I own a 2007 Tahoe with 246k miles. Oil changes done religiously at 5-6k and always use 5w30 full syn Mobil 1 with AC Delco PF48 filters. At 190k , was away from home and vehicle started showing many warning lights, service stabilitrak, service traction control, rough running, but once got on road it ran ok. Got it home and had all 8 AFM lifters replaced. Vehicle ran perfect until a month ago. Left home, oil pressure went to zero, warning light to shut off engine. Stopped, oil level perfect. So continued and oil pressure would go up and down and lights would go on and off, when I got home, truck was making a fairly loud ticking noise. Replaced oil sensor and oil sensor screen, all spark plugs( had at least 80k on them), dropped oil pan , replaced oil pump inlet tube oring, was hard and flat, and added the oil pressure divertor shield above oil filter in pan. Finished oil change with same 5w30 mobil one, had also run liquid moly engine flush through engine before work began. Cranked up with lots of optimism, same tick but maybe louder and sounds really loud under oil pan. Can't figure out exactly where its coming from. Any advice would be appreciated.
5.3 noise can't determine where its from
- Thread starter EWLake
- Start date
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swathdiver
Full Access Member
A tick and not a knock from underneath? When the lifters were replaced, were the lifter trays also replaced and the VLOM?
Do you have a mechanic's stethoscope or long extension to try and isolate the noise?
Do you have a mechanic's stethoscope or long extension to try and isolate the noise?
iamdub
Full Access Member
As swathdiver said- grab a mechanic's stethoscope and poke around. I'm sure you already know, but usually lower end stuff is a knock. But, the low end can tick and a lifter can knock and it all can vary depending on who's hearing it. Your best first step is to determine the general area (upper, lower, which bank, etc.). A spun bearing can sound like a lifter tick. A ticking lifter can resonate through the lower end.
Did you happen to check the oil for glitter when you drained it to do the lower end work? You can try unplugging one coil at a time to isolate it to a specific cylinder.
Oil was clean at oil change. No metal in pan, only some sludge from the engine flush. No codes thrown either. Very confusing.
I am not sure. I paid to have the AFM lifters repaired. Not sure about the VLOM. Don't even know what that is. Sorry.
smokymtn65
Full Access Member
Sounds like the pressure bypass in oil pump stuck open on you. Probably did enough damage to cam bearings to drop pressure below whats needed to operate lifters .
swathdiver
Full Access Member
Check your receipts. The VLOM is the part under the black intake with 4 solenoids that collapses the lifters for 4 cylinder operation. It is SOP to replace this anytime AFM repairs are done, especially on the 2007-2010 models as the later unit is much more reliable. When a solenoid slows down, it gets out of time and causes the lifter to self destruct.
In addition, the lifters are kept in position using these plastic type trays. Only the ACDelco trays work, the current aftermarket ones from China fail in moments leading to destroyed engines. With loose tolerances and the wrong material, they allow the lifter to spin which destroys the camshaft lobe its riding on.
I hope the solution is simple for y'all.
Truth! I lived this dream not once, but TWICE.
swathdiver
Full Access Member
I feel for you Dave, that's why I tell everyone, hoping they don't go through what you did.
TollKeeper
Full Access Member
I had the same problem on my Saab, and a few more. The solenoids on the VLOM get lazy, or just plainly quit working. This will cause a Zero/Low oil pressure event.
I plugged the VLOM oil passages to the AFM/DOD with a kit I bought, tuned out of the AFM/DOD... And its been smooth sailing since.
How could GM still sell such a disastrous, problematic, POS system is beyond me.
To plug the VLOM passages to the AFM/DOD solenoids is easy. Remove oil pressure sensor, remove oil screen located below the oil pressure sensor, put in the disc below to block the port, reassemble. You should take the VLOM off, and modify it, as indicated on CrazedPerformance Videos. Then send your PCM/TCM out for a simple tune. And done.
Disc
www.crazedperformancerepair.com
The tuner I used
I plugged the VLOM oil passages to the AFM/DOD with a kit I bought, tuned out of the AFM/DOD... And its been smooth sailing since.
How could GM still sell such a disastrous, problematic, POS system is beyond me.
To plug the VLOM passages to the AFM/DOD solenoids is easy. Remove oil pressure sensor, remove oil screen located below the oil pressure sensor, put in the disc below to block the port, reassemble. You should take the VLOM off, and modify it, as indicated on CrazedPerformance Videos. Then send your PCM/TCM out for a simple tune. And done.
Disc
VLOM Oil Galley Feed Plug | Crazed Performance R
This is the plug to disable the vlom from working or leaking when changed per my video instructions. (This is an updated version and not like the one seen in the original video.) Works on 2005 to 2014 GM DOD/AFM equiped vehicles. If your vehicle is newer (2014-2018) it will still work but needs...
www.crazedperformancerepair.com
The tuner I used
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