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[geoffr70]

Hello, I finished putting the car back together tonight after replacing my exhaust manifold gasket (drivers side). This job was a nightmare. I never ever want to do it again. Anyway, I fired her up, she wasn't running too well as she'd been stood for a few days, the battery was flat, she was cold, and the fuel was completely drained from the injector assembly.

Pulled down the street, and it was like driving a completely different car. She was lovely and smooth and quiet. Much better to drive, alot torquier and so much more quiet. There was a vac pipe that I must've missed last time so I connected it and the brakes were alot better. The handling was so much better, don't ask me how or why?!?! To sum up it was like a new car. I took her for a 20 min drive then I heard the terrible gas leak sound again. I'm devastated. It took me the best part of 20 hours over 2 days to do this and it's back to square one, only not quite as bad. I used a VX gasket, new nuts and studs, and all torqued up correctly to 20nm. i used a new gasket on downpipe and torqued the nuts to 20nm. All mating faces were cleaned up and there were no cracks in manifold.

Any ideas? Could it just be the downpipe? I hope so. As it happens the old gasket didn't look that bad, or as if it was leaking anyway.

PLease help someone! Thanks

[Kneepad]

Hello, I finished putting the car back together tonight after replacing my exhaust manifold gasket (drivers side). This job was a nightmare. I never ever want to do it again. Anyway, I fired her up, she wasn't running too well as she'd been stood for a few days, the battery was flat, she was cold, and the fuel was completely drained from the injector assembly.

Pulled down the street, and it was like driving a completely different car. She was lovely and smooth and quiet. Much better to drive, alot torquier and so much more quiet. There was a vac pipe that I must've missed last time so I connected it and the brakes were alot better. The handling was so much better, don't ask me how or why?!?! To sum up it was like a new car. I took her for a 20 min drive then I heard the terrible gas leak sound again. I'm devastated. It took me the best part of 20 hours over 2 days to do this and it's back to square one, only not quite as bad. I used a VX gasket, new nuts and studs, and all torqued up correctly to 20nm. i used a new gasket on downpipe and torqued the nuts to 20nm. All mating faces were cleaned up and there were no cracks in manifold.

Any ideas? Could it just be the downpipe? I hope so. As it happens the old gasket didn't look that bad, or as if it was leaking anyway.

PLease help someone! Thanks

I hope so too Geoff. You must be pretty down after that.
Is it possible that some vacuum pipe has blown off, some connector has came loose.

Wish I could be of more help.   

[amba]

I am also gutted for you,geoffr70 especially as it first sounded like you had sorted it out.

Are you sure it is nothing to do with the egr or the flexiy pipe that connects to the manifold on the drivers side.I am trying to think of words of encouragement for you,but I hope a decnt nights sleep and a fresh check may juts turn up a simple fix for you..well lets hope so.

[geoffr70]

Thanks Guys, I'm going to check them all again now, I made a few mistakes on the make up as I was in a rush and wanted to get finished, and had to redo them! Hopefully it'll be something daft that I've missed! If not I'll have to do it all again! IMO abs ecu like a walk in the park compared to this! Can anyone tell me why I bought a v6?

[aaronjb]

Can anyone tell me why I bought a v6?

Because it has almost the right number of cylinders (it's only missing 2, not 4)?

Sorry.. I know that doesn't help!

[Kneepad]

Pulled down the street, and it was like driving a completely different car. She was lovely and smooth and quiet.[/quote]

That's why   

[Brikhead]

Are you sure it is nothing to do with the egr or the flexiy pipe that connects to the manifold on the drivers side.

I do have the memory of a gold fish but I don't remember a flexi joint on the manifold from when I removed the cats from my 3.0?

I'm wondering if 20 n.m. may be the problem, it doesn't seem like very much to me...

[aaronjb]

Indeed, that's .. 15lb/ft? That's not even one white knuckle

[geoffr70]

After having a nights sleep and thinking logically about this I have found the problem, and know how to solve it quickly and easily! When disassembling secondary air injection I noticed a hole in the hose that bridges two metal pipes next to o/s bank. The hose is about 3 inches long. I didn't think anything of it, but had some hose lying about so cut it and replaced it on reassembly. Once everything was reassembled, there was something burning instantly, and giving off smoke. This stopped after 30 seconds and I assumed it was residue from where I had cleaned coolant. So as stated before, car ok twenty mins then back to normal blowing. On inspection I can see that the new piece of pipe has burnt through, which is the source of the noise. Which is why the original manifold gasket was in good condition - it didn't need replacing! How stupid, and annoyed do I feel now! What I don't understand is how did this pipe burn through instantly, yet it was cool to touch enough to put my hand over it (with engine running) to confirm that was the source of the noise?

[Marks DTM Calib]

After having a nights sleep and thinking logically about this I have found the problem, and know how to solve it quickly and easily! When disassembling secondary air injection I noticed a hole in the hose that bridges two metal pipes next to o/s bank. The hose is about 3 inches long. I didn't think anything of it, but had some hose lying about so cut it and replaced it on reassembly. Once everything was reassembled, there was something burning instantly, and giving off smoke. This stopped after 30 seconds and I assumed it was residue from where I had cleaned coolant. So as stated before, car ok twenty mins then back to normal blowing. On inspection I can see that the new piece of pipe has burnt through, which is the source of the noise. Which is why the original manifold gasket was in good condition - it didn't need replacing! How stupid, and annoyed do I feel now! What I don't understand is how did this pipe burn through instantly, yet it was cool to touch enough to put my hand over it (with engine running) to confirm that was the source of the noise?

That tells a story....you have either a blocked exhaust or cat as they should not be exposed to hot gases under normal operation.

[Andy H]

After having a nights sleep and thinking logically about this I have found the problem, and know how to solve it quickly and easily! When disassembling secondary air injection I noticed a hole in the hose that bridges two metal pipes next to o/s bank. The hose is about 3 inches long. I didn't think anything of it, but had some hose lying about so cut it and replaced it on reassembly. Once everything was reassembled, there was something burning instantly, and giving off smoke. This stopped after 30 seconds and I assumed it was residue from where I had cleaned coolant. So as stated before, car ok twenty mins then back to normal blowing. On inspection I can see that the new piece of pipe has burnt through, which is the source of the noise. Which is why the original manifold gasket was in good condition - it didn't need replacing! How stupid, and annoyed do I feel now! What I don't understand is how did this pipe burn through instantly, yet it was cool to touch enough to put my hand over it (with engine running) to confirm that was the source of the noise?

That tells a story....you have either a blocked exhaust or cat as they should not be exposed to hot gases under normal operation.

You don't think it is a faulty non return valve in one of the stainless steel pipes then?

[Marks DTM Calib]

After having a nights sleep and thinking logically about this I have found the problem, and know how to solve it quickly and easily! When disassembling secondary air injection I noticed a hole in the hose that bridges two metal pipes next to o/s bank. The hose is about 3 inches long. I didn't think anything of it, but had some hose lying about so cut it and replaced it on reassembly. Once everything was reassembled, there was something burning instantly, and giving off smoke. This stopped after 30 seconds and I assumed it was residue from where I had cleaned coolant. So as stated before, car ok twenty mins then back to normal blowing. On inspection I can see that the new piece of pipe has burnt through, which is the source of the noise. Which is why the original manifold gasket was in good condition - it didn't need replacing! How stupid, and annoyed do I feel now! What I don't understand is how did this pipe burn through instantly, yet it was cool to touch enough to put my hand over it (with engine running) to confirm that was the source of the noise?

That tells a story....you have either a blocked exhaust or cat as they should not be exposed to hot gases under normal operation.

You don't think it is a faulty non return valve in one of the stainless steel pipes then?

There are no one way valves in the steel pipes, the only one is where the rubber hose to the vac operated valve on the rad connects.

If you get an exhaust blockage then the gas pressure increases and it travels along the steel pipes to the opposite banks manifold exposing the rubber couplings to heat....they then melt and phut phut phut...

[Broomies Mate]

If your Omega has the standard exhaust, it should have separate pipes from engine through to tail pipe.

Check the pressure at each pipe and compare them.  They should be as close to equal as possible.

[amba]

Glad you have got it sorted out,geoffr70..amazing what a clear head and a nights sleep can solve.

Pity this pipe is not my problem but it is definitaly the nearside manifold gasket..when started from cold and block off the tailpipe you can feel the exhaust escaping from the manifold with your hand.Seems the only sound solution is to have the heads taken off and both gaskets renewed..this is the remedy advised by our resident mechanical wizard.

[Broomies Mate]

Glad you have got it sorted out,geoffr70..amazing what a clear head and a nights sleep can solve.

Pity this pipe is not my problem but it is definitaly the nearside manifold gasket..when started from cold and block off the tailpipe you can feel the exhaust escaping from the manifold with your hand.Seems the only sound solution is to have the heads taken off and both gaskets renewed..this is the remedy advised by our resident mechanical wizard.

You definitely do NOT need to remove the heads!  :-/