I've been preaching this for years about the LS engines. It's almost always the rear engine cover gasket! There's also a porosity issue with the OEM rear covers where they will weep oil through the metal cover. People will change the oil pan gasket and the leak will continue. They'll then replace the rear main seal and the leak will continue. They'll finally replace the rear cover and gasket and the problem is solved. The camshaft position sensor is not in the back top like older LS engines but that's also a common leak point due to the o-ring going bad over time.

You wouldn't think that the gasket on a blank plate to cover the attachement for the oil cooler on engines that don't have the auxiliary oil cooler would be that hard a thing to get right, but they leak like mad. I generally pull the driver's side front wheel and reach in with an extension to remove the bolts with the least grief.

In my days, I never wanted to hear rear main seal. Always looked up and often it was valve cover gaskets. Enjoyed the class.

Good morning Mr Kenny hope y'all have a wonderful day, thank you for this video, I always learn something from watching these.

EXCELLENT camera work and narration. I’m dealing with this same issue. Thanks!

I love looking at your videos I have learned a lot & fixed a few cars from watching you keep the videos coming I’m always watching 👍🏾👍🏾

Crankcase ventilation build up can cause havoc on leaks. Not saying it's a issue here but it sure is the first thing i go to with leaks. Replace the PCV valve most people overlook and forget about then check for leaks see what happens. A bad PVC valve will indeed reveal the weakest link on engine seals and gaskets... I've seen it happen many times.

Thanks for the video Kenny. I'll probably never use the information 'cause I'm a Ford guy right now, but you never know. Keep the good stuff coming.

We've had about 35 of the 6.0 engines in our fleet I've replaced the rear main and plate gasket in only 2 of them and they both had 300,000 plus on them. Very durable engines.

Another well done video Kenny. I hope you have a great day!

Great video. Can you do part 2 of how you fixed the leak

I watch all your vids here in England , ive been sleeping on the streets an in car parks but i just got a flat (i bed appartment ). To anyone in a similar situation, keep the hope bro or sis keep strong in your mindset, if you like god what the hell it cant hurt anything . Just keep yourself as personally clean as possible an your mind strong .if you need a chat I’m here for you all I’m NO guru but ive don it in England . Sorry for stealing your thread 😮😮

How many mechanics would go to this extent to diagnose an oil leak? Most would probably say you need a new engine!

I have the 5.7 litre Chevrolet LS1 V8 engine fitted into a VY Commodore sedan here in Australia & I replaced the old olive coloured rear main oil seal which was 13 millimetres thick with a 10 millimetre thick black Felpro rear main oil seal back in 2016 & I also replaced the seal carrier gasket as well because it's a lot easier to fit the rear main oil seal when the carrier is out of car since it's harder to replace it while you're lying underneath the car at home. The old seal carriers is deeper so I was very careful regarding how far to push it into the seal carrier. I have replaced the oil pan gasket because I was driving over rough road in a Commodore meaning that the oil pan bolts kind of vibrated loose !

I had a 1998 express van and the timing chain cover just split open. We bought it brand new . All decked out VCR, TV, headphone jacks fort. Regency . Anyway to change the cover I had to change oil pan gasket and timing gasket. Bottom of timing cover a rubber gasket was both covers gasket.

Good video! I was just notified by my dealership that I have a rear seal and plate leak. I will trouble shoot this myself but, what angers me so is with this dealership, every time I take mine or my wife’s vehicle in it’s something else. I don’t wanna say it’s sabotage but, every time they point out an issue I’ve gone in and repaired it myself. At seventy five, my days doing this are becoming harder. If they’re doing this to me, I can’t imagine what they’re pulling on the neophyte that has no sense of engines or cars. I take really good care of my vehicles but, I’ve had it with this outfit.

Hi that video helped me to find the leak on vehicle that I’m working on 👍🙏🏼

Thank you Kenny!

This is a great video! Direct and to the point. Thanks

Early models sometimes had a porous rear main seal plate that leaked thru the metal and you had to replace the whole plate.

You sure are a great diagnostic man.

I've seen many of these with a leak at the oil sending unit, they did put it in a wonderful place

Excellent camera work. Very helpful.

Thanks, a customer of mine let his son replace rear main on his Silverado now I have to figure out why transmission doesn't work. I had been looking for that leak prior to his son making more work for me on trans now.

Hope you get that job I have a 09 and would like to see the job done. Thanks Kenny.

Mr.Good Wrench , Leaks out (the Main Concern) and no second guessing! Too many part's replacers out there! Your videos are a learning tool with visual!

I have learned something, thank you! 🙏🏽

i've done these a few times. i pulled the engine replaced the rear plate comes with seal when it was easy to repair the exhaust leak at the left rear manifold and the list of all the other leaks . crank sensor oil filter housing oil cooler hoses ps hoses

Awesome video! I thought my 2011 suburban Ltz was just consuming a lot of oil…looks like I gotta take it in and have the rear main, the plate you were speaking of and the oil pan gasket replaced….not to mention my oil cooler lines…

great attention to detail. thank you

Oil leaks are a pain, especially if the transmission has to come out. $$$ It can be deceiving sometimes, that what appears to be a huge leak really isn't. A few drops of oil or trans fluid looks like a lake on concrete. That one is pretty significant though, since you cleaned it and all, you can tell it's pretty bad. At least if you pull the trans, you will be able to change the seals on the engine and trans, and that gasket you were talking about.

Great explanation of oil leaks on these engines.. Thanks Kenney..!

Thx for the advice, just bout an 07 Sierra leaking badly

Flying sparks garage has a good video explaining that plate and rear main seal. If anyone is curious to what it looks like. I believe it's the video where they're putting the transmission back in to a Corvette. Good info as always Kenny nice wrenching.

I thought that I had a leaking oil pan gasket on my truck but it turned out to be a leaking gasket on the driver’s side valve cover. I ignored the leak for about 10 years until it got so bad that it was starting to leak on the exhaust manifold. Luckily, the gasket wasn’t that hard to change.

@Wrenching With Kenny This helps me a lot. I have a 2008 Escalade EXT, basically the same truck as this, But mine is the 6.2 with 4WD. I have had a minor oil leak for a few years, about 4-5 drops on the driveway over night in addition to whatever it leaks out while driving. The truck has about 110K miles which is low for a 2008. But after I did an oil change last week the leak got about 10 times worse. Constant drip while running and once parked it will leave a 6" diameter puddle on a smooth surface like concrete. I'm at the point of putting my oil change catch pan under the truck instead of a sheet of cardboard. I assumed it was the RMS so I put in some blue Devil RMS additive. The leak has slowed, now down to under a quart a day on a very light 30 mile a day commute and seems to get better every day. But last night I cleaned everything then started the truck and got under with lights and I see now the oil is running down both sides of the back of the oil pan and collecting around the trans inspection port. Inside the trans inspection port it looked just like in this video, a little wet but not nearly enough to explain the amount of oil I'm losing. I'm thinking oil pan or oil pressure sensor as it's coming down both sides of the back of the engine. I still need to look at the back of the engine above the oil pan. Thoughts?

My 2006 Tahoe 4.8 is leaking by the starter like in your video. Also at the end of video that gasket you pointed to above oil filter mine is wet all around there with oil also. I'm going to clean it like you did and watch it idle to determine where it is leaking. Thanks for the video showing this.

Good Morning Kenny..! I’m not so sure about an Avalanche … or a truck named after an avalanche..and I am a Chevy Man .. can’t wait to see how you fix it ..good luck 🍀

Would a borescope make some of these awkward inspections a lot easier? Plus it could be recorded as documentation for the customer.

My issue started when I changed the oil on my 4.3 v6 2000 chevy pickup. After changing the oil I had big oil spots on my driveway . I suspected the crush gasket on my drain plug, so 20 miles later I drained my oil to replace the crush gasket on the drain plug, GOT IT.. Well I continued to have big and bigger oil spots. Shoot either wrong oil filter or double gaskets on the oil filter. 22 miles later I got a new oil filter and I changed it, NO double filter gaskets.. I thought maybe the oil filter was defective. Either way it should stop leaking. NO , still having bigger oil spots. Basically it was the oil pressure sending unit leaking. I replaced it and NO more oil leaks. Regardless why did it start leaking after I changed the oil ? Because that’s the way Murphys law works. I thought that was going to be the problem on Kenny’s video.

THANK YOU KENNY FOR THE FREE GAIN WE APPRECIATE YOU

If you are there at the rear main seal, change the plate and seal. Always

Nice to know the moved the knock sensor.

I replaced rear main front main and timing cover,, then a few days ago I done the sump just to find out it was the crank position sensor that’s about the starter motor 🤦🏻

Great video. I suspect that's what happened to my 2008. Also, what is the technical name for the oil cooler gasket though pointed out at the end. I might as well replace that while doing the job.

Tip: LS motors leak oil easily if the pvc system isn’t correctly working and set up right. LS motors leak oil from flywheel bolt holes on the crank flange when the bolts haven’t been sealed. Both of these conditions are usually found on hot rodded motors.

Thx. Good explanation.

On my 2000 Saturn 3.0 I have the similar issue. Of course 3 shops gave me all different diagnosis, and ALL were wrong. Valve covers, oil filter housing and oil cooler line gasket. It leaks in that same area between the engine and trans. I had the engine installed 2 years ago, and after about 6 months started the leak. It used to leak on the cardboard on my garage floor, but has since stopped in the past 6 months, but still leaks while running, because it still is wet and runs back along the trans and blows back on the exhaust pipe bend and smokes when the lights are on, and I can smell oil burning. I thought it was the main seal, but not sure what covers there are on a 3.0 around there. I put some 205 RE sealant in it and see what it does. The pan usually drains in about 3000 miles and I have to add a quart and a half between changes with synthetic oil. We'll see if that stops it. I'd hate to spend $800 to pull the trans to replace a main seal. I'm too old to mess with that kinda stuff myself anymore. Lol.

The oil cooler line connector block to engine block gasket, as well as the set screw plug in one end of the oil cooler line block is always suspect.

Nice job!

Also the oil cooler gasket near the filter leaks and is known for problems

Thank you so much that's where my Hummer H2 is leaking

I think your diagnosis of the seal plate is correct on this one. However, I've seen those CKP sensors leak a few times. The o-ring is an odd size so you have to get a new CKP to fix it.

Have this problem with my03 Tahoe. Not looking forward to pulling tranny. I’ll replace rear seal oil sensor and cover plate while it’s accessible. Some fun!

I rebuild transmissions and when ever I have the transmission off one of these engines, I always put my finger tip into the well where the cam sensor is located and have found many to be leaking, also there is a pipe plug where that block off plate is on the oil pan and it will leak and it cant be removed as installed, but when the transmission is out it can be checked for tightness or resealed.

I've seen a lot of oil pressure sending units on LSs leak oil.

ya some shop changed this on a 06 5.3 and its leaking worse now 40k miles later than it did when it had like 140k. Sucks removing a transmission on jack stands

I have a 2006 Silverado 5.3 Had rear main seal replaced about a year and a half ago along with oil pan gasket and valve covers. Still had the leak. Had to have some work done a few months ago. Asked them to check the leak. They said it was valve cover gaskets and they were replaced again along with something else underneath ( don't remember what). Stoll have a leak but not as bad.

Great video, I have the transmission removed out of my 5.3 Silverado, But it’s very clean in between the transmission and the engine, is this normal? Mine leaks and drips down the started just like your video shows it leaking

Excellent

For the longest time I thought I had a rear main leak. Then I did head gaskets and found that all the oil I thought was coming from the rear main, was actually coming down from the back of the valve covers.

What's the plate called ?

I have leak btwn the engine and trans on a 6.0 that occurs as it sits on a lift through winter storage. Is there oil trapped behind this plate that would drain out after the car has been sitting for an extended period of not running. All the oil should be in the sump by this point and not above the crank seal

Could the leak be caused by incorrect cleaning/sealing of the rear corners of the oil pan gasket, when it was replaced? (Where the oil pan gasket crosses the end of the rear cover plate and its gasket). J

I have a 2002 Blazer with less than 70k on the 4.3 and it leaks inconsistent,start up more and move out of shop park leaks about an 8 inch circle of oil on concrete. Drive for hours park on concrete, maybe 2-3 small drips ???? Not filter,rear main had new intake manifold gasket done last year,any suggestions?

Work at valvoline ane see this every day

My 4.8 is doing the same thing. Curious how much a reputable mechanic would charge to fix this. I usually tackle everything myself but pulling the transmission isn't fun.

Had a leak on my 2000 gmc 5.3. It was the oil cooler block off plate

Glad to know that is there I have to replace the transmission on my '01 Suburban so I'll go ahead and replace that seeing I have around 250k on the odometer

What’s the name of that plate and gasket, so I can look for it at the part store.

Do these aftermarket plates and seals work just fine? Theyre like $40 for everything. Or do you have to buy OEM expensive stuff?

Another way to find the oil leak is put that fluorescent dye stuff in the oil and use a scanner/viewer to see exactly where the oil leak is coming from.

Automotive Technician - the art and science of doing the almost impossible - for a reasonable fee.

I had taho 5.3 was a leak so dealer put dye in and could not dine the leak then I looked at it and realized it was the engine mount leaking 95 bucks for dye test and they were wrong

When changing the cam pos sensor on the older gen III engines (L59) how complicated is the relearn procedure? I hace adecent scanntool if that helps

Can someone share a part number and link for the "Plate Gasket" as it was mentioned to be the number one culprit before the RMS gasket. I can find the gasket for the oil cooler connection point "block-off plate" (although i dont have it by my 4.8L).

No, Gromit! Those are the wrong trousers!

So what is this plate called?? So I can order

That is 100 percent rear main seal housing leak.

I had a 3800 motor that leaked also on that rear main plate

@WrenchingWithKenny Well, did you replace it ? And was that the issue ?

Is this the part number for that seal/plate? GM Genuine Parts 12639250 LS Rear Block Cover

I have a 2005 Yukon 5.3L 4x4. Looks exactly the same. I may have a very slow rear main leak. I just got it and am watching it now after a fresh oil change. Has 216,000 miles on it. Seems to run great though. 3 questions: 1. Was there a cover on your inspection hole that shows the bottom of the flex plate? Mine does not have a cover of any type. I can see the bottom of the flex plate. 2. I have a pair of ramps that raises vehicles back or front tires by about 12". Would that be helpful to use for this job? 3. So the rear seal has two parts? A shaft seal, plus a shaft seal cover gasket? Does the cover seal just keep dust out? It doesn't have a gasket across the bottom of it, does it?

Any updates kenny?

Dude where is the follow up video regarding the problem?

I need part2

And another aftermarket cold air intake!!

Damn , that truck is clean underneath for a 2007

Where is the fallow up video on this one? 🙁

dont know how to fix this

2007 5.3, yup

That is what is got quoted 500.00 to fix

you're telling us it has something to do with removing the transmission?

Oil pressure sending unit on the top back of the motor. Pain in the ass to change.

how many hours is this job?

So yeah a rear main seal leak because these always get replaced as a unit

😎👍😎

🔧😃🔧

nope high octane gas wont repair this, but blue devil will, lubeguard seal fix will, and reseal 201 will, every conv oil, semi syn, full syn for the past 10 years comes with synthetic lower dose sealer built in

No chance it is a crispy oil pan gasket?