sorry folks - me again!
just found a hole in exhaust manifold at the engine end but not on the joint , on the pipe - seems to explain lumpy running of engine as lots of leakage and corresponding farty noises
i had the mid exhaust done recently but looking underneath i assume its not necessarily easy replacing just the manifold?
the old bolts look quite worn / rusted
any tips?
am i right re the possible link to lumpy running of engine? - remember im clueless re mechanics so feel free to use baby language
thanks
iain
exhaust manifold
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Ed Levin
Re: exhaust manifold
yes, you're right in thinking that this would explain the lumpiness. except for some race engines, engines are designed for backpressure against the exhaust valves, and to run smoothly a properly-designed exhaust system will balance, or equalize, the backpressure on all cylinders. a hole in one exhaust branch will reduce the backpressure on that cylinder and screw up the backpressure balance. hence, both the farty noises and the lumpy running.
Ed Levin
Ed Levin
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Tim Heath
Re: exhaust manifold
Most likely lumpyness will be down to the carbs being our of balance/needing reconditioning etc.
Manifold is a bit of artform in removal but assuming you have a few different 13mm ring and open spanners athe manifold and a welder to replace the welded bolts at the joint you should be fine. By a stainless one next time!
Manifold is a bit of artform in removal but assuming you have a few different 13mm ring and open spanners athe manifold and a welder to replace the welded bolts at the joint you should be fine. By a stainless one next time!
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P. de R. Lelercq
Re: exhaust manifold
Removing the manifold is not as bad as it looks. It's worse if you still have the stupid hot-air pipe thing; throw it away (unless you live in the Arctic Circle).
The three nuts on the downpipe flange are not too bad, although it helps to have a 3/8" drive, universally-jointed, 13mm socket and a long extension for the one in the middle.
If you buy a replacement manifold, check before that it does not have any "necking" on the bends - the factory ones didn't - I have seen many of these and they are rubbish.
The best bet is to find a 1600HF one (!): they were made from stainless steel to cope with all the heat I think as in my view, they were too small for the 1600 - they are the same dimensions as the 1300 one, but with the sensible addition of a couple of spigots at the ends to make life easier for the 2-into-1 downpipe gasket.
Paul
The three nuts on the downpipe flange are not too bad, although it helps to have a 3/8" drive, universally-jointed, 13mm socket and a long extension for the one in the middle.
If you buy a replacement manifold, check before that it does not have any "necking" on the bends - the factory ones didn't - I have seen many of these and they are rubbish.
The best bet is to find a 1600HF one (!): they were made from stainless steel to cope with all the heat I think as in my view, they were too small for the 1600 - they are the same dimensions as the 1300 one, but with the sensible addition of a couple of spigots at the ends to make life easier for the 2-into-1 downpipe gasket.
Paul
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P. de R. Lelercq
Re: exhaust manifold
You are welcome.
The hot-air pipe runs from the back of the manifold to the underside of the air filter inlet pipe; it is supposed to provide hot air in the winter to prevent (I presume) carburettor icing. It is completely unnecessary in typical winter in England etc.
Very often the beastly things have been removed and thrown out, thank God!
Paul
The hot-air pipe runs from the back of the manifold to the underside of the air filter inlet pipe; it is supposed to provide hot air in the winter to prevent (I presume) carburettor icing. It is completely unnecessary in typical winter in England etc.
Very often the beastly things have been removed and thrown out, thank God!
Paul
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lucas
Re: exhaust manifold
Well it is always a challenge getting it back............... But it is useless indeed outside of the artic circle.
Lucas
Lucas