Oil Consumption PCV Valve

[ddevore]

I have a 2002 Cadillac Deville DHS with 145,000 miles and it burns oil....a LOT of oil. I carry around a gallon of oil with me so I can fill it up every 2-3 times I fill up with gas (1 quart about every 600-800 miles). I was talking to someone about it and they said that the PCV valve is bad and I should replace it. So I bought a new one and removed the old one but, the new one is much bigger than the old one and I can't find one that is the right size. Figuring that since mine doesn't rattle and you can see straight through it that it must be bad and I really need to replace it. I searched for the right part but I can't find it then I read somewhere that the PCV valve is a always open design and it shouldn't rattle.

What I would like to know is:

1. Do I need to replace this PCV valve?

2. If I do then how do I find the right part?

3. Will this fix the oil consumption problem?

4. Is it even worth keeping this thing?

I keep thinking that it is expensive to fix and would be cheaper to replace it but a monthly payment is hard to swallow.

Any help would be nice.

[Cadillac Jim]

Rock Auto sells three, from $1.10 to $2.34. They look like this:

Your 2002 Deville is no more expensive to fix than any other car, except for big-ticket items like a transmission or engine rebuild or replacement, and even then, cost is in line for other 320 hp powertrains. Anyone who starts hyping cost should encourage the feet to start their stuff.

There are two principal ways that your can get oil sucked into the PCV: a PCV valve stuck open, particularly with a broken seal to the crankcase such as a missing or loose oil filler cap or oil dipstick. The other is misrouted vacuum hosing that somehow gets oil directly into the throttle body without going through the PCV. Also, overfilling the oil can cause massive oil-burning.

Another cause, that will burn lots of oil without smoke in the exhaust, is the use of really cheap oil, which will cause stuck rings. There are treatments for that; these are reminiscent of the old-fashioned Valvoline, Rislone, Gunk, and MotorPhizik gasoline additives or solutions that you poured right in the carbuetor. For your motor, there is no place to pour anything and in a high-compression engine such things are likely to cause hyrolock that breaks your motor real good. The newer procedures take a hot engine and pulls all the plugs (ouch!), then puts carefully measured special solutions in each cylinder for 1 hour to 1.5 hours, then sucks it out with a syringe that looks like a turkey baster (and actually may be a turkey baster). But an equivalent treatment is an oil change with 5W-30 Mobil 1 and a 500-mile road trip at highway speeds, followed by another oil change with 5W-30 Mobil 1; this is cheaper, lower risk, and lots more fun.

If the oil is leaking, that's another matter. Let us know if the crankcase is drenched in oil and it is leaving oil puddles under the car in the garage.

[KHE]

You should be able to clean the old valve with brake cleaner or carb. cleaner to get the ball to rattle.

[winterset]

Doesn't the N* have 2 pcv valves? One for cylinders 1357 and one for 2468? Honestly, i never checked, cleaned, or replaced mine, but i recall seeing 2 pcv looking parts sticking out of the oil coves, and both had that nylon tube.

Also make sure you check your oil level hot after the engine has been off for about 5 minutes.

Also maybe a little hard driving aka WOT is in order.

[KHE]

Also maybe a little hard driving aka WOT is in order.

I'll second that! My wife is the principle driver of the '97 STS and it starts to use oil and when I drive it and put the hammer down, there is a plume of smoke, then it clears up. It was using oil to the tune of 600 miles per quart and we took it on a long trip. I hammered the helI out of it and after 1500 miles, the oil level was not low, nor did I receive the CHECK OIL LEVEL message.

[Texas Jim]

My 2006 had over 140,000 on it when I traded it...

NEVER ONCE did I have to add a quart of oil between changes.

It had regular and frequent WOT treatments..

[KHE]

My 2006 had over 140,000 on it when I traded it...

NEVER ONCE did I have to add a quart of oil between changes.

It had regular and frequent WOT treatments..

To second Jim's post - I have never had to add oil to my '05 Sedan De Ville. I follow the oil life monitor too.

[barczy01]

I have a 02' Deville that eats some oil. I use 15w40 diesel oil in the Summertime and it really cuts down consumption.

GM does have a tsb for a ring cleaning procedure but it really doesn't work. It's more harm than good because it eats away the intake manifold gasket with its harsh chemicals. Stay away from the 5w30 and run a 10w-30 quality oil. What the others said above is correct, wind that motor up in second gear.

[ddevore]

Mine doesn't look like this. The top is identical but the flair is higher and the base is just over half the size of this one. I had this one purchased ready to go in but obviously it wouldn't fit and I couldn't find one the right size.

Rock Auto sells three, from $1.10 to $2.34. They look like this:

Your 2002 Deville is no more expensive to fix than any other car, except for big-ticket items like a transmission or engine rebuild or replacement, and even then, cost is in line for other 320 hp powertrains. Anyone who starts hyping cost should encourage the feet to start their stuff.

There are two principal ways that your can get oil sucked into the PCV: a PCV valve stuck open, particularly with a broken seal to the crankcase such as a missing or loose oil filler cap or oil dipstick. The other is misrouted vacuum hosing that somehow gets oil directly into the throttle body without going through the PCV. Also, overfilling the oil can cause massive oil-burning.

Another cause, that will burn lots of oil without smoke in the exhaust, is the use of really cheap oil, which will cause stuck rings. There are treatments for that; these are reminiscent of the old-fashioned Valvoline, Rislone, Gunk, and MotorPhizik gasoline additives or solutions that you poured right in the carbuetor. For your motor, there is no place to pour anything and in a high-compression engine such things are likely to cause hyrolock that breaks your motor real good. The newer procedures take a hot engine and pulls all the plugs (ouch!), then puts carefully measured special solutions in each cylinder for 1 hour to 1.5 hours, then sucks it out with a syringe that looks like a turkey baster (and actually may be a turkey baster). But an equivalent treatment is an oil change with 5W-30 Mobil 1 and a 500-mile road trip at highway speeds, followed by another oil change with 5W-30 Mobil 1; this is cheaper, lower risk, and lots more fun.

If the oil is leaking, that's another matter. Let us know if the crankcase is drenched in oil and it is leaving oil puddles under the car in the garage.

I can look straight through mine without seeing anything. I am wondering if it even has a ball in it. I will try and pull it out again and give it a good cleaning.

You should be able to clean the old valve with brake cleaner or carb. cleaner to get the ball to rattle.

[ddevore]

More information after re-reading your post.

I don't usually see smoke though when I start it up, specially on cold days, I can smell burning oil. I can smell oil in the front of the car but that is likely from the time that I left the oil fill cap off after filling it up.

I don't always use the best oil but I can change that. I was considering doing WOT to it which would be fun, I don't usually run this car hard because I like to be a little more conservative and I have a z28 for fun.

I have never seen any liquid dripping off the engine or any spots where I park.

I am about due for an oil change so I think I will get the oil changed and WOT it. I work 100 miles from work and go home on weekends so running a couple of hundred miles at high speed isn't much of a problem.

Thanks for the suggestions.

My plan (some from my previous post):

1. Pull the PCV valve again, I have seen another similar thing on the front row of cylinders which I will pull out also. Clean it/them and hope I have a ball inside and can get it to rattle.

2. If I can't get it filled I will hopefully find a good replacement.

3. Get the oil changed with 5w-30 Mobil 1

4. WOT it (FUN)

5. Run it for 500 miles or so and change the oil again with 5w-30 Mobile 1

These all sound better than turkey basting my cylinders.

Rock Auto sells three, from $1.10 to $2.34. They look like this:

Your 2002 Deville is no more expensive to fix than any other car, except for big-ticket items like a transmission or engine rebuild or replacement, and even then, cost is in line for other 320 hp powertrains. Anyone who starts hyping cost should encourage the feet to start their stuff.

There are two principal ways that your can get oil sucked into the PCV: a PCV valve stuck open, particularly with a broken seal to the crankcase such as a missing or loose oil filler cap or oil dipstick. The other is misrouted vacuum hosing that somehow gets oil directly into the throttle body without going through the PCV. Also, overfilling the oil can cause massive oil-burning.

Another cause, that will burn lots of oil without smoke in the exhaust, is the use of really cheap oil, which will cause stuck rings. There are treatments for that; these are reminiscent of the old-fashioned Valvoline, Rislone, Gunk, and MotorPhizik gasoline additives or solutions that you poured right in the carbuetor. For your motor, there is no place to pour anything and in a high-compression engine such things are likely to cause hyrolock that breaks your motor real good. The newer procedures take a hot engine and pulls all the plugs (ouch!), then puts carefully measured special solutions in each cylinder for 1 hour to 1.5 hours, then sucks it out with a syringe that looks like a turkey baster (and actually may be a turkey baster). But an equivalent treatment is an oil change with 5W-30 Mobil 1 and a 500-mile road trip at highway speeds, followed by another oil change with 5W-30 Mobil 1; this is cheaper, lower risk, and lots more fun.

If the oil is leaking, that's another matter. Let us know if the crankcase is drenched in oil and it is leaving oil puddles under the car in the garage.

[winterset]

Step 5 is uuncessary. Your oil will not get contaminated enough to warrant such a short change interval. You can be conservative with your driving, just do this WOT once every few months. That backpressure will make your piston. rings dance, and clean them up.

[Cadillac Jim]

One last point - don't use 5W-30 dino oil unless it's cool where you are. Check your owner's manual for temperatures if you want to use 5W-30 dino oil. 5W-30 Mobil 1 has hot-weather hot starting viscosity and film strength equal to 10W-30 dino oil so it' OK.

[ddevore]

I pulled the PCV valve and cleaned it but there is still no rattle. There does not appear to be a ball in it. I have pictures..

https://plus.google.com/104868800752715455963/posts/9EimPoWBce8

https://plus.google.com/104868800752715455963/posts/UCfejMX1xvf

This one is obviously not the same as pictured from Rock Auto.

Any thoughts on how to identify the correct one to replace this one?

(Edit: fixed the links)

[barczy01]

I believe the crankcase valve in the front valve cover is fixed made to stay in the front valve cover. The replaceable PVC valve is in the rear valve cover and picked up at any parts store for a couple bucks. The piston rings are probably stuck so do a couple wide open throttle runs. I would steer away from synthetic oil it tends to find leaks. Use a heavier oil 10w30 if you can.

[Cadillac Jim]

You aren't supposed to see through it. The part in the RockAuto picture goes in the rear cam cover on the passenger side. The breather connector on the front cam cover does not have a check ball and its hose goes into the air cleaner stream ahead of the MAF in the throttle body.

[ddevore]

The one in the pics are from the rear head cover on the passenger side as in the pic in the thread below.

http://www.cadillacforums.com/forums/cadillac-deville-1985-2005-including-1985/209340-vacuum-leak-found-causing-idle-issues.html

This is the problem I am having. The one that I find that everyone says will fit is too big to replace mine.

[Cadillac Jim]

That's the fresh air tube. The dirty air tube and PCV value are under it and the valve is farther forward on the cam cover.

[Jan Olsson]

The PCV valve is an orifice tube with a 3 mm hole in it. No moving parts in this one...

Also, as other mentions, a heavier weight oil decreases oil consumption but if you can you should use a dino oil. There really are no benefits from using synthetics as long as you don't have a supercharger or turbo, Check your owners manual, the last STSs for instance specifies the use of synthetics (or rather oils that live up to standard xxx which usually equals synthetic oil), but your car should be fine with standard of the shelf dino oil.

[Jan Olsson]

A post by BBF!

Posted 27 September 2008 - 04:56 PM

You are using a bit too much oil, you should do the WOT procedure, read these passages.

These are multiple passages written by the guru, he was involved with the development of the Northstar.

Northstar Oil Consumption

"It is not unusual for a Northstar to use more oil than some other engines. It is a high performance engine and has to allow a little more oil to the top rings for lube as as well as down the 32 valve guides.

Design intent for oil consumption would put the engine at about 4000 miles per quart consumption but due to the variables in production parameters there are engines that will use 1 quart per 1000-1500 miles.... perfectly normal and acceptable... but more oil consumption than "intended". Nothing will be wrong with the engine but the continuous oil adds are aggravating. If this is the case then understand that the engine is probably going to run a long long time like that as the cylinder walls , rings, valve guides, etc. like all that oil that you are putting in and the continuous oil adds fortify the used oil in the sump and replenish the additive package in the oil that is slowly depleted under normal usage.

Comparing the 4.9 to the Northstar is an apples to oranges deal. The 4.9 is an excellent engine for it's purpose but does not offer nearly the performance, durability, fuel economy and emission control capability of the Northstar. The Northstar is a high output engine and likes to be "used".

The best way to minimize oil consumption in a Northstar is to keep the sump filled slightly low (many are continuously overfilled) by only checking the oil level when hot and only filling the sump with 7 quarts of oil (7.5 with a dry filter at a change.) A typical 8 quart fill at a change is "required" to put the oil level on the full mark when cold but is actually overfilling the crankcase promoting oil consumption.

{C}{C}Use conventional mineral oil (synthetic is not required at all) as it tends to provide better oil consumption{C}{C}.

And last, but not least, air the engine out frequently. It likes to be used and red-line upshifts at WOT help promote clean combustion chambers, exercise the piston rings to keep them free of carbon buildup and keep them mobile and to ensure the engine is broken in and maximum sealing is obtained. The Northstar does not like to be babied around. It likes to be run hard frequently with a WOT blast in merging or whatever.... Even engines reported to use 1 quart per 1500 miles tend to improve to 2500 miles per quart or better when subjected to a regular schedule of use and "abuse"...

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The subject of oil consumption really does not have a "final" answer. The fact is that there is some variability in oil consumption in all production engines.... regardless of who makes them on which continent. All the manufacturers recognize this and virtually all of them will call oil consumption as great as 1 quart in 1000 miles "normal" "acceptable" "allowable" "within production tolerances" etc... This doesn't mean that all engines will get 1000 MPQ or that the engine was designed to get 1000 MPQ...it just recognizes the fact that there are going to be some engines that get 1000 MPQ that will be perfectly fine upon disassembly and will have nothing "wrong" with them.

The variables that usually enter into oil consumption are primarily associated with the piston/ring/cylinder bore. The number of valves or type of valve actuation has little to do with it.

The single biggest variable and the one that has been discussed at great length on this forum is the cylinder bore finish or the cylinder honing pattern. The higher performance the engine is the more attention must be paid to the honing pattern and retention of oil on the cylinder walls to lubricate the piston and rings at full load , high RPM operation. The Northstar engine uses a very aggressive cylinder bore finish that tends to retain a lot of oil to protect the piston and rings. When the blocks are honed at the factory there is a tolerance in the bore finish due to the fact that the honing stones will wear and need replacement. A brand new stone gives a slightly more aggressive pattern than a "used" stone....so a block honed with new stones will have a more aggressive finish and most likely will use more oil.

Another variable is bore roundness. Like it or not, the bores tend to "move" slightly as the engine heats up and cools down and bolt tensions relax, etc. over time. All this contributes to slight bore out of roundness that is not bad or good...just different.

Carbon buildup in the rings and ring sealing are also variables that come into play with break in, operating schedule, type of oil used, etc.

The one thing that I can attest to is that many, many customer oil consumption complaint engines have been torn down with absolutely nothing wrong found. The engines are often reassembled and put into test cars and driven by the engineers and more often than not the high oil consumption does not repeat itself !!! The single biggest common cause seems to be breakin...or lack there of. Many, many oil consuming NOrthstar engines are "fixed" by some full throttle operation. I often joke about "driving it like you stole it" but it really is no joke. The Northstar engine was designed as a high performance engine to be run hard and fast. Those that are run hard typically exhibit excellent ring seal, little carbon build up and good oil economy. We have seen engines with tens of thousands of miles on them that the rings have not sealed or mated to the sides of the ring grooves because the operating schedule was so light duty. The moral here is to flog it .... often.

In any case, the nice thing about the engines with the more aggressive honing pattern is that the pistons, rings and bores will last forever. It is very common to tear down a 200,000 mile Northstar engine and still see the original honing pattern in the cylinders. There is never any sign of cylinder wall wear and the idea of a wear "ridge" at the top of the cylinder bore is something that is laughable on a Northstar.

The other nice thing about a little oil consumption is that it adds tremendous safety factor to the oil change interval. Nothing could be better for the engine than an occasional quart of fresh oil. You can take the worst oil on the market and add a fresh quart every 1000 miles and over the life of the engine the wear will be better than an engine run on the best oil with no adds between changes.

While no one in the engineering community wants high oil consumption the fact is that there is some variability in the oil consumption of an engine manufactured at the rate of 1200 per day. The specs of what is "normal" simply reflects this...it does not imply that all engines would get this or that something is wrong with and engine that gets more or less oil consumption.

There have been a lot of engineering changes over the years on the Northstar aimed at reducing the overall oil consumption and reducing the variability in the oil consumption of different engines. Many changes have been made to the honing process to make it more consistent. Changes to the piston and ring groove treatment have been made to make it more resistant to wear, pound out and micro welding at low oil retention rates. Regardless, there is still some variability.

One other thing that affects oil consumption, or the customers perception of oil consumption, is the move toward longer and longer change intervals. With the allowable change interval reaching as high as 12,500 miles on a 2003 Northstar if the oil life monitor is followed this could mean the addition of 3,4 or 5 quarts of oil to a very healthy engine. If the owner changes their oil every 2000 or 3000 miles, despite the oil life monitor recommendations, then they would not have to add any oil between changes. The oil consumption is the same....the amount added between changes is all that is different. Yet, many customers do not make the distinction. Field surveyors repeatedly show that "acceptable" oil consumption means "not having to add between changes"...whatever MPQ that is...???

The issue of oil consumption is very emotional , too, as many people perceive higher oil consumption as 'poor quality" or an indication that something is wrong. Blue smoke, fouling plugs, noise, etc...is a sign of something wrong. Using 1 quart in 1000 miles might be perfectly normal for an engine that has the high limit "rough" hone finish and is perfectly in spec...yet it will be perceived differently.

The Northstar engine in particular was designed to be a high performance engine and to perform well at high speeds and high loads. The engines are tested at loads and speeds for time periods few customers will ever be able to duplicate. It is unfortunate that the engineering that goes into making the engine capable of such running sometimes contributes to more oil consumption... especially as the production machining tolerances are taken into account.

The items mentioned about overfilling also apply. Make sure that the system is not overfilled as any excess oil will be pushed out the PCV. The best bet is to always check the oil hot and keep it midway between the add and full mark. Don't always top off and don't top off cold to the full mark as that will overfill the sump.

Hope this helps rather than adding more fuel to the fire... so to speak.

Incidentally, there is a lot in the message board / forum archives... check using "oil consumption" and read up. Always keep in mind that for every "oil burner" you read about on the internet there are 10,000 or more driving around perfectly fine that the people are not posting about... You are always going to read about the horror cases on the internet".

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Occasional Full-Throttle Acceleration Is Good For Your Engine

There are many advantages to occasional full throttle accelerations with a Northstar and any engine.

It keeps the carbon cleaned out of the combustion chamber. This is maybe a little more important with the Northstar than some other engines due to the tight squish volumes between the piston and the cylinder head. It's designed this way to promote good in-cylinder mixture motion (good combustion) but it has the down side of providing a ready place for carbon build-up to touch the piston - causing noise. Ever heard of the Northstar "cold carbon rap" problem?? Simply put you'll hear a rythmic, piston slap-like noise when the engine is cold. Very prominent and very annoying. Cause: excessive carbon build up causing the the piston to contact the carbon on the head - causing it to rock in the bore and "slap" Much more evident when the engine is cold and the pistons haven't expanded to full diameter yet. Simplest and easiest "fix" for this: A few good WOT (wide open throttle) accelerations to clear the carbon out. That is all it takes to eliminate the problem and prevent it from re-occurring.

Occasional WOT accelerations also help seat the rings to the ring lands and exercise the rings and keep them mobile and from becoming stuck in carbon in the ring lands. At high RPM and WOT the rings move around on the piston - they actually rotate on the piston and will polish away any carbon and seat themselves to the sides of the ring grooves. This is especially important on the 2000 and later Northstars which had hard anodized top ring lands on the pistons. Very hard and wear resistant - also harder to break-in and seat the rings to the sides of the ring-lands to promote the best possible seal. Many oil consumption complaints on the 2000 and later engines are related, to some extent, with the rings never seating to the sides of the ring-grooves due to lack of load as the engine was babied around forever. Even engines with rings stuck in the ring-grooves due to carbon build up can eventually be freed up with enough high RPM operation.

WOTs warm up the engine thoroughly and clean out the exhaust due to temperature in the exhaust and high flow rates blasting particles, rust and such out of the system.

Here is the WOT Procedure

{C}{C}Frequent WOT operation will not hurt the engine or the transmission. They're designed for that. The healthiest engines that I have seen at high miles are always the ones that are run the hardest. Rings are free on the pistons and sealing; no carbon buildup.

The exercise that I think works best for many things is to select manual 2nd gear on an isolated stretch of expressway. This takes the transmission shifting out of the question if you are worried about hurting it. Start at 55 MPH or so and go to WOT in 2nd gear and hold it until the RPM reaches near the normal shift point - i.e. 6500 for an L37 and 6000 for an LD8. Hold the throttle wide open until the engine reaches, say, 6200 for an STS and then just let completely off the throttle. Leave the transmission in 2nd so that the engine brakes the car and creates some pretty heavy over-run conditions at high vacuum levels. Let it slow until it is about 55 or so and then go to WOT again and repeat. This exercise really loads the rings, allows variable RPM operation at WOT for several seconds continuously, creates heavy over-run which tends to unload the rings and make them move and thus exercise them in the ring grooves and it will blow-out carbon and the exhaust - all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.{C}{C}

The Northstar engine was designed/developed/validated to be run hard. It was expected that people would use the performance of the engine - which few people seem to do. The biggest single problem that many issues stem from is lack of use at full throttle by the owners. It just doesn't like to be babied around. The rings are low-tension by design for good high RPM operating characteristics and low friction/good power. They work best if "used" and kept free.

In every conversation with owners I have had, once the owner started doing the WOTs and using the power of the engine they report no more carbon rap, better oil economy, no "smoke" when they do light it up (keep the exhaust cleaned out. If you notice a "cloud" at WOT then you are not doing enough WOTs...) etc... A bit of judicious use of the other end of the throttle travel is a GOOD thing...

[Cadillac Jim]

Synthetic oil is not required for your Northstar to run according to specifications and to achieve reliability consistent with the warranty.

Synthetic oil has been recommended by Cadillac as a premium fill since at least 1997 for "better fuel economy" and higher film strength in situations of high stress or overheating. The "better fuel economy" is because the use of 5W-30 Mobil 1 has less crankshaft drag, which means that a little more engine power goes out the flywheel instead of toward heating the oil, which means a tiny bit more horsepower, which was enough for me for my 1997 ETC for the 14.5 years I owned it.

Another reason for using synthetic oil in any vehicle is sludge resistance. The lack of light hydrocarbons in synthetic oil means that it doesn't absorb condensed water and form sludge. If you go a long time between oil changes because you don't put a lot of miles on your car, you should consider synthetic oil to keep your engine cleaner over long periods without an oil change.

Yes, there is no advantage in engine reliability in normal use of dino oil in normal use of a Northstar. But there is a small but measurable improvement in gas mileage and performance, and the engine stays cleaner, particularly under the cam covers and cam chain covers where there is not a lot of oil being thrown around.

[Jan Olsson]

I wouldn't be too worried about sludge deposits. I believe this was an issue in the past. I have never seen any deposits in any engine run with modern dino oil. Of course there is a possibilty that there will be deposits if you never ever change the oil or if you don't use a quality oil.

[KHE]

When I had the engine apart in my STS a few years ago, it was spotless inside and all it ever had was conventional motor oil. The days of one oil being a sludge producer (think Penzoil or Amoco Super Permalube) are long gone. Even Penzoil is a good oil these days. The specs. are much more stringent and there is a compatability spec. - All motor oils must be compatable so if you put 7 different brands of oil in your engine, they must not react with each other or sludge up the engine.

[Cadillac Jim]

Sludge can be a problem in engines that don't get the oil hot enough to evaporate condensation in normal use, as a prominent Japanese manufacturer did with their four-cylinder engines for a number of years. That's not a problem with the Northstar, of course.

But, if you drive only a couple of thousand miles a year, and go a year or more between oil changes, you should either change your oil every six months or so regardless of mileage, or consider synthetic oil. My wife's car sees only a couple of thousand miles a year.