PCV problems continue

2071 Views 16 Replies 5 Participants Last post by Ranger, Jan 10, 2016

justjoe

Discussion Starter · Mar 16, 2015

Codes P 0171, P 0174 - need help on fix '04 Deville

Hi all,

I've been hunting down the cause of these codes (171/174) and checked plenum coupling, MAF etc. Turns out it is an intake vac leak from the back bank breather/pcv hose that goes into the intake underside on the drivebelt side. the elbow rubber hose is bad. The Question is can that be Removed/ Replaced W/O taking the intake off? It is tight there!

Any help,tips or experiences with this will be much appreciated

thanks in advance,The wisdom here is great!

Joe Viola

1 - 17 of 17 Posts

Submariner409

· #2 · Mar 16, 2015 (Edited)

Re: codes 171,174 need help on fix '04 deville base

It's tight - you need to remove the P/S pump for work room, and you'll need to pull the PCV piping apart using long needlenose pliers. If you can't find the original couplings in www.nalleygmc.com or on the Help ! racks at large parts stores the entire line - couplings, plastic pipe, etc, can be replaced by a proper sized length of reinforced fuel hose from any parts store. Your/our PCV uses a fixed orifice rather than the old PCV "rattle valve".

Maybe more in my albums - click my username, open the profile. Left column, Albums - 2 albums, 6 pages of late Northstar stuff.

Here's some additional homework .............

https://www.google.com/search?q=cadillac+forums+northstar+2002+pcv+leak&ie=utf-8&oe=utf-8

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Submariner409

· #3 · Mar 16, 2015

Re: Codes P 0171, P 0174 - need help on fix '04 Deville

............. and here's the line diagram of the assembly.

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justjoe

Discussion Starter · #4 · Mar 17, 2015

Re: Codes P 0171, P 0174 - need help on fix '04 Deville

As usual , great info. thanks Submariner 409!!!

justjoe

Discussion Starter · #5 · Mar 30, 2015

Hello again,

I posted previously about a leak in the pcv pipe that goes to the bottom of the intake on my 04 de vile base.

Well I replaced it today with reinforced fuel line as suggested. and still am getting po 171&174 current.

Here is my latest ?. Is the piece that goes into the valve cover like the old style pcv valves,i.e. is there a ball inside to restrict the gases somewhat? I ask this because it sounds to me as if vacuum is flowing totally un restricted into the intake at a high rate and I am wondering if this is the source of the unmetered air since I can't find any other leakage (plenum etc)

Thanks for any help
Joe Viola

Submariner409

· #6 · Mar 30, 2015

Later engines (mine included) use a fixed orifice instead of an old style "rattle valve". You pull the connector/hose off that fitting and it screams/whistles.

Pull your new line off the right (rear) cam cover and look into the fitting - small hole in there ?

Your earlier thread has been merged with this one for continuity.

justjoe

Discussion Starter · #7 · Mar 30, 2015

Thanks Sub!!!!

Ranger

· #8 · Mar 31, 2015

justjoe said:
Well I replaced it today with reinforced fuel line as suggested. and still am getting po 171&174 current.

Remember, the codes will not clear (unless you manually clear them) until you have 3 successful ignition cycles with no failure detected.

deleverage

· #9 · Dec 29, 2015

Submariner409 said:
Later engines (mine included) use a fixed orifice instead of an old style "rattle valve". You pull the connector/hose off that fitting and it screams/whistles.

Pull your new line off the right (rear) cam cover and look into the fitting - small hole in there ?

Your earlier thread has been merged with this one for continuity.

Submariner
I had a discussion with a mechanic this afternoon about the high oil consumption in my 99 deville. He indicated that PCV valves are often the cause of this. Based on your message above, do you know if the 99's have a PCV valve?

I used to fill oil to the upper mark on the dipstick until I read your advise. By getting the half case and rear main seals redone, and only filling to the half mark on the dipstick, I was able to get oil consumption from 1 qt per 1000 miles to 1 qt per 1900 miles...a big improvement. But if there is an easy way to get more improvement, I am all ears. I did read the posts on 'a river runs through' that you sometimes refer to.

Thanks

Ranger

· #10 · Dec 29, 2015

The '99 uses the rattle type PCV valve.

1 qt per 1900 miles is well above factory acceptance range and most owners of a '99 would pay for that kind of consumption. Think of the minor consumption as cylinder wall lubrication and thus longevity.

jmf1964

· #11 · Dec 30, 2015

I just had that exact repair done on my 04 (pcv elbow) last week, mechanic said he didn't have to move anything nor did he have to remove the intake. He used long needle nose pliers to get at the elbow. He charged me $85.00 for the repair and the car runs like new now.

deleverage

· #12 · Jan 8, 2016

Ranger said:
The '99 uses the rattle type PCV valve.

1 qt per 1900 miles is well above factory acceptance range and most owners of a '99 would pay for that kind of consumption. Think of the minor consumption as cylinder wall lubrication and thus longevity.

Thanks Ranger, but it is a sad day when one is to be encouraged for having a car that uses a quart every 2000 miles. Doesn't say much about Cadillac engineering. I have an 05 Lexus LS430 and I just change oil once per year and drive it. No problems. This Cadillac is constantly being worked on. Now don't get me wrong, it is a nice car and I love the ride, but this is not competitive with other offerings.

Submariner409

· #13 · Jan 8, 2016

Re: Codes P 0171, P 0174 - need help on fix '04 Deville

Within ANY automobile engine brand/model/year group there are some that use a lot of oil, engines that use a decent average of oil, or engines that are exceptional in their minimal oil use. Nature of the beast. It's called a bell curve.

GM says the acceptable oil consumption for a Northstar - with less than 35,000 miles, in private service, and driven normally - is 2,000 miles/quart. That figure was a miracle as little as 30 years ago. There is a specific GM TSB on the subject of Northstar oil consumption - about 2005 or 2006, I believe. The stickys in Engines; Northstar - piston ring cleaning.

My STS is fortunate in being way out on the right side of the curve - it uses less than 16 ounces of oil in 6,500 miles of driving, with "driving" ranging from plodding around Stevensville or screaming through the boonies in Caroline County. I have the receipts and hard copy maintenance tables for the car since it was initially bought in 06/02 and since I bought it in 11/05. I, too, change oil/filter once a year (4,500 - 7,000 miles), and so have never had to add any between changes.

I sympathize with the excessive consumption Northstar group - with a twist of fate I could have been there, too.

Remember: We're working in a forum filled with cars with problems - practically none are trouble-free, whatever the trouble.

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Ranger

· #14 · Jan 9, 2016

I thought GM said acceptable was 1qt per 800 miles and would not touch it under warranty with anything over that.

Ranger

· #15 · Jan 9, 2016

deleverage said:
Thanks Ranger, but it is a sad day when one is to be encouraged for having a car that uses a quart every 2000 miles.

I used to feel that way as well, but now I just think of it as extra cylinder wall and ring lubrication. For the mere cost of a qt of oil, you'll never have to worry about worn rings. If the HG's hold, it'll outlast the car.

Check out these two Northstar cylinder walls. Note the factory crosshatch hone pattern still readily visible at 130 & 170K. The oil that g

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deleverage

· #16 · Jan 9, 2016

Re: Codes P 0171, P 0174 - need help on fix '04 Deville

Submariner409 said:
Within ANY automobile engine brand/model/year group there are some that use a lot of oil, engines that use a decent average of oil, or engines that are exceptional in their minimal oil use. Nature of the beast. It's called a bell curve.

GM says the acceptable oil consumption for a Northstar - with less than 35,000 miles, in private service, and driven normally - is 2,000 miles/quart. That figure was a miracle as little as 30 years ago. There is a specific GM TSB on the subject of Northstar oil consumption - about 2005 or 2006, I believe. The stickys in Engines; Northstar - piston ring cleaning.

My STS is fortunate in being way out on the right side of the curve - it uses less than 16 ounces of oil in 6,500 miles of driving, with "driving" ranging from plodding around Stevensville or screaming through the boonies in Caroline County. I have the receipts and hard copy maintenance tables for the car since it was initially bought in 06/02 and since I bought it in 11/05. I, too, change oil/filter once a year (4,500 - 7,000 miles), and so have never had to add any between changes.

I sympathize with the excessive consumption Northstar group - with a twist of fate I could have been there, too.

Remember: We're working in a forum filled with cars with problems - practically none are trouble-free, whatever the trouble.

Submariner
Good point about the forum being a problem sharing forum, so we are getting the opposite end of the bell curve here vs. your experience. It is no wonder you love your car so much. I am happy there are some Northstars that are performing better.

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Ranger said:
I used to feel that way as well, but now I just think of it as extra cylinder wall and ring lubrication. For the mere cost of a qt of oil, you'll never have to worry about worn rings. If the HG's hold, it'll outlast the car.

Check out these two Northstar cylinder walls. Note the factory crosshatch hone pattern still readily visible at 130 & 170K. The oil that g

Ranger
I just spoke with a GM mechanic who moved out to Arizona from the Chicago area. He worked on chevy's and buick's mostly and they had a lot of trouble. But he indicated that GM went through a phase where they reduced the radial force in the piston rings with the hypothesis that that change would reduce wear. The result was that there was not sufficient radial force to overcome the 'gunk' that became embedded between the ring and piston groove, thus causing oil consumption. This was further exasperated by the computer oil monitoring system extending oil change intervals sometimes as high as 9000 miles which allowed the engines to build up more sludge. Then GM came out with their ring cleaning procedure where you pour a solvent into hot cylinders and soak the engine, thus breaking the bond of the gunk from the rings/grooves. This has been mentioned on this forum. So, is it possible that this is a cause of the oil consumption, and the lack of ring wear. I know the mechanic I spoke of worked on Northstars and did several HG repairs using timeserts. He did say that they had no comebacks from the use of timeserts when they had an adequate block to work with (non-porous casting or not destroyed from overheating). I am not a proponent of timeserts, just reporting what he said.

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Ranger

· #17 · Jan 10, 2016

So, is it possible that this is a cause of the oil consumption, and the lack of ring wear.

I suppose that is possible. I also heard that one cause was the compression ring being located to close to the top of the piston and I believe the pistons where later redesigned.

Noting wrong with Timesert as long as you use the Bigsert.

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