Do I really need a new engine? - Pontiac G8 Forum: G8 Forums - G8Board.com
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post #1 of 41 (permalink) Old 03-29-2019, 07:48 PM Thread Starter
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Do I really need a new engine?

It has been a very long time since I posted on this board. I am the original owner of a 2009 G8 GT and am now going on almost 10 years of ownership and over 211K miles.

The CEL came on a couple of weeks ago shortly after a fillup, so I did what I normally did with the gas cap to see if that was the problem. It did not go away, so I took it to the dealer today. They said that the code thrown was PO521 for low oil pressure. And the recommendation is a new engine!

That sounds a bit extreme. Searching for this code shows steps for the tech to check the oil filter housing and the Valve Filter Oil Filter.

They did say that it was showing 17psi at idle, which I believe is less than half what it should be?

In any case, I was hoping to get some opinions or experiences from fellow G8 owners who have run across this code.

Thanks in advance!

09 PBM G8GT Prem & Sport
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01/09/10: Fontana - 13.187 @ 106.67 MPH (DA Corrected - 13.036 @ 107.91)

Mulholland run 4/19/09
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post #2 of 41 (permalink) Old 03-29-2019, 08:27 PM
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17 is indeed a bit low. Maybe not half, but low.

Replacing the engine is a catch all quick fix. They clearly don't think it is worth spending a lot of time on a 211K engine. If it had 90k on it they'd be tearing into it no problem. You could always get a second and independent opinion, but I can sort of follow their logic.

17PSI is definitely low, but it's not half... A hot idling LS isn't going to be at 40PSI. If someone says theirs does, then they're either not being honest or are leaving out key details such as "it was at 40PSI when I started the car."

Mine idles at around 27-29 PSI when hot. That's considered normal. Yours seems to suggest a problem. It could be related to the oil pump, the plug in the rear of the engine (the plastic one), bearing clearances, or even a failed relief valve (if you still have yours in there).

If the relief valve is stuck open, it's open flow right into the oil pan....

But, all of these are shots in the dark without tearing into the motor; I just think they don't want to be doing that with a 211k motor..

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post #3 of 41 (permalink) Old 03-29-2019, 08:41 PM
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Definitely check the relief valve. I've seen plenty of DOD vehicles that have low pressure simply because the relief valve is stuck open, usually just oil crud that builds up inside. Also check the oil pressure sensor, sometimes the screen can get clogged up and give a bad reading.


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post #4 of 41 (permalink) Old 03-29-2019, 08:41 PM Thread Starter
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Quote:
Originally Posted by Jova007200 View Post
17 is indeed a bit low. Maybe not half, but low.

Replacing the engine is a catch all quick fix. They clearly don't think it is worth spending a lot of time on a 211K engine. If it had 90k on it they'd be tearing into it no problem. You could always get a second and independent opinion, but I can sort of follow their logic.

17PSI is definitely low, but it's not half... A hot idling LS isn't going to be at 40PSI. If someone says theirs does, then they're either not being honest or are leaving out key details such as "it was at 40PSI when I started the car."

Mine idles at around 27-29 PSI when hot. That's considered normal. Yours seems to suggest a problem. It could be related to the oil pump, the plug in the rear of the engine (the plastic one), bearing clearances, or even a failed relief valve (if you still have yours in there).

If the relief valve is stuck open, it's open flow right into the oil pan....

But, all of these are shots in the dark without tearing into the motor; I just think they don't want to be doing that with a 211k motor..
Thanks for the quick reply. I can see what you mean, that with that many miles, it's easier to say replace the engine.

My hesitation is caused by the fact that they had tried several times to find and fix a power steering fluid leak the past couple of months. If they were successful finding that, then I'd be more believing. This dealer gad done good work for me in the past, so I think they are trustworthy. But this is the biggest thing I've ever had to do.

I was planning on getting a second opinion, so I guess I'll see. I was just worried that the engine could sieze.

Again, thanks!
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post #5 of 41 (permalink) Old 03-29-2019, 08:52 PM Thread Starter
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Originally Posted by L_Alvis View Post
Definitely check the relief valve. I've seen plenty of DOD vehicles that have low pressure simply because the relief valve is stuck open, usually just oil crud that builds up inside. Also check the oil pressure sensor, sometimes the screen can get clogged up and give a bad reading.
Thanks! I'm planning to take it to the shop that did my struts and springs for a second opinion. I'll make sure to let them know of these possibilities.
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post #6 of 41 (permalink) Old 03-30-2019, 12:35 PM
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I had that code a few years back. It was the oil pressure sensor.

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post #7 of 41 (permalink) Old 03-30-2019, 01:13 PM Thread Starter
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I had that code a few years back. It was the oil pressure sensor.
I really hope it is that.
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post #8 of 41 (permalink) Old 03-30-2019, 02:09 PM
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Since Carlsbad doesn't get cold (as in really cold), an considering the total mileage you've attained (along with the existing psi at idle), my belief is that you could at least change the oil filter, and switch to a slightly heavier oil (like 10 W 40) one time thru. Even if you are unable to get a direct oil psi reading, you may be able to cancel that P0521 code. I only have 85K on my car, an the original oil pressure sensor displayed the P0521 code (after 9 years). Have never had any engine ticking or bad sounds ever. Installed a new sensor an 10 months later, I get the P0521 again. I have no idea how low the oil pressure has ever gotten (nor do I care) To me, engine sound would be the telling factor if the psi had dropped to zero (or very near it), an that telling sound(s) would happen real quick. In the service manual, I remember reading that the psi would have to drop to below 4 or 5 psi to trip the sensor (an set that sensor performance fault code P0521). So I elected to replace the oil filter an oil to see IF the P0521 fault code would cancel. I would never have believed that a filter could cause a way to drop the psi so much, but it obviously did. The P0521 code canceled an has been perfect since. I still use 5 W30 GF5 rated conventional oil. So maybe a test with 10 W 40 might solve your problem. I'm sure it can't hurt to try vs a new engine at this point. By the way, replacing the sensor (an the plastic tube shaped filter screen below it), is really a very easy job on this engine, if you choose to do that also. Course, this is just my feeling on this situation.
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post #9 of 41 (permalink) Old 03-30-2019, 03:21 PM Thread Starter
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Originally Posted by GOPHERIT View Post
Since Carlsbad doesn't get cold (as in really cold), an considering the total mileage you've attained (along with the existing psi at idle), my belief is that you could at least change the oil filter, and switch to a slightly heavier oil (like 10 W 40) one time thru. Even if you are unable to get a direct oil psi reading, you may be able to cancel that P0521 code. I only have 85K on my car, an the original oil pressure sensor displayed the P0521 code (after 9 years). Have never had any engine ticking or bad sounds ever. Installed a new sensor an 10 months later, I get the P0521 again. I have no idea how low the oil pressure has ever gotten (nor do I care) To me, engine sound would be the telling factor if the psi had dropped to zero (or very near it), an that telling sound(s) would happen real quick. In the service manual, I remember reading that the psi would have to drop to below 4 or 5 psi to trip the sensor (an set that sensor performance fault code P0521). So I elected to replace the oil filter an oil to see IF the P0521 fault code would cancel. I would never have believed that a filter could cause a way to drop the psi so much, but it obviously did. The P0521 code canceled an has been perfect since. I still use 5 W30 GF5 rated conventional oil. So maybe a test with 10 W 40 might solve your problem. I'm sure it can't hurt to try vs a new engine at this point. By the way, replacing the sensor (an the plastic tube shaped filter screen below it), is really a very easy job on this engine, if you choose to do that also. Course, this is just my feeling on this situation.
That would certainly be a quick way to see if it's not really the engine. Thanks!
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post #10 of 41 (permalink) Old 03-30-2019, 04:46 PM
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If it's still got the DOD delete system, it can cause issues with oil pressure also.

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post #11 of 41 (permalink) Old 03-31-2019, 07:06 AM
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Pardon the question, but does over 211k translate to 211,000 or 131,00 miles? How often are the oil and filter changed? Are you able to manually/electronically monitor the oil pressure? Could purchase quite a few chicken sandwiches if there was a dollar provided every time a dealership misdiagnosed a problem. From their standpoint, replacing the engine is the easiest, most logical and perhaps safest thing to do as it would certainly fix the problem. However, wouldn't replace an engine known for potential displacement on demand issues with another one just like it unless the "defect" was eliminated. Awhile back, used a crankcase cleaner no longer produced by General Motors on a vehicle that never reached over 40psi going down the boulevard. Long story short, it now idles around 40psi and gets up to 60psi on the freeway. Surmised an accumulation of sludge was either not allowing the oil to flow properly and/or the port was clogged. May or may not be the issue here and is merely just something to ponder.

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post #12 of 41 (permalink) Old 03-31-2019, 08:20 AM
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The op, being located in mild weather Ca and considering the miles on it, I would just switch to a heavier weight oil (10W-40) if the other items to check don't help.

Using a oil sludge cleaner is like playing with the devil (Pony Man-glad it worked for you). But when the sludge comes loose, depending on the amount, it may actually clog vital oil passages and result in engine damage that you didn't have before. So with 211K on it, I would try all the other suggestions and only use sludge cleaner before yanking the engine. (I previously had a description here of what I would do if I had to use sludge cleaner but deleted it as it really becomes a science/engineering experiment)
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post #13 of 41 (permalink) Old 03-31-2019, 08:44 AM
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...Using a oil sludge cleaner is like playing with the devil (Pony Man-glad it worked for you). But when the sludge comes loose, depending on the amount, it may actually clog vital oil passages and result in engine damage that you didn't have before...
For the record, have used the crankcase cleaner on at least seven different vehicles ranging from 390,000 to 130,000 miles with zero adverse effects. All but one of them are driven daily and one commented they have never heard the engine so quiet. It was recommended by a mechanic that has been in the business for well over fifty (maybe sixty) years. Said he used to buy it directly from the General Motors dealership.
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post #14 of 41 (permalink) Old 03-31-2019, 09:41 AM
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I recommend you do some research and diagnostics before you get a new engine. LS engines with DOD have a history of oil pressure problems.

First I recommend you get a mechanical gauge on the engine and determine the true oil pressure. Auto meter sells a fitting/adapter you can put on your mechanical gauge and hook it up to the oil pressure sensor. If the pressure is normal then your sensor is bad. There is a little metal screen in the hole where the oil pressure sensor is and sometimes that is clogged.

There are several other issues to work through. In no particular order:

1. The oil pump is dying. 211k on the engine so things do get tired but this is probably not it.

2. There is a O ring where the oil tube from the pump goes into the pan. That will dry rot or get pinched. 211k on the engine would tell me maybe its dry rotted.

3. The DOD system in the oil pan sometimes goes FUBAR causing oil pressure problems or excess oil consumption.

4. You need an oil change. My friends 2010 5.3 Silverado was having oil pressure problems. I put a mechanical gauge on it and it was fine but pressure would get lower as the oil got hotter. I changed the oil and filter and it fixed everything. I think the oil filter was plugged. I would change the oil and filter first, get a mechanical gauge on the engine and then go from there. If the engine runs fine, doesn't smoke, consume excessive amounts of oil, I don't think it needs replaced.
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post #15 of 41 (permalink) Old 03-31-2019, 10:00 AM
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I will agree with the plugged filter theory I’ve seen it many times on those motors with oil pressure problems and changing the filter does the trick oil pressure back to normal.
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post #16 of 41 (permalink) Old 04-01-2019, 03:15 AM
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Change oil pressure sensor and change your oil
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post #17 of 41 (permalink) Old 04-01-2019, 12:09 PM Thread Starter
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Quote:
Originally Posted by PONY MAN View Post
Pardon the question, but does over 211k translate to 211,000 or 131,00 miles? How often are the oil and filter changed? Are you able to manually/electronically monitor the oil pressure? Could purchase quite a few chicken sandwiches if there was a dollar provided every time a dealership misdiagnosed a problem. From their standpoint, replacing the engine is the easiest, most logical and perhaps safest thing to do as it would certainly fix the problem. However, wouldn't replace an engine known for potential displacement on demand issues with another one just like it unless the "defect" was eliminated. Awhile back, used a crankcase cleaner no longer produced by General Motors on a vehicle that never reached over 40psi going down the boulevard. Long story short, it now idles around 40psi and gets up to 60psi on the freeway. Surmised an accumulation of sludge was either not allowing the oil to flow properly and/or the port was clogged. May or may not be the issue here and is merely just something to ponder.
No worries. 211K miles on the odometer. From the information and recommendations so far, there are a number of things to look at before a full engine swap. I'm going to look at everything that I can and with the shop that I've worked with recently to try to eliminate all the possibilities.

Thanks for the reply!

09 PBM G8GT Prem & Sport
PPV Struts
Tein Springs
DBA 4000 Series Slotted T3 Rotors
Hawk Performance Ceramic Brake Pads
GM & Pontiac Badge Delete
V8 6.0 Litre Emblems
Rear Mufflers Deleted (replaced with straight pipes)
01/09/10: Fontana - 13.187 @ 106.67 MPH (DA Corrected - 13.036 @ 107.91)

Mulholland run 4/19/09
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post #18 of 41 (permalink) Old 04-01-2019, 12:13 PM Thread Starter
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Quote:
Originally Posted by 69project View Post
I recommend you do some research and diagnostics before you get a new engine. LS engines with DOD have a history of oil pressure problems.

First I recommend you get a mechanical gauge on the engine and determine the true oil pressure. Auto meter sells a fitting/adapter you can put on your mechanical gauge and hook it up to the oil pressure sensor. If the pressure is normal then your sensor is bad. There is a little metal screen in the hole where the oil pressure sensor is and sometimes that is clogged.

There are several other issues to work through. In no particular order:

1. The oil pump is dying. 211k on the engine so things do get tired but this is probably not it.

2. There is a O ring where the oil tube from the pump goes into the pan. That will dry rot or get pinched. 211k on the engine would tell me maybe its dry rotted.

3. The DOD system in the oil pan sometimes goes FUBAR causing oil pressure problems or excess oil consumption.

4. You need an oil change. My friends 2010 5.3 Silverado was having oil pressure problems. I put a mechanical gauge on it and it was fine but pressure would get lower as the oil got hotter. I changed the oil and filter and it fixed everything. I think the oil filter was plugged. I would change the oil and filter first, get a mechanical gauge on the engine and then go from there. If the engine runs fine, doesn't smoke, consume excessive amounts of oil, I don't think it needs replaced.
Thanks for the suggestions. I did change the oil to 10W/40 and the filter on Saturday. The CEL did not clear out, but I only drove it a few miles. But, it sounds like I do need to get a mechanical pressure reading to find out exactly what the pressure is now.

I will talk to the shop about these suggestions when I bring it in for a second opinion. What was encouraging is that the shop told me that yes, they do engine swaps, but he wanted to take a look at it first before doing something like that.

09 PBM G8GT Prem & Sport
PPV Struts
Tein Springs
DBA 4000 Series Slotted T3 Rotors
Hawk Performance Ceramic Brake Pads
GM & Pontiac Badge Delete
V8 6.0 Litre Emblems
Rear Mufflers Deleted (replaced with straight pipes)
01/09/10: Fontana - 13.187 @ 106.67 MPH (DA Corrected - 13.036 @ 107.91)

Mulholland run 4/19/09
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post #19 of 41 (permalink) Old 04-01-2019, 12:15 PM Thread Starter
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Originally Posted by Gettag8 View Post
Change oil pressure sensor and change your oil
Thanks! I changed the oil and filter on Saturday (went to 10W/40). The CEL did not go out, but from another suggestion here, I need to get the actual pressure now with the new oil.

I will bring up changing the sensor to the shop I'm taking it to.

I really appreciate all the responses here!

09 PBM G8GT Prem & Sport
PPV Struts
Tein Springs
DBA 4000 Series Slotted T3 Rotors
Hawk Performance Ceramic Brake Pads
GM & Pontiac Badge Delete
V8 6.0 Litre Emblems
Rear Mufflers Deleted (replaced with straight pipes)
01/09/10: Fontana - 13.187 @ 106.67 MPH (DA Corrected - 13.036 @ 107.91)

Mulholland run 4/19/09
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post #20 of 41 (permalink) Old 04-01-2019, 01:57 PM
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Does the engineering mode show the oil pressure?
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