My 4runner has what sounds like water sloshing around the dash area when i have the heater on, but when i turn it off there is no sound- can hear it only when heater is on, need help please.How do i fix or correct this thanks.

 

Typically 1 of 2 causes, generally you are hearing gas trapped in the coolant rushing through the heater core.

1. Air trapped in the cooling system. To purge, park on a hill, radiator uphill and then open the cap, heater on and run the engine up to temp. until the t-stat opens and lets any trapped air burp out, top off as needed.

2. Leaking head gasket letting exhaust gas leak into the cooling system. To test for this, pressure test cooling system looking for a pressure rising and falling with engine revs. Or NAPA sells a coolant test kit for $20 or so that checks for exhaust gas contamination in the coolant. If either found, replace head gasket and check head for flatness (it may be warped).

 

4Crawler thanks for the rapid response, will do the purge and hope that is what is wrong with it, it has rained alot in the last week. but i dont see any water trapped in the cowl. Thanks alot for the great info.

 

mines sloshing too.. it must be the heater core..I've tried parking on a hill and letting it warm up to burp the system but it's still sloshing.. :/ my heater doesn't get real hot @ idle either.. but when i'm going down the road with throttle it is blowing good.


and now I'm wondering if it's causing my idle to bounce on cold starts.. I start it up.. idles at 2k steady.. then after fan goes off.. it starts to bounce for a minute.. then idles great. and runs great.. Just had a long block 3vze installed.... new plugs... TPS... needs exhaust... could it be a bad o2 sensor?

Sorry for thread jack

 

@jdamore-

Check your thermostat. The coolant to the heater bypasses the t-stat, so if your temp slider is over towards hot, coolant should flow through the heater core and right back to the water pump, bypassing the radiator. If the heater's not getting hot, that would suggest the t-stat is stuck open allowing coolant to favor flowing through the less restrictive radiator. It could suggest that the coolant path through the radiator is restricted- possibly failing hoses, corrosion, scale build up, or....

 

Could also be your cab drains...you'd hear water sloshing around with the heater on or off though. The last time mine got plugged up a few gallons came out.

 

In the past, I have pull off both the heater hoses and back flushed it with a hose straight into the heater core. Amazing the crud that will come out of that little box.

My olds intrigue had a similar issue with it and it ended up being an air bubble in the heater core causing my fits. Back flushed it the same way, problem solved.

 

This may be a stupid question but is there a write up on how to do that? i am an idiot when it comes to this stuff...

 

There is no write up on this. Just something a lot of mechanics do in the shop.

I personally have a couple of extra pieces of hose I keep around just for this. Take the hoses off the heater core where they go through the wall. Slip on the temp hoses, Use the garden hose to flush water both directions till clean.

Re-install the original hoses and you are complete.

 

Yep, garden hose with a tapered nozzle and just disconnect the heater hoses from the engine/heater valve and shove hose into the return line (that is the one that is not hooked to the valve) and slowly open the nozzle until water flows through and out the inlet line. Repeat forward and back flushing a few times until you only get clear water out.

 

thank you seems easy enough