leaky exhaust manifold, advice please

[gsbodine]

Hello all,<br />I've got a '94 Toyota 4x4 that has had a slightly leaking exhaust manifold for a while. I have kept putting off fixing it because of costs. <br /><br />I didn't think there was too much chance of this leading to more serious problems, but a co-worker the other day was saying that it could mess up something or other if I didn't fix it. I don't even remember what it was because it sounded so odd to me, but I thought I would ask some of you here who are obviously more qualified to answer to this.

 

[voxmorgan]

Re: leaky exhaust manifold, advice please

You can burn the valves up from the lack of back pressure and then you will be looking at costs. Best to replace the manifold now then have to replace the manifold and have a valve job done later.

 

[gsbodine]

Re: leaky exhaust manifold, advice please

thanks vox, I didn't realize that lack of backpressure would do that.

 

[SoulWinner]

Re: leaky exhaust manifold, advice please

Dude, you would have to have one big leak to effect back pressure. The biggest problem with manifold leaks is the noise. Some engines have a big overlap in valve timing that will allow the exhaust valve to suck in cold air if there is a leak, and this can mess up the valve, but on your little toyota that isn't an issue.<br /><br />What is an issue is the aluminum cylinder head. The studs that hold the manifold on the head are steel, and the different metals combined with the extream temps causes galvanic corrosion between the stud and the head which can lead to all kinds of complications, such as twisting off the stud if the nut is frozen.<br /><br />A couple of questions, is this a 22r or a v-6? Is it the factory stock manifold o a header? The four cylinder is a lot easier to work on, and while your at it you can DX the whole EGR set-up. If the motor has a header, figure leaks are just part of life. I have never seen a header that didn't leaks occasionally because they just not a strong as cast iron and warp over time.

 

[gsbodine]

Re: leaky exhaust manifold, advice please

ah, ok. Thanks, SW. <br /><br />It's a 22-R. Stock manifold. It's a little noisy and you can see some exhaust in the engine bay, especially on a cold day, but it's not huge. By far, most of the exhaust still comes out the tailpipe normally. <br /><br />are you saying that I shouldn't mess with the manifold for fear that I might break them because of a frozen nut? I just am not sure I am understanding what you are recommending. Thanks a lot for the reply.

 

[ehenry]

Re: leaky exhaust manifold, advice please

Ol'Norse, you haven't said what the problem is other than you have a leak. I own a 22R in an 86 4X4. Is is the manifold gasket or is it the two coated copper rings where the exhausts pipe connect to the manifold?

 

[gsbodine]

Re: leaky exhaust manifold, advice please

Well, I think it's the gasket. I described the symptoms above as I know them. I have not tried to disassemble the manifold connection; I've only peeked in. There aren't any visible cracks, but you can see some exhaust seeping from the bottom where the manifold attaches to the block. <br /><br />Thanks.

 

[JasonJ]

Re: leaky exhaust manifold, advice please

Have you tried tightening the nuts? Otherwise, replacing the gasket is fairly straightforward. Just use a good penatrant on the nuts, and you should be okay. I have always hated that noise, it makes it sound like a lifter issue...