Oil and Coolant consumption Chevy Trailblazer 4.2L 2007
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Originally Posted by Falcon_LS
Part number is 12575660 in case you need it.
Checked the valve. makes a whistling noise when I block it.
The vacuum is really weak to non-existent.
Surprisingly I did find a bit of oil in one end of the "PCV" hose where it meets the valve.
Not much but it's definitely getting up there somehow.
I did a sizzle test on the oil dipstick and seems to be a negative (smoke not sizzle).
I ran the engine again with the radiator cap off, a negative, no bubbles or bursts.
Part number is 12575660 in case you need it.
Checked the valve. makes a whistling noise when I block it.
The vacuum is really weak to non-existent.
Surprisingly I did find a bit of oil in one end of the "PCV" hose where it meets the valve.
Not much but it's definitely getting up there somehow.
I did a sizzle test on the oil dipstick and seems to be a negative (smoke not sizzle).
I ran the engine again with the radiator cap off, a negative, no bubbles or bursts.
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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.
does the nipple/valve connecting to the intake resonator with the "PCV" hose supposed to have vacuum though?
i thought it's just a valve on the valve cover that blow by gases goes up and back into the intake through the throttle body, or do I have this reversed in that vacuum sucks air in, mixes with the blow by and then it goes out through the exhaust manifold?
thanks again for the help.
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.
does the nipple/valve connecting to the intake resonator with the "PCV" hose supposed to have vacuum though?
i thought it's just a valve on the valve cover that blow by gases goes up and back into the intake through the throttle body, or do I have this reversed in that vacuum sucks air in, mixes with the blow by and then it goes out through the exhaust manifold?
thanks again for the help.
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The nipple on top of the valve cover supplies fresh air to the PCV system and should have a strong vacuum at idle, which will gradually drop as RPM increases. At idle, with the hose off, you should be able to hear a whistle-like noise coming from it. You could spray a bit of carb cleaner down the nipple to clear off any dirt inside, which may have accumulated over time.
Originally Posted by Falcon_LS
The nipple on top of the valve cover supplies fresh air to the PCV system and should have a strong vacuum at idle, which will gradually drop as RPM increases. At idle, with the hose off, you should be able to hear a whistle-like noise coming from it. You could spray a bit of carb cleaner down the nipple to clear off any dirt inside, which may have accumulated over time.
Hey Falcon thanks for the response again. really appreciate it.
Do you know how the valve nipple is supposed to look like at the bottom?
Is it a clear passageway? the reason I ask is that I tried to spray brake cleaner (that's all I had on hand that time) with the thin extension and it stops down about an inch.
it looks like i would have to take the entire valve cover off as it seems to be sealed permanently to inspect it otherwise.
The nipple on top of the valve cover supplies fresh air to the PCV system and should have a strong vacuum at idle, which will gradually drop as RPM increases. At idle, with the hose off, you should be able to hear a whistle-like noise coming from it. You could spray a bit of carb cleaner down the nipple to clear off any dirt inside, which may have accumulated over time.
Hey Falcon thanks for the response again. really appreciate it.
Do you know how the valve nipple is supposed to look like at the bottom?
Is it a clear passageway? the reason I ask is that I tried to spray brake cleaner (that's all I had on hand that time) with the thin extension and it stops down about an inch.
it looks like i would have to take the entire valve cover off as it seems to be sealed permanently to inspect it otherwise.
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There is a sheet of plastic or aluminum, depending on the construction material of the valve cover, underneath the valve nipple. If you take a look at this listing on eBay, you will see the overall contruction of the valve cover.
To clean up any blockage, I would suggest carb cleaner, which is heavier than brake cleaner and won't evaporate as quickly. It will also stay in there longer, helping to soften any dirt. Worst comes to worst and you have to pull the valve cover off, leave it in a 50/50 mix of Simple Green Industrial Cleaner/Degreaser and water overnight. Keep me posted!
To clean up any blockage, I would suggest carb cleaner, which is heavier than brake cleaner and won't evaporate as quickly. It will also stay in there longer, helping to soften any dirt. Worst comes to worst and you have to pull the valve cover off, leave it in a 50/50 mix of Simple Green Industrial Cleaner/Degreaser and water overnight. Keep me posted!
Originally Posted by Falcon_LS
There is a sheet of plastic or aluminum, depending on the construction material of the valve cover, underneath the valve nipple. If you take a look at this listing on eBay, you will see the overall contruction of the valve cover.
To clean up any blockage, I would suggest carb cleaner, which is heavier than brake cleaner and won't evaporate as quickly. It will also stay in there longer, helping to soften any dirt. Worst comes to worst and you have to pull the valve cover off, leave it in a 50/50 mix of Simple Green Industrial Cleaner/Degreaser and water overnight. Keep me posted!
Hey Thanks,
I put some seafoam through there as well a couple of times.
the vacuum seems to have intensified and more consistent whistling noise.
if I see improvement with the oil consumption I'll update here.
if anything may have to pull the valve cover off and I'll update in that case as well.
thanks again, Falcon. appreciate it.
There is a sheet of plastic or aluminum, depending on the construction material of the valve cover, underneath the valve nipple. If you take a look at this listing on eBay, you will see the overall contruction of the valve cover.
To clean up any blockage, I would suggest carb cleaner, which is heavier than brake cleaner and won't evaporate as quickly. It will also stay in there longer, helping to soften any dirt. Worst comes to worst and you have to pull the valve cover off, leave it in a 50/50 mix of Simple Green Industrial Cleaner/Degreaser and water overnight. Keep me posted!
Hey Thanks,
I put some seafoam through there as well a couple of times.
the vacuum seems to have intensified and more consistent whistling noise.
if I see improvement with the oil consumption I'll update here.
if anything may have to pull the valve cover off and I'll update in that case as well.
thanks again, Falcon. appreciate it.
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