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I paid too much for an exhaust manifold to replace a cracked one. I sunk almost $200 into the head, and I believed the cracked exhaust could affect the exhaust valves by causing them to get cold air exposure and crack. Now I hear it shouldn't be an issue. I also had both manifolds resurfaced. Now I'm about to redo everything I've done on the engine again, and I'm going to have a solid manifold. Are you telling us the crack doesn't matter, Bob?

New studs and ready to go!

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'78 1.8L 4-speed Fleetside

The only thing more beautiful than a sunset is a sunrise.

Yes i am. Well it depends.

If the cracks not open too wide it will fill with carbon and remain fairly well sealed. This would be the sort of crack you find when you strip/change a motor. Unnoticable untill you see it, most of the time if you put it back on you will forget the crack is even there.

If it has cracked wide enough that you can hear it leaking thats a different story of course. Ive never heard the valve thing before, cant say i think it could be true, engine bay air is warm, its got to go up the runner in the head to get to the valve, thats a fair way it would be warm by the time it got there. And thats only with the engine switched off.


Looking at the pic, id sorce some better nuts to use for the exhaust flange. Those nuts dont look to be any better grade than mild steel and the spring washers wont handle the heat either, both look like the ones that go rusty quick as well. (i could be wrong im just looking at a little picture.) I would suggest a suspension componant or similar nut with a built in flange/washer off a jap car. Its got to be the right pitch thread of course, these are usually pretty hard nuts.


Thats Ok i bought a whole motor just for the exhaust manifold to use in mine. Cost me $200 and came with a 5 speed box and i had to drive an hour each way to get it. It had a con-rod out the side and the only thing i kept other than the exhaust manifold and the gearbox was the inlet and the sump the rest was knackered.


Bob

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Current project, 1979 KB Isuzu Ute.

Daily driver, '86 Rodeo Spacecab.
Chasing parts for Isuzu Impulse.

Two things I want to address;

1. There is a possibility of burning a valve with a cracked manifold. The closer the crack is to the head port, the greater the chance. I agree bob, that the underhood air is warm, but not as much as inside the combustion chamber. There is a reversion effect during the opening and closing of the intake and exhaust valves. This will draw the cooler underhood air in through the crack if it is large enough.

2. As far as the manifold stud nuts go, You can buy brass ones at most any parts store. If the ones in the pic are either stainless or plain steel, they will be hard to remove after comparatively few miles. The brass ones will usually come off fairly easy. Broken studs are a pain.

Hope this helps.

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If you think no one cares, try missing a couple of payments...



FIAA!

SFPP!

Thank you Aussie & Mississippi...I'll be knackered if I didn't enjoy that feedback.

I didn't know there were brass exhaust studs, but it sounds worth looking into. My hope is I never have to take it off again. The manifold in the picture came with two badly worn and rusted steel studs. They were cut off with a Dremel® tool, then drilled out, starting small and working up size by size until all the bolt metal was removed, but the threads undamaged and intact. A tap was used to further perfect the threads, and the new high-grade exhaust studs installed.

I didn't look for high-grade nuts. I just grabbed a couple that fit. I should
get some better ones, good eye Bob.

The weather is thawing out and maybe I'll be sticking my head in under the hood like Litemup!

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'78 1.8L 4-speed Fleetside

The only thing more beautiful than a sunset is a sunrise.

AHH, that's brass nuts, not studs. The studs are the regular stuff.

_________________
If you think no one cares, try missing a couple of payments...



FIAA!

SFPP!

Oh okay. Brass nuts. Somehow it didn't click, but now I understand clearly. That is a good tip. I'll see if I can get them before I have to fire it up. I'm not sure if those nuts in the picture are stainless or not. The studs are in there real tight.

I just put my tarp up, and I'm going over to my post to show y'all what my new sun visors look like.

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'78 1.8L 4-speed Fleetside

The only thing more beautiful than a sunset is a sunrise.

Yea, I've never heard of that before, but reading it here, it makes perfect sense.

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OK, I'm over it. Where's the beer?

I've found the brass nuts in the auto parts store under the HELP! brand. most parts store have a section. I've always used 'em on stock V-8 manifolds and I've found both standard and metric.

_________________
If you think no one cares, try missing a couple of payments...



FIAA!

SFPP!