Engine makes creaking/metal expansion sound

I hope someone can help me with this.

Two years ago, I had a tuneup, new plugs and all, flushed fluids, new oil the works. Then drove on several 4 hour road trips. I come back and begin to notice that the car is making metal expansion sound or creaking sound like it gets too hot. The temp sensor looks good. Also, my fuel milage has dropped from 420 miles per tank to about 320 or 350.

I get new spark plugs. (yeah the BOSCH titaniums) and the fuel milage goes up to about 380-400 per tank, but the creaking sounds remain. I take it to a couple of places. The water and oil systems are good. The dealer wants to sell me a new engine, another says it's the transmission going bad.

The transmission gets a fluid change with no problems noticed.

So last month, I put the Iridium NGK spark plugs (new) back in and the milage drops to 320 a tank.

So I need to use this car more now. Am I looking at thermo sensors, O2 Sensors, new(err... that thing that goes to the spark plug, ugh, brain dead, core something) as problems

Worse, I wonder if I have lost a gasket. I checked under hood, no oil leaks or any other kind of leak. There is a faint smell of gas, so I am going to check to make sure all the plugs got seated.

I really want to start with the thermo sensor, but I hear that can be a pain, so I am taking suggestions.

Thanks in advance.

Keith

Reply to
Keith
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Wow, I forgot to mention I own a '96 Maxima.

Keith wrote:

Reply to
Keith

It sounds (smells?) like you have a fuel leak. If you are smelling it, its leaking out somewhere. Look at all the fuel lines and hoses, especially the ones leading into and out of the fuel filter (between the steering column and the engine, back by the firewall).

Another possibility, which might also be happening, is that the knock sensor is dead. That will cause the timing to be permanently adjusted for low octane gas. It will set a code in the ECU when it goes, but it doesn't light the check-engine light. You can read it out yourself with a screwdriver, or take it to AutoZone and they will read the codes for you.

Miles per tank doesn't really tell us anything. My '96 I30 (same engine,

200 lb heavier) goes as far as 480 miles on a tank if its all highway driving, or as little as 330 if city. Run a couple of tanks of gas though it and compute the mileage (total number of miles driven divided by total number of gallons used). It should be getting ~28 MPG for all highway driving and ~22 MPG in city driving.
Reply to
E Meyer

What maxima modello have u got?

Check and/or replace all belts. For tst purposes take them off: is the sound out??? If so, the source was pwrsteerin, alt and-or A/C.

Replace all gas hoses, filter, regulator, also both rails connecting end hose.

Reply to
Wiikinki

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