Engine: 2.1 Carb B21A: manifold to downpipe studs

[prisspringle]

the exhaust is blowing at this join so i've ordered the gasket(£1.12 with vat) but they couldn't supply the bolts so does anyone know the size's so i can go grab some.

thanks chris

[malb]

Chris, Other than telling you that the system uses studs and nuts, suspected american UNF thread and needs a 15mm socket to remove/replace, I can't help you re size.

However if you approach the nuts from below the car with a 15mm socket, about 18 inch of extensions and a ratchet it should be possible to release and refasten the exhaust flange nuts from below without damaging the nuts or studs. If possible wear enclosed eye protection to protect eyes from falling muck.

Jack front right side and place on stands (lift both side if prefered)

There are three studs/nuts on manifold flange, outer front (nearest front wheel, inner front (nearest block) and rear (behind down pipes).

I normally tension a bungy strap (elastic cargo strap) so that it wraps around bonnet hinge and both hooks are onto the bridge piece between the two tubes (attach point for lower bracket to bellhousing). This supports the exhaust and you can push it down from above to release/ replace gasket, but don't need to hold exhaust up while you start nuts etc.

18 inches of extensions will let the ratchet operate below the pipe for the two front nuts, but reduce to 9-12 inches for the rear nut, with the ratchet above the the pipe. Make sure that the extensions run close to parallel with the pipes to avoid side loading studs.
Not really enough room to use open ended or ring spanners.

[prisspringle]

from what i have seen there just studs? or atleast the one closes to the bulkhead is... they all look like they have never been undone, so i can see myself drilling the buggers out and tapping the manifold( luckly i've got my tool box in the boot)

place your bets now on how many unfriendly words i'll be saying to do this job!

chris

[malb]

Originally Posted by prisspringle

from what i have seen there just studs? or atleast the one closes to the bulkhead is... they all look like they have never been undone, so i can see myself drilling the buggers out and tapping the manifold( luckly i've got my tool box in the boot)

place your bets now on how many unfriendly words i'll be saying to do this job!

chris

Can't be just studs. Studs (in this context) is length of round metal threaded from either end, one end screws in as a semipermanent fixture while the other end has a nut attached to retain the flange.

If you just have a bolt head at the base of the flange, someone has already had the thing apart and botched it. More than likely they have drilled out the studs and retapped for oversize bolts. Then the exhaust flange has to be drilled oversize to cope and something nasty is done to the gasket as well, most likely making it leak which is about where we started this thread.

Maybe consider hunting around for a decent mainfold with good or easily replacable studs so that you don't have to end up bodging the gasket.

[prisspringle]

i'll have to investigate things a little. the gasket wasn't blowing from near a bolt tho from the center ( bulkhead end) and spread out...

i'd rather not buy a new one as i'm after a bmw 6 to put in rather soon. theres only the missing/snaped maiold stud to deal with nx.....

chris

[prisspringle]

rite i've had a look at things and there stud and nut it helps looking at things in day light!

any ideas on thread size and type?

chris

[Mike_Brace]

They are (or should be) M10. It is really best to take the manifold off and do this on the bench - heat does help them come out but if they shear off they can be then drilled out without too many problems - this is one I tend to take to the independent exhaust specialist.

Mike

[prisspringle]

i was hopeing that they are metric i've got a tool box full of drills and taps so i can take measures if its gonna be a pain.

would running the engine then leaving it till the maifold is warm to touch help free things?

[Clifford Pope]

You don't necessarily know yet that there is anything wrong with the present studs. Soak the nuts in P-Blaster or something like that and leave overnight.
Then from underneath use a well-fitting socket on a long extension and try loosening one. If you can get it to move a bit, apply more lubricant and screw it backwards and forwards a bit to get the rust out. Ease it gently, gradually increasing the range of movement. There generally comes a point when you know it is properly loose and isn't going to shear the stud.

Do the nut back up again reasonably tight, and work on the next one. Then when you are confident they can all three be freed, you can do the gasket job with confidence. But if you get it half apart and then shear a stud, you are stuck with an unuseable car.

[prisspringle]

well that was very easy, far far to easy, done in 30mins till i felt a leak from the engine size so i had to jack the car back up, so ended up taking 50 mins.

why is the jack so funny on the 240's?

chris