Oil and Coolant consumption Chevy Trailblazer 4.2L 2007

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Since I bought the car at 70k miles, the coolant level and oil is being consumed about 1 quart per 5k-8k.

- There is no consistent smoke out of tailpipe. some slight smoke comes out initially during morning start but only lasts for a minute.

- No leakage anywhere.

- The coolant also looks clear (red) and has no signs of mixing with oil.

- oil cap has no indication of being "milky"

However, I noticed a couple of symptoms:

- when I hit the gas hard I sometimes notice a smell (fumes)

- I noticed oil cap has smell of gas (leaky fuel injector?)
 
The oil consumption is well within what I would consider normal.

Dexcool has the affinity to evaporate on a hot engine/cooling components before it hits the ground.....Look for pink/white/orange crusty build-up at the water pump, hoses, & radiator.
*Overfilling the system will cause the excess coolant to be vented.

A UOA is not a bad idea!
 
put some uv dye in the coolant. be sure to buy the dex-cool acdelco official one off amazon not the one from the auto parts store that specifically states not to use it with dex-cool. i agree with the other poster that dex-cool can leak externally but you'll never find the leak. and yes do a uoa to make sure it's not ending up in the oil
 
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I think I will do a compression test tomorrow on the cylinders.

and order a kit to do the UOA.

thanks for the advice.

this diagnosis in this video is also curious to me: https://www.youtube.com/watch?v=55_AGTPZSIU

does anyone have a similar theory on this engines they have a faulty design which apparently sucks oil through the PCV and then gets fed back through the intake and throttle body?
 
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Originally Posted by clinebarger
The oil consumption is well within what I would consider normal.

Dexcool has the affinity to evaporate on a hot engine/cooling components before it hits the ground.....Look for pink/white/orange crusty build-up at the water pump, hoses, & radiator.
*Overfilling the system will cause the excess coolant to be vented.

A UOA is not a bad idea!



Is the oil consumption really normal though?

I mean I have heard this before and it sounds like it's supposed to be a design feature, not a design flaw.

My last oil change I drained about 4 quarts of old oil as opposed to close to 7 quarts that supposed to be in.
I check my oil weekly but for someone who doesn't check their oil regularly (which is most people) I assume their engine would be seized.

Not to mention, it's really difficult to get a good oil reading if the surface is not completely level.

and the oil pressure gauge gives you the same reading if you have 4 quarts and you have 7 quarts.

IMHO, these cars are junk designs and they should reimburse everyone who has purchased one of these.
 
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Originally Posted by tookien
Originally Posted by clinebarger
The oil consumption is well within what I would consider normal.

Dexcool has the affinity to evaporate on a hot engine/cooling components before it hits the ground.....Look for pink/white/orange crusty build-up at the water pump, hoses, & radiator.
*Overfilling the system will cause the excess coolant to be vented.

A UOA is not a bad idea!



Is the oil consumption really normal though?

I mean I have heard this before and it sounds like it's supposed to be a design feature, not a design flaw.

My last oil change I drained about 4 quarts of old oil as opposed to close to 7 quarts that supposed to be in.
I check my oil weekly but for someone who doesn't check their oil regularly their engine would be seized.

Not to mention, it's really difficult to get a good oil reading if the surface is not completely level.

and the oil pressure gauge gives you the same reading if you have 4 quarts and you have 7 quarts.

IMHO, these cars are junk designs and they should reimburse everyone who has purchased one of these.


i got my envoy/trailblazer back from my ex borrowing it... 15k miles later without oil change or ever even checking the oil. i had to add 5 quarts to get it to full on the dipstick. it still ran fine at well over 200k. so if we calculate consumption that's 1 quart every 3k. and thats with bulk conventional.
 
Run it with the radiator cap off and look for bubbles. Get a combustion gas detector or dip test to check the coolant for combustion gas. Put a pressure tester gauge on the radiaor cap opening and look for the needle jumping back and forth.

And check the fuel pressure after it has been sitting for an hour. If its down from spec the injectors are leaking.
 
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Originally Posted by tookien
does anyone have a similar theory on this engines they have a faulty design which apparently sucks oil through the PCV and then gets fed back through the intake and throttle body?


It's not a faulty design. The 4.2L just does not have a PCV valve - air flowing into the engine through the throttle body is mixed with blow-by through the crankcase ventilation in the intake manifold. As the throttle blade opens, vacuum is reduced in the manifold, allowing gases from the crankcase to go straight into the combustion chamber through the ventilation pipe mixed with fresh air. It's pretty neat, and it also helps prevents oil from flooding the intake. Crankcase ventilation is non-serviceable.

What are your oil change intervals? Are you basing your drains on the OLM? What oil and filter combination are you using?

When you say 1 quart per 5,000 - 8,000 miles, that is a vast spread. I suggest you use a decent engine flush, not the cheap kerosene based stuff, to clean the piston ring area and switch to an ACEA A3 approved 0W-40 or 5W-40 at a bare minimum. If you can find something like Delvac 1 5W-40 or Petro-Canada Duron UHP 5W-40 as a synthetic HDEO, even better.

As for the coolant level, check your radiator cap and the surrounding area. It's not uncommon for the cap not to sit flush, even though you tighten it as hard as you can, causing a minor coolant leak that requires a top off every other month. If it leaks, you just may need a new cap.

Lastly, take a close look at your exhaust manifold on the passenger side. Even a minor crack causing a leak will end up with the smell of fumes in the cabin.
 
Originally Posted by DONWATERS
Run it with the radiator cap off and look for bubbles. Get a combustion gas detector or dip test to check the coolant for combustion gas. Put a pressure tester gauge on the radiaor cap opening and look for the needle jumping back and forth.

And check the fuel pressure after it has been sitting for an hour. If its down from spec the injectors are leaking.


there are no bubbles coming from the radiator with the cap off with the car running.
 
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Originally Posted by Falcon_LS
Originally Posted by tookien
does anyone have a similar theory on this engines they have a faulty design which apparently sucks oil through the PCV and then gets fed back through the intake and throttle body?


It's not a faulty design. The 4.2L just does not have a PCV valve - air flowing into the engine through the throttle body is mixed with blow-by through the crankcase ventilation in the intake manifold. As the throttle blade opens, vacuum is reduced in the manifold, allowing gases from the crankcase to go straight into the combustion chamber through the ventilation pipe mixed with fresh air. It's pretty neat, and it also helps prevents oil from flooding the intake. Crankcase ventilation is non-serviceable.

What are your oil change intervals? Are you basing your drains on the OLM? What oil and filter combination are you using?

When you say 1 quart per 5,000 - 8,000 miles, that is a vast spread. I suggest you use a decent engine flush, not the cheap kerosene based stuff, to clean the piston ring area and switch to an ACEA A3 approved 0W-40 or 5W-40 at a bare minimum. If you can find something like Delvac 1 5W-40 or Petro-Canada Duron UHP 5W-40 as a synthetic HDEO, even better.

As for the coolant level, check your radiator cap and the surrounding area. It's not uncommon for the cap not to sit flush, even though you tighten it as hard as you can, causing a minor coolant leak that requires a top off every other month. If it leaks, you just may need a new cap.

Lastly, take a close look at your exhaust manifold on the passenger side. Even a minor crack causing a leak will end up with the smell of fumes in the cabin.





thanks.
apparently it's letting the oil through as well.
what is your opinion on the video diagnosis I linked to with the PCV modification?

I am using synthetic oils (always) Mobil 1 and Castrol, and synthetic oil filters.
initially I was using 5w-30.
my last oil change I switched it to 5w-40 to try and reduce oil consumption, and had to top it off after the first month with a little less than 1 quart.
I would say that 3k miles is when I have to top off with 1 quart, now that I think about it more based on my driving.

it's not that bad and I can live with it.

BUT, I would really like to find out why it's happening because there are no obvious signs.
 
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I would skip the Seafoam, it's not going to do much for your situation.

Three important things to check first:

You have a vacuum hose that runs from the block directly to the intake manifold on the driver's side of the engine, to the right of the PCM. Pull that hose off and make absolutely sure it is not blocked. If it is, I suggest you get some Simple Green Industrial Cleaner and Degreaser, pour some into bucket undiluted, enough to cover the hose, and let it sit overnight.

Next, pull the intake resonator off and check to see if there is a strong vacuum from the nipple behind the oil fill cap on the valve cover at idle. It should make a whistling sound with the hose not connected.

Finally, although you may not have a check engine light, check to see there are no codes stored in the PCM, particularly a P0014.

A couple of notes; this engine has a reverse flow cooling system with variable valve timing on the exhaust side, allowing for 25º of cam phasing, which eliminated the need for an EGR system. While this setup allows for a 25% reduction in hydrocarbons and a 40% reduction in nitrogen oxide, the engine runs hot. If you have any issues with the camshaft actuator, triggering a P0014, this will throw the system off course.

Although others may choose to disagree, I think it is especially important to run a relatively low NOACK (span>10%) oil in this application. Over the 130,000 km of my ownership running an MB Sheet 229.5 approved oil with span>10% NOACK, I have never had any issues with the PCV system. The area surrounding the vacuum nipple on the valve cover and the resonator is bone dry on mine with 210,000 km on the clock. I follow the OLM with a simple drain/refill of 6 liters at the 50% mark (usually 7,500 - 8,000 km) and a filter replacement once I'm under 1%. I have never had to add any oil, either during the first 7,500 - 8,000 km phase before the drain/refill, or after. When you switch to a different oil, you may initially have oil consumption for the first two oil changes before it normalizes.
 
Originally Posted by Falcon_LS
I would skip the Seafoam, it's not going to do much for your situation.

Three important things to check first:

You have a vacuum hose that runs from the block directly to the intake manifold on the driver's side of the engine, to the right of the PCM. Pull that hose off and make absolutely sure it is not blocked. If it is, I suggest you get some Simple Green Industrial Cleaner and Degreaser, pour some into bucket undiluted, enough to cover the hose, and let it sit overnight.

Next, pull the intake resonator off and check to see if there is a strong vacuum from the nipple behind the oil fill cap on the valve cover at idle. It should make a whistling sound with the hose not connected.

Finally, although you may not have a check engine light, check to see there are no codes stored in the PCM, particularly a P0014.

A couple of notes; this engine has a reverse flow cooling system with variable valve timing on the exhaust side, allowing for 25º of cam phasing, which eliminated the need for an EGR system. While this setup allows for a 25% reduction in hydrocarbons and a 40% reduction in nitrogen oxide, the engine runs hot. If you have any issues with the camshaft actuator, triggering a P0014, this will throw the system off course.

Although others may choose to disagree, I think it is especially important to run a relatively low NOACK (span>10%) oil in this application. Over the 130,000 km of my ownership running an MB Sheet 229.5 approved oil with span>10% NOACK, I have never had any issues with the PCV system. The area surrounding the vacuum nipple on the valve cover and the resonator is bone dry on mine with 210,000 km on the clock. I follow the OLM with a simple drain/refill of 6 liters at the 50% mark (usually 7,500 - 8,000 km) and a filter replacement once I'm under 1%. I have never had to add any oil, either during the first 7,500 - 8,000 km phase before the drain/refill, or after. When you switch to a different oil, you may initially have oil consumption for the first two oil changes before it normalizes.



hey thanks for the response. I will check those hoses.

I have never had a P0014 code.

I will try Penzoil next time, apparently it has a lower NOACK.

I still may have a blown head gasket, I will get around to performing a leakage test on the coolant as well as compression test of the cylinders this week.

so far the only thing suspicious is I smell gasoline on the oil - which could dilute the oil and I assume increase oil consumption.

I also checked that PCV hose and it's dry.
 
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sometimes its hard to see a dexcool leak if its slow make 100% the water pump is good and double check bottom of rad for slow leaks. I always shake the fan on these when ever working on them as they are small and will fail quickly when they start to go.
 
Originally Posted by tookien
hey thanks for the response. I will check those hoses.

I have never had a P0014 code.

I will try Penzoil next time, apparently it has a lower NOACK.

I still may have a blown head gasket, I will get around to performing a leakage test on the coolant as well as compression test of the cylinders this week.

so far the only thing suspicious is I smell gasoline on the oil - which could dilute the oil and I assume increase oil consumption.

I also checked that PCV hose and it's dry.


Definitely check that hose on the driver's side going from the block to the intake manifold. I am a little skeptical of a blown headgasket, but it's worth crossing off your list. The headgasket on this engine has a small oriface for the PCV system, which can be blocked by excessively dirty oil.

The 4.2L came with Delphi Multec-II injectors. The early variants of these were known to leak, and I had a '97 Suburban with the Vortec 7400 that was notorious for this. Trav was able to help me out, and I got a set of updated 21 lb injectors for it. While the Multec-II's are better, the lack of a fuel filter starting MY2004 does not do them any good.

I cannot speak for Canada, but over here, despite the fact that I run Euro V gasoline (equivilant to U.S. Tier III), I start having injector problems around the 50,000 km mark. I guess stations around here are not so good at cleaning their tanks. Symptoms include:

  • Misfire on cold starts until the engine reaches operating temperature
  • Engine vibrations in gear
  • Engine lacks power until it hits 3,000 rpm
  • Fuel dilution


If you have any of these symptoms, I know you mentioned fuel dilution, you might want to take a close look at your injectors.

Pulling the injectors off on this application requires removal of the intake manifold. I have two sets of injectors for each car I own, and my tune up consists of installing the set of cleaned injectors, spark plugs, igntion coil boots, intake manifold/throttle body gaskets and oxygen sensors. Takes about 2-3 hours to get through, since the battery tray, etc. has to come off for easier access.
 
Originally Posted by Falcon_LS
Originally Posted by tookien
hey thanks for the response. I will check those hoses.

I have never had a P0014 code.

I will try Penzoil next time, apparently it has a lower NOACK.

I still may have a blown head gasket, I will get around to performing a leakage test on the coolant as well as compression test of the cylinders this week.

so far the only thing suspicious is I smell gasoline on the oil - which could dilute the oil and I assume increase oil consumption.

I also checked that PCV hose and it's dry.


Definitely check that hose on the driver's side going from the block to the intake manifold. I am a little skeptical of a blown headgasket, but it's worth crossing off your list. The headgasket on this engine has a small oriface for the PCV system, which can be blocked by excessively dirty oil.

The 4.2L came with Delphi Multec-II injectors. The early variants of these were known to leak, and I had a '97 Suburban with the Vortec 7400 that was notorious for this. Trav was able to help me out, and I got a set of updated 21 lb injectors for it. While the Multec-II's are better, the lack of a fuel filter starting MY2004 does not do them any good.

I cannot speak for Canada, but over here, despite the fact that I run Euro V gasoline (equivilant to U.S. Tier III), I start having injector problems around the 50,000 km mark. I guess stations around here are not so good at cleaning their tanks. Symptoms include:

  • Misfire on cold starts until the engine reaches operating temperature
  • Engine vibrations in gear
  • Engine lacks power until it hits 3,000 rpm
  • Fuel dilution


If you have any of these symptoms, I know you mentioned fuel dilution, you might want to take a close look at your injectors.

Pulling the injectors off on this application requires removal of the intake manifold. I have two sets of injectors for each car I own, and my tune up consists of installing the set of cleaned injectors, spark plugs, igntion coil boots, intake manifold/throttle body gaskets and oxygen sensors. Takes about 2-3 hours to get through, since the battery tray, etc. has to come off for easier access.



seriously thanks a bunch for all that info.

will get back on the results.
 
FWIW, my daughter has driven a 2002 Trailblazer for the last 5 years. Before that it was my parent's vehicle. It has 180K or so miles on it now and it uses no discernible oil between changes. I usually change it yearly which is around 6-7K miles for her. It also never uses any antifreeze. Maybe we're lucky, but I just wanted to give you another data point.
 
Originally Posted by tookien
seriously thanks a bunch for all that info.

will get back on the results.


Please keep us posted!

Originally Posted by mrdctaylor
FWIW, my daughter has driven a 2002 Trailblazer for the last 5 years. Before that it was my parent's vehicle. It has 180K or so miles on it now and it uses no discernible oil between changes. I usually change it yearly which is around 6-7K miles for her. It also never uses any antifreeze. Maybe we're lucky, but I just wanted to give you another data point.


The 4.2L is a great engine that was way ahead of its time, as was the GMT360 platform. Build quality, particularly interior plastics, left quite a bit to be desired, but that was a typical move by American manufacturers run by bean counters. It was a great SUV all round, pretty disappointing GM ditched this platform in favor of FWD based unibody crossovers.
 
Originally Posted by Falcon_LS
Originally Posted by tookien
seriously thanks a bunch for all that info.

will get back on the results.


Please keep us posted!

Originally Posted by mrdctaylor
FWIW, my daughter has driven a 2002 Trailblazer for the last 5 years. Before that it was my parent's vehicle. It has 180K or so miles on it now and it uses no discernible oil between changes. I usually change it yearly which is around 6-7K miles for her. It also never uses any antifreeze. Maybe we're lucky, but I just wanted to give you another data point.


The 4.2L is a great engine that was way ahead of its time, as was the GMT360 platform. Build quality, particularly interior plastics, left quite a bit to be desired, but that was a typical move by American manufacturers run by bean counters. It was a great SUV all round, pretty disappointing GM ditched this platform in favor of FWD based unibody crossovers.



So far I checked the hose. It wasn't totally clogged but there was dirt built up which I cleaned out.
This hose is brittle I will end up replacing it.

Going to check the valve tomorrow, will update on that.
 
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