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[Harison213]

Hi everyone.

The exhaust manifold on my 2.2 miggie was blowing some time ago with an inch long crack on the top surface. Got it replaced with a new one and same thing happened within few weeks!

Is it just me being unlucky or could there be something wrong somewhere else? For information I used new gasket and studs and they were all torqued properly.

Cheers.

--- modified: on the top surface not bottom!

[Abiton]

Check that the thermostat housing isn't leaking where it seals against the head, and spraying coolant onto the manifold; that could cause crackage.  Look for any signs of evaporated coolant around its perimeter.

Pretty sure that's what caused the front-most stud on ours to give up.

[tunnie]

what kind of gasket did you use?

[Harison213]

Check that the thermostat housing isn't leaking where it seals against the head, and spraying coolant onto the manifold; that could cause crackage.  Look for any signs of evaporated coolant around its perimeter.

Pretty sure that's what caused the front-most stud on ours to give up.

Ermmm, actually the front bottom stud on mine was also missing when I was replacing it! Not the easiest thing to get it out.

Will check for signs of leaking around there. Cheers.

[Harison213]

what kind of gasket did you use?

I got the gasket from Vauxhall but the manifold was aftermarket. Trying to find the invoice now to see if I can get it changed.

[Omega3]

Unfortunately same thing happening on mine. New GM gasket fitted, along with new studs etc 18 months ago and starting to blow top front corner again. Seems this is a common problem. I live in an area with alot of speed humps and often wonder if the constant flexing of the exhaust system has an effect.

[tunnie]

got 2 x 2.2's here, none of them do it, both 100+ plus (mine is 128k)

What kind of gasket do GM give these days, is it multi-layered?

[Abiton]

Where did the first mani crack, and did the second one go in the same place?  Got a picture?

[Harison213]

What kind of gasket do GM give these days, is it multi-layered?

Yes, it is multi-layered

Where did the first mani crack, and did the second one go in the same place?  Got a picture?

Yes and no! I actually took off the heatshield this morning and was horrified to see three massive cracks, one of which was at the same area as the old one.

This is a picture of the old manifold. You can just about see the crack to the left of the area with different colour:


And this one's the new one (few months old now) with 3 massive cracks:


Any idea why it's gone this bad in only few months? Also what are those white stuff on the manifold? I can't remember splashing water or anything and there are no signs of water leakage from around the area. The heatshield has always been on.

Also I replaced all the studs when changing the manifold but the two studs in the middle are considerably different in colour to the outer ones. Does this mean anything? Like the middle pots run warmer or something?

[Abiton]

That's a shocker! 

Looks like your new manifold has nearly fallen in half.

I'd be tempted to pop the other one back on.  That crack doesn't look big enough to let anything in/out; are you sure it wasn't just the blown gasket making the noise 'cos of the broken stud?

Pretty sure there's a similar crack on ours, no noise.

[tunnie]

thats just a few months old 

Is the engine using any fluids? water / oil? Getting good mpg?

[Harison213]

That's a shocker! 

Looks like your new manifold has nearly fallen in half.

I'd be tempted to pop the other one back on.  That crack doesn't look big enough to let anything in/out; are you sure it wasn't just the blown gasket making the noise 'cos of the broken stud?

Pretty sure there's a similar crack on ours, no noise.

Yes it is a shocker and I wasn't expecting it to be this bad 

I was thinking calling the motor factor I bought this from to see if I can get a replacement. The old one blows when cold but goes nearly silent once at normal temperature. It's still enough to fail the MOT though (on emissions) and that was why I got it changed in the first place.

If they don't change it I might get the old one welded although I've heard it won't last long.

thats just a few months old 

Is the engine using any fluids? water / oil? Getting good mpg?

MPG is very low around 23 (used to be 32ish) for combined dual carriageway/urban. Not burning any water or oil although for a while in summer it used to heavily *smell* burnt oil whenever I got out of the car. This went away after an oil change.

[tunnie]

get the codes read, only thoughts are its over-fueling, and the mixture comming out of the exhaust is much richer than it should be  :-/

Good mixture of anti-freeze in the coolant?

[Harison213]

get the codes read, only thoughts are its over-fueling, and the mixture comming out of the exhaust is much richer than it should be  :-/

Good mixture of anti-freeze in the coolant?

Coolant mixture should be good. It was changed when I did the cambelt (if I'm right it was with your help at the Birmingham meet) and hasn't been topped up much since.

Could slight over-fueling over a long period of time damage lambda sensors or the cat? There are no signs of damage, backfires or anything but there was a rather thick layer of carbon inside the downpipe which I thought could affect the accuracy of the lambda sensors, hence pumping more fuel in and hotter exhaust gas. Any idea on this?

[Harison213]

Well I got two pending codes and can't find them on the net - guess they're manufacturer-specific codes: B0118 and C3007. Anyone knows what these are? For information MIL is off and the faults were listed as pending; no freeze-frames.