burning oil?

[jmpidgeo]

seems that my 6.5TD (1995 L65 model) burns a bit of oil, but I can not tell. Is it normal for these older diesels to burn oil? I checked the oil after I changed it, probably about 2000 miles, and it took 2 quarts to fill it to the top mark. Maybe I did not fill it enough when I changed it, but I don't know. I checked it the other day, about 1200 miles later, and it did go down about 1/2 to 3/4 of one quart. Is this normal, or should I be worried at all? Any help is awesome. Thanks.

[DmaxMaverick]

Less than 1 qt. per 1000 miles isn't excessive, and considered normal by some folks. The type of vehicle usage also has an effect on how much oil is consumed. Many of these engines "use" more than that with no issues, for many miles.

[john8662]

How many miles are on the rig?

How much blow-by do you have coming out of the oil filler tube when the engine is idling?

any more than 1qt in 1k miles and you can be concerned, some use it, some don't (mine).

What oil are you using?

I noticed that using Delo in place of the Pennzoil I used to run (no more) resulted in increased oil consumption. I'm happy with the Rotella-T I'm running now, almost no oil consumption in my higher blow-by '82 6.2 pickup (who knows how many miles...).

J

[moondoggie]

Good Day!

I've owned 5 6.2/6.5's, & my daughter's got an 89, & all have used ~ 1 qt/2000 miles. I'm not even remotely concerned about this amount of consumption. ;)

Blessings!

[jmpidgeo]

the rig has 118k miles on it. I have not checked for blow by, so I don't know about that one.

[Robyn]

OK listen up grashopper.
The little can on the right valve cover is called the CRD valve.
Basically its a PCV valve. It is connected via a hose to the turbo intake. These things get crapped up and will allow too much suck on the crankcase and will pull oil over.
Now the inside of the cold side of the turbo is always a mess on these things even when new so dont panic. If the air filter gets too dirty they will tend to suck more oil over the top too.
Replace the CDR valve and the air filter. Give it a go. If this corrects the issue all is well.
Another area is the turbo shaft seals, they can go away over time and allow far too much oil to pass and you dont see it it just blows right into the exhaust stack downstream from the engine and burns in the down pipe.
Food for thought, try the CDR and air filter first.
Best to ya

Robyn

[Bnave95]

Give the CDR a bath in diesel oil first before replacing. I clean my twice a year.

[Turbo Al]

The CDR also gets my vote esp after changing the oil if it is not working right is will suck a lot of oil out of the engine BUT when mine was doing it there was a VERY noticable smoke (oil burning) trail behind me.
Al

[jspringator]

Do you just pull it off and cover it in diesel for a few hours, drain and reinstall?

[Robyn]

It Just plugs into the rubber gromett in the valve cover.
I tried washing mine and ended up replacing it.
My rig did not leave a noticeable trail of smoke though. I was using a quart to two in about a month or so and I do a lot of sporatic short hops from the ranch here at Cloud Mt into town to my shop which is 10 miles round trip. Then it might sit unused for a week then get a hard trip 50 miles round into Portland and back.
Mine was so crappy I just replaced it even after washing. This rig I bought used off a Gyppo car lot almost undrivable and covered in bird poop.
The condition of everything was unknown as it had come though a wholesaler.
If you know the schedule of oil changes and things you may be able to decide if you have a good chance in cleaning versus replacing.
They are about $45 new so a washout is worth a try.
BTW the condition of that air filter is important as it will if dirty lead to a higher standing vacuum in the air intake wich can pull harder on the CDR.
Unlike gas engines that let filtered air into the engine and pull the blowby out with the PCV the 6.5 uses the CDR to create a standing Low pressure area in the crankcase (Small vacuum) to remove the blowby but also to help eliminate oil leaks.
I read this in the service manual about the oil leaks and was puzzled but it makes sense. if you have air trying to get in oil is not going to get out unless its a big leak. The diesels tend, with their high compression, to have more blowby than their gas cousins. (Comparatively) If the oil filler is puffing smoke this is too much. A small amount of visible vapor is normal but should go away with the engine slightly above idle.

Robyn

[jmpidgeo]

alright, i replaced the air filter. same deal...oil burning no stop. right now as we speak my CDR valve is soaking in diesel fuel. It did not look all that bad when i looked in, but i don't know if you can tell by looking at it. the diesel i am soaking it in is definitely dirty though.

If this does not solve my problem, what could be causing the oil burning?

[65TD]

Already mentioned but try replacing CDR if cleaning does not help. Then you know how old it is and start a replacement schedule.

Turbo was mentioned.

You want to check for blow by to see if it's rings, cylinder wear.

Some types of oil burn easier than others.

[sailun]

I've always needed to add a quart about every 1200/1500 miles, ever since I got her, over 145,000 miles ago. Was initially concerned, but got over it.

All the other repairs/issues made me forget about oil usage.

Never any noticeable smoke, but plenty of drips in the driveway. (oil filter adapter)

I should clean/replace my CDR, also. Probly 75k since I did it last.

Any way to definitively test CDR operation ?

Does Amsoil smoke any differently than fossil when burned ?

Here's a CDR puzzle for everyone.

I bot my burb with 11k miles on it, in 2001. (Yes, 11k miles in 4 years. 148k since then.)

When I first started towing a camper(2001), on the first few trips some people told me that my truck was on fire, or overheated, or something. It sure smelled on fire. Looking under the hood, all the factory paint on the metal tube from CDR to intake was burned/wrinkled from excessive heat. I've never seen another like it.

What could possibly cause this ?

[65TD]

It was on fire.

Maybe someone cleaned the CDR with a combustible liquid.

Infernal combustion. :eek:

[65TD]

This should work as it was written by an expert on the subject of CDR testing.

:D


CDR testing can be accomplished with 4' section of clear plastic tubing, sized to fit the dipstick tube.


Form a 3" U-bend , with 12" vertical columns. This could be attached to a piece of 1 x 6 with large u-staples, parallel-spaced at one inch intervals for indication of measurement.


Important - do not crush or deform the plastic tubing.

Place the free end over the dipstick tube, ensuring tight fit, with no leak-by. Position the manometer vertically, where the upper end of the U is lower than the end over the dipstick tube.

Note: this is to prevent water siphoning into the oil pan thru the dipstick tube.

Pour colored water into the U section such that about 6 " of water is in each leg, about 4 - 6" below the top of the open end.
Have someone start the engine, bring the rpm up to about 2000, keeping close watch on the water level in the U-tube. If the water in the dipstick leg rises an inch, the water in the open leg will drop an equal amount. Adding the drop level to the rise level, this would indicate vacuum at two inches on the Water Column.

Vacuum at idle should be around 1", depending on air filter restriction; at 2000 rpm, the CDR should limit vacuum to 4 - 6" WC on a calibrated Manometer. The shade-tree version should indicate close to those figures, depending on accuracy of staple intervals.

If the level in the dipstick leg drops, and the open leg level rises, this indicates the crankcase is slightly pressurized.

27" WC is equal to 1 PSI (Pound per Square Inch) 1psi is equal to 2" mercury
Atmospheric pressure is 14.7 psi, or 29" mercury, or 396" WC, rounding off

The CDR should never be solvent-cleaned, as various solvents can dissolve the diaphragm, again resulting in a 'no-way' valve.

Some truck manuals indicate replacment at 30,000 miles. This refers to the early style CDR and oil-cap breather system, used up through mid-'80s. By '88 - '89, the CDR system had been revised to its present configuration, where the CDR cannister is on the passenger-side valve cover, with one external connecting hose to the intake system.

Early failure-prone systems can be easily upgraded to the late setup - 1 valve cover with grommet seal, 1 CDR, 1 hose.

Replace the CDR in the late systems when it fails the Manometer water column test.

[sailun]

Thanks, 65TD.

Maybe fire caused by valve stuck closed, heat coming back from turbo ignited the stagnant air/oil fumes ?

[65TD]

What did it smell like?

A rat, fur ball, rubber, lightern knot?

[Mark Rinker]

I am concerned by your CDR being 'covered in diesel fuel'. Obviously, there shouldn't be diesel there, just oil vapor.

My guess would be that you have injector issues, ring issues, or both. The oil burning problem/terminally low MPG could be a result of either, if your oil is getting diluted by fuel from a hung up injector.

How many miles on the injectors? If they are over 100K, you could replace and do a compression test at the same time...

[65TD]

He is cleaning it in diesel fuel.

:D

[Mark Rinker]

ooops...my bad.

Anyway - how many miles on the injectors?

[jmpidgeo]

ooops...my bad.

Anyway - how many miles on the injectors?

I have got no clue. I bought the truck with 115k on the ticker, and the only things I know of that were new were alternator, glow plugs, and fuel filter as of 3-4 months prior to me buying it. I have 123k on it now, so im not sure how many miles are on the injectors in total.

[sailun]

Well, I never tested the CDR, I just cleaned it with diesel, and re-installed.

Immediately felt like I was draggin' anchor, and MPG's dropped from 15.5/16 to 14.5

So, I bot a new one at the stealer ($69 + tax) two days ago, popped it in.

Still feels like draggin anchor.

Me thinks, if it ran so well dirty, and got better mpg, then re-create the dirty CDR condition, probably stuck open.

So, I stuck some duct tape over the little vent hole, presto-chango, everything feels OK again, no anchor draggin.

Try it out, see if you feel a difference, post your results here.

Of course, it will only make a difference if your CDR is working as factory intended. No difference if already stuck open, or shut.

Insights welcome.

[65TD]

Not sure why that would be the case but you talking about building up some vacuum in the crankcase, especially if the air filter is a bit restrictive.

Not a good idea. Under normal conditions a working CDR is optimal.

Might want to do a nanometer test on the system.

[sailun]

Well, my friend, I can't explain it either.

Based on my limited reading about crankcase venting and oiling systems in Harley motors, it sounds like reduced crankcase pressure produces several effects: Pistons go up and down easier/faster, and oil not forced out between the seams as much. Also rings are not fighting opposing forces.

Remember 60's cars had simple breathers on the valve covers to let air/pressure out, then emission controls forced move to PCV valves and hoses to aircleaner, etc, etc. ? And HP went down.

So, what is the true intent of the CDR ? PCV valves kept us from blowing oil into the atmosphere, burning it instead.

Keep oil out of the intake air stream under load ? Allows air and oil vapor into airstream while running lightly, but not under load.

Is it just a device to pass emissions testing ?

I don't think it's a performance enhancing device.

Any effect on oiling inside the motor ?


To repeat, I'm no mechanic, I only know what I read/stumble upon.

Experts, PLEASE weigh in.

Try it, tell me what effect it has on your rig.

[65TD]

CDRV

When it works as it's intended it maintains a vacuum in the crankcase and regulates this vacuum at a certain level.
1" WC at idle and 4" to 6" WC at full load.

This in turn prevents oil seals from leaking.

An open vent will not give the desired vacuum. An open valve would allow unregulated vacuum dependent on the turbo boost and air filter system flow capability.

Unlike a gas engine Harley the diesel crankcase is a closed system. It will pull air in instead of blowing it out. This will come in from the seals if it were not for the CDRV or some venting system.

The difference between the flow of the air filter and the flow of the turbo is coming from the crankcase. Without a CDRV it is unregulated. So for some it may be OK. For others it could be a major problem as it would suck all of the oil out of the motor.

[sailun]

Thanks for the good explain, 65TD.

I'm starting to see it. Closed system is why there's an o-ring on dipstick and fill cap, and spring loaded diaphragm in the CDR.

With all our mods to get more air, like open, low-restriction air filters, and no filter box, we might be upsetting the balance ?

I'm guessing that if turbo gets all it's air from the filter, easily enough, then it could not pull enough vacuum to overcome the crankcase vacuum, and pull the CDR open ? Or worn turbo, or wrong spring in CDR.

Especially when lightly driven. I only tow a few times a year.

Mine sure performs better with the vent taped over, according to butt-dyno, and how far down I need to push the pedal.

Try it out, and tell me what you think. Only costs a piece of tape.
That's the cheapest experiment we'll ever see, with these babies.

Thanks again.

[JohnC]

Sailun:

The ony way I can figure a bad CDR would increase performance is if your air filter or intake is restricted. Unless you're sucking so much crankcase oil in it's giving you a power boost...

[65TD]

I'm wondering exactly what the tape is doing at this point. It would be wise to test this with a nanometer and see.

[sailun]

I cleaned my Amsoil foam air filter pretty thoroughly about 6-7k miles ago, so I think I'm getting good flow thru the filter. I'm also running w/o the lid on the airbox, and I cut additional holes in the fender-side of the airbox, so I think I'm breathing pretty easy.

Almost no black smoke on hard accelleration, if there was any less smoke, I would say there's none. (Maybe that Amsoil burns REALLY clean ?)

Vent hole in CDR allows atmosphere in behind the diapragm, so diaphragm can move in response to changing pressure/vacuum, and open/close the opening leading to the valve cover /crankcase.

Oil consumption doesn't seem any different than when I got it with 11k miles, a quart about every 1200/1500 miles. No blue smoke.

If you tape over the vent hole, diaphragm cannot move, or at least, cannot move as easily.

I'm havin trouble figuring out how vacuum is generated in the crankcase, seems to me we would have hot air expanding, and possibly some combustion blow-by past the rings.

I'm guessing that in factory configuration,
diaphragm is normally closed,
then pressure builds up in the crankcase,
turbo suction, spring pressure, and crank pressure reach equilibrium,
then diaphragm opens, crank pressure is sucked out,
diaphragm closes.
Repeat.

Is crankcase vacuum actually the result of turbo/intake airstream suction ?
I think it is, especially when I tape over the vent, keeping diaphragm open.

Well, that's my half-baked idea. Please correct as necessary.

I'll try to make up your water-column tester tomorrow.

Anybody else try this yet ?

[65TD]

It should be fully open at idle. Not much vacuum but enough to draw out the blow-by gasses.

As the vacuum from the intake of air increases it should compress the spring to limit the vacuum.

I could not try anything as I am not around my truck at this time.

[JohnC]

The vacuum is generated by the velocity of the airflow through the intake between the air filter and the turbo inlet. The higher the velocity, the lower the pressure. The restriction of the airfliter also contributes and a clogged air fliter will draw a ton of air from the crankcase if the CDR isn't working. This pulls dirty air past the seals, which is not a good thing...

[damork]

My truck uses a quart of Rotella 15w-40 at about 1000-1200 miles. Rotella 5w-40 or Mobil Delvac 1 5w-40 let's me go over 2000 miles before adding a quart. I changed the CDR with new units twice since I've owned the truck but never noticed much difference - the CDR units I changed may have been okay when a swapped them out, but was doing so as a preventative measure.

[sailun]

Well, I pulled the tape back off the vent on the CDR, running it as stock, as everyone recommends. And to be honest with you, it didn't feel any different this time.

No I don't know why.

And, I'm unable to make any MPG comparisons at this time. Too many variables, cold weather, winter mix fuel, short trips, no highway driving, slow drivers in the snow.

Thanks for everyone's input. It was interesting. I wish I had the ability to do some data-logging, at different speeds, RPM, and loads.

Let me know if anyone tries it.