Exhaust Manifold to Catalytic Converter Nuts

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Click4
Posts: 3
Joined: Tue Jun 21, 2022 10:26 pm

Post by Click4 »

Any tips on Undoing these?

Only 2 nuts, visually good access to lower ones but having difficulty undoing them due to awkward angle and being seized.

Any tips?

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Lunar
Posts: 1984
Joined: Wed Apr 26, 2017 9:02 pm
Location: Frimley Surrey

Post by Lunar »

Not sure I can help much, but the usual thing of soaking the nuts in releasing fluid overnight (not on a hot exhaust) and maybe tighten to loosen to “crack” the seal.
If you can get a long extension in and a correctly sized (may need tapping on with the surface rust) impact socket, you might then have room to work properly, or even get yourself space for an impact gun.
Alternatively pop down to a local garage and ask them to start them off for you.
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XZ4
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Location: Tayside. Scotland

Post by XZ4 »

I would be getting a garage to do that as they can use a lot of heat on seized bolts. You don't want them snapping.
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cj10jeeper
Posts: 1913
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Post by cj10jeeper »

Always difficult due to the endless heat cycling they have been through. Worst thing you can do is fit a socket or ring spanner and just wrench them. You 'll be having rounded faces or the manifold off to extract snapped studs

I'd soak them overnight with fluid, few good taps to crack them then get some heat on them and an impact wrench. Alternative I'd use a nut splitter if there is access or cut into them with a dremmel and split
If in any doubt go to an exhaust shop and pay to get them loosened, rather than regret it
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Click4
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Joined: Tue Jun 21, 2022 10:26 pm

Post by Click4 »

Just updating,

Finally got cylinder head off. It’s been weeks as parts were on back order and had other jobs to do.

(I’m a mechanic)

Was completely seized, tried heat, penetrating fluid, wouldn’t budge.

Tried using a flexi head ratchet but the funny angle of the nut on the engine side meant it had a shearing effect.

Took off the corners of the nuts even with a hex socket which gripped sides instead of corners.

In the end I used a dremel to cut a slot in the side of the nut.

Then a set of Irwin bolt removers which are designed for rounded bolts / nuts and it came undone eventually.

Just got to try and get the studs out now which will be easier said than done and replace them with new ones I already have 😩.

Glad went down the route of taking head off rather than drilling injector out, found bad supercharger coupling, worn supercharger bearings, deteriorated supercharger insulation pads, rotten cylinder head locating dowels, rotten bolts on the cam cover and a few other places, carbon starting to buildup on the backs of the inlet valves.

Just expensive in parts, far more expensive than getting somebody out to remove them in situ, but will be worth it by the car and go back better than it came apart, all new chains as well going on.


Thanks for the prior advice, much appreciated!

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simpleR
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Joined: Tue Oct 31, 2017 11:56 am

Post by simpleR »

Hi and welcome.

Which model do you have? Presuming a pre-2015 v6.
As its been a month between your 1st and 2nd posts, what's the circumstances of stripping it down?
400 Sport AWD - MY18 - Black, pano roof and thats about it 8-)
Click4
Posts: 3
Joined: Tue Jun 21, 2022 10:26 pm

Post by Click4 »

simpleR wrote: Sat Jul 23, 2022 10:00 pm Hi and welcome.

Which model do you have? Presuming a pre-2015 v6.
As its been a month between your 1st and 2nd posts, what's the circumstances of stripping it down?
it’s a 2015 vehicle.

Just haven’t had time and also some parts were on back order from dealer and I stripped down the supercharger also then had the difficulty with the nuts.

It was 2 stuck injectors which had failed from leaking bonnet vents.

I know that there’s companies out there which can remove in situ, but to be honest found so many other little things like the rotten bolts and supercharger bearings worn, coupler worn, going to sling new chains on it etc. that it was better in the end for the vehicle that it was stripped down, given a chance to inspect things.
simpleR
Posts: 2447
Joined: Tue Oct 31, 2017 11:56 am

Post by simpleR »

Hope you get it all sorted and back on the road for summer.
400 Sport AWD - MY18 - Black, pano roof and thats about it 8-)
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