"Where's my oil going?"

[Reprise]

About to change my oil (3rd time by me, and probably 5th time since having the truck); this happens every time, and I promised myself I'd bring it up the next time I changed the oil.

As you 5.3L owners know, our engines require 6qt at change, vs the extra quart that the I-6s require. Here's the thing... within a week or so after a change, I'll lose that 6th quart, per the dipstick. But after I add the quart to replace it - the engine doesn't use / lose any more for the remainder of the OCI - and since I drive < 5K /yr, that's basically an 'annual' oil change.

While I've been working on the truck the past few months (new water pump, plug replacement, among other things), I've noticed *no* leaks from front cover, valve covers, etc. There *is* a slow leak from underneath - but the best I can tell, it's from the bottom - either the oil pan or the rear seal, would be my guess, based on what I see on the first 2" or so on the bottom of the bellhousing (I don't see an 'active' leak there, but it does look 'dirty' / 'darker' in that area, so that leads me to believe the rear main seal has gone south). Obviously, if I'm not leaking enough to change the level of the dipstick over a year's time (after putting in that extra quart as mentioned above), it has to be a pretty slow leak.

Wondering if anyone else with the 5.3 has experienced similar issues, and discovered the cause. Given that I do check the oil level every time I start it up after sitting awhile, I'm not really looking forward to pulling the motor for the pan (plus it's a 4x4), or the trans for the main seal (I suppose that would be the easier of the two) until spring. I'm not even sure I'd do the main seal myself, to be honest, as I have limited room, and work alone.

If it does turn out to be the main seal, what's going to p!ss me off even more about that, is that it was likely visible when I had the trans rebuilt a year or so ago - by the time I thought to bring it up, they were already done with the R&R. But if they were worth their salt, IMO, they would have known that I'd have readily approved replacement of that seal, had they called and said "we noticed..."

 

[Matt]

Do you have DOD active? I thought the 5.3 with the DOD ate oil for some reason.

 

[Reprise]

Do you have DOD active? I thought the 5.3 with the DOD ate oil for some reason.

Sorry - I should have mentioned - mine is an '03, so no DoD. But you're absolutely right, otherwise. Someone posted recently w/ their analysis of 'why' the early DoD engines eat oil - recommended reading, if you're interested: )

 

[Capote]

Have you removed the rubber seal on the bottom of the bell-housing or removed the small aluminum cap on the side to take a peek inside that area? If there's any sort of oil build up on that bottom seal or signs of oil leakage/spray inside the bell-housing, it's a sure bet there's a leak.

 

[Reprise]

I've done neither, actually. I know the aluminum cap is intact (although I'll have to look up how to remove it - AFAIK, it's not threaded - and as I think about it, it's probably a 'turning' exercise, as I recall slots / tabs on the cap / housing.

I think the rubber seal is actually *gone*. Will check these out tomorrow when I'm changing the oil. Thanks for the tip!

 

[Capote]

I've done neither, actually. I know the aluminum cap is intact (although I'll have to look up how to remove it - AFAIK, it's not threaded - and as I think about it, it's probably a 'turning' exercise, as I recall slots / tabs on the cap / housing.

I think the rubber seal is actually *gone*. Will check these out tomorrow when I'm changing the oil. Thanks for the tip!

It's just a small thin cap, that can come out with a pick or tiny flat-head screwdriver, or a knife. I circled it here for you brother.

 

[Mooseman]

Just an fyi for @Capote , the V8 don't have the rubber plugs at the bottom of the bellhousing. Those are only for the 4.2 to access the rear pan bolts.

 

[djthumper]

It actually shows on a few sites the 5.3 as having a capacity of 7 QTs at oil change for the 2003s.

 

[Capote]

Just an fyi for @Capote , the V8 don't have the rubber plugs at the bottom of the bellhousing. Those are only for the 4.2 to access the rear pan bolts.

Ohhh, well shoot. Disregard my post

 

[Mooseman]

Still a good idea to look via the other metal plug.

 

[mrrsm]

Before considering any seal failures as the cause... please have a look at this information:

These are some interesting articles about the G M 5.3L Engines suffering from excessive oil consumption; due in part to AFM (Active Fuel Management) issues as being the prime culprit:

https://parts.olathetoyota.com/blog/4920/gmc-chevy-afm-oil-consumption

http://www.silveradosierra.com/vortec-5-3l-v8/latest-theory-on-oil-consumption-t57177.html

This one ostensibly covers “The Recommended GM Fix for the LS4 Engine with AFM having excessive Oil Consumption":

http://cars.forumsee.com/a/m/s/p12-12663-0233607--oil-consumption-gm-s-official-fix-for-the-ls4.html

 

[Mooseman]

Sorry - I should have mentioned - mine is an '03, so no DoD.

That ain't it.

 

[Reprise]

Picking this back up, after changing the oil, putting in a container of UV dye, and getting one of the USB borescopes to take a look.

I checked all around the outer surface of the engine with the blacklight, after 2hrs or so of runtime after putting the dye in. Not a trace of the dye, anywhere.

Removed the inspection cover from the trans bellhousing, and scoped the flywheel / TC / crank area. (for those wondering, the cover pries off. Three tabs hold it in; turning the cover has no effect on removing it.)

I'll start by saying these aren't the best pics; if I need to take additional ones, let me know, as I still have the truck up on stands at the moment (Sunday, 12/3).


Here, you can see the oil around the outer edge of the bellhousing, large inspection cover removed. The interior appears dry for the most part (more pics below.)


Second pic of the area; other side.


Picture of the borescope cam; to the left is the torque converter; to the right is the flywheel. There are two available holes to poke the scope through. The upper one is closer to the crank seal, but I get a better view from the lower one. Indeterminate at best. But things look dry. I would expect that if the rear main seal were leaking, that I'd see evidence of oil in the area, slung around.
(I do have a couple of pics in this area, but would likely have to take additional ones; they don't show much.)

The next two are in the pan area; both are the passenger side. Driver's side is very similar (again, I took pics, but will post them / additional on request).
Pan is on the left in both; center is the starter (which I hope has many more miles left in it!); top area is the bellhousing.


So...thoughts so far? I'm starting to now think 'pan' instead of 'crank seal'.

Other areas of the engine (front, upper, valve covers, etc.) - no leakage (and again, no UV dye observed anywhere - yet)

 

[mrrsm]

After seeing that much dripping oil... My initial guess would be that if anyone ever had the Transmission out of this vehicle and even just slightly nicked or marked the outer race at the End of the Crankshaft... as the Crankshaft roams back in forth inside the block during periods of acceleration and deceleration ...a Leak around the Rear Main Seal would simply be inevitable ...and the results back there would look just as your images show. Unless the Oil Pan was removed on a prior occasion and.then dinged, bashed, dented or FUBARed during a prior repair... it is a very unlikely suspect ...since there is nothing dynamic moving between the interface of the edge of the Oil Pan and the Crankcase to entice a leak once the RTV hardens in between during its assembly.

Also, the Crankshaft Seal itself is nested inside of an Aluminum Bolt-On Flange and it is made as a One Piece Unit... so the only way it can leak is either if the Crankshaft is seriously out of balance due to a loosened Harmonic Balancer Bolt causing excessive vibration with the HB... or if the Main and Thrust Bearings are in such bad Shape down in the bottom end that the contact surface between the PTFE Seal and the smooth edges of the Crank Outer Race surfaces have simply wallowed out the seal over many millions...even billions ...of RPM cycles.

The White Paper written about PTFE (Teflon) Engine Seals indicates that they should ordinarily last at LEAST 180,000 Miles with normal use and maintenance ...and oddly enough...its actually Gravity itself that causes them to 'slouch and leak' and in the end... defeats them after that amount of time in long and arduous service.

This video involves the GMC Envoys for the 4.2L Engine... but it also has additional diagnostic and repair suggestions worth watching that may help with getting closer to finding out where the leak(s) are occurring:

https://www.carcarekiosk.com/video/2003_GMC_Envoy_SLT_4.2L_6_Cyl./fluid_leaks/oil

 

[Reprise]

After seeing that much dripping oil... My initial guess would that if anyone ever had the Transmission out of this vehicle and even just slightly nicked or marked the outer race at the End of the Crankshaft... as the Crankshaft roams back in forth inside the block during periods of acceleration and deceleration ...a Leak around the Rear Main Seal would simply be inevitable ...and the results back there would look just as your images show. Unless the Oil Pan was removed on a prior occasion and.then dinged, bashed, dented or FUBARed during a prior repair...

Weeelllll...LOL

The trans *has* been out of the truck - but this leakage predated that event. The shop that did it is pretty decent, IMO - they do a lot of work on LSx engines, including two of their project cars - one of which is a '71 Monte with a twin turbo LS2. Now, if there isn't an issue with the rear main...that would explain why they didn't call and tell me they noticed a leak from it - as I know that would've been a perfect time to address it - and they know I would've readily given the approval for it, given all the info I gave them on the 4L60, what I did to it, and what I wanted from it (we're talking 2.5 pgs of single-spaced document, and the shop owner told me he read that *very* carefully...LOL)

Anywho...I haven't had the motor out of the truck, but I've spent a lot of time around / on / underneath it the last couple of years (probably more time than I spent driving it, TBH) - and I've not noticed anything amiss with the pan.
It's not leaking from the front of pan, the drain plug, or the filter / boss.

It's also rare that I detect any leakage on the garage floor or driveway. And yet, it does leak - from somewhere, as you can see in the limited photo gallery I posted. It does not visibly burn oil (as in blue exhaust smoke, so it's not a ring issue). When I changed the oil a couple of weeks ago, and poured the discard oil into the 5qt bottle...it only came up to the 4qt mark - so it was *two* quarts low (which didn't appear to be the case, based on the dipstick).

And it wasn't a case of underfilling, either, based on the dipstick - when I fill it, I know the spec is for 6 quarts - and I throw all six in at once.

Suffice to say, I'll be checking the oil more frequently (I usually always check it before I drive it, since it sits for so long between drives.) Was planning on making it my DD this winter - it's a great truck now that I've spent the last couple of years maintaining it...and since it snows out here, it's good to have the 4WD (although it was 60 freaking degrees today, on Dec 3!)

Appreciate the porosity info - I will be reading that. Sadly, the video didn't help me a lot, but I won't hold it against you... ::laughing::

 

[mrrsm]

I just wanted to mention that I often paint these pictures with very wide brushes because beyond the needs of the OPs ...lurking out there in the shadows are so many others who are facing the same problems and may need to have as much information as possible if they happen to be too shy to ask for themselves.

In the immediate season of cold advancing on us...you more than likely already have a firm grip on this problem... but since this video is not only On Topic...it is also interesting and entertaining. So it is worth mentioning again as a reminder to all following this thread and also suffering with any Loss of Oil Issues to beware having the wrong viscosity oil poured inside their engines... (too high for the purposes of either slowing or stopping Engine Oil Leaks...with catastrophic potential during Deep Cold Weather):

...and this ESSO Film from Canada serves the same purpose:

 

[Mounce]

Everyone assumes that no smoke = no oil burning through motor but it's false. Cats do a very good job at cleaning the exhaust prior to it leaving the vehicle. Unless oil is dumping directly into the exhaust you're not likely to see smoke on a newer vehicle.

Losing oil but no major leaks, nothing but some small un-measurable seepage? One answer, you're burning.

 

[mrrsm]

Absolutely... and a Compression Test would figure out whether one, a few or all of the cylinders could be the offenders here. The main cause is that so much Carbon builds up in and around the Piston Rings and Grooves that it restricts their expansion and contraction, allowing too much oil to bypass the rings, collecting and burning excessively in the combustion chambers. Of course the Oil Leaking out of the back of the engine remains as something still in need of investigation.

The treatment involves using either the GM Top Cylinder Treatment... or the BG-44 to loosen the rings up and clean out the excess carbon build-up around the Valves. Good Call on the CAT @Mounce ... I didn't even think about it 'cooking' the stuff well enough to stop the "Blue Smoke" exhaust from showing its ugly face as before in the early 1980's... and now hiding a multitude of sins.

Now... while this video drags on a little at the beginning, the VOP (Video Original Poster) does do a Great Job of explaining exactly How to Use the GM Top Engine Cleaner to get rid of the Carbon Build-up in his GM Colorado Truck (...it has the 5 Cylinder version of the 4.2L TB and Envoy Engines)... BUT the principles shown here will still apply in doing this to your 5.3L Engine to Clean Out The Carbon in the Top Cylinder areas...and loosen up the all of those Piston Rings:

Incidentally... It is NOT necessary to build one of these units from scratch... you can purchase a Cylinder, Ball Cock Valve and Air Pressure Guage System that includes everything needed to do this job (Tank-Wise). Additionally, you will require some High Octane Gasoline and the GM Top Engine Cleaner... along with a decent length of Fuel Line and proper fuel line clamps as well... from here:

https://www.amazon.com/dp/B009EXEYJC/?tag=gmtnation-20

 

[Reprise]

Thanks, guys. Appreciate your continued interest.

Before we start getting into 'de-carbonization' (is that a word?) - I found the pics that I took with the borescope, and will post them later tonight.
Thinking that my leakage may be from pan (mostly) *and* rear seal (slightly-?)

One additional note - the engine has very good power (especially now that it has a tune) - not sure if that is indicative of whether or not I've got (excessive) carbon buildup. But I'm willing to accept that diagnosis if proven, and it looks like it would be good to do a compression test. I'll need to get a tester (and take out the spark plugs...ugh!) Won't be able to do that 'today'.

More pics later tonight.

On edit: Removing the plugs would allow me to put the scope into each cylinder and do a cursory check of the walls, etc. - so there's that.

 

[Reprise]

OK. As promised, more pictures. Unfortunately, the three that I decided to share as the 'best' - largely look the same. I also ran these through a bit of Win10 'post-processing'...



This morning, I thought I saw a better pic, but these look to be the best indicators in the main seal area. Top blue area is the converter; bolt heads and the plate edge below is the flywheel connection; below is the center 'cover' area. There's not a 'lot' of oil here, but you can see the 'dried' area to the LH side.

Anyway, I still have the thing up on stands. If you want a new round of pics, let me know. I know I suck at smartphone camera work...lol.