Significant oil burning/poor milage
11-26-2004, 03:41 PM
#12
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Originally Posted by marc_w
My '00 4.3 truck had a similar problem later in it's life, up around 85K+ miles. The thing was a DOG - especially on the highway... it couldn't hold 70mph up the mild hills here in Massachusetts. (you'd step on the gas, and you'd slow down until you downshifted to 3rd).
I don't recall how much oil I was burning, but it was more than a quart a oil change. I never saw any evidence of where it was going. Plugs were clean(ish), and there was never any smoke out the exhaust. My gas mileage was horrible - around 12-13mpg.
Right around 95K miles the motor gave me a huge, HUGE fit... I started it up one 0*F night up North, and I thought a rod was going to come through the block - I've never heard an engine make a noise that loud and live. It rapped for about 30 seconds and it just went away. It sounded like someone with a medium sized ball-peen hammer wacking the side of the engine block. I took that as a sign the motor was real tired, and I got rid of the truck shortly after that.
The motor was one of those that always ticked it's whole life. The only thing I had done to it was a K&N drop-in filter, and a Borla cat-back. Looking back, there is the possibility that I over oiled the K&N, mucking up the MAF, and throwing off my gas mileage and highway power... but I can't say for sure now.
I used Mobil1 5w30 and usually Fram filters for about 90 of those 95K miles. I now understand thing thing about Fram filters, but I'm also very leery about M1 now too.
The truck was very well maintained otherwise, which really rubbed this problem in my face. FI cleaner, fuel filters, etc. - they were all done.
Sorry I can't give you any real help...
Maybe you could pull an oil sample, and send it off to be analyzed? (what is it, about $20-30?) I have the contact info in my PM's if you want it?
I don't recall how much oil I was burning, but it was more than a quart a oil change. I never saw any evidence of where it was going. Plugs were clean(ish), and there was never any smoke out the exhaust. My gas mileage was horrible - around 12-13mpg.
Right around 95K miles the motor gave me a huge, HUGE fit... I started it up one 0*F night up North, and I thought a rod was going to come through the block - I've never heard an engine make a noise that loud and live. It rapped for about 30 seconds and it just went away. It sounded like someone with a medium sized ball-peen hammer wacking the side of the engine block. I took that as a sign the motor was real tired, and I got rid of the truck shortly after that.
The motor was one of those that always ticked it's whole life. The only thing I had done to it was a K&N drop-in filter, and a Borla cat-back. Looking back, there is the possibility that I over oiled the K&N, mucking up the MAF, and throwing off my gas mileage and highway power... but I can't say for sure now.
I used Mobil1 5w30 and usually Fram filters for about 90 of those 95K miles. I now understand thing thing about Fram filters, but I'm also very leery about M1 now too.
The truck was very well maintained otherwise, which really rubbed this problem in my face. FI cleaner, fuel filters, etc. - they were all done.
Sorry I can't give you any real help...
Maybe you could pull an oil sample, and send it off to be analyzed? (what is it, about $20-30?) I have the contact info in my PM's if you want it?
I don't think you have to worry about the M1. I've been using it for many years...have a Civic (1.5L) with 204k and used it in a 86 Chevy 305 for about 120k until I sold it...the Honda engine runs like it always has and the 305 was running fine when I sold it.
11-26-2004, 11:05 PM
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Originally Posted by ACDenali
Whats up fellas, my dad has a 2001 Sierra C3 with 49k miles. Never abused, etc...anyways I changed the oil about a month ago in it. Today after washing I checked it and it was about 2.5 quarts low. I figured maybe it was a mishap since I had the truck running earlier. I let it sit all day, and checked again and it only had a tad bit more on the stick. Now, the truck has been getting very poor fuel milage lately. He gets around 230 miles per tank where as I am getting close to 300 with my Denali with 4.10s. His used to get about 310/tank. We are wondering what the problem might be...any ideas? Could the oil consumption/fuel economy be related? Any info is appreciated.
11-27-2004, 09:52 PM
#15
Here's the part# for the fixed orifice PCV valve: 12572717
and here's the TSB:
__________________________________________________ __________
Engine - Greater Than Normal Oil Consumption
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 01-06-01-029B
Date: July, 2002
TECHNICAL
Subject:
Higher than Expected Engine Oil Consumption
(Replace PCV Valve)
Models:
2002 Chevrolet Avalanche
1999-2002 Chevrolet Silverado, Suburban, Tahoe Models
2002 Cadillac Escalade, Escalade EXT
1999-2002 GMC Denali, Sierra, Suburban, Yukon Models
with 4.8L, 5.3L or 6.0L Engine (VINS V, T, N, U - RPOs LR4, LM7, LQ9, L04)
This bulletin is being revised to clarify the parts information. Please discard Corporate Bulletin Number 01-06-01-029A (Section 06 - Engine/Propulsion System).
Condition
Some customers may comment on higher than expected engine oil consumption. They may further comment on consumption in the range of 3,200 km (2,000 mi) or less per quart (0.946 liter) of oil under normal driving conditions.
Cause
The condition may be due to the positive crankcase ventilation (PCV) valve flow rate under certain engine operating conditions.
Correction
1. Verify that the oil consumption is not the result of an oil leak or other engine concern.
2. The dealer should perform an oil consumption test. The vehicle should have accumulated over 6,450 km (4,000 mi) before establishing the oil consumption rate. Reference Corporate Bulletin Number 01-06-01-011, Information on Engine Oil Consumption Guideline, for details.
3. Remove the PCV valve and inspect the hose going to the intake manifold for signs of excessive oil being present.
4. If excessive oil is present in the PCV hose, replace the PCV valve (Type 948C) (2) with a new-style fixed orifice PCV valve, GM P/N 12572717 (1). See the illustration shown.
Important: The new style fixed orifice PCV valve contains no moving parts, and does not rattle when shaken.
If the vehicle has an orifice style PCV valve, investigate other causes for high oil consumption.
__________________________________________________ ________
Hope this helps!
and here's the TSB:
__________________________________________________ __________
Engine - Greater Than Normal Oil Consumption
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 01-06-01-029B
Date: July, 2002
TECHNICAL
Subject:
Higher than Expected Engine Oil Consumption
(Replace PCV Valve)
Models:
2002 Chevrolet Avalanche
1999-2002 Chevrolet Silverado, Suburban, Tahoe Models
2002 Cadillac Escalade, Escalade EXT
1999-2002 GMC Denali, Sierra, Suburban, Yukon Models
with 4.8L, 5.3L or 6.0L Engine (VINS V, T, N, U - RPOs LR4, LM7, LQ9, L04)
This bulletin is being revised to clarify the parts information. Please discard Corporate Bulletin Number 01-06-01-029A (Section 06 - Engine/Propulsion System).
Condition
Some customers may comment on higher than expected engine oil consumption. They may further comment on consumption in the range of 3,200 km (2,000 mi) or less per quart (0.946 liter) of oil under normal driving conditions.
Cause
The condition may be due to the positive crankcase ventilation (PCV) valve flow rate under certain engine operating conditions.
Correction
1. Verify that the oil consumption is not the result of an oil leak or other engine concern.
2. The dealer should perform an oil consumption test. The vehicle should have accumulated over 6,450 km (4,000 mi) before establishing the oil consumption rate. Reference Corporate Bulletin Number 01-06-01-011, Information on Engine Oil Consumption Guideline, for details.
3. Remove the PCV valve and inspect the hose going to the intake manifold for signs of excessive oil being present.
4. If excessive oil is present in the PCV hose, replace the PCV valve (Type 948C) (2) with a new-style fixed orifice PCV valve, GM P/N 12572717 (1). See the illustration shown.
Important: The new style fixed orifice PCV valve contains no moving parts, and does not rattle when shaken.
If the vehicle has an orifice style PCV valve, investigate other causes for high oil consumption.
__________________________________________________ ________
Hope this helps!
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