12 replies to this topic

[ricekikr]

Rebuilding my 1st Mini.

Stock manifold/downpipe.

Does the downpipe-manifold have a gasket or something to keep it from leaking? It looks like it'l leak.

Or should I use some exhaust putty or something similar?


Edit: additional question.

How come the exhaust doesn't have any flexible joint?

Edited by ricekikr, 21 November 2012 - 10:37 AM.

[maccers]

It needs a gasket on the cylinder head end. If its going into a y-piece first or straight onto a system it will need some form of sealing at all joints where you have clamps. I used a different sealer to the messy holts fire gum stuff, cant recall the name of it now!

If you have a catalyst system, that bolts in, they will need a correct gasket here.

[DeanP]

I think it all depends on the quality of the downpipe, mine is a poor connection and the angle is slightly wrong so leaks a bit. I try to use holts tape, gets it through the MOT, but a few days later it's leaking slightly again. If anyone could recommend a decent quality standard downpipe that fits to the standard manifold good and proper?

[ricekikr]

Mines all standard. The part that concerns me is where the downpipe and manifold meets.

Is there an easy - permanent fix for this?

[charie t]

if it has the taper joint, it requires some exhaust paste to seal it. if it is a flat joint, it reqires a gasket. Flat joints would indicate a catalic converter is fitted, paste should not be used anywhere before the cat
After market exhausts that slot together require exhaust paste also

[ricekikr]

It's tapered.

Where can I buy the sealing ring? Is it like a gasket?

When I removed the exhaust, it didn't look like it had any gasket/sealing ring.

[charie t]

There is no sealing ring, paste is all there is

[ricekikr]

There is no sealing ring, paste is all there is

Ahh ok. Paste it is.

Has anyone welded a flange to the exhaust to make a better seal? Cast but doable.

[DeanP]

Originally the sealing rings, where a fibre/wire/asbestos affair, there is a slight taper on them at both sides. But they seal by been compressed in the joint, by the clamp.

That's interesting and would make sense.

[ricekikr]

Originally the sealing rings, where a fibre/wire/asbestos affair, there is a slight taper on them at both sides. But they seal by been compressed in the joint, by the clamp.

I call them donuts lol, sealing ring didn't register (brain fart). Gona check local auto supply. Minispares doesn't have them. Wonder why they didn't come stock on 91 1275..

Thanks for the info guys. =)

[charie t]

good luck

[tiger99]

How old is this car? I ask because I know for a fact that from 1959 to at least 1984, there never was any kind of sealing ring, the female taper of the downpipe was simply clamped against the male taper of the manifold. I have not (yet?) owned a later model, so can't tell if a sealing ring was introduced with the SPi or MPi.

The correct procedure is to first find the best clamp that you can. The two bolt variety seem to me to be better than those with a single bolt. The early cast clamps were possibly better than the later pressed ones, although that is debateable.

If you have a catalyst, you MUST NOT use any sealing paste upstream of it. If there is no cat, the use of some paste is preferable.

First, check that everything is a good fit. A downpipe which has been used, and may have pulled out of its clamp, will need to be carefully dressed back into shape, welding and grinding flush any cracks in the flared end. If using paste, you put it on thinly on the inside taper of the downpipe. The entire exhaust should be hanging loosely in its rear mounts. Press it up tightly against the manifold with a jack, and check that it is sitting correctly. Now, optionally put paste on the outside of the joint and a single wrap of thin aluminium or copper foil, fit the clamp and tighten. Not using foil, put paste in the groove of the clamp instead.

Once the manifold joint is tight, work from back to front, doing up each mount. The lower mount to the diff casing is very important, and may need shims, washers or other method of adjustment to make it fit.

It is worth taking your time and doing it carefully, to avoid the extreme nuisance of the exhaust separating from the manifold when you are out enjoying your Mini.

[ricekikr]

How old is this car?

Mainstream Cooper. Cat's getting deleted.

Clamp is 2-bolt cast. Some corrosion but looks cleanable.