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Why Does My Car Truck or SUVs Engine Knock Why Oil Changes Are Important

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Created on: 2019-12-20

In this video, you'll learn why skipping oil and filter changes is a surefire way to destroy your engine!

Engine knock? Okay. So, we know that the Jeep has an engine knock. Let's look at a couple of things that we can look for that might give us a hint of what's going on. First thing we're gonna do is check the oil level. If you have a low oil level, that's gonna cause an issue. Come right over to our dipstick. You can see it says engine oil right on it. We'll pull it up. Just gonna take a look at it. As it is right now, I'm not seeing much of anything on there. Just gonna kind of wipe it down. We could take a...Wow. Look at how nasty that oil was. I'm gonna dip it back in and we're gonna recheck it again. Okay. Here's the safe zone, here's the ad zone, and then here's where your engine's pretty much empty of oil, which is exactly where it is. So, having low oil like this, that'll definitely cause an engine noise and it'll also cause engine damage. So, let's wipe it off again. Take a peek. That oil is disgusting. Unbelievable. Okay. I would like to do an oil change on this to start. We're gonna drain the oil. I wanna inspect the oil and see if there's any metal in it. Okay? So, before we get under there, we'll just take off this oil cap. This lets us know the exact oil that we need to use in this, 5W20. You need to use the right oil. We'll set this right over here and let's get under the vehicle. Okay. So, we're under the vehicle. I've got myself a nice clear cup because there's something I wanna do with it. As I start draining this oil, I wanna try to catch that first bit of it. I wanna try to get at least half a cup here. And then we're gonna look inside and I wanna see if we can see any metal. Okay. Be very careful not to get any of this splashed on our hands. Oh, yeah. Okay. I'm just gonna close this up for now so we can inspect this oil. Wow. Look at that brass. That's all fragments of the crank bearing. So, now that we have a good sample of that oil, let's just drain the rest of it out of here and we're just gonna pay attention to what comes out. Okay? Mud. Mud's what's coming out. Okay. So, we have our old oil right here, if that's what you wanna call it, and some brand new oil right here. As you can tell, there's a very big difference in color. And there's also gonna be a very big difference in lubrication for the engine. Okay, friends, I'm super excited. I've got my teammate, Sue, here, and she's gonna explain to us, in a way that both you and I can understand, what's going on inside this engine.

Thanks, Len. So, Lenny did a diagnostic on a lower end knock. So, I wanna explain to people what that means and how to diagnose it quickly. You can have lower end or higher end, which they call upper end knock or lower end knock. On this particular case, on this Liberty, it was a lower end knock. And the obvious was there was no oil in it. So, when we got it here we heard it instantly when we drove it in, and we said, "Hey, great opportunity to show people what happens." So, we hadn't drained the oil yet either. And we wanna catch that on film for you guys. So, when he drained it, and he saw the brass floating inside that oil, I was like, "Well, this thing's no good." It's not even like keen and recover from this one. You'd have to tear it apart and rebuild it. That particular engine also, quick note, cannot be rebuilt. Yeah. I couldn't find any aftermarket. I don't wanna say it can't be, but I tried and tried to find just a crank and bearings because I was thinking that would be a great show, but I could not find them anywhere. So, they're kind of like, what they call a throwaway engine. It does have 180,000 if that matters. So, could be keep going too if someone did oil changes. So, that's the key, oil changes.

Oil changes.

So, here's a crank. This happens to be a Subaru boxer engine. It's what we had hanging around. So, we took it apart, Lenny and I, to show you guys what a car bearing is. Because there's a lot of misconceptions on what a bearing is in a car. It's not the same as a wheel bearing or like a roller skate bearing, right? Believe it or not, this is what we call bearings in the engine on a crank. It's basically a formed piece of metal with a special coating on it. And there is a brass layer in there. And what happens is, this car, really from a lack of oil changes, started to get that coating chipped away.

Oh boy.

So, the Subaru was gonna have another problem too, other than the obvious of why we took it apart. And you'll see the brass flakes. You can almost see if you look real close to the camera. You kind of see the brass in there. And when it starts to flake off, and it goes into the oil, and it causes damage like this. This surface is so smooth, it's supposed to be...You can see all the wear marks. Now, that's normal wear for a car that had this kind of mileage on this Subaru. But those are connected in the piston. So, here we have a piston head, connecting rod, wrist pin, and here are the bearing caps. So, these bolt around the crank and those bearings sit right in there. They sit right in this seat. You see that? That's how they sit in there, right? It causes that nice circle, has the oil fill right there. The oil jets into the bottom part of the bearings where it hits the steel in there. And here's a crank. So, you've got your main bearings. The main bearings on a crank or an engine are gonna be the ones in the center of the shaft. Those are the ones that don't do a rotation. Okay? So you take your piston, when it goes into the cylinder head, and we'll mount it right here. You see the oil jet hole right there?

Yeah. Oh, yeah.

So, that's where the oil comes out, and pressures out. Look at that. You can see that right on this crank. Look at that recording, it looks like a record player. See that, those lines?

Oh, yeah. Yeah.

Look at this, one of these bearing's stuck on there. So, this is gonna sit right in here, goes like that. Then the cap goes on. And of course, you bolt it up, torque it to the proper specs. And this is also when you get new bearings in a crank or a polished crank, when you're rebuilding an engine, there's many procedures to get this before it's even done. So you don't just put the bearings in, snap it together. There's so much testing you have to do. There's a torque specs and then you squash. There's a test strip, take it out, you measure your test strip, and that'll tell you if you have the right bearing too. There's a lot of procedures.

Wow. There's a lot to it.

Yeah, there is. So this is the block. So this is where the crank sits in. The crank sits right in here. And you have your rear part of the engine. This is the flywheel side. And upfront here, on this happens to be where the front crank seal. So you'd have your front crank seal and your rear main seal. Here's a piston, we left one in this for you to show you. So the crank would go right through here. This would be attached like I just showed you on that one. And this is the motion that's gonna go up and down. So, here's the piston head. So, when the crank turns, this is gonna go just like this, inside the cylinder.


Right? And what happens here is, on this particular car and most cars, the oil pump drive is in the front. So, the pickup screen will come down and it'll sit in the middle. And it's trying to get all the oil from the bottom of the oil pan in the center, where it gathers the most, and then goes into the pump. You always find the furthest bearing usually from lack of oil changes, this will go before the one closest to the pond. So, lower end noise, usually a bearing goes and you start seeing the brass in the oil.

Awesome. Well, great. That's great, Sue. Thanks a lot for explaining that.

Yeah, I hope it helped.

That makes a lot of sense.

All righty.

Okay. So, we know that engine's wasted. We heard the knock, we saw the brass, the oil is garbage. It's time for a new engine/possibly a new automobile.

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