My son had his 2015 Duramax 6.6L 99,xxx miles oil changed at a shop and they used a CQ red oil filter. My son drove the truck 20 miles and when he started the truck up the next time it had a very loud knock. Extremely loud and the truck had around 30 psi oil pressure according to the gauge. I went and bought a AC Delco filter and changed filters and oil pressure is back up to between 60-70psi. Sent the CQ filter off to Mann for testing and they say no defects found in the filter. Thoughts as to what could have happened?
Oil pressure 6.6L Duramax
- Thread starter jsnphllps
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He would have more than likely found out a whole lot more about that filter if he'd cut it open himself.
You marked it with the UV ink? If you did be real surprised if you really get back your filter.
Yes sir, I marked the filter with UV ink so that I know when I get the filter back that it is the same one I sent in. Do you not have confidence that Mann will return me my filter? I mean I think they will but I went the trust but verify way.
Originally Posted by jsnphllps
when he started the truck up the next time it had a very loud knock. Extremely loud and the truck had around 30 psi oil pressure according to the gauge.
30 psi oil pressure won't cause a knock. Perhaps they accidentally started it up without oil?
when he started the truck up the next time it had a very loud knock. Extremely loud and the truck had around 30 psi oil pressure according to the gauge.
30 psi oil pressure won't cause a knock. Perhaps they accidentally started it up without oil?
The filter they removed may have been loaded with debris causing the high pressure. The new filter was more free flowing thus the lower pressure. Are you talking about pressure at idle or cruising?
There are plenty of Duramax forums with more knowledgeable people,
http://www.dieselplace.com/forum/index.php
https://www.duramaxforum.com/forum/
https://www.silveradosierra.com/
but 28 psi hot idle seems very good and 60-70 seems too high unless it's right after a cold start.
http://www.dieselplace.com/forum/index.php
https://www.duramaxforum.com/forum/
https://www.silveradosierra.com/
but 28 psi hot idle seems very good and 60-70 seems too high unless it's right after a cold start.
The filter probably collapsed on the inside.
I have seen a few occurences of collapsed filter reading the diesel forum.
Is it a shop provided filter? If so, they probably put a $1-$2 filter.
I would at least get an ACDelco or above like Napa Gold or Wix, Mobil1, favorite here Fram Ultra.
I have seen a few occurences of collapsed filter reading the diesel forum.
Is it a shop provided filter? If so, they probably put a $1-$2 filter.
I would at least get an ACDelco or above like Napa Gold or Wix, Mobil1, favorite here Fram Ultra.
Was the CQ filter the right one? I had the same thing happen in a Toyota, even when hot and turned off ten minutes, knocked like crazy. Put a Toyota on and all fine even when cold. Not mentioning the brand but a good brand. Never could figure it out except the filter was quite old and I think that was the reason. No visible defects in the filter.
Originally Posted by atikovi
The filter they removed may have been loaded with debris causing the high pressure. The new filter was more free flowing thus the lower pressure.
If the oil pressure sensor is located after the filter, then lower pressure means lower flow if all other factors are the same (oil viscosity/temp, engine RPM), and assuming the pressure sensor is operating correctly. I'd say this vehicle has the pressure sensor located after the filter like 99+% of vehicles.
In order to choke down flow going to the oiling system from a positive displacement oil pump, there would have to be enough flow blockage/restriction to cause the oil pump to go into pressure relief way before it should.
The filter would have to be very restrictive to do that, and also have a faulty and/or very undersized bypass valve. I suppose a collapsed center tube could do that, but the OP said the filter checked out OK by the manufacturer (Mann). Will be interesting to see if the UV marked filter comes back. OP should cut it open when received back if Mann didn't cut it open.
The filter they removed may have been loaded with debris causing the high pressure. The new filter was more free flowing thus the lower pressure.
If the oil pressure sensor is located after the filter, then lower pressure means lower flow if all other factors are the same (oil viscosity/temp, engine RPM), and assuming the pressure sensor is operating correctly. I'd say this vehicle has the pressure sensor located after the filter like 99+% of vehicles.
In order to choke down flow going to the oiling system from a positive displacement oil pump, there would have to be enough flow blockage/restriction to cause the oil pump to go into pressure relief way before it should.
The filter would have to be very restrictive to do that, and also have a faulty and/or very undersized bypass valve. I suppose a collapsed center tube could do that, but the OP said the filter checked out OK by the manufacturer (Mann). Will be interesting to see if the UV marked filter comes back. OP should cut it open when received back if Mann didn't cut it open.
dnewton3
Staff member
At idle, the Dmax should have around 90-100 psi of oil pressure on the dash gauge with cold oil.
At idle, it should drop to around 30-35psi with hot oil.
The oil pressure, when oil fully warmed, will go up to around 45-60 psi (depending upon rpm), as you drive it.
At steady state 1600rpm, it should be around 50psi or so.
Obviously, give or take a few psi depending upon grade of oil and gauge inaccuracy.
This is true of 10w-30 and 15w-40, of which I'd run both in my Dmax.
Without knowing what rpm and temp your son's engine was at, we can only guess. But you can see what would be normal from my info.
Is your son running any oil additives? What was the CQ filter number?
I agree with Zee; it's hard to reason that both the media was so restricted AND the BP failed. That's really two distinct and separate failure modes in the same filter. Almost unheard of.
At idle, it should drop to around 30-35psi with hot oil.
The oil pressure, when oil fully warmed, will go up to around 45-60 psi (depending upon rpm), as you drive it.
At steady state 1600rpm, it should be around 50psi or so.
Obviously, give or take a few psi depending upon grade of oil and gauge inaccuracy.
This is true of 10w-30 and 15w-40, of which I'd run both in my Dmax.
Without knowing what rpm and temp your son's engine was at, we can only guess. But you can see what would be normal from my info.
Is your son running any oil additives? What was the CQ filter number?
I agree with Zee; it's hard to reason that both the media was so restricted AND the BP failed. That's really two distinct and separate failure modes in the same filter. Almost unheard of.
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Sounds like someone started the truck with no or little oil (the shop?) I'm interested in seeing the filter when you get it back.
So some people don't get confused, not all Duramax generations have the same oil pressure ranges. LLY is known for a having a really low warm idle pressure, like ~15 psi. Cruising and cold pressures are usually about the same as other generations.
So some people don't get confused, not all Duramax generations have the same oil pressure ranges. LLY is known for a having a really low warm idle pressure, like ~15 psi. Cruising and cold pressures are usually about the same as other generations.
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