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Matt, Engineer
Category: Car
Satisfied Customers: 21876
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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I smell gas inside the car when the heater is on. ?

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I smell gas inside the car when the heater is on. ?

this sounds like there's a gas / petrol leak under the hood as the heater draws its air in from just below the windshield so it will pick up any under the hood fumes

I'd check carefully around the engine fuel system especially the tops of the injector seals for any signs of wetness / fuel and replace o-rings as required also look on the end of the injector rail for signs here and also where the rubber fuel line joins the fuel rail

I don't think there's anything wrong with the heater
Customer: replied 4 years ago.

Is it possible that there's a leak at the fuel filter? (This is a second hand vehicle with 150K miles and we're unaware of previous maintenance efforts.) What happens if the fuel filter is never replaced?


I think that the fuel filter is mounted to the vehicle frame just below the driver's seating area so while it should be replaced it unlikely to be the source of the smell

the fuel filter is a silver or black bell-shaped container connected to a black hose at both ends. and should be changed every 20,000 miles
Customer: replied 4 years ago.

Replacing the O-rings is rather labor intensive, correct? Any idea how much it will cost?


replacing the injector o-rings isn't too bad a job but you do need have to dismantle the inlet manifold a bit to be able to withdraw the fuel rail off the back of the injectors

I'd say allow 2 hours labour to do this job plus the cost of the o-rings ( a few dollars each)
Customer: replied 4 years ago.

I once had to have O-rings replaced on another car because of a "vapor lock": The car wouldn't start because the O-rings were old and dried out. This cost me over $2000. Did they take me for a ride?


that does sounds rather excessive as the worst injector accessibilty I've ever encountered still only took 4 hours from start to end to replace o-rings / change the injectors and that involved partially dropping the engine out of the car

and o-rings should only ever cost a few dollars each at most
Customer: replied 4 years ago.

I was hoping that I was onto something else - a cheaper route - with the suggested replacement of the fuel filter. Do you know for sure that the fuel filter is located away from the firewall?


the information I have is for the 'quest' model of Nissan minivan

this has the fuel filter under the vehicle

if your's is a different model then its possible the filter is in the engine bay as the other location was on the back of the engine bay low down

I'd suggest the next thing to do is take a look into the engine bay havign turned the ignition on but not run the engine

this will prime up the fuel system and put it all under pressure

then carefully examine all round the fuel system looking for leaks

you get a strong smell with neat fuel so this should help with locating it
Customer: replied 4 years ago.

I have the Quest. Very good. I will follow your advise. Q.: What do you mean, "you get a strong smell with neat fuel...."?


bit of an english expression, 'neat' means undiluted

so if you have gas leaking out directly of a seal or past a pipe then it'll give off a very strong smell whihc will help you track it down
Customer: replied 4 years ago.

Great answers! Thank you! I'll accept after I send this final transmission.

No problem

glad to have helped
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Customer: replied 4 years ago.

Rating was submitted.

Much obliged