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CDR Valve

13K views 16 replies 6 participants last post by  Joe Mc 
#1 ·
My engine is using quite a lot of oil(completely empty in four weeks). Surfing the net I came across mention of a CDR valve, similar to a pcv valve used in cars. Apparently if the valve is bad it can leak oil into the intake of the engine. Has anyone else heard of this. I have a 86 f250 6.9L. Thanks
 
#2 ·
Oh ya, a bad CDR will allow too much oil to go back into the intake.

If it's bad, potentially you can over-heat the cylinders and or blow a head from the higher BTU's of the oil burning.

Take the air cleaner assembly apart. If the wing-bolt holding the hat on has excessive oil on the threads then you CDR could be bad. Also, check for small particles under the intake screen. This might be the rubber from a bad CDR.
 
#3 ·
So, I finally have to ask, after reading so many post.

Has it been proven that the oil entering the intake from the CDR is what is blowing the head gasket? Or maybe the higher heat is turning a weak head gasket into a blown head gasket.

I'm runing %100 WMO, as are MANY others, and no one seems to be blowing gaskets any sooner than on pump diesel.

Maybe i would understand if its because you've only got two higher-heat cylinders and i'm running all 8 cylinders the same temp.

Sorry to go off topic, my CDR is bad, but i'm not loosing near that much oil.
 
#4 · (Edited)
So, I finally have to ask, after reading so many post.

Has it been proven that the oil entering the intake from the CDR is what is blowing the head gasket? Or maybe the higher heat is turning a weak head gasket into a blown head gasket.
Probably a combination of both. CDNSARGUY has stated that when oil enters the intake it naturally rolls backwards to the rear passenger cylinder. So, most of the oil is concentrating on the rear two cylinders and the 6.9 is known to have leaky head gaskets there.

I would think the Higher BTU's on those cylinders would be the first thing to worry about. It could potentially raise your egt's to the melting point.

I know too that the 7.3 went to a bigger head bolt to compensate for the head gasket issues of the 6.9, so the 6.9 has more head issues anyway.

Hopefully Pete will chime in to correct me if I'm wrong.
 
#7 ·
The rubber baffle inside the cdr is suppose to allow vapors through but not oil. When the rubber breaks down, it allows too much oil to get sucked through.
 
#8 ·
I've been meaning to install a gauge to keep a closer eye on EGT's. Can anyone recommend a cheap one?

I haven't read about too many problems in non turbo motors with higher EGS's caused by running WMO. If i remember correctly, the BTU level of regular motor oil isn't too much higher than that of pump diesel.

I also didn't realize the 6.9 had more head gasket issues than the 7.3, thanks for the tip.
 
#9 ·
The rubber baffle inside the cdr is suppose to allow vapors through but not oil. When the rubber breaks down, it allows too much oil to get sucked through.
No it doesn't and it's not a baffle. The CDR is an approximately 1" diameter unmetered orfice that's always open under most all engine conditions and RPMs allowing crankase gases to constantly bleed into the intake stream. The rubber diaphragm is spring loaded to stay in an open position. If the rubber diaphragm broke, if anything it would partially block the flow of crankase blowby, therefore you'd have less oil-laden crankase fumes rather than more.
 
#10 · (Edited)
O.K. so I don't have all the techincal lingo down, but doesn't it react to engine intake vacuum too. So when the intake vacuum is higher, it closes it down to not allow too much oil through???? I've always understood that you observe more blow-by when at idle.

Also, I've always read that when the rubber breaks down, you get more oil in the intake??

That's what I've always understood about it.

http://www.thedieselstop.com/forums/f31/massive-blow-220677/
 
#11 ·
cant one remove the CDR and by pass it? i hear about getting more performance with out one? any thoughts?

oh yeah anyone know where to get a cheap EGT gauge?

thanks!
 
#12 ·
Do a search on here for road-draft tubes if you want to get rid of the cdr, the topic has been well covered.

I don't know why you want to install cheap gauges in your truck, the stock ones are an example of CHEAP gauges and most replace them.
The gauge you are looking for is called a pyrometer.
I am running the R3607TR. Click here for where I bought mine.
 
#14 ·
Do a search on here for road-draft tubes if you want to get rid of the cdr, the topic has been well covered.
sorry joe i only have 5 mins left at the computer here and my local library. if someone would post some info here that would be great! im thinking of pluging the hole for the cdr with jb weld? i have tones of oil in there and cant find the cdr at any of my auto parts stores... thanks yall!
 
#15 ·
I would be worried that sealing off the cdr hole would increase the pressure in the block and cause oil to weep past the mail seals.

The cdr is available from Ford and International.

You can install a RDT (Road Draft Tube) from the cdr, a valve cover, or the oil fill tube.
The RDT should extend a little below the truck to get some airflow around the end of the tube. These tube usually drip a little oil and when you get to do a search you can read about the ways people have tried to catch this drip. The other problem with the RDT is that if you have much blow-by other people may think that your truck is on fire when your at a redlight, this has been reported by some using an RDT. I have seen stock RDTs on trucks, tractors and even a 1931 model A.
 
#16 ·
thanks for the info joe. i went to my local diesel shop and they set my up with the RDT. and i was realy concerned after i made it cuz it leaked oil and looked like a fire. but now that i know thats normal i feel great! what if i run the tube up instead of down to stop the leak. kinda like a exaust stack? thanks alot for the info! it sure helped! oh and my local ford dealer does not offer the CDR anymore. my international dealer had to order it and with tax and the order charge the total was nearly 100$ good thing for the RDT!
 
#17 ·
My local dealer is also like yours, can't get any parts for these old trucks. But the dealer 15 miles away has them or can get them for me, so try another dealer.
One of the on-line dealers I have found is Titus-Will Ford. Click here for their website.

In theory the end of the tube should be in an airstream, this is why the usually extend a few inches below the truck. If you run the RDT through the hood it would need to be a foot or so above the top of the windshield, in part to get good airflow around the end but also to keep the oily vapor off the windshield.
 
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