Hey guys, so recently my heat seems to only work when im accelerating or coasting, when im at a stop idling, it starts getting cold. I topped the coolant in the radiator, made no change, any ideas what could be happening?

 

The symptom you describe is classic low water. Maybe you have air pockets trapped in the engine.You'll have to raise the front end and run the engine with the radiator cap off until the thermostat opens to let the air out.

 

DennisMik might be right regarding the air trapped in the system. When I recently swapped out my radiator I had to bleed the air out using a Lisle 24680 Spill-Free Funnel. You can also make a tool to do this. I also had to perform this on our old 02 Altima back in the days.

Here is the troubleshooting process for the Altima:
http://ww2.justanswer.com/uploads/ba...7c06heater.pdf

 

The heat is low due to one of the two things. The coolant levels could be low not enough coolant to heating core or low enough that the coolant is just enough to flow in the engine and heating core. The radiator could have low or no coolant with air pockets. The other cause can be the thermostat could be stuck half closed or half opened. The first method is just to check if you have coolant to the max. The heater climate on full and on defrost position and let the car run to normal temps. open radiator cap and fill the radiator to the top. The air pockets should bubble out while car running and the heat on blast and the coolant is filling up,check for heat immediately. If the thermostats bad you will notice as you fill the radiator up, it will slowly fill up to the top. The other way you can tell if the thermostats bad the car running at normal temps you can have one hand on the upper rubber hose and check to see if the hose are either hot or cold, if it's hot it's a good working thermostats. If the hose is cold the thermostats could be stuck closed. The one other method that's well known is to squeeze the hose to hear the fluid move and the thermostat fluctuate. If everything passes the only thing is left is the water pump.

 

Yes, I had heard of this being an issue as well but how did air get into it all of a sudden? I havent opened the radiator cap or done anything with the coolant, so a lil bizarre to me. When you say raise the front end, like can I do it on a slight uphill? Should I take the cap off and then start the car?
Thanks for that but doubt I can make that on my own. Ill try the method with the radiator cap off, then starting the car to let any car out once the thermostat opens
So I filled the radiator with coolant today and nothing changed. So like I metioned in the reply to the first post, I should undue the radiator cap off and then start the car? you said turn car on, then take cap off and top up, once the car is on, dount ill be able to touch the radiator cap due to heat? or im not sure how long it takes for it to heat up.
You mention to check rubber hoses, where are they located?

PS. Another thing, my coolant for some reason has no levels mentioned on it, its half full so im assuming its fine for now? Here are the pics of it
https://photos.app.goo.gl/jkG5xQqpBv9JJZZE2

 

To simplify your answer the radiator cap should be off before the car is running cold. The caps off start the car it should take 5 mins to completely warm the car up first. The radiator would either be full or half depends on your issue. If the radiator is half, fill it up with coolant heat on full blast on defrost position. If the heat gets better and the radiator was low on coolant filling it up with the car running releasing the air pockets, The problems solved. The work can be done on a flat surface would be better.

 

One thing you can do is remove air bleeder bolt on top of thermostat. Make sure coolant comes out and then reinstall. Always refill radiator SLOWLY when doing fluid changes and start with air bleeder bolt removed.

I have had air pocket issues unless I do these two things. Now, zero issues whatsoever. Just keep it mind if doing a coolant change.

 

thenewguy,
Look at the radiator. The upper portion will have a hose connected to it. Then look towards the bottom and you will see another hose heading back towards the motor. vqmaxman wants you to get your hand on that upper hose to ensure the functionality of the thermostat which is a good way of verifying that it is operational. Hot fluid goes from the motor towards the top of the radiator flows down the unit and back towards the motor after being cooled off.

 

I had the same symptoms on my old Hyundai. Air pockets form when there's a leak somewhere.

 

It won't suck in if you have a bad leak.
For example when my water pump was leaking, I had to fill the radiator with coolant because the system was unable to suck the coolant from the tank.
And if you had air in the system it should escape out of the top of the plastic tank. There is an air escape.

 

You show a photo of the overflow tank and you keep saying the radiator. Are you calling the plastic tank in your photo the radiator? That would be incorrect. The plastic tank is commonly called the overflow tank but it is a thermal expansion tank. When the engine warms up, the coolant inside expands and goes into the expansion tank. if there is air in the radiator/engine, nothing will go into the tank.

If you have a thermostat that is half open or whatever, the temperature gauge should be indicating that the engine is too hot or cold. What does the temperature gauge indicate?

 

Thanks, I will try that
Will give it a try, thanks
Will try this, thanks
Actually the reason for me posting the pic kinda got lost in all the posts. The reason why i posted was to show you guys, I have no H or L markings on that overflow tank, i know thats not the radiator lol. Arent you suppose to top that off as well and make sure its not low? I thought theres supposed to be markings on it to guide how much to add, or no?
I had actually filled up by radiator prior to making this post thinking that will solve the issue, but it didnt hence why i made the thread. I havent tried filling it up with the car on so as suggested here so will do that in the upcoming days.
My temp gauge shows perfect readings, as in once the car is at optimal temp, its right smack in the middle so I assume, thermostat is working fine?

 

Air bleeder bolt on thermostat? Where is that?

 

I would also check the radiator cap itself also. Sometimes the cap could be bad and not allowing the coolant to be sucked back in.

 

I have a 2000 and it's on the hat...directly on the thermostat housing. On the driver side of engine. If you remove it with fluid in engine, please be careful since it will get pushed up and out as you unscrew and it will fall into who knows where. Hard to reach with your hand, is all. It's just a 10mil bolt, or thereabouts. Slowly fill radiator until coolant comes out hole...replace bolt....then finish. I Have problems if I dont do it that way.

 

in all the many posts I have read here on the org, I have never seen this mentioned. Would it be possible for you to post a photo of the bolt?

 

 

The 2001 A/T has no bleeder bolt. The 2002 may not even have an upper stat.

Either way if you remove any bolt going directly through into the motor, coolant system, p/s system, A/T,M/T system you will need to dip the bolt in PTFE sealant before installing it.

 

The residue seen is from fluid change. It doesn't leak and never has leaked and I never use a sealer. I suppose it could, but there is a washer on the bolt....seals flush.

 

That may very well be an undocumented bleeder. That bolt is in the thermostat housing and holds nothing in or on. But then, that thermostat was a failed 2 year experiment on the 2000 and 2001 models, so I can understand why it is undocumented.

 

Dennis...what sort of experiment? I'm interested. My thermostat itself worked good as far as I could tell. Replaced it a year or so ago when my output gasket leaked but it had been operating ok. Are you referring to the thermostat or the whole housing assembly area?

 

The entire thermostat and piping. Only the years 2000 and 2001 of the VQ engine have it. It was not on the 1995 through 1999 and removed in 2002. Whatever the idea may have been for it, it didn't work out as it was removed from the engine.

 

So did the op figure out the original problem