2002 Blazer 4x4 with Vortec V6.
Under acceleration, you can hear a liquid preculation sound from behind the stereo and AC control panel on the dash board. Under decceleration, you do not hear anything. Under G-load turns you do not here anything.

This issue only occurs under acceleration. My thought is an issue with the Heater core or possibly water pump. Suggestions.

Another thing, this truck has developed a intermittent rattling sound at idel, weither in gear or not. I have cycled through all gears and do not find it louder or softer at any one time. I thinking the sound is coming from the area of the exhaust tube to the Cat Converter and a the muffler area. I have not yet inspected the drive shaft and U-Joint for issue yet. Any other suggestions of where I can look.

Drivability is normal. No codes in computer or chassis. AC is working fine, needs to be serviced due to age, but still fully functional at this time.

 

I have the same thing on my -97 4.3l vortec. Under acceleration only.
I have had some troubles with the cooling liquid not being transported around enough. Have had a motor temp at max and still only cold air form the coupe fan.

Is it the waterpump? Maybe a blockade in some of the tubes? It only happens occasionally.

 

both hoses going to heater core at firewall should be warm/hot. put a plastic bag around distributor cap to shield from fluid, remove both hoses and flush both with a garden hose for better performance. check rad.fluid for a couple days to top off fully.

 

Warm up the engine with the rad cap off. Fill it with water and make sure the resevoir jug is full to specs. It is just low coolant. Mine does the same thing if it gets real low on coolant.

 

I have the problem which occurred tonight but not during acceleration only when coming to a dead stop. Ill be checking fluids tomorrow and make I will also try a few of the things mentioned above great advice thanks.

 

Hey people... New to this forum... I think my bro belongs to this forum as he just recently "re-joined the S10 " community. Hey bro... Anyway, this sound your hearing, it's air in the heatercore. The heatercore is the top most part of the cooling system and, air rises... Every now and then, I mean months, you may need to add a bit of coolant, ok... IF this is happening frequently, I say every week or so, yer' losin' it somewhere. Look around, under, "&" smell the exaust... This is what my problem was. INTAKE GASKET ... Typical 100k+... Make sure the oil has no milky look to it and see your banker I mean your mechanic a.s.a.p. Hopefully it will leak twards the exaust side of the gasket and not the oil-port side. OR, it may only be a leaky hose, easy fix... But then after my intake gasket went, the radiator split... Oh yea... I gots lotsa info for you people... Be back soon.. Later...

 

Issue Resolved, The prec sound is a result of a fail safe theromstat, that I installed in the truck. Unlike a normal theromstat, this one has a small hole in the body that is allowing an air bubble to form. All my gaskets and things are fine.