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ATTENTION anyone with oil pressure issues

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For those of you who've changed the oil pressure sensor & screen, how the #%@#! did you get to it? Did you remove the whole manifold? I've got the parts for this fix, but I'm about to give up & let the mechanic abuse his knuckles.


Any hints would be appreciated.




I have a 2007 5.3L Suburban LTZ with 200,784 miles on it. The oil pressure was sitting at 0 and was occasionally dumping to 80 and back down to 0. I replaced the oil pressure sending unit in it today.


The intake manifold on my 5.3L has a sound dampening cover on the back that's bolted on and the brake booster hose runs through it. This makes it very difficult to get to the oil pressure sending unit. I have a snake camera and probably could have replace it without removing the manifold but it wasn't worth the aggravation. I've read of others with the back cover using u-joints and extensions to replace it but it's really tight. I'm 6'5" and I couldn't reach back there even when standing on a ladder.


Disconnect your battery first.


It didn't take very long to get the intake manifold out. The hardest part was removing the fuel injector connectors. The plastic has hardened making them not work as expected. You're supposed to be able to slide the connector up and push then pull the connector off but I couldn't do so. There's a youtube video on how to get them off:



I left the fuel rails attached. Make sure to remove the fuel rail pressure. Next, use use a fuel line removal tool to pop off the fuel line. Plug the fuel line from the fuel rail if you don't want gas pouring out. I had a little rubbery cap that I slid over the tube. Works great. Remove the positive cable from the alternator as it's in the way (Disconnect the battery first!!). After you have all the connectors disconnected and tubes removed, remove the 10 bolts holding the intake manifold to the engine.


You should now be able to pull the manifold out. You now have easy access to the oil pressure sending unit and filter.


First thing I like to do is place rags or paper towels in the intake holes to keep debris and parts from falling in there. Remove the oil pressure sending unit and discard. Don't reuse the old one because if you do and the problem persists, you'll have to take it all apart again.


The filter is tiny and my fingers are big so there was no using my fingers to get it out. My 11 year old daughter wanted to help at this point and offered to stick her fingers in the filter to get it out but I decided to use a different method. Some people use a curved awl to get the filter out. If you are reusing your filter, the awl will most likely damage it. Instead, the filter has two protrusions on the top that we'll use to get it out. using needle nose pliers, I gave the filter a twist to make sure it was loose then gently grabbed one of the protrusions with it and it came out no problem.


I've only run Mobil 1 Fully Synthetic since I got the car with 7,000 miles on it. The filter was completely clear with no sludge or any other debris. I sprayed it out with some brake cleaner, dried it and popped it back in. Replace yours if damaged or if you don't feel comfortable reusing it.


Next, put some sealant on the threads of the new oil pressure sending unit and install it. I believe the torque was 26 ft. lbs.


Clean the area around the intakes. I vacuumed everything out good first as some rodent put tiny acorns all up under the intake manifold.


Inspect your intake manifold gaskets and replace if needed. I cleaned and reused mine as they were fine.


Installation is the reverse of removal. The intake bolts have a specific sequence and two stages of torqueing them down. I believe the first round is 44 in. lbs. and the second round is 89 in. lbs.


Double check that you have everything hooked back up, reconnect your battery and fire her up! Check for leaks and if all is well, take her for a test drive.


It sounds like a lot of work but it's really not. It took me about 1.5 hours from start to finish and that included eating a quick dinner and putting my kids to bed. It probably took me 1 hour but I've been taking apart cars and putting them back together since I was 10. If you don't do much car work, I'd give it about 2 hours. If you have the rear cover and are trying to get to it without removing the manifold, good luck and allocate at least 4 hours for scraped up hands and dropped tools, filter and oil pressure sending unit. Not to mention aching stomach and chest from laying in the engine bay along with aching knees from leaning over into the engine bay.

Edited by KTruck75
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Thanks, KTruck75. I figured it would be about like that.


I did see another YouTube video where they disconnected the fuel line, then zip-tied the metal (a/c?) tube to some electrical lines to bow it out of the way. Somehow, they shoved the brake booster vacuum hose up out of the way, though I can't tell if they removed the end that connects to the manifold. And if they did, I have no idea how they did so, since I can't envision what kind of pliers could reach back into that space to get to the hose clamp. So, with those 2 hoses & the metal line out of the way, I could see that freeing-up just enough space to get back in with a socket and an articulated extension.


I drove the truck over to the mechanic's place yesterday, & shoved an envelope through the door slot with a note & the keys in it. I'd prefer to pay for 2 hours of his shop time & have the thing done correctly, than to jerk around with it for 5 or 10 hours of my time, and end up with all the soreness & aggravation.


I'm kinda surprised to hear that your screen was clean. I've been diligent about oil changes with this truck, & air filters, too. The only thing I can think of is that I'm on my second OCI using MaxLife, so maybe it has some detergents that loosened stuff that hadn't been causing a problem before. I asked the mechanic to save the old screen, so I'll post back on what it looks like.


Thanks again,



Edited by Folically Challengjed
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  • 2 weeks later...

These units are also known for cracking and leaking, it will give the impression of a bad rear main seal.


Sara (2001 Z28) had hers replaced after 9 years. The engine heat is the culprit in the units cracking.

Edited by Gurrzt
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  • 4 months later...

I wonder if there is a way to make it so the oil pressure switch is kind of remote mounted. Could some creative plumbing with high-pressure lines and proper fittings be used to move the switch (and screen) a few inches so it could be changed in the future without removing the intake manifold?

Edited by GB13SierraSLE
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I had this same issue, truck went to the dealer about 6 times, After they Changed the scender, screen, and Threw an oil pump at it. it lasted a week then the truck was puffing white smoke at startup. they cleaned and changed the screen 3 times and then changed the oil and its been fine since...

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  • 2 months later...

I just fixed one of these last Saturday.

Our issue was actually low oil pressure. Our Oil Pressure sending unit appears to be good.


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 the 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.

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 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.

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 book said to tighten to 240 lbs. 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 a major oil leak if they are not replaced.

The U tube video, 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.

The timing cover will have a new gasket but the mating surface to the oil pan will depend on the old oil pan gasket to seal so I recommend a thin coating of " The Right Stuff" on the bottom of the timing cover and a thin bead where the block, oil pan and timing cover meet. It worked for us, no leaks at all. Clean all the surfaces really well, it does not take much to create a leak path for hot oil.

Clean the harmonic balancer seal surface well also, and lubricate it and the new seal before installing to avoid damaging your new seal.

Same with the new Oil Pick up tube O Ring, lube it well with oil or assembly lube to make sure it does not stick or get cut on install.

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 the new Water Pump Gaskets and the Oil Pump O Rings.

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.

HOPE THIS HELPS. Good Luck with yours.


PS: my buddy is so happy he has been sending me pictures of his gauges on start up every morning. No engine noise and always 65 psi on first start, sometimes higher when it is cold out, 40 degrees temp.

I now wish I had installed the new Melling pump in my truck, I just changed the O Ring on mine.

Thanks for sharing the notes about the sending unit filter. Good to know.

Edited by Westlotorn
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I never drove my buddy's 2005 before we replaced the oil pump. He claimed his low oil pressure light was coming on frequently and in his case the engine would start ticking at the same time the light came on.

Because of these two facts I did not consider the gauge an issue. We just fixed the problem.


The High Pressure or High Volume pumps are normally not needed unless you have an issue. Worn our bearings will leak more than bearings in good shape so more oil drips to the pan and less is pumped into the engine.

Only happens with worn engine bearings. My buddy's truck had 230,000 miles but did have frequent oil changes and it has fantastic oil pressure after our work with the stock pump from Melling, M295 I think the number was.

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  • 2 weeks later...

Just want to add my two cents here, and it will benefit no one but my own need to :rant: .


What an assinine place to put a fairly crucial sensor, not to mention the need for more expense having to replace intake gasket as well. I am a firm believer that if you have it exposed, might as well change it when it comes to gaskets. I gave it the million dollar try by not removing the intake.....and well I am off to find some bandaids and a beer to curb my ire.


A good reason to have a good mechanic and shop at your dispossal. If nothing else, they have built up the scar tissue where it is needed most.


Thanks, I feel better.


Edited by Cobra_fd
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  • 4 weeks later...

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