Chasing low oil pressure....

[Searay45db]

On 2005 GMC Yukon XL Denali 6.0 L I have been chasing the low oil pressure for a while. Have finally been able to associate a pattern with this. When the weather started getting colder, I would get low oil pressure on start-up. I replaced the sending unit, no good. Other video's show a filter beneath the pressure switch that can cause this, but this does not start till 2007.

After the car warms up, good oil pressure. So long story short, that means it's a seal. How am I so sure? Few years ago my Kubota Diesel Tractor hydro static transmission stopped working when it got cold. Would put it in the garage, let it warm up, and it worked. A guy in Northern Canada on the Kubota forum had me add a seal adaptive I never heard of, that was 2011, tractor still works like new today.

I added the seal additive, and it has greatly improved, but it still needs to be replaced. So there are two areas for the seal. The easy place, is the pick-up tube or-ring. The hard place, the two o-rings n the oil pump. So the logical plan would be to drop the plan, and replace that o-ring, but I guess unless i's a total failure, you could not tell and would have to move on to the oil pump. Any other options?

 

[clandr1]

I'm facing the same issue (2005 5.3 with 175k on it). I'm going to start with the pick up tube o-ring and, if the issues remains, will reluctantly replace the oil pump. I plan on dropping my pan tomorrow.

 

[Searay45db]

I'm facing the same issue (2005 5.3 with 175k on it). I'm going to start with the pick up tube o-ring and, if the issues remains, will reluctantly replace the oil pump. I plan on dropping my pan tomorrow.

Let me know what happened? Interesting plan, as if it does not work, you have to drop your plan again....

 

[clandr1]

Dropped my pan and replaced my oil pickup tube o-ring and the oil pan gasket. The original o-ring was not in very bad shape, so my heart sank at the thought of having to replace the oil pump. However, it was slightly compressed and was starting to get stiff so I replaced it and put everything back together, hoping it was the culprit.

Thankfully it did fix my issue after I replaced it. Oil pressure has returned to normal.

I started around 9 am, took my time, and was done in about 3.5 hours.

I spent about $70 at the dealer for the o-ring and the gasket.

 

[Yoslick]

only an oring on the pickup tube, didnt see any seals in or on the oil pump when I replaced it? Have seen where a combo of the oring and the releief valve in the oil pump affected the oil pressure but never a leaking oil pump itself... Let us know what u decide to do.

 

[swathdiver]

Glad you got it fixed. Haven't seen ramps like those in near thirty years! Are those Wavian Jerry Cans?

 

[clandr1]

Glad you got it fixed. Haven't seen ramps like those in near thirty years! Are those Wavian Jerry Cans?

Thanks! Those ramps were given to me a few years ago - they were left in a house by a renter and I was lucky enough to snag them. I'm not sure what type of cans they are, I just picked two of them up at the local army/navy surplus about 10 years ago and they have held up well over time. The smaller tan one was purchased new about three years ago and holds my two cycle mix fuel. They all work very well!

 

[clandr1]

Dropped my pan and replaced my oil pickup tube o-ring and the oil pan gasket. The original o-ring was not in very bad shape, so my heart sank at the thought of having to replace the oil pump. However, it was slightly compressed and was starting to get stiff so I replaced it and put everything back together, hoping it was the culprit.

Thankfully it did fix my issue after I replaced it. Oil pressure has returned to normal.

I started around 9 am, took my time, and was done in about 3.5 hours.

I spent about $70 at the dealer for the o-ring and the gasket.

View attachment 190276

I thought it was worth mentioning that I've been running Mobil 1 high mileage 5W-30 religiously since I hit about 75,000 miles, and use either Bosch, Wix, M1, or AC Delco oil filters. I send my oil off to Blackstone Labs once or twice a year, and so far they have only shown I have slightly higher silicon and lead levels than normal, although neither one are high enough to worry about right now. I guess it's possible that the o-ring was made of silicon and was slowly deteriorating, which is why they found it in the oil samples in the past. Not sure about the lead though, I assume my bearings are starting to wear, and I'm assuming the o-ring going bad didn't help things since I'm sure my oil pressure was a hair lower than it should have been for a little while.

It'll be interesting to see how this o-ring replacement impacts my future oil analyses (if at all).