"liquid" sounding clunk shortly after start up

[bdjcl]

'98 4runner Limited, 203k miles. About 15 seconds after I start the 4runner, I'll hear what sounds like a liquid clunking sound coming from the passenger side of the engine bay. a/c compressor is off. I was initially thinking maybe coolant bubbling through the heater core, but I've flushed the cooling system a few times and just put a new radiator in.

My other thought is maybe something in the power steering rack? I'm at a loss, any leads?

 

[jross20]

I think I have this too, is it the brakes or something?

 

[bdjcl]

I think I have this too, is it the brakes or something?

The splashing sound I'm hearing sounds more like the viscosity of coolant or washer fluid or something, not something more viscous like brake fluid. Also I think the master cylinder is in front of the driver.

 

[BoomerBob]

Any chance it's the rear heater core under the passenger seat?

 

[Mr. Goodkat]

Does it sound like trickling water? Mine does it too when the temperature outside drops. I replaced my be radiator last year and it started doing it right after. There have been other posts on it and apparently there's an air bubble in the cooling system somewhere.

I drove my front end on ramps, took the cap off, let it run and get up to Temp with heat on for the front and back seat and I still couldn't get the bubble out....

 

[bdjcl]

Any chance it's the rear heater core under the passenger seat?

hmmm, no...it sounds like it's up in the engine bay

 

[bdjcl]

Does it sound like trickling water? Mine does it too when the temperature outside drops. I replaced my be radiator last year and it started doing it right after. There have been other posts on it and apparently there's an air bubble in the cooling system somewhere.

I drove my front end on ramps, took the cap off, let it run and get up to Temp with heat on for the front and back seat and I still couldn't get the bubble out....

Nope, it's like one sudden "clunk", like dropping a rock in a bucket of water.

 

[Mr. Goodkat]

That's an odd one.

Does the sound happen once upon startup or does it repeat as the vehicle is thinking? Then does it slowly go away?

 

[pluton]

Could it be the normal self-test performed by the ABS device under the hood? On mine it happens at about 5 seconds after I turn the ignition on, whether I immediately start the engine or not. It's probably not loud enough to hear once the engine is running, though.

 

[BoomerBob]

Nope, it's like one sudden "clunk", like dropping a rock in a bucket of water.

Can you record and post this sound?

 

[Clockworkmotors714]

Possibly your blend door/blend door actuator arm making the noise. Does your air channel to the multiple locations available on your climate control system. For example switch from feet, to face, to defroster?

 

[bdjcl]

That's an odd one.

Does the sound happen once upon startup or does it repeat as the vehicle is thinking? Then does it slowly go away?

happens just once

 

[bdjcl]

Possibly your blend door/blend door actuator arm making the noise. Does your air channel to the multiple locations available on your climate control system. For example switch from feet, to face, to defroster?

all of that seems to work fine, that also wouldn't explain the liquid splashing sound

 

[bdjcl]

Can you record and post this sound?

I can try, not sure if it will come through

 

[Bad Luck]

I can try, not sure if it will come through

When you filled your coolant did you use a spill free funnel and elevate the front end?

 

[bdjcl]

When you filled your coolant did you use a spill free funnel and elevate the front end?

yep, I guess I could hook it back up and try to burp it some more

 

[Bad Luck]

yep, I guess I could hook it back up and try to burp it some more

It's worth a shot. You probably already know this but make sure the vehicle gets hot enough to open the thermostat, and the front and rear heat are on. I ended up raising my 4Runner a couple feet in the front to get an air pocket out.

 

[T4R2014]

Could it be the normal self-test performed by the ABS device under the hood? On mine it happens at about 5 seconds after I turn the ignition on, whether I immediately start the engine or not. It's probably not loud enough to hear once the engine is running, though.

On 96-97 it runs about 5 seconds after switching the ignition to the "on" position. But on my 1998 Limited the test runs after the starting it and driving off a few feet. I think this is what OP is experiencing.

 

[bdjcl]

On 96-97 it runs about 5 seconds after switching the ignition to the "on" position. But on my 1998 Limited the test runs after the starting it and driving off a few feet. I think this is what OP is experiencing.

yes, that's exactly when I hear the sound, after starting it and driving off a few feet. Is the liquid I think I'm hearing likely brake fluid?

 

[T4R2014]

yes, that's exactly when I hear the sound, after starting it and driving off a few feet. Is the liquid I think I'm hearing likely brake fluid?

Possibly, all I know is that it is the ABS pump, which is cycling brake fluid.