Cold start Oil Pressure issue solution 5.3L 2005

Westlotorn · November 15, 2015

I want to share what I have encountered and Thank those that helped ID the problem and offer solutions.

I have had 2 GM Tahoe/Yukon' bodies, a 2002 and a 2003 and just finished helping fix a 2005.

When these get older a O Ring on the oil pump pick up tube gets old and hard and stops sealing so your engine starts sucking air rather than oil.

I read about this and on my 2002 with 135,000 miles pulled the pan, replaced the O Ring and put it back together, no leaks, better oil pressure. Knocking at start up eliminated except after the truck had sat for 3 weeks when it would rattle on start up but quiet down quickly.

Pulling the oil pan involves dropping the front differential down, that is not to hard but you need a good pitman arm puller so you can take the Idler arm and Pitman arm off and move the steering control arm out of the way. Installing the oil pan takes special care, many post that the pan leaks after they replace the gasket. I used Fel-Pro gaskets and followed Fel Pro installation instructions and had zero leaks. If you tighten the pan in the wrong sequence it will leak because the pan is torqued from two surfaces. Follow instructions and you will be fine.

Replacing just the o ring did help a lot on this 2002 Tahoe oil pressure.

Now the most recent repair, my buddy has a 2005 5.3L and asked for help. We discussed his issue, his oil pressure was worse than my Tahoe by far, he had trouble getting over 20lbs on start up and had lifers clacking. Because of this we decided to replace the Oil pump in addition to the O ring. We did this from above and did not pull the oil pan.

His is very quiet on start up, has 65 psi on cold start now at the turn of the key and zero rattles in the engine. If I had the chance to do my Tahoe over again I would replace the oil pump also.

I am going to attach how we did his below, this note is in another post but I thought it might help others repair their low oil pressure issue. Hope this helps. Mark

Posted 08 November 2015 - 04:22 AM

I just fixed one of these today. 2005 5.3L started flashing the low oil pressure light a couple weeks ago. The lifters would start ticking when the oil pressure light popped on. Sure sign the oil pressure was actually low.

This is my buddy's truck, he has had it since new, changes oil regularly at 3,000 miles. Now has 230,000 miles.

We assumed the Oil Pick Up tube O Ring was the problem but at 230,000 we decided to change the pump while in there. Only because I thought the by pass in the pump might have been sticking.

We pulled the water pump, harmonic balancer and timing cover then took the cover off the oil pump removed the geroter gears of the oil pump. Took off the one bolt that holds the screen on to the oil pump we were very careful and did not drop the bolt into the oil pan. Actually we unscrewed it enough to see the threads. Made a loop with dental floss and looped the bolt. Tightened the dental floss on the threads and finished removing the bolt. When it comes loose it falls straight down into the pan but we retrieved it with our dental floss.

We cut the tab on the oil pump tube as instructed in D Rays Garage Utube. Thanks D Ray!!!!! This allowed much easier installation of the pick up tube into the new pump.

Again to get clearance we pulled the gears out of the oil pump to help install. Once the pump was in place we put the pump back together and torqued the bolts.

The big bolt on the Harmonic balancer is really tight. My IR Impact with 180 PSI of air would not break this bolt loose.

We put a 18 inch breaker bar with a deep 15/16 socket on the bolt and rotated it till the breaker bar rested on the power steering pump body. With it tight in that position I bumped the key on the starter.

The bolt instantly broke loose. The truck did not start but even if it had the bolt would have spun out fine.

The truck had been starting with very poor oil pressure, very slow to pressurize, the gauge was slow to hit 20psi at idle and would not go much higher and sometimes much lower.

On first start up with new oil, did not prime pump other than to put oil on the gears and wear surfaces the engine fired up and in 3 seconds had 65 PSI at idle.

Once hot this came down to 45 psi at idle and 65 psi at 3,000 RPM hot. No rattle or lifter noise it sounds brand new again.

We took the old oil pump apart completely and it was in perfect shape, could have gone back in but we had the new one so it was used.

The O Ring on the pick up tube was old and hard, no longer round in shape it had flat spots on both sealing surfaces so it was our failure point.

A stinking $2.00 O Ring caused us 12 hours work.

NOTE: it took two of us to remove the oil pump. I held the pump and twisted it clockwise while my buddy had a screwdriver with a wide flat blade prying the oil pump pick up tube down out of the pump.

Going back in this was done in reverse. We could not get the pump on without both of us working.

Putting the oil pump gears back in on install we installed the crankshaft gear first and the outer oil pump gear second. It would not install when we tried in reverse the first time.

While in there we installed a new Water pump, Thermostat, all hoses and belts including the ones that feed the Throttle body 2 hoses for this.

It is so nice to have it start quietly and see the oil pressure hit 45 on a hot start right away with a turn of the key.

12 hours for us, 2 guys doing the job with all the proper tools.

PS: I used a OTC 5 Ton 3 Jaw puller and it worked perfectly to pull the harmonic balancer. A thick washer on top of a 7/8 deep socket worked as a spacer up against the crankshaft for the puller to push against.

There are three indentations on the back side of the Harmonic Balancer to hook the puller in, they are designed for this purpose and it worked very well.

We used a 12 inch 1/2 inch drive extension to slip between the holes inside the balancer center and out to the block left side of balancer to tighten the balancer bolt.

The OEM Balancer bolt is exactly 4 inches long from tip to the underside of the bolt head.

We bought a extra bolt 5 inches long to pull the balancer back on when we did the install. It worked very well.

We used the 5 inch bolt to push the balancer back on the first inch or so. The factory bolt is too short to do this job but once you get it part way in switch to the factory bolt and continue.

We used the old 4 inch bolt to push it the rest of the way on. We tightened this to seat the balancer on the crankshaft. The balancer is neutral, has no timing or alignment marks so it can slip on in any position. The book said to tighten to 240 lbs to seat the balancer in proper spot on the crankshaft. My torque wrench only goes to 150 so I used the 18 inch breaker bar with a 2 foot extension pipe on it to get it that tight.

Per instructions we then pulled the bolt one more time and re installed a brand new balancer bolt. $14.00 on line purchase Amazon. These bolts have a rubber sealant on the underside of the head and could be an oil leak if they are not replaced. We used a little bolt sealer on the threads as a back up. Same as head bolt sealer.

The Utube video from Le Roys Garage and other reading helped do this job correctly the first time. We had no leaks, it is quiet and has GREAT oil pressure again.

Our timing gears and chain appeared perfect, not much slop so we did not replace them.

Don't put this job off, a friend of ours spun a bearing while he ignored his low oil pressure and needed an entire new engine.

We installed a Melling M295 Oil Pump Standard replacement pump. Did not choose High Volume or High Pressure and we had 45PSI Hot Idle. Very good!

We used quality Fel-Pro Timing Set gaskets which came with new Water Pump Gaskets and the Oil Pump O Rings so even if you don't replace your oil pump the Timing Set will give you all the needed gaskets.

The 5 inch bolt is a Metric bolt M20 x 2.0 thread pattern. We needed a thick washer to work with this bolt but it did the job perfectly for install.

Went about 1/2 way on with this bolt then switched to the old OEM bolt to seat the balancer then switched to the new OEM bolt for final torque.

The timing cover and oil pan gaskets use a rubberized silicone bead for sealing. The parts need to be very clean so they can seal. Because the mating from the oil pan gasket to the timing cover depends on the old oil pan gasket to seal I recommend using some of " The Right Stuff " sealant, put a thin coat across the bottom of the timing cover right before installing it, make sure both corners where the oil pump, timing cover and engine block meet get a thin bead before the timing cover goes on just to help the old gasket seal to the timing cover.

HOPE THIS HELPS. Good Luck with yours.

I should have admitted, the two of us doing this project are nearly 60 years old so we get up and down slowly, inspected and cleaned everything we worked on. I think 30 years ago I could have done this in 8 hours or less. But Hey, we made no mistakes and it is working perfectly.

Again, if I had my 2002 to do over again, I would replace the oil pump. I can't believe how much faster his new Melling pump picks up the oil pressure on start up.

jimlem · December 8, 2015

Nice write up. Thanks.

certified22 · May 6, 2016

This is an old post that was submitted along time ago and while it is informative it's not completely accurate you don't need the pitman arm puller first you just have to lower the differential a hair to wiggle the pan out I too used fel pro gasket and have zero leaked when I replaced this o ring only it didn't help my oil pressure a bit so I moved on to the pump and I just replaced my pump with the same Mellings pumps as this guy used and I replaced my timing set as well when finished zero leaks and I still have no oil pressure so what's up know doc?