gasket fault?

[cowman]

mk1 2500 has develpoed a constant "hiss" at idle or whenever foot is taken off accelerator pedal at any speed. Not overly load but enough to be annoying.
Only just started to hiss and have had nothing removed for 6 months.

I suspect from listening under the bonnet that it could be exhaust manifold gasket or intake gasket but thought i should ask as someone may have had a similar problem or another suggestion before i take it apart.
Could it also be carb to inlet?
The part i dont understand is why only at idle as i would have thought a gasket blown would be constant.
Thanks, Glen.

[GT6 M]

Hi Glen, if itsonly at idle, then it will most likely be on inlet side ,.

as the throttles are closed, so making a bigger vaccuum,.

get a bit of pipe, bung it in yer ..Lug Ole.. and put it over the inlet side,.

and listen for ..leaks..,   cant say where , but this method will find it,.

or when ye have found what ye think it is, put some water over it,

if it dissapears, for a while, and comes back, then this is it,

good luck


ohhh, if ye cant find any ..leeks.. in engine bay,  try a .. green grocer..  :) ;) :P

regards Marcus

[junkuser]

Failed vacuum hose give these symptoms,

[Richard B]

or a split in the Brake Servo's vacuum diaphram  :'(

[cowman]

Thanks for the info, will try hose/ear on inlet to see if i can locate better.

Im a dummy when it comes to brakes, so if its a split in brake diaphram wouldn't the brakes have less effect? Sorry if this is a stupid question but i need to learn somewhere!

Thanks, Glen.

[ferny]

If it was on the exhaust side it'd sound like a tinny, flappy fart.

Spray small amounts of WD40 around where you suspect it's leaking and the engine note will change if any gets sucked in.

[CRAJ]

cowman wrote:

Thanks for the info, will try hose/ear on inlet to see if i can locate better.

Im a dummy when it comes to brakes, so if its a split in brake diaphram wouldn't the brakes have less effect? Sorry if this is a stupid question but i need to learn somewhere!

Thanks, Glen.

A servo problem would result in a lot more effort required from you at the pedal, for the same braking.
If I roll my car down my drive rather than starting her up, the brake pedal is almost solid and the brakes feel poor in comparison to normal.

Colin.