Swishing sound in engine compartment

[AugMeo]

Hi,

I have a 1999 1500 4x4 with 5.9 V8 and have recently replaced the plenum pan gasket. Truck runs great with no oil loss or knocking now. The only problem is when I start the truck up I hear a swishing sound from the engine compartment, sounds like from the passenger side. I would give it gas and it would make the swishing sound, but after awhile it goes away. This sound is more like water/liquid swishing around. All this started after I put some Mopar conditioner/cleaner in the TB as stated to do in the TSB 09-05-00. It's been about 3 weeks since I performed the TSB and the swishing continues.

Any input would be great.
thanks.

[NascarNut]

I have the same problen in my 98, it all started when the heater core was leaking. The fluid got low and i heard the same sound, after fixing the leak it still does it on occasion but it stops when its warmed up.
probably still a little air left in there or something, may not be your problem but thought I would mention it just in case.

[scoutinkeith]

yep, sounds like air in the cooling system to me too. the best way that I have found to get all(well, most anyway) of the air out is, with the engine cold, remove the radiator cap and start the engine. keep an eye on the coolant leval, as the engine warms and the thermistat opens, if there is air in the system, the coolant leval in the radiator will drop. as the coolant leval drops, add more coolant to keep it topped off. when the coolant leval stops dropping, you should have all the air out. the just reinstall the radiator cap and you should be good to go.

[BleedDodge]

I wonder if maybe that gasket was replaced improperly and it's pressurizing?

[AugMeo]

Originally Posted by scoutinkeith

yep, sounds like air in the cooling system to me too. the best way that I have found to get all(well, most anyway) of the air out is, with the engine cold, remove the radiator cap and start the engine. keep an eye on the coolant leval, as the engine warms and the thermistat opens, if there is air in the system, the coolant leval in the radiator will drop. as the coolant leval drops, add more coolant to keep it topped off. when the coolant leval stops dropping, you should have all the air out. the just reinstall the radiator cap and you should be good to go.

Thanks!!!! I did this procedure today and it worked!!! No more swishing!!

[Josh318]

I just replaced my plenum gasket about a month ago and have been having the same problem with the swishing sound. I'll try out the advice as well and let ya'll know if it worked. Thanks for the tip!

[Josh318]

Filling the coolant worked, no more swishing! Thanks for the help.