fluid "like" noise in dash

wyogmc · October 25, 2003

Greetings,

I am new to this group and I have tried to search for an answer and I’m coming up empty. I have just purchased my first GM product: 1999 GMC Sierra 2500 ext cab 6.0L

The only problem I have found with my truck is that when you accelerate from a stop you hear a loud fluid like rushing sound in the dash. The sound is usually present in all driving conditions but at a lower level. I have tried to burp the antifreeze system with no effect and I’m now open to suggestions.

Thanks for your help,

Mike Magee

99silveradoz71 · October 26, 2003

I have the same problem/symptoms in my 99 Rado as well.

chevroletmb · October 26, 2003

quite a common problem actually

some of the new stiyle trucks have a coolant restrictor

in the heater hose quick connects just before the

heater core. the restrictor is what makes this noise

the fix is simply to removed the restrictor. the hard part

about it is disconnecting the quick connects. special tools

are required and even then they can be a real pain.

antirice · October 26, 2003

hmmm....our '99 Astro does the same thing

wyogmc · October 26, 2003

Thanks for the information. I will contact my local dealer and see if they can remove the restrictor for me.

Thanks again,

Mike

chevroletmb · October 26, 2003

i don't know of any retrictor in the safari

maybe in the intake coolant fitting

backflushing the heater core can help this problem too

sonjaab · October 27, 2003

GUYS..........What you have is a bubble or air pocket in your

cooling system. My 97 did the same gurgle in the dash

thing. You have to "burp" the system. I did it by looseing

up the top rad. hose and burping out the air pocket.

These new GMs with NO rad. cap are a PIA !....geo

wyogmc · October 27, 2003

GUYS..........What you have is a bubble or air pocket in your
cooling system. My 97 did the same gurgle in the dash

thing. You have to "burp" the system. I did it by looseing

up the top rad. hose and burping out the air pocket.

These new GMs with NO rad. cap are a PIA !....geo

What was your exact procedure?

Thanks,

Mike Magee

asepgrad98 · October 28, 2003

this would be worth a shot:

Draining and Filling Cooling System

Caution

With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.

Notice

When adding coolant, use DEX-COOL® coolant. If silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

The following notice applies to the 4.8L, 5.3L, and the 6.0L engines only.

Notice

DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.

Drain and Fill Procedure

Important

If you do not follow the procedure below, a low or high coolant level condition and/or vehicle damage could result.

Park the vehicle on a level surface.

Follow the steps below in order to remove the radiator surge tank fill cap:

Slowly rotate the cap counterclockwise.

Stop rotating and allow the hissing to stop.

After all hissing stops, continue turning counterclockwise in order to remove the cap.

STEP 3 ->Remove the drain hose from the left side of the radiator tank and repositon the hose to a catch pan.

Open the radiator drain cock.

Allow the system to drain completely.

Inspect the engine coolant:

Discolored -- follow the flush procedure below.

Normal in appearance -- Continue with the next step.

Close the radiator drain cock.

Important

When filling the cooling system use a 50 to 60 percent concentration with DEX-COOL® coolant.

Fill the system through the radiator surge tank opening.

Pre-mix a 50 to 60 percent solution of DEX-COOL® and clean, drinkable water.

Slowly add the pre-mixed solution to the system until the level is slighlty above the surge tank split line.

Start the engine.

Idle the engine for 1 minute.

Loosely install the surge tank cap. Do not allow the system to build pressure.

Cycle the engine from idle to 3000 RPM in 30 seconds intervals until the engine coolant reaches 99°C (210°F) and the thermostat opens.

Shut off the engine.

Refer to step 3 in order to remove the radiator surge tank cap.

Start the engine.

Idle the engine for 1 minute. Fill the surge tank to ½ inch above the COLD FULL mark on the radiator surge tank.

Install the radiator surge tank cap.

Cycle the RPM. Idle the engine to 3000 in 30 second intervals until the engine coolant reaches 99°C (210°F).

Shut off the engine.

Top off the coolant, as necessary, to ½ inch above FULL COLD mark on the radiator surge tank.

Rinse away any excess coolant from the engine and the compartment.

Inspect the concentration of the coolant.

Flush Procedure

Important

Do not use a chemical flush.

Block the drive wheels.

Place the transmission in park (P) or neutral (N).

Engage the parking brake.

Run the engine until the thermostat opens.

Stop the engine.

Follow the drain and fill procedure using only clean drinkable water. Repeat the procedure if necessary, until the fluid is nearly colorless. Refer to the drain and fill procedure.

Fill the cooling system. Refer to the drain and fill procedure.

sonjaab · October 30, 2003

MIKE...I just loosend the upper rad. hose while hot and running.

Do this while cold tho!

Made sure to have a catch pan and the overflow bottle is full

with cap off. SURE a PIA and messy but cured the problem.

The air pocket just hissed out. BE CAREFUL THO !

Was SICK of the dealer BS ...CANNOT DUPLICATE!.....geo

number9 · October 30, 2003

My truck does this as well - but only once in a blue moon. Seriously, I may have heard this 5 times over the course of owning it since 1999.

asepgrad98 · October 30, 2003

do NOT remove hoses while the truck is hot.

wyogmc · October 30, 2003

It's snowing like crazy right now, and I'm going out of town for a couple of days. When I get back, I will burp the system. I will let you know what happens. I really appreciate your suggestions and they make sense.

Thanks again,

Mike Magee

sonjaab · October 30, 2003

AS..........SORRY.....Meant to say loosen the upper rad. hose while

COLD. Then run it up to when thermostat opens and hot flows!

Coolant will now run thru and hiss and drip some and "burp"

out the air pocket from the loose upper hose.

PIA, messy, and HOT....Use caution and face protection and

gloves etc !!!!!!

Its the only way I know how to do it !

Althought the factory procedure above might work for ya too!

..............geo

Z71GUY · October 30, 2003

I was talking to my local dealer about this yesterday and the service manager said there is a restrictor plate that they add to slow the fluid down....

anyone hear this before?