I'm removing the exhaust manifold and the six nuts that bolt to the head are no problem. However there are a pair of nuts and bolts that hold the up-pipe to the manifold end and as soon as I got a socket to it, the edges of the nut crumbled and left me with something more 12-sided than 6. It WAS a 14mm, but now it's almost small enough to fit a 13mm spanner. I'm having to use a two foot long torque wrench just to get these nuts to shift so something like mole grips is just not an option at all.

So the problem is, how to remove this nut/bolt? All I can think of at the moment is:

• Get hold of a six sided 14mm socket
• Cut the nut off somehow

I don't have a grinder or welder, but I do have some rotary files (burrs) plus other normal useful tools like a cold chisel and a bloody club hammer, gas torch, a jigsaw (but dont think I could cut steel with it), junior hacksaw etc.

Obviously if I can get it off without cutting it, and somehow restore the correct facings to the nut, that would be better, then I could have the job done all in one day. Any help appreciated.

PS I don't want this to happen again. It looks pretty obvious to me that you've got a nut in the hottest part of the manifold, exposed to water every day under there - no wonder it rusted. I don't know whether it's a genuine Subaru nut/bolt or whether it needs to be a special kind to cope with this kind of use.

 

They are very difficult i know.

iirc, one is easier to see/get-at than the other. Start there. I would try to split the rounded nut, and to do this try to drill into a side of the nut right down to the bolt. Consider the bolt consumable.
Once you drill down to the thread of the bolt drill bigger and bigger with WD40 as a penetrant and that will free it all off. The other side will be harder but the tension will also be off it more. You may be able to free it off with a 14mm/13mm or other size socket.

You can use brass nuts on steel bolts (Halfords) or stainless hardware when replacing.

As ever, most jobs like this are a sod on an Impreza.

Graham

 

Brilliant, I'll give that a try. Luckily the one that's tucked up out of the way is OK, that feels like it's going to come loose. It's the one that's easier to get at that's being a sod, presumably because there's no longer any heatshield on it and it's been exposed to the elements for while.

I'll give the drilling a go Graham. Cheers

 

Hope it's off, the job done, and you are having a beer!

 

could you not get a nut spliter on it?

 

All done. After half a day of hacksawing, jigsawing, drilling, whacking with a screwdriver and mallet, I gave up and went to Halfords. Bought a nut splitter and tried it out - WOW. Went straight through it. It took another ten minutes of wangling once I'd split it on two sides - the nut and bolt were like one solid continuous piece of kryptonite that had been forged in the fires of the sun, but in the end I did get it off, knackering the splitter in the process.

Now I've got the next problem - getting the crossover pipe separated from the headers and replacing the up-pipe gasket which has been blowing.

 

LOL: :

 

I love doing my own work on the car LOL. Why anyone would go into business fixing other people's as well, I don't know!