Vacuum Noise

[Ungawa]

Hello All,
I have owned our 2002 5.3 since it was new, but every once in a while when accelerating the engine makes a loud suction noise under the hood. What causes this and why is it intermitten?

 

[Doubeleive]

Hello All,
I have owned our 2002 5.3 since it was new, but every once in a while when accelerating the engine makes a loud suction noise under the hood. What causes this and why is it intermitten?

do you have more details? have you looked under the hood for anything obvious? check the air intake system and air filter. take the air filter lid off and look inside see if maybe the filter is damaged.

 

[Ungawa]

do you have more details? have you looked under the hood for anything obvious? check the air intake system and air filter. take the air filter lid off and look inside see if maybe the filter is damaged.

Yes Sir I have, I’ve been down to replace the knock sensors. I have pulled the throttle body multiple time to clean it. It only make the suction noise sometimes, only while in gear accelerating. It’s still runs great, but it just does not seem like it is something it should be doing. It drive me nuts when it makes the noise. It did it before I replace the knock sensor and still does it after. I thought it could be related to the intake manifold gasket, but I change it out with the knock sensors. I’m stumped.

 

[Doubeleive]

Since it is a 02 it could be the fan clutch maybe

 

[afpj]

Since it is a 02 it could be the fan clutch maybe

Oooh, That's a good one for Tarzan to consider, but since owned from new, he'd know fan clutch noise? Wonder if it's actually engine compartment vs cabin, like HVAC related? WAG here without hearing it.

 

[Ungawa]

Since it is a 02 it could be the fan clutch maybe

not familiar with exactly how the fan clutch works or it’s purpose, do you mean the clutch is slipping?

 

[Doubeleive]

not familiar with exactly how the fan clutch works or it’s purpose, do you mean the clutch is slipping?

either slipping or locking up if does not do it consistently it's maybe something to look at, gauging the feel of a fan clutch by hand is difficult it works by heat so if it's not working properly it could be a problem maybe it's getting stuck occasionally? I haven't had a vehicle with a fan clutch in a good while so just going off memory

2. Excessively loud cooling fans​

Another common symptom of a faulty fan clutch is excessively loud cooling fans. If the fan clutch gets stuck in the engaged position, which is not uncommon, it will cause the fans to fully engage even when it is not desirable for them to be on. This may result in an excessively loud engine from the fan blowing at full speed. The sound may be easily audible and present at all times when the engine is cold and hot.

 

[Ungawa]

I think your on to something, I really appreciate the info. The fan clutch has to be it. I even used starting fluid on the engine looking for vacuum leaks and it just idled normally. I inspected every hose on it over the years multiple times. Has to be the fan clutch. Thanks man. I will let you know.