My 2005 TB has 332k km on the odometer. The engine consumes a lot of oil. I am adding 1-2 quarts every month. The valve cover gasket was replaced, but it did not solve the problem. I can see the oil on the oil pan and the front differential, but I think the leak is not from the differential. It seems that I have a combination of the oil burning by the engine and a leak, maybe from the rear seal. Replacing the seal is not real for me - I cannot do such a repair by myself. I simply don't have a place and facilities for such kind of job. Also, the local mechanics will not replace the seal, and even if they will, I don't think they can do it properly. Also, the cost of such a repair will be too high. So, I would like to understand what I can expect from this truck. Maybe it would be better for me to find another engine (or another car)?
Excessive oil consumption
- Thread starter santon
- Start date
In a Nut Shell...: Black "Mung" Carbon:
The issues, cause and origins and the useful solutions that Do NOT Require Mechanical Interventions using instead the ACDelco TEC (Top Engine Cleaning) Solvent for the TOP END Pistons, Cylinders and Upper Piston Rings and Valve Seats are very well documented HERE:
...and for the cause and origins leading to a possible need for the Berryman's CHEM-DP Treatment of the BOTTOM END Engine Block areas to avoid breaking into the Engine with Tools... can be found HERE:
The issues, cause and origins and the useful solutions that Do NOT Require Mechanical Interventions using instead the ACDelco TEC (Top Engine Cleaning) Solvent for the TOP END Pistons, Cylinders and Upper Piston Rings and Valve Seats are very well documented HERE:
NEED HELP Thread 'high engine oil consumption'
...and for the cause and origins leading to a possible need for the Berryman's CHEM-DP Treatment of the BOTTOM END Engine Block areas to avoid breaking into the Engine with Tools... can be found HERE:
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@mrrsm , he's got external leaks, not an internal problem, so cleaning the pistons and pickup tube won't do a thing for him.
First, I'd confirm where the leak is coming from. You should clean the entire area and see exactly where the oil is coming from. You could add an ultraviolet dye and, with a UV light, see where it is coming from. It might not be the rear main seal.
I don't understand why your local shops are reluctant to do this job if it is the rear main seal. Not a particularly difficult operation; drop transmission, replace seal, re-install transmission. Maybe they're just afraid of North American vehicles? The seal can also be obtain already installed on the rear cover and even include the RTV sealant. Mahle was the original OEM part for GM.
If all else fails, you could try a seal restorer as a last ditch effort. BlueDevil seems to have good results. These videos, which actually uses a TB, but with a V8, tried it and seems to have reduced the oil leak.
Replacing the engine would be even more difficult and doubt that any shop would want to do this if they don't even want to just replace the seal.
First, I'd confirm where the leak is coming from. You should clean the entire area and see exactly where the oil is coming from. You could add an ultraviolet dye and, with a UV light, see where it is coming from. It might not be the rear main seal.
I don't understand why your local shops are reluctant to do this job if it is the rear main seal. Not a particularly difficult operation; drop transmission, replace seal, re-install transmission. Maybe they're just afraid of North American vehicles? The seal can also be obtain already installed on the rear cover and even include the RTV sealant. Mahle was the original OEM part for GM.
If all else fails, you could try a seal restorer as a last ditch effort. BlueDevil seems to have good results. These videos, which actually uses a TB, but with a V8, tried it and seems to have reduced the oil leak.
Replacing the engine would be even more difficult and doubt that any shop would want to do this if they don't even want to just replace the seal.
These days they simply want to replace oil, filters, and brakes. They can drop the transmission and put it back. They can replace the entire engine too. But the overall cost will be similar to or even greater than the price of this vehicle. For the same money I can probably find another TB. In general, I tend not to go to the shops, but there are things that I cannot do by myself.
As suggested by Mooseman, clean and try confirm the location of the oil. Is it possibly coming from a more forward position as the front axle "assemblies" that run thru the oil pan... if so maybe those can be done. Although as posted, if your shops aren't willing to do a rear seal, then maybe even front axles seals aren't happening either.
If the Engine vibrates radically at idle... and considering the very High Mileage on this Engine...worn Main Bearings (and Worn Out Motor Mounts) may allow the nose of the Crank to wobble around enough mostly during Idling to have worn or stretched the Front Timing Cover PTFE Oil Seal enough to begin to leak.
Without any disagreement with these possible leak point(s) occurring via "Weeping Seals" ...
"PT" and "FE"
... 1-2 Quarts of Oil Loss Per Month is -=too excessive=- on anything less than a torn PTFE Seal and this is what prompted the suggestion to look at Combustion Gas Compression Rings Blow-By forcing that oil out of the engine under excessive Crankcase Pressures driving the Engine Oil up and out of the Air Box Plenum and down through the Throttle Body and Intake Manifold Runners to be Burned Up in the Cylinders and CAT as a Primary Suspect.
Likewise, the rear seal can also be compromised if the #5 Mains Thrust Bearings have either failed or worn out... but you would be noticing other Timing and Ignition Issues (P0016, P0017, P0345) between the Camshaft (CMP) and Crankshaft (CKP) Sensors if this where the case. A Cracked Flex-Plate follows on once the Thrust Bearings let go and the Crankshaft begins to hunt fore and aft excessively affecting the PTFE Oil Seals.
It is important to remember that these PTFE Engine Seals provide passive, constant Oil Sealing WITH NO DIRECT PUMPED OIL PRESSURE ever being applied against them internally. And so this is what prompted my original concerns due to the high volume of oil loss occurring on such a well worn High Mileage Motor. Both of these malfunction events may turn out to be involved.
Without any disagreement with these possible leak point(s) occurring via "Weeping Seals" ...
"PT" and "FE"
... 1-2 Quarts of Oil Loss Per Month is -=too excessive=- on anything less than a torn PTFE Seal and this is what prompted the suggestion to look at Combustion Gas Compression Rings Blow-By forcing that oil out of the engine under excessive Crankcase Pressures driving the Engine Oil up and out of the Air Box Plenum and down through the Throttle Body and Intake Manifold Runners to be Burned Up in the Cylinders and CAT as a Primary Suspect.
Likewise, the rear seal can also be compromised if the #5 Mains Thrust Bearings have either failed or worn out... but you would be noticing other Timing and Ignition Issues (P0016, P0017, P0345) between the Camshaft (CMP) and Crankshaft (CKP) Sensors if this where the case. A Cracked Flex-Plate follows on once the Thrust Bearings let go and the Crankshaft begins to hunt fore and aft excessively affecting the PTFE Oil Seals.
It is important to remember that these PTFE Engine Seals provide passive, constant Oil Sealing WITH NO DIRECT PUMPED OIL PRESSURE ever being applied against them internally. And so this is what prompted my original concerns due to the high volume of oil loss occurring on such a well worn High Mileage Motor. Both of these malfunction events may turn out to be involved.
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But the OP is complaining of "excessive oil loss".... not sure tranny oil would be the culprit... but maybe he has multiple problems.
Thank you, guys. There is a lot of information here! The leak is definitely not transmission fluid. It could be the differential oil, although I checked the level recently. Also, the front differential oil seal (the external, not the inner one) and the valve cover seal were replaced by me not too long ago. So, maybe I have the combination of oil consumption and oil leak. The PCV system was clogged when I bought the truck, and I managed to clean it somehow. The truck barely passed an inspection today, because of the emissions. The CO levels are high. The cat is probably clogged - attached is the Torque-generated graph of the upstream and downstream O2 sensor. So, besides the leak, the engine is probably burning oil. Overall, the truck runs well, no misfires or error codes.
Attachments
the O2 "trace" doesn't look good IF that was taken from a warm engine as the downstream should not be "waggling".
The amount of usage is "high" but it depends on the amount of miles run during that time. Compression testing might confirm a "mechanical problem" (ie. rings) and the resulting burning of oil from that direction... maybe. Color of plugs might also show something. What does your vacuum levels look like at idle and constant throttle running? It doesn't look good but at least your "oil cycle" is bringing in "fresh oil" regularly...
The amount of usage is "high" but it depends on the amount of miles run during that time. Compression testing might confirm a "mechanical problem" (ie. rings) and the resulting burning of oil from that direction... maybe. Color of plugs might also show something. What does your vacuum levels look like at idle and constant throttle running? It doesn't look good but at least your "oil cycle" is bringing in "fresh oil" regularly...
The graph is definitely pointing towards a bad cat. I'm surprised the money light isn't coming on and giving a code like P0420. Might not be clogged if power is OK but it's not doing its job.
A few ways to tell if it's burning oil without smoke. Check for oily residue in the tailpipe and ask someone to observe your tailpipe while you rev the engine for some smoke. This would cause your cat to be contaminated and make it non-functional. You can also pull the spark plugs and check their condition. This would also be a good time to check compression.
Check the PCV system and the resonator box if there is a lot of oil in there. This could indicate excessive blowby that is pushing more oil into the intake.
A few ways to tell if it's burning oil without smoke. Check for oily residue in the tailpipe and ask someone to observe your tailpipe while you rev the engine for some smoke. This would cause your cat to be contaminated and make it non-functional. You can also pull the spark plugs and check their condition. This would also be a good time to check compression.
Check the PCV system and the resonator box if there is a lot of oil in there. This could indicate excessive blowby that is pushing more oil into the intake.
Well, the engine was not hot enough when I observed the O2 sensor traces. This was my mistake. Today I checked again, and the downstream O2 sensor signal is steady.
I think the end of the tailpipe has some oil residue. I will check the resonator and the spark plugs. Thanks!
I think the end of the tailpipe has some oil residue. I will check the resonator and the spark plugs. Thanks!
If the catalytic converter is not clogged, what could be the reason for the high CO levels? I must say that I did not drive enough before the inspection. I think it is always good to drive for half an hour at a highway speed.
I wish I could understand the condition of this engine and make some kind of estimation on how many miles it could do. Then I can decide what to do - to sell or keep it. Meanwhile, somebody offered me a 1997 GMC Yukon in very good condition, but this could be too much for me in terms of gas mileage and maintenance. It will probably be worse on gas than my TB.
I wish I could understand the condition of this engine and make some kind of estimation on how many miles it could do. Then I can decide what to do - to sell or keep it. Meanwhile, somebody offered me a 1997 GMC Yukon in very good condition, but this could be too much for me in terms of gas mileage and maintenance. It will probably be worse on gas than my TB.
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My first guess would be a rich mixture. Put the question to the Googler and got this:
What are your fuel trims like?
What are your fuel trims like?
LTFT: -5.47, STFT: changing between -0.75 to 6.25. The air filter was replaced yesterday. Spark plugs must be OK, they are original ACDelco and they are not that old. I believe the ECU/PCM is OK I never had problems with it. There are no error codes, no misfire. Exhaust leak - the exhaust manifold was cracked, but at that time, I passed the inspection. Now I have a new exhaust manifold. The O2 sensors seem OK, their signals look good today. The MAF sensor - I will try to clean it.
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The LTFT is saying it's pulling back a little fuel but it's not excessive. As long as trims are within -10 and +10, it's fine. With an exhaust leak at the manifold, it would have been more positive as it would think it's falsely running lean. Cleaning the MAF may also help.
Spark plugs I suggested to see if there is any evidence of oil burning on them.
Other than fuelling, I don't know what would affect CO levels. The cat seems to be working well but I don't know if the O2 sensor would detect a failure for just the CO output.
Spark plugs I suggested to see if there is any evidence of oil burning on them.
Other than fuelling, I don't know what would affect CO levels. The cat seems to be working well but I don't know if the O2 sensor would detect a failure for just the CO output.
Another thought. What is being reported as the coolant temp? (actual OBD reading, not the gauge) Maybe it's running a bit cold.
The coolant temperature is 87-88 deg. C. The thermostat was replaced about 2.5 years ago
That's pretty bang on as mine runs the same temps.
Here's a thought. Maybe the oil burning, if any, could be the source of the CO since it is caused by an incomplete combustion. I'd pursue checking the engine's mechanical health.
Here's a thought. Maybe the oil burning, if any, could be the source of the CO since it is caused by an incomplete combustion. I'd pursue checking the engine's mechanical health.
Yes and plug condition (i.e. oily)
That's also a good point. Incomplete combustion. Might not be enough to trigger a code.
Regarding the CPAS (Oil Control of the Exhaust Canshaft between 0-25 Degrees that acts just like an EGR at Idle) might have Clogged or Lost-Ingested fine S/S Screens drawn into the Camshaft Phaser. The CPAS can be rendered inoperative at the Electrical Connector if contaminated with Dirty Motor Oil and if it fails to help regulate the engine Idle... -=Random Engine Misfires can occur=- that may not necessarily throw either a P0014 or a P0017 Code because the range of the solenoid action behavior of the CPAS regulating How Much Oil enters, reverses or by-passes the Cam Phaser ...is Infinite.
The R&R of this device first requires the R&R of the Power Steering Pump and there are a myriad number of Threads here and Youtube Videos that describe these procedures, but from a Diagnostic Understanding approach ...I much prefer THIS Video from James Danner (Paul "Scanner" Danner's Brother) doing this precise Diagnosis with a Snap-On Solus Pro Scan Tool along with using BOTH the Snap-On Vantage and the Vantage Pro Graphing Multi-Meters getting plenty of exercise to (1) Identify the Component Failure and (2) Confirm The Repair after the eventual R&R of the CPAS Unit.
Please note how Rough this Engine was running due to being 3 Quarts LOW on Motor Oil and how violently it shakes while Idling with a Known BAD CPAS.
The R&R of this device first requires the R&R of the Power Steering Pump and there are a myriad number of Threads here and Youtube Videos that describe these procedures, but from a Diagnostic Understanding approach ...I much prefer THIS Video from James Danner (Paul "Scanner" Danner's Brother) doing this precise Diagnosis with a Snap-On Solus Pro Scan Tool along with using BOTH the Snap-On Vantage and the Vantage Pro Graphing Multi-Meters getting plenty of exercise to (1) Identify the Component Failure and (2) Confirm The Repair after the eventual R&R of the CPAS Unit.
Please note how Rough this Engine was running due to being 3 Quarts LOW on Motor Oil and how violently it shakes while Idling with a Known BAD CPAS.
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check the MAP sensor and possibly replace it. Ultimately, the system's "air uptake" seems to be less than the system is expecting... not by much. The health of the cat is still somewhat suspect(what is the o2 downstream reading?) depending on what was happening in previous history, length of time with things like cracked exhaust (did you check your fuel trims prior to the change?) Cleaning the MAF won't hurt either.
Depending on what you can do (tooling), I believe that an analog vacuum gage can help spot things like "valve issues" and other things depending on the gage response. As suggested, a compression test may highlight mechanical issues.