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Smells or Ticking Diagnose a Car or Truck Exhaust Manifold Leak

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Smells or Ticking Diagnose a Car or Truck Exhaust Manifold Leak

Created on: 2020-09-15

This video shows you how to diagnose hard to find and reach exhaust manifold leaks.

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Ooh, that's an exhaust leak. They were told they don't have an exhaust leak. Somebody checked it out. They couldn't find one. I definitely hear something. We're going to need to check this out.

Hey, friends, it's Len here from 1A Auto. If you've been keeping up with our videos like I know you have, you know how to check for exhaust leaks. Unfortunately though, sometimes checking for an exhaust leak isn't going to be the tried-and-true hold your hand against the exhaust and look to see if you find an exhaust leak. Sometimes they're going to be a little less apparent, and sometimes they might even be a little hidden. Essentially, you just want to start up the vehicle and then listen, see where that exhaust leak sounds like it's coming from. Is it coming from the back of the vehicle or the front of the vehicle? It'll kind of give you a starting point on where to start looking. But the best way to start looking would be essentially if you can get underneath the vehicle. So, if you maybe want to put it up on jack stands, or on a lift, if you're lucky enough to have one, you'd want to have the vehicle started, and then you'd want to come right over to the tail pipe and try to cover it. When you cover it, you want to try to feel if you have any pressure. If there's no pressure trying to blow your hand off of there, more than likely, there's a leak someplace. To check for a leak, of course, if you had a second person, they can continue trying to hold it, and you could feel along any of the seams on your exhaust, and then, of course, just follow down along the tops and the bottom of the pipes, assuming that they're not very hot, and just feel and see if you feel any air coming through. You can just give it a little listen and see if you find any noises coming from any of the joints or seams. Keep making your way all the way across to the front. And essentially, where we're heading to right now, for us particularly, is the manifold on this vehicle.

Generally, what happens if you have an exhaust manifold leak of any sort, you're going to especially be able to hear it when the engine is cold, or at least when the exhaust is cold. The reason for that is because when things are cold, they tend to contract, especially metal. So if that happens, if you have a discrepancy in the metal, such as a crack or an imperfection of some sort, it's going to be very apparent, and the exhaust fumes/noise is going to be able to make its way out through it. Once the vehicle warms up or the exhaust warms up, the metal is going to expand and, of course, it's going to kind of close up that crack. So, you might notice that your exhaust leak tends to go away after you've driven down the road maybe a couple miles.

Real quick, we should probably talk about what an exhaust manifold is. The exhaust manifold is going to be the part of your exhaust that's going to mount directly to your engine. This is where the combustion from inside your engine is going to come out of, and then lead its way down to the rest of your exhaust, such as your catalytic converter and then, of course, down to the muffler and out the tail pipe. Now, some manifolds are going to be right out in the open, and it's going to be very easy to see almost everything. Some manifolds, on the other hand, are going to have nice covers over them that are going to help protect everything from the heat that's going to be emanating from it. What you actually need to do when you're trying to diagnose an exhaust leak from a manifold is, of course, to get these shields off of here, because that's the only way you're gonna be able to get a good grasp on what's going on behind them.

All right. So, we've got the manifold out so we can take a quick look at it. There's going to be a couple common places that you'd want to look for a leak on a manifold. One of the first places that I would look, especially if I have it out, would be right along this area right here. It should be very flat, because, of course, there should be a gasket that runs across these in between the manifold and the engine itself. If when looking at the manifold, you happen to see that there's a lot of raised areas and lower areas, you can kind of make a pretty good inclination of where you might have a leak. Obviously, it needs to be as smooth as possible. Sometimes what you might happen to see is some black or even some white coming along those lower areas. That's going to be pretty much where the exhaust leak's coming from.

Some of the reasons why this might actually occur might be because possibly the hardware loosened up a little bit and it created a gap in between where the gasket's supposed to hit up against the engine or even the manifold. And then, of course, what you might get is buildup or even corrosion of the sort. If you have anything like that, and you notice that your hardware's loose, you're probably going to have an issue that looks a lot like this. Another reason why you might find a leak on your manifold could be something due to a simple crack. A lot of times, they're going to be hard to see, because more than likely, you're going to have some shields over your manifold, and that's to kind of help dissipate the heat before, of course, it gets close to any of the other engine components.

Behind those shields, what you'll oftentimes find is a tiny little hairline crack, maybe along the tube. Generally, it's going to be along a curve of some sort. Manifolds are, of course, very curvy. Sometimes you might find it in between one of these areas where two parts come together, or even maybe along one of the bends. So, pretty much you'd want to check them all out. And generally speaking, if you do happen to see something that looks like a crack, it probably is. And also, you might happen to see a little bit of black or even white along those cracks.

But check out your whole manifold, make sure you don't have any leaks coming along any of your tubes, and, of course, turn it over and do the same on the reverse side. A common reason why you might find that you have a hairline crack on your manifold, whether it's in one of the grooves, or out like this, would generally be because you have to imagine how much heat is actually coming to these manifolds. There's a lot of heat that's created inside your engine inside the combustion chamber. It's going to be getting forced out directly to your manifold. So, this is going to be pretty much one of the hottest parts of your exhaust. So, think about how hot this might get. And then, of course, it cools down when you turn off your engine. You start it back up, you run it, it gets hot, you rev it up, it gets hotter, and then it cools back down. Hot, cold, hot, cold, back and forth. Of course, the metal is expanding and contracting as that's happening, and you might find that you have an issue.

If you find that you have either a crack on the manifold, as I said, or even an issue with the gasket in between the manifold and the engine, you might potentially hear a ticking noise under acceleration, generally when the vehicle is cold. Once it heats up, more than likely the noise will go away. So if you hear a loud ticking noise when you first start up your vehicle and then it goes away, you probably have an issue up near your manifold.

One last thing I want to talk about on the manifold is the donut gasket. This is going to be the gasket that goes between your manifold, and, of course, the downpipe. Generally speaking, it's going to have spring tension on it because of those spring bolts that you have to remove. Overall, it's very common for this part to leak. Especially if your springs are loose, the exhaust is going to be able to force its way out in between the two pipes.

One of the things about these pipes that you might happen to notice is they tend to have a lot of shields around them. And just like the manifold, around the shields is generally where you're going to find a leak. These shields unfortunately are welded onto the pipe, so they're going to be a little bit harder to get off. It's not just something you can unbolt generally. So, what I'm going to do is since the manifold's out and out of the way, I'm going to take a peek right inside that pipe. The best way to take a peek inside the pipe and find out if you have a crack of any sort is, of course, while you're looking in, hold a flashlight on the outside. If you see any light shining in into the dark area from the outside, you know that you definitely have a leak. And like I said, generally speaking, that leak is going to be found right along the weld where the heat shield's put onto the pipe. So, take a quick peek. If you don't see any leak, you're probably doing all right. This one needs to be replaced.

Another place to look for a leak would be right between the manifold and the actual engine itself. A lot of times what happens is is they'll have a buildup of corrosion, or maybe even the gasket that's supposed to be between the two just kind of dissipates or goes away over time. Other things that might happen is if the bolts or nuts that are holding the manifold to the engine tend to loosen up or break off, that, of course, is going to cause a leak as well. In either case, if you have a leak, you're more than likely going to see some black soot around the holes. So, just take a quick peek. See if you see any areas around the ports that look like they have a lot of black soot around them. That would kind of give you an inkling on where to start looking. Generally speaking, if there's a gasket, you'd of course want to take it off of there, inspect it thoroughly, clean down the engine completely, and, of course, if you're going to be reusing your manifold because it might still be in good condition, you'd clean down that surface as well, go ahead and put it in with a new gasket, some new hardware, and bolt it back up.

So, if we take a look at the gasket that goes between the manifold and the engine itself, when you look at it, you want to look to see if you see any dark areas, something that looks a little black, maybe like this. Or maybe even if you were to look at the other side, we see a much larger area that's black. The reason why they might be discolored like that is because, like I said before, if there's a discrepancy in the metal, whether it's a raised area or a pitted area, it's going to allow the exhaust to seep through, and it's going to make its way in between either the manifold and the engine, or the gasket, and, of course, it's gonna make a sooty area where it's coming out of. So if when you remove your manifold and you see this on your gasket, you know that that's pretty much where your leak was coming from.

Okay, friends, we tried to make you a nice informational video about different places you can look for exhaust leaks on your vehicles, aside from the regular check your muffler, check your mid-pipe type situation. A lot of times, if your vehicle is cold, or at least your engine's cold, and you start the vehicle, you might hear a ticking noise. If you know you hear a ticking noise when you first start it up, but it goes away after your engine's warm, more than likely you have an issue up by the manifold. There's a couple of different issues you might have with the manifold, such as the crack, as I mentioned, or even an issue with the gasket in between the manifold and the engine itself, in which case, once the metal expands and it gets hot, the exhaust noise is going to generally go away. Aside from that, if you need any parts, you can always check us out at And if you like the video, please make sure you smash on the like button for me, like, comment, and subscribe, because it would mean the world. Thanks.

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