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MG MGF Technical - noise on decelartion

Any reasons for the following.....

Strange nosie coming from lower engine area on dropping of revs, sounds like a squealing/shrill noise as if something is spinning or loose - however the noise comes and goes - I know this is a vague desciption, but any suggestions would be appreciated. Also when static and rev up and above 4000 revs it is more audiable

Thanks

Simon
Simon

>98 VVC

I can not give you any dirrect advice about this issue, but the early VVC's had a 'relaxing cam bolt' issue, if this is allowed to continue (ie you drive the car) then the cam bolt will come free and the engine will eat itself. However on the + side this should come from the top end of the engine.

Have you tried the old hosepipe to your ear method to track down the noise with more accuracy?
Will Munns

Will

Thanks for the advice, I'll give that a go - in the confines of the garage i think, otherwise i might get some odd looks from the neighbours. Really hope it's not the cam bolt - where is it located just so i can rule this out first?

thanks

Simon
Simon

There are two cam belts on the VVC, one for each end of the engine, the cam bolts hold the cam pullys onto the cam shafts, the whole arangement is under a plastic cover.

So you are looking for noise at the top of the engine, coming from either plastic cover at either end of the engine.
Will Munns

Could be a number of things really, but the first that comes to my mind is bearing in the water pump. Just a suggestion (I'm no expert!)
Andy.
A Mayne


If it were the water pump bearings, would I expect noticable loss in efficiency. As the temp gauge is always spot on(one knotch below half way)- from the noise it would suggest the water pump would be completed knackered- but then again Iam definately no expert.

Simon B
Simon B

>If it were the water pump bearings, would I expect noticable loss in efficiency

The water pump will continue to work at the same effeciany because it is being spun at the same speed, problem comes when it jams, pulls the timing out and your engine eats itself.

Location:

Water pump is driven by the 'major' cam belt, on the LHS of the engine 2/3 of the way down the plastic cover, forwards a little.
Will Munns


After 15 mins shimmering under my MGF, the noise is coming from either the exhaust box or the cat, sounds like a knocking noise which then turns into a shrill-rattle at high revs - the noise goes if you stabilise the exhaust by hand - it sounds as if there is something within either of the above rattling around - any ideas? should i start to reach for the chequebook?

thanks
Simon
Simon B

Could be the flex-pipe
http://www.mgf.ultimatemg.com/mgf_flexipipe.htm

Dieter K.

Err, apology. Hit the Enter to early.
Solution could be the amazing support bracket if you can't see any damage to the mesh.

http://www.mgfcar.de/exhaust_bracket/
Dieter K.

Dieter,

I'll have a look tonight, although the flexi pipie mesh is pretty well worn!

thanks

Simon
simon

Simon,
Sounds like good news!
Will Munns

Will,

The noise definately does't originate from the cam belt cover - only sound from the top of the engine is the hiss of my K&N- so I am pretty relieved - thanks for your advice though.

Simon B

I know you said it was from under the engine, but with noises, it's always best to rule out the most destructive first :-)

The flexipipe is an item known to die over time, the exaust may be an excuse to replce it with a 'stainless' item ;-).

The only item of worry in the exaust system is the cat, these break up internally if you hit them hard, and there have been some mentions of bits being sucked back into the engine, but this is _very_ rare.

As will all exaust parts, avoiding Rover will save you many £s, buy second hand off new crashed F (www.mgfcentre.co.uk / www.midlandmgf.com) or see your local exaust specialist for a pattern part.
Will Munns

This thread was discussed between 08/09/2003 and 09/09/2003

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.