Exhaust manifold for my old Buick...I think.
 

I think I've asked this question before. The bug to work on it has bitten me again.

1980 Buick LeSabre Limited, 4.1L V6. It rots in my yard because I'm too broke to work on it, but I really want to get it roadworthy. I'm pretty sure it's got a leaky exhaust manifold. There's plenty of exhaust noise under the hood.

How do I confirm that it's an exhaust manifold leak and identify which side it is?

What step do I take next? Remove it and see if it's flat, as well as checking the head to see if that's flat? Try replacing/doubling the gasket? Get it milled flat again (assuming it's warped)? Or just skip straight to buying a replacement?

If I have to buy one, would one from a junkyard be a waste of time/money? It doesn't seem like I'll have an easy time finding a brand new one at any price...and if I do manage to find one I bet it'll be expensive.

Edit: Where would I find part numbers? Also, looks like there normally isn't a gasket.

Edit 2: Well, maybe I could find new headers for cheap on ebay, the 3.8 stuff is supposedly the same and I'd just have to worry about fitting the LeSabre which is not the usual recipient of headers.

There isn't normally a gasket between the head and manifold, but they can be obtained, and it wouldn't hurt to put them in. Rusty has a manifold leak. First off check to see that all manifold bolts are there, and that they're tight. Sometimes they just work themselves loose, and you can just tighten it back down. Rusty's problem is that the bolt snapped off in the head, and I'm too lazy to fix it on a vehicle that only gets driven 50 miles a month at best. You'd only need a new manifold if the old one is cracked. Also check the donut gaskets between the exhaust and the manifold. Those can go bad and create a similar problem. Replacing the manifold is probably not necesssary, and donut gaskets are cheap.

Seafoaming the engine would help you see where the leak is :D

It could have rusted where it and the cylinder head meet, or cracked, or one of the joints where the manifold and pipe meet could be rusted out.

A junkyard one would be fine since you can inspect it before you buy. Where I live, each manifold goes for about $20 at a private yard.

When you find the spot that is leaking, you may want to start with muffler patch- it comes in a big tootpaste type tube. The patch may last up to a year (I use it on my 1943 tractor exhaust manifold that has rust holes through it). After patching and driving it for a week and seeing other problems, you may realize that you'd rather not spend any more time on it.

I wouldn't buy the headers unless you are sure you have room for them (no frame interference) and you will have to get all of the old exhaust manifold bolts out first (and have enough left remaining to hold the headers on).

Old exhaust manifolds/exhaust fasteners are never easy to remove.

Use only 6 point sockets on these old bolt heads. It's likely you'll need to use a hammer to pound them onto the rust encrusted bolts. Also make sure you are applying force perpendicular to the bolt- try to avoid using swivel joints on your sockets.

If you have a small arc welder, you can always weld a nut to the top of a rounded off bolt head- I've had to do that before.

Good luck with whatever you decide!

That's good news. I'll have to try that. Cheap/free fixing this would make me very happy. Then I could go on to worrying about fixing the carburetor...then upgrading the transmission.

Edit: This post is regarding Jay's post.

I have no welding equipment. I'm pretty decent at removing small broken fasteners, large ones probably not so much.

I do have a couple tubes of muffler bandage stuff, they're packaged with additional material (one with metal mesh, another with a roll of what looks like actual bandage) but they might be the same stuff anyway.
https://contentinfo.autozone.com/znet...00161/image/8/https://contentinfo.autozone.com/znet...00155/image/8/
Actually, the one on the left is sold without the metal mesh material too, as "Joint & Crack seal".

Seafoam might be a good idea, it makes a lot of smoke when it burns, right? So I'd see where smoke comes out. Anything cheaper that will smoke without harming the engine?

I'm not too worried about the viability of the car, but I am worried about paying for parts/supplies...money is in very short supply. The car has 36,000 miles and my grandfather bought it new, which makes it worth more to me than to others; it's also generally a car I really like driving, which also makes it worth more to me.

On upgrading the transmission... You have 2 choices. The Metric 400 4 speed OD, and the Turbo 700 R4 4 speed OD. I'd probably go with the Turbo 700 R4. In any event, make sure the tranny you pick is 1987 or newer. The 87 & newer OD trannys are better than the first versions released in the early 80's. I put a Turbo 700 R4 in Rusty, and I put a Metric 400 in the BWH. You'll probably need to relocate the transmission crossbrace, and depending on configuration, you may need to switch out the driveshaft as well. The 4 speed trannys are usually a few inches shorter than the TH 300 which is most likely in your LeSabre. If you have any detailed questions just let me know.

For the tranny I was thinking a 4L60E with an independent controller. I'm pretty sure those controllers exist. Anyway, that's far in the future; I'd have to fix the exhaust leak, replace most of the rest of the exhaust, and fix up the carb first.

I wouldn't go that far ahead. A T700 R4 is the OD tranny that the car came with from the factory in later years. Any special parts needed (Like if you need a different driveshaft) will be available at your local scrapyard. No controller is necessary. It may be necessary to switch out the plug on the transmission harness, but the existing electronics will be able to lockup the torque converter. This is what I did with Rusty and the BWH.

-Jay

Yeah- that's the muffler patch. I mix in some fiberglass insulation to give mine more strength.

I bet a 50/50 mix of gasoline and engine oil very slowly dribbled down the primary side of the carb throat would make it smoke pretty good. Duct tape the tailpipe shut and it should make seeing the leak much easier.

Good news everyone!

I don't think there's a problem with the manifold at all. I was working on tracing the positive battery cable to see where it's broken (it's not, I was just getting such a bad connection that there was 12v but not enough amps to even run the radio or dash buzzer), and I noticed something else out of place.

The heat stove (as it's called in the Haynes manual) pipe was off the manifold! That's the factory WAI, used when the engine is cold. I think all my exhaust noise is coming out of the big gaping hole in the manifold that's supposed to have a pipe attached.

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