Crankcase venting

[cjd]

Can someone explain how the 6.5 liter normally aspirated engine is vented?

I changed injectors last month. I must have loosened the oil dipstick seal, as the next time I went on the freeway oil was all over the bottom of the truck. It was so bad I thought it was a power steering/brake boost leak, but the only source I could find was the loose dip stick. When the dip stick is removed running, it'll spray all over the fender with blowby. I tightened the dip stick seal and the leak appears gone...but that has me wondering where all that blowby is actually venting when the engine is running? There is no exhaust smoke.

A couple other questions are what do you guys see for oil pressure at idle and at speed? And, what are the usual coolant temps? Mine runs about 15 psi hot at idle and 55 psi above 1500rpm. Coolant has always been at 230 on the gage (which may not be correct). It starts and runs great.

 

[Mogman]

Can someone explain how the 6.5 liter normally aspirated engine is vented?

I changed injectors last month. I must have loosened the oil dipstick seal, as the next time I went on the freeway oil was all over the bottom of the truck. It was so bad I thought it was a power steering/brake boost leak, but the only source I could find was the loose dip stick. When the dip stick is removed running, it'll spray all over the fender with blowby. I tightened the dip stick seal and the leak appears gone...but that has me wondering where all that blowby is actually venting when the engine is running? There is no exhaust smoke.

A couple other questions are what do you guys see for oil pressure at idle and at speed? And, what are the usual coolant temps? Mine runs about 15 psi hot at idle and 55 psi above 1500rpm. Coolant has always been at 230 on the gage (which may not be correct). It starts and runs great.

That's what the CDR valve does, it vents the crankcase to the intake.

 

[Coug]

Use a laser thermometer to verify the temp.
As long as the fan comes on, the temp drops, and the fan kicks back off, then everything there is good.
Oil pressure senders/gauges for these seem to be all over the place, but as long as it has oil pressure showing on the gauge and it goes up and down with engine speed, then you're probably good. It's very unusual for the oil pump system to fail.

 

[cjd]

Thank you both for the responses. Where is the CDR valve located? Every other diesel I have owned had a road draft tube. And, I guess if there is no oil in the intake, then my blowby must not be too excessive??

 

[owensexport]

The CDR valves are removed when they De-mil the trucks at GP.
Make sure you replace it or you will be sucking un-filtered air into your engine.
Also change the two hoses as they are usually dry rotted. Easy to take care of
when you are messing around with the CDR valves.
Check the parts manual for the location, P/N and how it hooks together.
Parts can be got from Macmotors or the usual gang of idiots.
CDR valves you can get at any auto parts store or off of Ebay... Same as
a 1985 Diesel Blazer

 

[Mogman]

The CDR valves are removed when they De-mil the trucks at GP.
Make sure you replace it or you will be sucking un-filtered air into your engine.
Also change the two hoses as they are usually dry rotted. Easy to take care of
when you are messing around with the CDR valves.
Check the parts manual for the location, P/N and how it hooks together.
Parts can be got from Macmotors or the usual gang of idiots.
CDR valves you can get at any auto parts store or off of Ebay... Same as
a 1985 Diesel Blazer

Good catch!!!! I forgot to ask if his truck originally had fording ability, non fording trucks do not get the CDR valve removed.
But it is imperative that he know, one little nut washer etc. gets in that hose and the engine is toast!!!

 

[owensexport]

They pull CDR valves from most trucks in Yermo, fording or Non-Fording.
Makes no sense

 

[cjd]

Anyone got a pic, or general location to look for the valve? I am not proficient with the parts manual...it kicks my ass for hours, and then I ask you guys and get the part numbers quick, LOL.

It sounds like CDR is the equivalent of a PCV valve on a gasser? Why would it be removed to demil? I do have the Marine fording set up. If it is pulled on mine, I am amazed I haven't been blowing oil for the last 2 years...

 

[Mogman]

It is on the right side of the engine between the valve cover and the intake manifold, if it is missing there will be a bracket with two holes in it where it mounts.
If you have driven it for two years without one you are damn lucky you have not turned the motor into toast.

 

[Mogman]

 

[cjd]

Thank you. Mine does have the valve. Based on the amount of oil coming out of the dipstick that was only 1/2 turn loose, open vent hoses would have to smoke and spew oil like hell. So, my impression is that this valve is a crankcase vent? It limits blowby back into the intake manifold? Is it controlling vent by manifold pressure like a PVC, or is it using some other input for vent control? I have no oil in the intake to the filter at all.

 

[Mogman]

Thank you. Mine does have the valve. Based on the amount of oil coming out of the dipstick that was only 1/2 turn loose, open vent hoses would have to smoke and spew oil like hell. So, my impression is that this valve is a crankcase vent? It limits blowby back into the intake manifold? Is it controlling vent by manifold pressure like a PVC, or is it using some other input for vent control? I have no oil in the intake to the filter at all.

You got it!