Blowing noise

[firedrake1942]

Going off the motorway yesterday I detected a different note from the engine of my 57 948cc and pulled over to check. It appears on revving that I have a 'blow' it does not appear to be coming from the manifold / exhaust joint bit hight up towards the front of the engine and I could feel air when revving in this area, distinct from the air displacement form the fan.

Am I right in assuming that the manifold gasket has blown. if so, is it likely that i can get the manifold off without disassembling the joint with the exhaust pipe ?

[dalebrignall]

if its blowing around the manifold then the manifold gasket might be on its way ,i have not tryed to remove the manifold with the exhaust still attached i presume it can be done , just plus gas the nuts before hand , on a cold engine

[firedrake1942]

Thanks Have ordered a gasket set. It appears that the 1098 gasket will fit the 948

jm

[les]

I should imagine you might need to loosen the nearest exhaust mounting strap, to allow the manifold and pipe to come away together but you may find, doing it the way you describe, that the manifold to pipe seal gets disturbed anyway.

[greendefender123]

I used to do that on b series engine that was in a kitcar. Just undone the fixings it would slip off the studs fairly easily and i would tie it back. I always had the engine apart on that thing. Tho abit different on a minor but certainly worth a try.

[myoldjalopy]

I'm sure you have checked the manifold nuts for tightness? I actually had one of the nuts drop off once - which caused some air to leak in and cause an occasional misfire.
However, the manifold should pull back with the carb and exhaust pipe still attached. You can then tie it back out of the way. That's what I did when replacing a head gasket last year. It is possible though that the pipe/mainifold joint may get disturbed, as Les mentions, as the typical clamp isn't the best design for the job..............

[dalebrignall]

you can get a cast iron clamp from esm or mini mine far better than the pressed steel one

[firedrake1942]

There is a cast iron clamp on there but i suspect i will disturb the joint anyway. Thanks for all the advice . I have checked the bolts but was cautious about over tightening .

jm