Exhaust gasket and studs

[BAZ]

Help! my spit 1500 has got a blown gasket on the exhaust joint just under the manifold where the twin pipes join ,problem is fitted the gasket but the studs in the cast manifold are worn and the nuts tighten then just spin ,tried putting a spacer to bring the nuts down the thread a bit but didnt work , any other ideas, is it possible to take the studs out in position ?? or will I have to take the manifold off 

BAZ

[Dicky Blighter]

If you can get the exhaust out of the way (might have to drop a mounting) you can get the studs out without taking the manifold off but it's a real struggle. If you are really unlucky though one of the studs will shear and the manifold will have to come off anyway (guess how I know!)

[BAZ]

thought it might be the case ,looks like bloody knuckle job in situ ,thanks for info will go for it weekend , could try to tap the studs down a size maybe metric so dont take to much metal off

BAZ

[Clive]

[quote by=Dicky_Blighter link=Blah.pl?b=spit,m=1181030060,s=1 date=1181030541]If you are really unlucky though one of the studs will shear and the manifold will have to come off anyway (guess how I know!)[/quote]


More like if you are lucky you may end up with one stud not sheared  :-/ :'(

Once the stud go they need to be replaced, and I think trying to reduce dize (6mm??) would not be that helpful, or even at all easy. Bite the bullet, take the manifold off and do the job. I have taken to drilling he broken studs out (to a clearance size), and then using a stainless nut and bolt, often the bolt head needs a little modifying though.

However the 1500 manifold is notorious for gaskets. Better to fit a 4 branch, or the 1300 single outlet manifold with matching frontpipe. Much more reliable :)

[Dicky Blighter]

[quote by=cliftyhanger link=Blah.pl?b=spit,m=1181030060,s=3 date=1181036237]
... Better to fit a 4 branch, or the 1300 single outlet manifold with matching frontpipe. Much more reliable :)[/quote]

I now have a 1300 single outlet manifold - still blows the gaskets regularly. manifold has now got stud holes drilled out clearance and bolted up with cap head (hex socket) screws as you can get a hex drive and extension on easier than a socket in the tight space particulary on the one nearest the engine.

Anyone got a spare 4 branch? :)

[BAZ]

Thats it then it has to come off i will probably drill them out and put bolts in i've got a glut of brass nuts and bolts and stainless one's to ,the wife thinks the bedrooms gettign decorated this next weekend HUH

BAZ

[heraldcoupe]

The old studs will unscrew if you apply enough heat, you will need oxy to do this though. You can then insert new studs of the original size. Drilled out studs can be a real pain, they are rarely drilled centrally,
Cheers,
Bill.

[Nick Moore]

My car used to have a cast iron 1300 manifold and blew its downpipe gasket with depressing regularity. As Cliftyhanger suggests it was replaced with a Kipping first generation extractor setup and has never bothered me again. Many years later I read somewhere that the reason the cast iron manifolds blow is that original downpipes protrude upwards from the gasket flange to locate inside the manifold, thus providing more positive location. My downpipe never had that extra inch, so the additional flexing was probably the cause of serial gasket failure.

Still, Baz, your car could be trying to tell you it wants extractors!

[heraldcoupe]

When Karen was running a 1500 Dolomite, I obsessed over mounting the manifold and front pipe as rigidly as possible, to prevent flex. I later found an article in a very old copy of the Courier, where removing the exhaust hanger at the gearbox was recommended. I tried this, and the tendancy to blow downpipe gaskets at will was greatly improved. Until that time i was getting no more than 3000  miles between gasket changes.After this the car did 4500 miles without failure, it was sold with the gasket still holding well.
The theory was sensible, the rigid front mounting acted as a fulcrum, so any flexing was concentrated at the downpipe joint. Taking out this mounting allowed more gentle movement along the entire pipe, with less stress on the front joint.
Cheers,
Bill.