sloshing in heater core (?)

I am wondering if anyone else has experienced this :

In my 92 RMW, I hear a sloshing noise coming from the heater core area (under the dash). Recently I have had the cover off....to repair the a/c condensation drip I had there.....and I know it is not fluid in the cover or housing. Which leaves me to suspect the heater core itself.

Also I tend to only hear it for a short time or so after start up. This has me thinking that when the temperature of the coolant rises the pressure in the system rises and the sloshing is less prevalent. But that's just my theory.

It's not that big of a deal to me, but its nagging me a bit. I like everything to work as intended (or better ) and I figure that when the car was new this did not happen.

I'm curious if anyone else has had a similar experience, and as a bonus.....how did they eradicate the sloshing? LOL

On my LT1 cars, if the level in the tank is low, then I get burbling. You might also try flushing your heater core. You could just be hearing fluid turbulence.

yeah I was thinking I should flush it out, top off the coolant etc.

I just took the aluminum radiator out of my parts car, it has a factory oil cooler too (and yeah, I took off the oil hoses and by pass). So I will be swapping out the radiator in my daily driver with this aluminun one.....at the same time I am adding the dual electric fans I scored off an Impala SS.

Anyway while doing this work to the cooling system I will flush the heater core.

Thanks

I just thought of this - there should be a (this is where I don't know what it's called) valve in one of the heater hoses. I was told when mine let go that it's purpose was to prevent that "sloshing" It's a little plastic part and I know this would make more sense if I knew what it was called. Anyway maybe this will help!

Flow restrictor in one of the heater hoses is what 94X2 is trying to say.

ah ha! cool. (or is that "warm" ?)

Thanks for the replies.

Yes. I've had a few 88-98 Chevy trucks and they also are prone to makes the gurgling noises if the little restrictor is taken out.

I don't know that it's harmful to leave it out but it may serve to dampen the "hit" the heater core takes when the rpms are increased suddenly. One of my trucks blew the feed hose to the heater core almost in half going up a hill, so yeah, there can be some pressure there.

Yep. I blew a heater hose right off a fitting on my 9C1 doing some high-rpm burnouts before the thermostat opened. Keep the restrictor in place.

Old post but was there a solution that worked? I AM a little skeptical that the pressure in the heater hoses is enough to blow one out unless already weakened and needing to be replaced. Of course these darn things are in that area that is almost impossible to get hands into to do anything or I'd just replace like I do on most cars I acquire.

I read something about this the other day. I copy and pasted it below. Your question about leaving the restrictor out reminds me of a famous quote of Boss Kettering "Parts left out of a design cost nothing, and cause no service problems." Times have certainly changed since then, but at least 2 of GM's engineers thought that restrictor was needed. I'd keep it.


"WATERFALL" NOISES

• Drain elbow clogged
• Heater core clogged
• Elbow came off the drip tube
• Air in coolant, bleed the system

Your condensation is pooling in your tray because your elbow came off the driptube. Could be air in coolant. Check to make sure coolant is up to the required level in the reservoir and use the bleed screw on the thermostat housing on the waterpump to bleed that oxygen out. If that is not your problem, then you need to flush your heater core out. Find the two hoses that go into the firewall on the passenger side. Disconnect them both from the water pump and flush that bad boy out until the water runs clean. Be sure to flush both ways. I had this same problem. The heater worked fine, but it still needed a flush. ~JeffM

I've heard the sloshing twice, both times the coolant recovery tank was empty and after filling it the sloshing went away. Not quite sure how the slosh and low tank are connected but twice is proof they are. Low coolant is from the dripping weep hole in the water pump and is getting fixed before I run low on coolant and don't notice it in time, radiator was an inch down each time. The overflow tank is sometimes 3/4 inch lower after a drive to the store and I try to remember to fill it back when I get home but sometimes forget or drive longer than I thought. Distance doesn't change the loss but driving time does so if I leave at the wrong time and get stuck in traffic I can have the engine running 1/2 hour instead of 10 minutes.