Hissing under load

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Chrish85
Posts: 7
Joined: Fri Apr 14, 2017 10:31 pm
MGF Register Region: South East

Hissing under load

Post by Chrish85 » Tue Jul 25, 2017 7:57 pm

Howdy all,

im scratching my head with my car at the moment. when the car is in gear and under load, there is a weird hissing noise each time im press the accelerator.

Never when its in neutral.... just when in gear.

I've checked the throttle body area and as many vacuum pipes as i can find and they all seem ok.

im more active on facebook than i am on here, thats for sure, the opinion on their is that it might be an inlet manifold gasket, however, when i look at what the typical symptoms all mention coolant loss, which, my car hasn't lost a drop.

Any idea's anyone?

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Tipper
Posts: 720
Joined: Sat Dec 06, 2008 3:39 pm
MGF Register Region: Devon & Cornwall
Model of Car: RV8 + ZS180
Location: Exeter, Devon, UK

Re: Hissing under load

Post by Tipper » Wed Jul 26, 2017 10:00 am

I don't know the immediate answer, but which model is it?

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Green Squirrel
Posts: 515
Joined: Sun Oct 14, 2007 9:36 pm
MGF Register Region: South East
Model of Car: 1996 1.8i

Re: Hissing under load

Post by Green Squirrel » Wed Jul 26, 2017 10:06 am

Check for leaks on the air filter and inlet - mine always makes a roar when I put my foot down BUT that is by design with a K&N filter. :lol:

Chrish85
Posts: 7
Joined: Fri Apr 14, 2017 10:31 pm
MGF Register Region: South East

Re: Hissing under load

Post by Chrish85 » Wed Jul 26, 2017 11:34 am

I've got the 1.8 mpi... I've contemplated removing but the air filter box and popping a cone filter in place but it's a Nov 1995 model and I'd like a keep it close to standard as possible although I've got a s/s back box on It :) there's no drips coming from underneath when it's running so I've ruled out an exhaust leak

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Green Squirrel
Posts: 515
Joined: Sun Oct 14, 2007 9:36 pm
MGF Register Region: South East
Model of Car: 1996 1.8i

Re: Hissing under load

Post by Green Squirrel » Wed Jul 26, 2017 2:28 pm

Mine is a 1995 ordered MPi delivered in 1996 which we have owned since new. I waited for the warranty period to expire before fitting the K&N cone. The box can always be refitted !!

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paul_mgb
Posts: 58
Joined: Sun Nov 06, 2011 3:14 pm
MGF Register Region: Midlands
Model of Car: MG TF 135
Location: Bromsgrove

Re: Hissing under load

Post by paul_mgb » Tue Aug 01, 2017 2:40 pm

My daughters TF, used to make a whooshing noise under load, it also didn't go as well as it should have done. This was following a Head Gasket Failure. It turned out to be a faulty stepper motor/idle speed control valve (the cylindrical thing attached to the inlet manifold). I swapped it for a second hand one and the problem went away.

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