Strange Hissing Sound?

[Jor-el]

There is an intermittent hissing sound coming underneath the vehicle, not from the engine bay... what might be the problem guys?

Vehicle is a 2013 Mitsubishi Lancer EX

According to the owner this comes on cold start and disappears after some time.

Edited June 11, 2016 by Jor-el

[Jor-el]

Turns out the hissing noise is a norm for Lancer EXs. Who knew? Harry_aq, Bracket, can you guys shed any light on this?

http://www.lancermotoringclub.com/showthread.php?12819-Hissing-sound-from-under-carriage

http://www.lancermotoringclub.com/showthread.php?45505-Hiss-sound-from-undercarriage

http://www.lancermotoringclub.com/showthread.php?42475-Hissing-Sound-from-undercarriage

http://www.lancermotoringclub.com/showthread.php?21510-buzz-buzz-sound-at-the-rear

http://projectlancer.net/forums/topic/20913-fuel-pump-making-a-hissing-noise/

Edited June 13, 2016 by Jor-el

[Rumesh88]

If the noise is from back part of the car, it is worth having a look at the connections to the EVAP control system vacuum lines connected to the charcoal canister located closer to the fuel tank and behind one of the rear wheels (I trust that's where the canister is located in Lancer EX).

[Davy]

I was just going to say the same thing Rumesh! It's quite possible that the issue is with the EVAP system since this happens when the when the engine is cold which is when the EVAP regulates the pressure inside the system. The canister is behind the passenger side rear wheel in the Lancer EX.

[Jor-el]

Is this a serious issue? Does it affect any other parts of the car in the long run?

Edited November 23, 2016 by Jor-el

[Rumesh88]

Is this a serious issue? dunno how long owner had run the car with this problem. Does it affect any other parts of the car in the long run?

the thing is,I feel like I can "persuade" him to sell the car,(not because of this issue!!) he said he's gonna give it a thought

How serious it is depends on what causes the leak if there is one. It can be a simple thing such as a loose or damaged hose but if it is a damaged charcoal filter it may cost a bit more to replace.

[Jor-el]

double post

Edited June 11, 2016 by Jor-el

[Jor-el]

Hissing sound update.

So the car was taken to Kandy UM service center.

The mechanics' response was "ah oya petrol pump eka wada karana sadde ne - onema petrol engine ekaka oya sadde enawa"

So the update is, according to the latest emissions test report the HC (HydroCarbon/Unburnt fuel?) amount is increased.

Is this connected to the hissing noise?

If so what should be done to rectify this?

Edited June 29, 2016 by Jor-el

[Dushyantha]

Even if the equipment at the emission test was working correctly the HC emission would greatly depend on the engine temperature and the outside temperature . so . a small deviation like that would be negligible i suppose . And i think the petrol pump in the lancer is located inside the fuel tank itself . Hence there wouldn't be much of a sound . There maybe a possibility that i may be coming form the petrol pump as the mechanic said .

edit: just remembered . you could check if its the petrol pump by getting someone to switch on the car but not start it after keeping the car for sometime. so that the petrol pump works for a small time to prime the system . if its the same sound . then it sure is the pump

Edited June 11, 2016 by Dushyantha

[Jor-el]

edit: just remembered . you could check if its the petrol pump by getting someone to switch on the car but not start it after keeping the car for sometime. so that the petrol pump works for a small time to prime the system . if its the same sound . then it sure is the pump

Thanks Dushyantha, the sound doesn't appear until the engine starts.

[Twin Turbo]

The power steering pump is a possible candidate or the release bearing (clutch)?

Or the timing kit bearings,+ drive belt tension er possible.

Edited June 12, 2016 by Twin Turbo

[Jor-el]

The power steering pump is a possible candidate or the release bearing (clutch)?

Or the timing kit bearings,+ drive belt tension er possible.

The sound doesnt come from engine compartment... it's most clearly heard from the rear of the vehicle. PS pump is in the engine compartment ne?

Edited June 12, 2016 by Jor-el

[Dushyantha]

Can a tiny leak in the exhaust cause a hissing sound ? and then once it heats up , maybe due to expansion the leak gets smaller that the hissing isnt heard .
better check your exhaust pipes for any damage