Hino 155 loud screaming noise

[apollomaestro]

I've got this 2007 Hino 155 that makes a loud screaming noise from the exhaust when accelerating, but it stops as soon as I let off. Already ruled out the turbo, any other ideas what it could be?

 

[abracadabra]

Well have a look at the flex pipe or there could be some loose gaskets in the exhaust system too. I get you about that noise I mean I had that experience too but not with my Hino. Even a small leak can drive you crazy!

 

[BoxTruckDoc]

I once had a similar issue with my old truck where there was a noise that turned out to be a small exhaust leak near the flex pipe. It was pretty loud when I stepped on the gas, but it went away when I eased off. Once I replaced the gasket and the flex pipe, the noise completely disappeared.

 

[apollomaestro]

I once had a similar issue with my old truck where there was a noise that turned out to be a small exhaust leak near the flex pipe. It was pretty loud when I stepped on the gas, but it went away when I eased off. Once I replaced the gasket and the flex pipe, the noise completely disappeared.

Good to hear that! Did you fix it yourself or did you have to bring it somewhere? Im not really a handyman so i have to ask.

@abracadabra
Absolutely, flex pipes and loose gaskets are often the usual suspects for those annoying exhaust noises. Thanks. I never thought a leak could cause this. Will check that out for sure .

 

[c@bb@g3_k]

I once had a similar issue with my old truck where there was a noise that turned out to be a small exhaust leak near the flex pipe. It was pretty loud when I stepped on the gas, but it went away when I eased off. Once I replaced the gasket and the flex pipe, the noise completely disappeared.

yeah, actually the most common cause of a screaming or whistling noise under acceleration is an exhaust manifold gasket leak.
The pressure from the exhaust gases under load forces its way through a small tear or gap in the gasket, making that high pitched sound.
As soon as you let off the throttle, the pressure drops and the noise stops. Look for black soot or carbon tracking around the exhaust manifold's mounting points on the engine block. That's a sure sign of a leak.

 

[tuna_salad]

Good to hear that! Did you fix it yourself or did you have to bring it somewhere? Im not really a handyman so i have to ask.

@abracadabra
Absolutely, flex pipes and loose gaskets are often the usual suspects for those annoying exhaust noises. Thanks. I never thought a leak could cause this. Will check that out for sure .

If you want to try and find it yourself before you take it in, I got a simple trick for you.
With the truck cold, have someone start it and then hold a rag or a tennis ball firmly over the exhaust tip.
That will force air out of any leaks, making the sound way easier to pinpoint.
You'll probably be able to hear a loud hiss or feel the air escaping