Last week a 2000 357 had its muffler replaced. It’s now losing power and has a hissing noise. Two injectors were changed after diagnosis. The problem is still there. The boots, air filter, fuel pump hose and turbo have been looked into for additional problems but everything seems fine. Any suggestions?
Most mufflers are directional. Look for a arrow,it should be pointed away from the motor. Some are stamped and others laser etched. More info about what motor would help also. @pushbroom @spsauerland
It’s a Cummins engine, N14-460HP The direction is facing away. The feedback is: it’s okay unloaded but lacks power while loaded. I can hear the difference in sound while the truck moves around the yard but I’m unsure if that’s because it’s a new muffler or it’s chocking up a little. The engine was recently rebuilt in January of 2019 and may only have about 30,000 on it.
Run it with out the muffler and see if the problem is still there. There might be a chance they got the wrong muffler and there is to much back pressure being created when the engine is under load since thats when the problem seems to happen. Does the truck have a single muffler or dual mufflers?
Check fuel pressure,air to air,air filter etc. after the basics are checked, then find someone with a laptop to go for a ride. Try using the cruise control and see if it makes a difference.
Hissing noise is excess back pressure trying to go somewhere, anywhere. Just un-clamp it and give it a try around the yard, it should be normal again, without the hiss. Even muffler manufacturers screw up sometimes. Or muffler "orderers." Or stock pickers. Try the old one and see if it works.
