Might be my worst nightmare.... low oil pressure, tick noise after 75+mph

[DenaliReyes]

So... 2005 Denali XL 6.O Vortec 211k miles

I have been searching and I might have a problem with my engine losing pressure through either rear main seal leak, plugged oil pick up tube, broken gasket or bad oil pump.

I bought this truck from texas at 207k miles. Drove it to michigan, the first season it went through was that damn polar vortex.

That shtuff jammed my radio and now the screen doesnt work. Also it froze some freeze lines, co.ing from Texas it didnt have much antifreeze.

Well all the antifreeze has been taken care of.
Its I added a bottle of bars leak stopper, it didnt do much, I stil see a little antifreeze on the freeze line by the valley pan.

I recently changed the intake manifold gasket, cleaned the heads where the filter would go. Removed the knock sensors, cleaned them, it was dirty, had no sealant so there was gunk in the front one. Cleaned that up. I eventually will need to replace them.

I have an oil catch can because I figure this would take care of the white smoke that was coming on during cold starts... it fixed it.

So back to the main issue I have.

When I speed up from 50 to 70+ after a while I'll hear ticking noise from the driver side valve covers.

I cleaned the and changed valve cover gaskets recently, the rockets look good and clean, no gunk shtuff like that.

I have not tackled the oil pick up tube, is it a big job?
Can I get to it with out removing the harmonic bal? Maybe through the oil pan? Well that's my next project, starting with the small jobs. Eventually I'll just replace the engine if the cost is similar to just getting another engine on it.

I have used 0w30 on it, the pressure drops quick. At 5w30, not as much. I'm going to drain and fill with 10w30 mobile 1 and add Lucas oil leak stopper.

Any other ideas I should try out before giving up and just getting an engine?

At what milage should I just give up and look for replacements.

I want this truck to last, it is in great shape, no rust compared to what I used to find here in detroit.

Thank you amigos for your help

 

[OR VietVet]

You will not lose pressure thru a rear main seal. You can leak oil there and low oil can cause a loss of pressure if the loss is big enough. Have to drop pan to get to the oil pickup tube. If is the original oil pump that could be the problem. With 200+k miles the bearing clearance could be big enough for oil pressure probs as well. No where in your post do you say what the oil level reads when you hear the noise. I believe the oil called for on that rig is 5w-30. When you experience the ticking noise what causes it to go away? Slow down? Add oil to full? Shut off and let sit and cool down? Etc........

 

[iamdub]

The oil pressure is ok, but then drops when you reach 50-70+ MPH and is followed by ticking?

If this is the case, then it should also drop if you were to rev it in Park or Neutral and hold it at the same RPM it'd be when cruising at those speeds.

If it does this and the pressure goes up if you slow down, then I'd guess your problem is either low oil level or a worn pump.

 

[DenaliReyes]

You will not lose pressure thru a rear main seal. You can leak oil there and low oil can cause a loss of pressure if the loss is big enough. Have to drop pan to get to the oil pickup tube. If is the original oil pump that could be the problem. With 200+k miles the bearing clearance could be big enough for oil pressure probs as well. No where in your post do you say what the oil level reads when you hear the noise. I believe the oil called for on that rig is 5w-30. When you experience the ticking noise what causes it to go away? Slow down? Add oil to full? Shut off and let sit and cool down? Etc........

Much appreciate your help. The ticking subsides once I slow drive 25 mph or below. Sometimes I have to stop and turn off then back on in a minute or two.
It starts to tick once I pass 70+.

As for the oil level, it's normal not low. I always used 5w30, tried out 0w30 to see if the ticking would stop, trying a thicker oil next to see if that changes anything until.i actually find out what's wrong.

 

[DenaliReyes]

The oil pressure is ok, but then drops when you reach 50-70+ MPH and is followed by ticking?

If this is the case, then it should also drop if you were to rev it in Park or Neutral and hold it at the same RPM it'd be when cruising at those speeds.

If it does this and the pressure goes up if you slow down, then I'd guess your problem is either low oil level or a worn pump.

Thank you.

The oil pressure stays steady at 20 after it warms up. But I would have to drive it for that because if I just turn it on, it goes up to 30nthen down to 5 and the alarm goes on.

I have to steady rev it to keep the pressure above 20.


After a while like 10 mins of driving it stays at the low 20sh.

 

[iamdub]

While the weather is still warm, try a heavier synthetic oil like 15w-30 or 15w-40. I say synthetic, not just because it's a superior lubricant, but pertinent in this case because it maintains it's viscosity grade better in the changing operating temperatures. No, this isn't a solution to your problem. It's more of a diagnostic and to possibly keep the low pressure warning off to avoid the nuisance.

 

[OR VietVet]

Those pressures are not even close to normal. Oil pressure gauge needs attached and watch while driving and see if it reads the same. If so, then I would start at the oil pump and may find a bad gasket at the oil pump pickup.

 

[DenaliReyes]

Those pressures are not even close to normal. Oil pressure gauge needs attached and watch while driving and see if it reads the same. If so, then I would start at the oil pump and may find a bad gasket at the oil pump pickup.

Thanks , I'll definitely look into it. I plan on driving down to texas in the spring, do I must get this ride ready.

 

[iamdub]

Those pressures are not even close to normal. Oil pressure gauge needs attached and watch while driving and see if it reads the same. If so, then I would start at the oil pump and may find a bad gasket at the oil pump pickup.

True that the first usual suggestion is to use a mechanical gauge to verify the factory sensor and gauge is accurate. But, unless I'm misunderstanding, he's having ticking that coincides with the pressure drop, and that's undoubtedly a mechanical issue regardless of what numbers the gauge read.

 

[OR VietVet]

True that the first usual suggestion is to use a mechanical gauge to verify the factory sensor and gauge is accurate. But, unless I'm misunderstanding, he's having ticking that coincides with the pressure drop, and that's undoubtedly a mechanical issue regardless of what numbers the gauge read.

As an old guy that ran shops for years I was always taught and always suggested that the tech needs a base line to work off of. If he shows good pressure with a mechanical gauge that could mean two problems. The sensor or gauge as well as a mechanical problem causing the noise that may or may not be attributed to low oil pressure. It could also back up the theory that the low oil pressure has caused the mechanical problem. I like to see if there is a flare with the pressure, a steady or non steady drop or erratic jumpy readings that could also point to oil pump or pickup problems or bearing problems. Sounds corny but when I worked on rigs before running shops I kept a notebook, now notes in a cell, on any big job that came along and I used that to advise the owner along the way. I did this because of this or I came to this conclusion because of this.

I liken this to a head gasket problem. 9 out of 10 times a head gasket goes because the engine overheats. You can fix the obvious after testing to find compression problems and a leak down test but that is never the overheat problem 98% of the time. It is a result of the problem that caused the overheating. Pressure testing before teardown may and likely will bleed off pressure quickly because of a major leak somewhere and/or leaking at the head gasket. I just always err to the side of caution.