Are you sure you did not put it in backward? Did you make sure the little tiny hole was set to the up position? Did you run the heater?

You can also try using one of these to let the engine run and let most of the air out... Funnel

 

Yes to all, would be pretty bad if someone put it in backwards...though I'm not sure why that would contribute. Does running the cabin fan matter if the temp control is on hot?

 

Sounds like you have a bad cap!
The cap is supposed to allow the pressure to increase up to the spec. cooling system heats up; older system is around 6 psi or somewhere around that. Newer system has higher pressure!
Anyway, where the pressure drop below the spec., cooling system cools down, it is supposed to allow the coolant to flow back in from the reservoir!

 

The coolant does flow back in normally when it cools. It just doesn't get sucked in when the engine is running. Do you mean it's supposed to only get sucked in when the engine cools? That would explain the one thing I suppose, I'm still just curious as to why I can't get more coolant in there.

 

When engine is running, the coolant heats up and pressure increases, so some of the coolant will be push out into the reservoir until the pressure reaches the cap spec.
As long as the coolant is hot, the pressure in the system will be maintained at the cap spec. level.
When the engine is off, the coolant cools down, then the pressure in the system reduces, it create a vacuum and draws the coolant back in!
Normally, when testing the cap, not only it needs to be tested for holding pressure to spec, but also to see if it will release when there is a vacuum.

As for not getting more coolant back in, did the cooling fan come on? That is usually the only time the coolant get draw back in when the engine is running!

 

It sounds like that was your issue, not letting it do its job (let the system fully cool before removing the cap to check level).

However, it might be wise to change the cap just as a precautionary measure. I recently replaced a radiator and thermostat after about 120k miles / 15 years and although the system had been running fine prior I used a pressure testing set and found the radiator cap was just beginning to fail. The new cap tested good.

 

I just changed the thermostat on my 1MZ-FE, and I drained a little over 5 quarts, but I can only get a little over 4 quarts to go back in. I have run the engine for a while and left the radiator cap off until it started splashing out, but it still appears to be full even though I know it is not. No coolant flows into the reservoir even after the engine is hot.



Both the upper and lower radiator hoses get warm at the proper time, so coolant is flowing, and the thermostat is opening around the proper 175-180 degrees.



How else do I get the air out?



Important point - even though the engine ran 20 minutes while a quart low on coolant, it did not suck any coolant in from the reservoir - UNTIL I removed the radiator cap, after stopping the car and letting it cool a minute. As soon as I broke the seal of the cap, it sucked in the little coolant that was in the reservoir. I thought it was supposed to suck coolant in from the reservoir while running if it needed it - and how does it make any sense that removing the cap would create a vacuum that wasn't there before? Very odd to me.

Some engines have air/coolant bleeders to remove the air from the coolant system.

 

Was the heater on and open when ya filled and burped it?

 

The car was not on when I drained it or when I filled it - so whatever came out should have gone in, no?

 

When re-filling cooling systems one must pour the new coolant in very slowly. The slower the better. Air will probably become trapped and an issue in filling. Engines are different and don’t always need the slow treatment so one needs to find the useable filling rate for each engine.

The diesel engine in my boat needed the slow treatment. Very slow. Other engines I’ve experienced are fairly easy to fill at a rate that few would have a problem with.
I haven’t had an engine that had burping vents. If one does being aware of where they are tho could prevent spilling coolant in amounts you’d not like.

Another thing to consider is attitude of the engine. If you’re on an incline the engine may take fluid readily and being high on one side could be equally as troublesome. It may take fluid readily with one side or end of the engine high/low.

If you have a drain hole on the bottom of the block (Threaded) filling from the bottom up may work better. On a diesel engine on a boat I had there was a threaded hole and I installed a little ball valve on an appropriate sized fitting to make draining less of a mess. No garage floor to put a container on .. just a boat bilge and one dosn’t want oil and engine coolant in the bilge water that will be pumped over the side. That’s even worse. Good luck …

 

Well, now I've got a weird sloshing fluid sound I can hear from inside the car when I first move it. I think I had that at one point in the past, but got rid of it somehow (probably when I did other coolant work). I assume that's just the sound of coolant moving because air is in there, anyone confirm that?

I got a no-spill tank, stuck it on, and ran the thing for 45 minutes, and it didn't seem like much air was coming out to me. A tiny bit of fluid just raised up into the tank nice and slow when it got hot, then went back down when I turned it off.

The heater was running the whole time and pushing out good hot air. Rad hoses both get nice and hot and the engine temp stays at a nice even operating temp.

It sucked in a bit more coolant from the overflow reservoir afterward, but not much. So, the cap seems to work. But I'm pretty sure there is still air in there. Seems a little silly how stubborn this is. It still does not push the normal amount of coolant out into the overflow tank when it runs (though, it is 30 degrees here so the engine only gets to 190 tops).

Any other ideas? Is the design just kinda bad and it takes forever if you truly want to get all the air out? I'm wishing I had loosened the thermostat-side sensor when I had first filled - that would have allowed air out as it filled. I didn't see anything making that clever suggestion, so if you're reading this before attempting, you heard it here!

 

41,
I would (at this point) pour in coolant until it was up to the hot/warm mark on the tank. Let it cool down like 3 hrs or so. Then start it and see if your bad symptoms have disappeared. Check the fluid level regularly for several warmups. Any more air in the system should enter the surge tank and you‘ll know it’s experienced “burps” when the coolant level in the tank goes down. Coolant went down to replace the air in the bubble. If the coolant disappears down the to the bottom of the tank and thus down the “exit” hole on the bottom of the tank you can/should add coolant until it’s a bit above the exit hole. The burps should get less and less until the coolant level is always at the “full” or “hot” level while the engine is warm/hot.

Chase the “sloshing“ as another problem.

 

From your description, everything is fine and working normally.

 

Some things are, but no - from my description, I've got a weird sloshing fluid sound in the cabin, and it still does not push the normal amount of coolant out into the overflow tank when it runs, because it's not taking in all the coolant that it should.

 

Use a coolant funnel.... attach it to the radiator, fill it, start the engine and let it warm up... the waterpump will help the coolant move around and burp the system. It is sooo much easier to use a funnel. I will never go back to not using one.


If not, just run it till its hot, fill the overflow, and let it suck back / cool... when cool refill the radiator again. Check it a few more times after it cools down from a driving cycle... NEVER open the cap when hot....

Just a classic case of a stubborn air pocket in the system.

 

Use a coolant funnel.... attach it to the radiator, fill it, start the engine and let it warm up... the waterpump will help the coolant move around and burp the system. It is sooo much easier to use a funnel. I will never go back to not using one.


If not, just run it till its hot, fill the overflow, and let it suck back / cool... when cool refill the radiator again. Check it a few more times after it cools down from a driving cycle... NEVER open the cap when hot....

Just a classic case of a stubborn air pocket in the system.

Thanks, I've already done all that, but I guess I'll keep checking it every time I drive and see if more goes in...

 

Plugged AC drain? Did you check that?

 

Thanks, no, but I’m not sure what you are suggesting, how does that impact whether the coolant goes in?

 

Once it is nice and hot, try periodically revving the engine up to about 5K RPM a couple of times to push out any bubbles that may be trapped in the heater core, which could be the source of the sound you're hearing.

Good luck!

 

Hey I’m a brand new member so I can’t start a thread, plus doing so would just piss some people off “you didn’t search the threads, there’s plenty of discussions about this”😂but I did, and can’t find anybody with my exact situation and resolve. Here’s how it went: I’m driving and I get a check engine light, luckily I was driving to advance auto, so I pull up in the parking lot and plug up my scan tool. P0115. So I go in and grab a new coolant temp sensor along with what I originally came for. When I came out I tried to start the car (before putting the new sensor) and it would start, then die. Then it didn’t want to start at all. I took the old sensor out and then tried to start the car again, it started up with no problem. Then I installed the new sensor and went about my day. About 15 minutes later on the freeway I look at my temp gauge and I’m overheating, I immediately pull over and there was a good amount of smoke coming out of the small hose that is routed into the cap on the coolant reservoir. I get it towed home and left it alone for a few days. I went ahead and installed a new thermostat today, to no avail. Here’s where I’m at: 1. Heater does not work. 2. Radiator fans are not engaging. 3. Both the upper and lower radiator hoses never get hot and there’s no pressure like you’d expect to feel if there was coolant running through them. 4. Vehicle still will overheat if I let it idle too long. Don’t know if I left anything out but hopefully that’s enough info for somebody to have a suggestion. Thanks.

 

Did you put the thermostat in the same way it came out? The spring side goes towards the engine not the hose.

 

Did you bleed out the air in the system after changing the thermostat?

 

I did not. But the car was already overheating/no coolant flowing through either radiator hose before installing the new thermostat

 

Did you put the thermostat in the same way it came out? The spring side goes toward the engine not the hose.

 

on a camry, the only way to properly bleed the system and to get the system up to pressure and allow the thermostat to open is to run it with the cap on, otherwise the radiator hoses will get hot but without pressure the stat wont open hence no hot air in the car, even if there is hot air the thermostat still needs to open to fully bleed out, install the cap, run engine for about 30ish minutes to a hour while keeping watch on temp gauge than let it cool down completely 3 hours or so than check coolant level

 

That is interesting what you say. But not true. The thermostat is a wax cylinder that expands with heat. The test for a thermostat is to have it out of the vehicle, putting it in a container of water that is being heated (with a thermometer in the water) to see at what temperature it begins to open. No pressure involved at all. The key is to get the water pump flooded so it can pump the coolant. You don't need pressure in the cooling system to do that. Some folks will massage the lower radiator hose (that goes to the thermostat housing and to the water pump) in an effort to flood the water pump. If that is something you can do, that is a good thing. But one needs to be careful, and one needs to massage the hose away from the radiator and towards the thermostat housing. This is why I like lifting the front of the car up on jacks - it is to get the radiator higher than the water pump - adds in flooding the water pump cavity where the impeller is.

 

that is actually true. i was going by the last engine swap i did 2 weeks ago where the guy wanted to use the old stat instead of new one and it was kind of rusted so i guess it needed the extra help from pressure. is it possible he got a defective thermostat? the original poster

 

I just went through this same problem when I replaced my radiator and transmission lines as well as upper and lower hoses. When I filled the coolant their seemed to be air still in the system. I had used a never spill huge funnel and let it idle for about 15 min while raising the idle to about 2500 rpm’s at times. Well after letting it cool down overnight I needed to add water. This is what I did for the next couple of days check water level cold at the cap and add water in the reservoir. It finally settled down to a consistent water level in the reservoir every morning. Stubborn little air pocket, I like Honda’s bleeder valve much better.

 

This: Lisle 24680 Spill-Free Funnel | ToolDiscounter Jack the front of the car up as well.

 

Best............ tool.........ever.