Blow by question

[True IDI Blue]

My oil pressure is pegged on my gauge so I replaced my CDR and after start up oil pressure is still the same. Took the oil cap off and I am getting a regular puff of white smoke. With cap off there was no change in the oil pressure. Truck is an 84 with only 81K miles and is second motor 7.3 idi. Any ideas?

 

[IDIBRONCO]

The factory oil pressure gauges in out trucks are slightly better than an idiot light. It could bee the sender, it could be the gauge itself. An aftermarket gauge is the only way to tell what your oil pressure actually is. I prefer the mechanical gauges, but the electric ones work just as well. After installing a real gauge, don't be alarmed at the low oil pressure at an idle. I think the minimum is 10PSI at a hot idle. As long as you have 10PSI for every 1000 RPMs your engine turns, you're fine. One more thing, the CDR has nothing to do with oil pressure.

 

[True IDI Blue]

Thanks but what about puffs of white smoke coming out of open oil cap

 

[Macrobb]

IDIs have large ring gaps from the factory.
They make a *ton* of blowby, which goes through the CDR normally and is burned. It's not a Cummins which can run a RDT and be fine; it's an IDI.

Blowby isn't a sign of anything, really. Freshly rebuilt engine will produce plenty.

 

[True IDI Blue]

White puffs of smoke mean anything?

 

[chillman88]

Took the oil cap off and I am getting a regular puff of white smoke.

Truck is an 84 with only 81K miles and is second motor 7.3 idi

The way you describe it the white puffs of smoke just simply means it's running. If you're that worried about it then post a good video to YouTube and link it here. It sounds like you're describing normal blowby for these engines. Your white puffs of smoke have NOTHING to do with your high oil pressure on the factory gauge.

1. Don't lose sleep over the smoke. Post a video if you're worried about it.

2. Buy a decent oil pressure gauge and post up the readings at idle and at normal running RPM.

3. Why did you change the CDR because of an oil pressure issue? From what I've seen it seems like the only real function of the CDR is to block the oil vapor from entering the intake in a runaway situation. Other than that it's just an open "elbow" so to speak. It only closes at high RPM.

 

[True IDI Blue]

True but I was scanning through old CDR threads here and it was an option. This truck has sat for 8 years in a garage and did not get much attention from the former owner and I have been working through one issue after another trying to get the truck as close to top running condition as I can. I did change my return fuel hose today and it is not smoking nearly as bad. Cold starts right up with no extra peddle sconce I removed two extra fuel filters on the frame and installed a block fuel pump. Fuel consumption is at about 18 mpg but I am using oil. Located several leaks that need to be addressed. Are there any pvc valves on this motor? With work 4 of July is my next truck day. Thanks for all the help.

 

[Selahdoor]

The CDR IS this engine's version of a PCV valve.

 

[nostrokes]

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Get a good set of aftermarket gauges and ignore the factory one's. I prefer mechanical gauges, but even s good set of electrical one's are better than stock.

About the only reason to replace the cdr is if it fell apart. It's just a one way valve that is pretty much always open. My truck has enough blow by to smoke out the neighborhood but doesn't use a lot of oil, think it leaks more than it burns..

 

[david85]

My test for blowby is that vapor should get pulled back in by the time you get the engine speed about 1000-1200 RPM. This is by no means scientific though. If it runs well, it's likely fine. However, if you're really worried about it, try taking a video and upload it so we can see what you're seeing.

 

[Chris Helton]

I played the blow by game last week. As lots of members said before, seems to be common for these engines. I had turboed my 6.9, and never really gave much thought to the blow by prior to the conversion, but did notice the inside of the intake was very oily. I tried the road draft tube like I ran on my cars back in the day, and she looked as if she had dual exhaust... I ended up running a banks breather adapter which mounts to the front timing cover, into a catch can and back to the CDR. It seems to do a better job of pulling off the vapor while keeping oil itself in the engine. I think my issue was getting splashed liquid oil pulled up into the CDR. Long story short, she has less oil smoke out the tail pipe and the intake track is staying cleaner. A catch can is easier to do on a turbo just due to placement of the CDR, but with a little thought you could probably fab something up using the original CDR mounting point on your NA. My catch can was a plastic mayo jar, which I'm considering replacing with a tig'ed aluminum tank, but now I'm thinking of leaving it just because it looks so cheesy!

 

[idiwelder]

I had a similar issue with an 83 6.9 that sat for a lot of years. The factory oil pressure gauge was pegged until completely warmed up it would come down. Turned out to be the oil pressure relief valve in the oil cooler had stuck shut after so many years sitting. After pulling the oil cooler and cleaning the valve up it had perfect oil pressure.


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