help 1999 7.3 hissing under low acceleration
 

my 1999 is hissing under low acceleration,hot or cold,
i changed the EBV and tube
turbo pedastel / base new o rings,
muffler and pipes ,stock

its intermitent at low rpms,feels as though it looses power till hissing goes away
the turbo was inspected and is in good condition as far as the impelar and bearings.
changed oil,fuel filters,all intercooler hoses and turbo hoses seem to be tight no carbon,no carbon on down pipes donuts,new glow plugs,starts and runs great except for the hissing and power loss
HELP PLEASE

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OH and there are no codes !!
on snap on scanner,comes up clean!

There should be no codes... Your truck is doing what it should under light accel and when idleing.

Your Exhaust Back Pressure Valve is closing, causing the noise and also putting your motor under more load to help it warm up. I'm betting you live somewhere that it does not get cold very often and now it is???

Completely normal.

im in nj
 

cold about three months a year,my tem only gets up about a third of the way,before half way mark,
WOULD A HOTTER THERMOSTADT HEL THE ENGINE RUN AT A NORMAL OP TEMP,IF SO WHAT DEGREE THERMO SHOULD I RUN,
THANK YOU FOR THE HELP

Most have been running a *203 that I've seen on here, mine is a *195. It was only 3 degrees this morning and mine was perfect ( temp third of the way up, and the heater blowin hot enough to cook a deer shoulder:tu:)

IM GOING TO UP THE THERMOS ON MY TRUCKS ALL 3 HAVE SIMILAR ISSUES,WITH THE EBV ,STAYING OPEN TO HEAT UP THE ENGINE,THANKS FOR YOUR INPUT,

dose it sound like its sucking air in the exahust, mines been doing that lately just wondering

Yes, thats it.

It closes to build back pressure, not opens. FYI

the sound is more like the pressure releasing somewere under the hood,like a prolonged blow off valve sound,long hiss until you remove your foot from the pedal,at low rpms,

Its your EBPV...

THANK YOU CSIPSD,NEW EBPV AND TUBE,GOING TO UP THE THERMOSTADT TOMMOROW,THANK YOU ,GREAT SITE

can it hurt any thing if your driveing down the road and it dose it. my trucks been doing it but not all the time it might not do it for a day or it might do it twenty times in 4 miles.

i was told by several techs its normal
 

im not to familiar with the noise but my truck is running fine,the mod says its normal,hes the man with the tech questions,

it wont hurt anything as long as it opens back up when you hit the pedal. if you got your foot in it and its doin it just limp it home very very slowly. low rpms

97 f 250 bad brakes new master cylinder and pads and rotors
 

im trying to find the name of the vacum ran off the belt on the drivers side of the motor
im guessing its a vacum booster
any sugestions for sponge brakes

ok thanks how hard are they to change

It's supposed to do that under light acceleration when it is cold outside. It will stop shortly. It should also stop if you get down on the accelerator. It's the exhaust back pressure valve doing it.

mine did same thing. just could not get warm enough to stop the valve from closing. Local uphoslter made me a grill cover for 20 bucks. brought my oil temp up about 15 degrees and it runs much better and quieter. Cheap and easy to take back off in the summer or if towing too.