I'm hearing a loud hum from (I think) the transmission.

I hear the hum clearly (and loudly) when the auto is in neutral. When
I put the auto in DRIVE, and not moving, I still hear the hum. But
when I accelerate, the hum is not as loud and at highway speeds I don't
hear the hum. It seems to go away, but it might be that the engine
noise is blocking it out.

Anyone have this problem with a Nissan transmission? Is it something
that proceeded a failure and can be fixed now, or is the hum something
that comes about with an older Nissan?

Thanks in advance for any tips, suggestions, comments,

Manjo 1995 NIssan Quest with many miles on the odometer

Sounds like it may be coming from a "buzzing" pressure regulator. There
could be a number of reasons this would be happening including improper
fluid level, airated fluid (fluid level too high), restricted filter,
and defective pressure regulator. You need to take it in for analysis.

Professor
www.telstar-electronics.com



Manjo wrote:

Professor,

Thanks for the tip. It makes sense it could be the pressure regulator.
I'll check out the regulator this weekend to see if it's the source of
the noise.

Manjo

a buzzing pressure regulater valve is not something your ordinary mechanic
should try and deal with. the transmission is RE4F04A/V and has a 3 lvl
valve body 10 or 11 1/4 inch checkballs and 2 3/8 check valves not to
mention small pins that could fall out during disassembly or cleaning. if
trans is buzzing it may be a stopped up filter as the torque converter is
known to experience TCC failure <torque converter clutch> also called lock
up clutch. pan drop and check filter if it has the appearance of soft brown
material in the screen it is stopped up and restricted which is common to
buzzing noise as the oil pump is starving for fluid. be careful changing
filter .. do not clean the screen 50 micron screen and will not come
clean..must be replaced
"Manjo" <manjo1111 (AT) gmail (DOT) com> wrote

Professor,

I located the pressure regulator (just in front and to the right of the
exhaust manifold). I put my ear close to it and flet it with my hands.
It was not the source of the noise and no vibration.

I then checked under the hood and could not find the soruce of the
buzz, although I could hear it clearly inside the van.

I decided to look further back on the van. I found the buzz to be
coming from the rear of the vehicle (motor on, vehicle in park). AS
far as I can tell now, the noise is coming from in fornt of the rear
axle. My thinking now is the fuel pump, which I beliefve is in the
fuel tank, is causing the buzz. There's nothing in the lower
mid-section of the van that "moves" that could be casuing the buzz.

If it is the fuel pump, is the buzzing a sign the fuel pump is failing,
or about to fail completely? On our last long trip, I was pulling a
small trailer (3,000 pounds including load), and had a hard time
getting up some hills. I'd press the gas pedal to the floor and in
some instances, the van would not drop a gear and would not accelerate.

Let me know what you think about the fuel pump being the problem.

Thanks,

Manjo

djmcreynol,

Thanks for the reply. The pressure valve is in the fuel system.
Although I'd like to get into the transmission, I think I'd need more
room and at least someone who has worked on one of these before to
guide me.

I think the buzz is from the fuel pump. I was able to determine the
buzz was not coming from the engine compartment, but further back. The
buzz is heard best in the van passenger area, but only because the
vibrations are being carried forward from the fuel tank where the fuel
pump is located.

IF it is the fuel pump and the pump is making the buzzing noise, is the
pump about, or close to failing? Or can I drive with it as it is?? I
think I'm experiincing some loss of power. When I pulla small 3,000
pound trialer, there are some highway hills that are tough to climb and
when I floor the gas pedal, sometimes the van does not drop down a
gear, and I get no acceleration.

Please let me know what you think about the fuel pump.

Thanks,

Manjo