Is this manifold OK to reuse? No visible cracks... (1 Viewer)

[Tighe]

Hi all,

I'm trying to track down a ticking noise that comes from the driver's side after the engine has warmed up a bit. Follows the rev range. I assumed it was a manifold gasket or a cracked manifold. I removed the manifold this weekend and didn't see any cracks.

I made a Photobucket album with more pics here, but there are a few below for reference. I don't see any cracks, and I'm not sure where else I should be looking. I have not measured it but the manifold sure seems to be in plane- I'll use two gaskets when I reinstall it anyway, but in general I didn't see any issues. Some flaking of the metal, but no cracks.

Any ides of what else I should be looking for?

The block looked pretty clean and without any signs of an exhaust leak at the gasket.

The gasket also looked fine, I think...

 

[Spike Strip]

If you've got the J-pipe blocked off and you're sure that gasket is good, look for black soot marks around the horn rings, etc, for places that exhaust may have been escaping. Cracks in the exhaust manifold...

Is that a crack on the exhaust mani right in the center of the picture?

 

[Tighe]

Do you mean in this area?

I will look again when I'm home from work but as far as I remember that was solid.

 

[Spike Strip]

Yes. From pic, it looks like hella big crack ($Hillary sized) to me...

 

[Output Shaft]

The gasket's metal crush rings have black soot coating beyond the ring in places. There shouldn't be any soot outside the rings. There's been a leak past the gasket. Exhaust leaks "tick".

I'd triple check the flatness of the assembly. The manifold assembly is rarely perfectly flat if it has never been machined.

 

[Tighe]

Thanks for the responses. In retrospect perhaps I have not looked at this closely enough. I was looking for larger indications of leakage. I will look again at all the parts again after work.

If the manifold is indeed cracked- is that something that's repairable, or would it warrant a replacement?

 

[Output Shaft]

Usually the crack is in the center of the aluminum intake manifold, under the carb. Not the cast iron ex manifold.

If there's no obvious soot stain eminating from a suspicious crack area, I doubt it's leaking through a crack. My guess is the flange to gasket seal.

 

[Tighe]

In the third picture I posted you can see the area underneath where the carb sits- there are no cracks here. There's what appears to be a slight ripple but it's not a crack. I've seen these crack in this area before- the aluminum portion of this manifold seems solid.

I'm going to drop the manifold off at a shop and have them test it.

By flange to gasket seal do you mean the gaskets between the intake and exhaust manifolds? Is it worth replacing these anyway, while I have the manifold out? I hear some folks put a block off plate here...is that for when there really is a crack in the aluminum under the carb?

 

[Output Shaft]

No,
I meant the sealing surfaces of the manifold that seal against the gasket, that seals against the head.

If the manifold assy is truly flat, you can place it face down on a flat surface, like a Formica table top, and not be able to slide a piece of paper under anywhere.

 

[Tighe]

Great, thanks for the clarification!

 

[Spike Strip]

That crack circled in red, on the exh, looks like it extends all the way from the intake mating surface to the bottom, near the downtube flange. You'll have to use a good light and check on the inside of the exhaust.

Cast Iron is very difficult to repair and usually not worth it since I have a good low-mileage spare I will sell for a price that's prolly way less than finding a competent person to fix it ...

Looks like that assy may have been apart once, already.

Start soaking those fasteners in PB blaster or Kroil.

 

[Tighe]

PM'd you.

That crack circled in red, on the exh, looks like it extends all the way from the intake mating surface to the bottom, near the downtube flange. You'll have to use a good light and check on the inside of the exhaust.

Cast Iron is very difficult to repair and usually not worth it since I have a good low-mileage spare I will sell for a price that's prolly way less than finding a competent person to fix it ...

Looks like that assy may have been apart once, already.

Start soaking those fasteners in PB blaster or Kroil.

 

[Tighe]

Took another look but it's too hard (for me) to tell if there were any through-cracks so I dropped it off with the mechanic for further inspection. They'll also check it for level-ness. I asked them if it's nearly level, can I get away with two gaskets? He said they don't recommend it as one gasket usually ends up blowing out.

 

[Output Shaft]

Machine that sucker if it isn't perfectly flat.

 

[NeverGiveUpYota]

@Tighe Can I ask? Whatever happened with the machinist and this manifold? In that pix of the area right below where the carb sits, to me, it looks like a crack. Was it?

 

[Tighe]

I had the manifold planed at a block welder- he hot dipped it and we both inspected it up close there were no cracks. New gasket from Beno and back on she went, leak free.

I don't know if I got lucky or how common it is for these manifolds to crack - there was some minor flaking/chipping but that was it.

 

[NeverGiveUpYota]

Ok. Thanks for the update. I've got what appears to be a hairline fx in my intake at 'ground zero' as Ryan @CaptClose so I'm weighing the next step as I'm having a hard time getting my truck to run off choke on a rebuilt carb (I did and I feel very good about) and the fact that I've tweaked my timing by hand/feel. I've just ordered a good timing light and a compression gauge so I feel that I need to get those things done correctly before jumping the gun on pulling the intake.

 

[Tighe]

You may check with @Breitz6989 or @Spike Strip for a replacement!

 

[NeverGiveUpYota]

Ha! Seems @Breitz6989 is the wrong one for my intake. He and I both have 87's. And already chatting to Spike.
I am in close contact w/ a welder. Other than convincing him it's the only true most economical option and that it's been done, I don't believe it would be hard for me to get it done.