Water Sound From Heater Core?

[vetterbett]

I have a question about my dads S-10 Blazer, there is a water sound that comes from the heater core as you accelerate from a stop. Now this happens even if the heater is off, there is no leak from the heater core at all inside the driver compartment or the engine bay. I have never heard of this happening at all so I don't know the answer so I figured I would come here and see if this was a problem someone else has had??

[Zembonez]

It's air in the system. You are losing coolant. I had the same symptom in my 01 Silverado when the intake manifold started leaking internally. Pretty common 4.3 V6 problem apparently.

[dshannon]

I had this problem in my Jimmy before my lower intake gasket blew. mixed coolant with the oil, and deystroyed a crank bearing. I have also heard you can fix it with a new rad cap, if the intake gasket isnt starting to leak. check your coolant level religiously

 

Dan

[rriddle3]

If you have not noticed a loss of coolant level in either the reservoir or radiator, then you probably do not have a coolant leak. A coolant pressure test will only show if there is an external leak. You did not say what year the truck is, but I would suggest a complete coolant system flush and fill, paying special attention to doing a thorough heater core flush, making sure you have all the air purged from the system, and replace the radiator cap with a Stant lever model cap. If the heater core is failing and a core flush doesn't do the trick, replacing the core is a big job.