MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - Exhaust blowing

Last year I had an annoying buzzing noise from my exhaust when cold at idle and around 2000rpm. I'm fairly sure this was the common noise which is sometimes fixed using the downpipe bracket, but before I really got anywhere with it the noise mysteriously disappeared! Two weeks ago it came back and has been getting gradually worse. This morning it sounds like the exhaust is actually blowing slightly - if you sit parked, rev the engine and let it fall to idle it sounds buzzy, rattly and uneven. Not good! :( On the move the exhaust sounds a bit like it's got a sore throat - the normally burbly SP exhaust has a nasty rattly overtone.

Sooo...is the leak likely to be between the downpipe and the manifold (ie. where the bracket would go)? What's the best way to find the leak? Is it DIY fixable (if the cat nuts are anything to go by, I wouldn't even touch them!)? And a final thought - 2 months ago the car was at Brown and Gammons after an HGF. This would obviously have resulted in the head coming off, might this have caused the exhaust leak? If so do I have any come-back?

TIA as always!

Tim.
Tim Jenner

Tim, on my F it was definitely the flexi pipe that was zizzing (just made that word up, seems to fit the bill). I put a couple of large hose clips round the outside and got some relief. No idea how long it would last as I sold the car shortly afterwards. I had already replaced the exhaust and cat at a previous service so I knew they were OK.

The flexi is visible from just under the car - get under and have a look, then start engine and have another look. You shouldn't need to jack it if you just want to look although one wheel up on kerb will give extra clearance for bellies like mine.
JohnP

Thanks, John. I looked at the flexi last year when I was having the zizzing noise (good word, btw!) and it LOOKED ok - http://homepage.ntlworld.com/tim.jenner/images/kvx/technical/Flexipipe_right.jpg Of course, that was lots of miles ago! How did you determine that the flexi was the source of your noise?

I'll try to get it over a friend's pit at the weekend, that way I can give it a prod whilst the engine is running to see if it stops the noise.

Cheers,
Tim.
Tim Jenner

Tim

A few breaks in the flexi bit were a give away. I reached under the car, grabbed the pipe and got stung by sharp bits.
JohnP

Tim

Also look on Tony's site at the new Flexi Pipe section http://www.apttony.co.uk/

gives a good view of what you should see.

HTH
JohnP

Tim,

The best way to find out the source of the blow is to get under the car and feel for the escaping gasses. Probably best done when the engine is stone cold to avoid burning yourself. If these areas seem ok it may be the Exhaust manifold gasket, occasionally a stud becomes loose and vents gas, this is easily solve with a spanner. The only other place which can cause a problem is the manifold itself cracking, this is all but impossible unless the internal welds have been ground out, was this done when you had the HG replaced.

TBH I would have thought that it will turn out to be the flexi but have an good investigation first.

Tim
Tim

Thanks for the suggestions, guys - it turns out that it's a bit more obvious that that! See http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&mode=thread&access=&subject=69&source=T&thread=200405122045261405

Time for a new exhaust, me thinks...
Tim.
Tim Jenner

This thread was discussed on 12/05/2004

MG MGF Technical index

This thread is from the archives. Join the live MG MGF Technical BBS now