1998 Buick Lesabre Excessive Oil Consumption

You said the upper intake is coated so there is either a crack in that upper intake clean it and look it over very carefull and check the lower intake and gasket to it being on wrong or something. If you are using that much oil it should be smoking like crazy. How was the engine rebiult? Meaning was it just a rering job or was the block bored and honed and new pistons and rings and etc. Let me know what you can and we will take it from there. Also check to make sure that the metal oil sheild in the intake is not missing.

[quote:bc1b5013af="racefan966"]You said the upper intake is coated so there is either a crack in that upper intake clean it and look it over very carefull and check the lower intake and gasket to it being on wrong or something. If you are using that much oil it should be smoking like crazy. How was the engine rebiult? Meaning was it just a rering job or was the block bored and honed and new pistons and rings and etc. Let me know what you can and we will take it from there. Also check to make sure that the metal oil sheild in the intake is not missing.[/quote:bc1b5013af]

ALL INTERNAL COMPONENTS ARE NEW. THE MACHINE SHOP TELLS ME SINCE THIS ISN'T A "SMALL BLOCK" CHEVY ENGINE, IT'S A V-6 3.8, A METAL OIL SHIELD IS NOT USED. CAN YOU CONFIRM IT IS REQUIRED BY SHOWING A SCHEMATIC OF IT IN AN ASSEMBLY TYPE DRAWING? THANKS.

Ok the shield they are refering to is the shield for the EGR passages in the front of the upper intake where the exhaust crossover is and such. You are sure that the the gaskets for the intake upper and lower are on correctly and didn't slip during installing?

[quote:ed7ce91ed5="racefan966"]Ok the shield they are refering to is the shield for the EGR passages in the front of the upper intake where the exhaust crossover is and such. You are sure that the the gaskets for the intake upper and lower are on correctly and didn't slip during installing?[/quote:ed7ce91ed5]

The shield is in place - the tech working on it questioned how the EGR would permit ooil entry -
The gaskets have never been found to be out of alilgnment during the many, many tear down inspections (6-8 times?) and the engine idles smooth and runs like a top.

Ok good have the plugs been pulled to see if any are building any soot? Does the intake have any cracks upper or lower? As for the EGR it will not allow oil into the intake.

[quote:200d57b74f="racefan966"]Ok good have the plugs been pulled to see if any are building any soot? Does the intake have any cracks upper or lower? As for the EGR it will not allow oil into the intake.[/quote:200d57b74f]

We are now using the second GM factory upper intake assembly, just to be sure we're not missing a hairline fracture. There is no fouling on any of the plugs. The lower intake assembly was filled with laquer thinner, left overnight, and found to be at the same level in the AM. We are on our 6th PCV valve.

Is it possible that the crankcase is creating too much pressure and forcing the oil up, rather than vacum drawing it up? Thanks.

How much vacuum does the engine have? Is the breather side of the system clean and doing its job. Have checked the compression to make sure that is all level and at the proper. If by chance the compression rings have the gaps lined up then you will get a lot of crankcase pressure. This is why I put them at 10 and 2 and the oil rings at 4,8,6 oclock. I would do a compression test just to make sure where it stands.

[quote:b675ee06ce="racefan966"]How much vacuum does the engine have? Is the breather side of the system clean and doing its job. Have checked the compression to make sure that is all level and at the proper. If by chance the compression rings have the gaps lined up then you will get a lot of crankcase pressure. This is why I put them at 10 and 2 and the oil rings at 4,8,6 oclock. I would do a compression test just to make sure where it stands.[/quote:b675ee06ce]

A leak down check has been done twice with passing results - vacuum runs around "19". New air filter. All rebuilding and trouble-shooting is, and has been performed by a machine shop that has assigned their two best 30+ year experienced techs to this repair. They're stupified at this point. I shared that to let you know that in their opinion, no stone has been left unturned. Clean plugs, no smoke, runs like a top @ idle and hiway speeds, no oil residue at the tailpipe, yet gets only 800 miles to a quart of oil. An absolute mind bender for sure!

It still don't mean the compression rings haven't turn. So what was the compression numbers? I am an engine specialist (performance engines to be exact) and have been schooled in this field and been doing it more then 25 yrs I am only trying to help as there is no other reason if all else is good that the crankcase could be loading up with pressure.

Hi there... I have a 99 Buick Lesabre and just went thru something very similiar. After having lots of work done, I still had the same problem. Turns out the upper air intake on our engines are notorious for this problem: the EGR stovepipe is made of plastic and eventually (on mine, it was at 115,000 miles) it deteriates to the point there is a hole in there. Very hard to find if you don't know it's there. You have to stick a screwdriver up inside of that hole to feel it. Anyways, you can get an aftermarket upper intake manifold. Waaaay cheaper than GM's. Problem fixed. I can't say for certain that this is your problem too, but upon research I found out that on this particular design, it's not an "if"... it's a "when".

[quote:05d20efada="racefan966"]It still don't mean the compression rings haven't turn. So what was the compression numbers? I am an engine specialist (performance engines to be exact) and have been schooled in this field and been doing it more then 25 yrs I am only trying to help as there is no other reason if all else is good that the crankcase could be loading up with pressure.[/quote:05d20efada]

Whoa! Please accept my apology if I offended you, or gave you an impression I was questioning your abilities. Sorry. I was only offering up a little background for your reference. We are certainly looking for someone to help us solve this problem once and for all.

I don't know if a compression test was done. The shop only refers to a "leak down" check. I'll ask about a test being done Monday. Thanks for your input. It's appreciated.

[quote:c6dbd25cfe="dougandlaura"]Hi there... I have a 99 Buick Lesabre and just went thru something very similiar. After having lots of work done, I still had the same problem. Turns out the upper air intake on our engines are notorious for this problem: the EGR stovepipe is made of plastic and eventually (on mine, it was at 115,000 miles) it deteriates to the point there is a hole in there. Very hard to find if you don't know it's there. You have to stick a screwdriver up inside of that hole to feel it. Anyways, you can get an aftermarket upper intake manifold. Waaaay cheaper than GM's. Problem fixed. I can't say for certain that this is your problem too, but upon research I found out that on this particular design, it's not an "if"... it's a "when".[/quote:c6dbd25cfe]

Thanks for the input. All of my components are new because of the EGR stovepipe failure. Dan

Not affended just explaining that I do have some years in the field incase you thought you were talking to a shade tree mechanic thats all so no worries. Did you find out if they did a compression test or not? If so let me know what was found with numbers ok. thanks and sorry if I sounded like I was upset. Get back to me ok. Thanks.

[quote:b352457afc="racefan966"]Not affended just explaining that I do have some years in the field incase you thought you were talking to a shade tree mechanic thats all so no worries. Did you find out if they did a compression test or not? If so let me know what was found with numbers ok. thanks and sorry if I sounded like I was upset. Get back to me ok. Thanks.[/quote:b352457afc]

I was told that both the leak down test results and the compression test results were within tolerances. They didn't have the exact numbers in front of them when I called to ask. We're standing still scratching our collective heads, not sure where to check next. Thanks.

I still believe that the compression rings in one or more cylinders have lined up there gaps or the cylinders may not have been bored so one is out of round.
Can you tell me if the block was bored or just honed and what rings were used ie-molly or cast. Was your old engine rebuilt or was it a reman engine from a builder?

[quote:1928a5ed20="racefan966"]I still believe that the compression rings in one or more cylinders have lined up there gaps or the cylinders may not have been bored so one is out of round.
Can you tell me if the block was bored or just honed and what rings were used ie-molly or cast. Was your old engine rebuilt or was it a reman engine from a builder?[/quote:1928a5ed20]

The original block was bored and fitted with new pistons and rings. Today they are removing the lower intake manifold. The manifold area was filled with solvent (laquer thinner) last night and was nearly gone this AM. The shop techs are thinkng there's a porosity problem. I'll let you know what they learn after doing a solvent test on the bench to locate the area that's weeping through. Thanks.

Ok do that as this is very puzzling for me as well. I hope it is just an intake or something like that.

[quote:efe1173cb0="racefan966"]Ok do that as this is very puzzling for me as well. I hope it is just an intake or something like that.[/quote:efe1173cb0]

The intake component was removed and filled with solvent overnight. The solvent was gone in the AM but no signs of leaking through the non-ferrous material. It must have evaporated?

I llike your theory about pressure in the crankcase vs. vacuum. The repair techs dispute the theory due to the results of the compression and leak down tests. Can over-pressurization occur even though the cylinders pass the tests? If so, how can I explain it to the techs? Thanks.

As an engine builder myself as well as lots of schooling on cars it is not impossible. The oil is coming from somewhere and if it in the pcv system and not able to rid it self of all the crankcase pressure then the intake fills with it there fore using oil. I am not saying that they don't know what they are doing I am just saying that this can be a possible cause. See you have three ring pistons a top compression ring and second compression ring and three piece oil ring at the bottom. They have gaps and if the compression ring gaps happen to have lined up or come to close to lining up then you will get excessive crankcase pressure and it will be relieved through the pcv system. Is there any oil in the air filter area too?

[quote:01e70b64fe="racefan966"]As an engine builder myself as well as lots of schooling on cars it is not impossible. The oil is coming from somewhere and if it in the pcv system and not able to rid it self of all the crankcase pressure then the intake fills with it there fore using oil. I am not saying that they don't know what they are doing I am just saying that this can be a possible cause. See you have three ring pistons a top compression ring and second compression ring and three piece oil ring at the bottom. They have gaps and if the compression ring gaps happen to have lined up or come to close to lining up then you will get excessive crankcase pressure and it will be relieved through the pcv system. Is there any oil in the air filter area too?[/quote:01e70b64fe]

No oil in the air filter system. I understand the piston rings. What I'm not able to understand is if the ring gaps line up, wouldn't they create an unsealed cylinder condition? The loss of compression should show on the compression test, which it doesn't. The techs are willing to pull the engine and take a peek, but their ABC's of compression knowledge indicate they need to look elsewhere first. Only, they don't know where to look next. Your continued interest in resolving my problem is appreciated. I hope you hang in there with us.

So just out of curiousity has any one checked to see if the engine will produce pressure through the pcv system when it isn't hooked to vacuum? If you remove the pcv and open the oil cap does it push compression through there? I must admit that this is an interesting problem which is usually a ring or valve problem but it sounds like this may not be. How tight are the valves anyway? I don't mean disconnect the PCV system and drive it as that would not be good for the engine gaskets but while it is in the shop with like a fuel pressure tester will it produce any pressure. Just idea's

[quote:e53a525f91="racefan966"]So just out of curiousity has any one checked to see if the engine will produce pressure through the pcv system when it isn't hooked to vacuum? If you remove the pcv and open the oil cap does it push compression through there? I must admit that this is an interesting problem which is usually a ring or valve problem but it sounds like this may not be. How tight are the valves anyway? I don't mean disconnect the PCV system and drive it as that would not be good for the engine gaskets but while it is in the shop with like a fuel pressure tester will it produce any pressure. Just idea's[/quote:e53a525f91]

Thanks for the ideas, I'll certainly ask, but unfortunately at this point the engine is tore apart and we won't be able to check till it's back together.

Ok great let me know what is found.

[quote:4c92f68079="racefan966"]Ok great let me know what is found.[/quote:4c92f68079]

The engine was reassembled using a FelPro gasket for sealing the intake to the heads. The FelPro gasket has a seal around the entire outer perimeter AND around the EGR ports, whereas the GM gasket did not. Testing will begin on Monday to see if I get more than 800 miles/qt. of oil. All of your past input is appreciated. Thanks.

No problem let me know how it turns out. Thanks for keeping me informed.

[quote:083279b088="racefan966"]No problem let me know how it turns out. Thanks for keeping me informed.[/quote:083279b088] Only 811 miles before a qt. of oil was needed. Car back in shop. Engine tear down this week. I hope they find the smoking gun. i'll keep you in the loop.

oil rings nearly welded to pistons. not certain why. incorrect size? shop says no way to measure before installation due to design. know a secret to confirm they are >30 over like the compression rings? Thanks.