Undoing manifold studs and nuts

[keithyboy]

I have to put a new front pipe on my wife's car. The original has been on there 13 years. I've doused them with plusgas and will do so a couple more times. When it comes to undoing the nuts at the manifold I'll use an impact socket but would you go with a breaker bar or an impact gun?

[mk2cossie]

Breaker bar, as you can feel if the nut or stud is going to undo or shear off

[foldy]

Definately use hand tools.

A tommy bar rather than a breaker bar though.

The plus gas should've done the trick, but they'll probably still be tight.

Once the nuts are off and you've got the manifold off, get the studs out (two nuts locked together), then replace with stainless studs.

I got some as a kit from ebay for my Fiesta, and they have a hex insert to fit them without using two nuts.

[Wilk]

Plenty of copper slip on reassembly

[rattlecan]

All good ideas but, heat, heat & more heat on the nuts, before you attempt undoing them

[mertzman]

As above but go easy to start with. It's easy to apply more force when needed rather than stat drilling and tapping later!

[cobblers]

Depending on how easy access is, it's easy to overlook just driving the car for 10 minutes as a way of heating up and loosening off exhaust fasteners. Obviously it's not practical if you've got to squeeze your hand in against the pipe but it can help.

[keithyboy]

Cheers gents. I had a look last night and the studs are actually like wheel studs with a spline and a shoulder so if they do snap I should be able to persuade them out rather than drilling.

[m1keh]

All the stuff above is fair comment. Sometimes it can help if you just give the nut or bolt a tweak tighter before undoing it. It can help to crack the rust off.

Also, try to brush all the old muck out of the threads with a wire brush before you start. It can be hard to get in, but it'll help avoid the nuts getting tighter as they come out, by binding on the muck in the exposed threads.

[scimjim]

Decent hex sockets/spanners too - they grip better than the bi-hex.

[keithyboy]

Someone once said "two out of three ain't bad (unless it's manifold nuts)."

They were 'kin tight but two came off with a good tug on the breaker bar. The 3rd rounded despite using a single hex impact socket. There was no room to get in with any sort of weaponry but there was just room to unbolt the manifold and finagle the manifold and front pipe out from underneath as one. The offending nut yielded to a chisel without even damaging the stud. The nut was very soft indeed.

[colnerov]

Hi, Put them back with Copper coated 'K' nuts, the Copper coating stops them seizing and rusting together again in the future.

www.ebay.co.uk/sch/i.html?_odkw=k+nuts&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xcopper+coated+k+nuts.TRS0&_nkw=copper+coated+k+nuts&_sacat=0

Colin

[keithyboy]

Someone once said "two out of three ain't bad (unless it's manifold nuts)."

They were 'kin tight but two came off with a good tug on the breaker bar. The 3rd rounded despite using a single hex impact socket. There was no room to get in with any sort of weaponry but there was just room to unbolt the manifold and finagle the manifold and front pipe out from underneath as one. The offending nut yielded to a chisel without even damaging the stud. The nut was very soft indeed.

[MrSpeedy]

Don't try and just undo them in one go.
Once you've cracked them, keep screwing them back up half as much as you unscrew them. This will help stop it seizing up and shearing the stud