebody will point it out to me).
As I recall, the 6.9 had a large rubber doughnut gasket that sealed the CDR valve to the intake manifold and there was a metal tube that fit on the bottom of the CDR valve which was sealed with a rubber O-ring, then that whole assembly fit into a rubber grommet which was fitted into the turkey tray. If it is not leaking, I'd leave it alone.
As I recall, the 6.9 had a large rubber doughnut gasket that sealed the CDR valve to the intake manifold and there was a metal tube that fit on the bottom of the CDR valve which was sealed with a rubber O-ring, then that whole assembly fit into a rubber grommet which was fitted into the turkey tray. If it is not leaking, I'd leave it alone.
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Crankcase depression regulator valve
Thanks for the info. I did get a part number from the Ford parts web site.
The reason I'm looking at the CDR is that I get a fair amount of blue-white smoke, and Dieselmann lists a clogged CDR as one possibility. Since replacing it is one of the cheapest options, I thought I'd ty that first. I don't think I have major problems, because the truck starts instantly and runs well.
Paul Brassey
1986 F-350 Crew Cab 6.9L
The reason I'm looking at the CDR is that I get a fair amount of blue-white smoke, and Dieselmann lists a clogged CDR as one possibility. Since replacing it is one of the cheapest options, I thought I'd ty that first. I don't think I have major problems, because the truck starts instantly and runs well.
Paul Brassey
1986 F-350 Crew Cab 6.9L
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Joined: Jun 2001
Posts: 295
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From: Fort Wayne, IN. USA
Crankcase depression regulator valve
Yes the CDR should be replaced from time to time. I have been told every 30,000 miles. I change mine once a year, which is normally about 40k miles. Some guys have gone to a RDT (Road Draft Tube) which replaces the CDR. They plug the hole going to the intake, then run a tube from the valley pan down to below the truck and vent the fumes under the truck. I have not gone to this setup yet, the guys that run this type of setup are seeing lower EGT's. This is one of the mods that I have planned just as soon as I can get the time.
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Crankcase depression regulator valve
What is the advantage of removing the CDR? Is it just to avoid having to replace it again? Or does it improve performance? I don't suppose the State Patrol will be crawling under the hood to see if it's there, since some of the parts guys don't know what it is.
1986 F-350 XLT Crew Cab C6 6.9L
1986 F-350 XLT Crew Cab C6 6.9L
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Joined: Jun 2001
Posts: 295
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From: Fort Wayne, IN. USA
Crankcase depression regulator valve
It regulates the pressure in the crankcase, if you don't vent the pressure you can cause oil leaks, so if you remove it you need to make a RDT. Also with the RDT, you are not running blow by (vaporized oil) back into the engine, which I have been told causes higher EGT's. Also cuts down on the smoke from the exhaust pipe. Which I don't care either way on the smoke, as I like to look back under hard pulls and see the black smoke a rolling...
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