Miket2006

I have a 2004 Maxima with a 4 speed Auto with about 145k miles. I just did a trans rebuild last week and it runs like new again.
So i have an issue with the coolant system. I have replaced the radiator, thermostat, & radiator cap. My issue is coolant is being pushed back into my overflow all the way to the top. My temp gauge stays in the normal range. If i get in it and do 20 minutes of highway driving around 65mph the temp stays in normal. when i get back home and open the hood, i see the overflow full to the very top and the upper hose is hard to squeeze. I open the vent cap & all i see is air come out to the overflow. So this is what i have done so far.
1. replaced radiator with new.
2. replaced the radiator cap. (with air vent lever)
3. replaced thermostat.
I bought a new water pump, but haven't installed this yet.

One thing i did try last night was, i left the vent lever open on the radiator last night and unplugged the fans. I let it warm up just a hair over 3/4 of the way on the gauge. Around this temp it keeps small tiny air bubbles (sorta constant) going into the overflow. Then i plugged the fans back in and the temp goes back to normal within less than 2 minutes. If I let the car idle, there is no air bubbles what-so-ever. Could this be my that water pump is bad???? To me the engine just feels a little extra warm, i mean if i keep my hand on the air the fans are blowing, the air feels pretty hot. Like after a while it requires me to move my hand.

I believe the constant bubbles are normal since they only show up when the engine is technically overheating. So my conclusion is that the coolant is staying in the block and not circulating and thats why the engine feels hotter than normal and coolant starts to bubble therefore sends it to the overflow.

I dont know what else to check other than in the mornings when i start the car, it sounds like there is slight noise coming from what could be the water pump. It almost sounds like a lifter that bled off and taps until oil pressure is applied. But the sound goes away within a couple of minutes.

Miket2006

*Update*
So i went ahead and replaced the water pump along with the guide where the tensioner pushes against and my water pump was bad. The guide was broken about 1 inch from the top causing the plastic to slide down and make the timing chain rattle. If i turn it by hand it makes a noise so the bearing was starting to go bad. So long story short, my water pump was creating extra heat (due to the bad bearing) and causing poor circulation. This is why i would get very little bubbles in my reservoir (and reservoir overflowing) due to the water at its boiling point within the block causing bubbles to push out my coolant, therefore, my cooling system always had air and i couldnt bleed air out from constant small bubbles. Once i started the car and bled system it took no time at all. i even had rpm held at 2k & 3k for 5 minutes and no bubbles.
Hopefully someone has use of my experience.
Mike T.

DouglasT

2007 Maxima I bought new now has 218000+ miles. Starting to overheat at stop lights and sitting still, idling. I noticed the AC cooling fan working but not the radiator fan. Where might the fuses be. Has anyone faced this problem with the fan? How did it get resolved. Love the car and looks like new. Thanks for reading.

anolkayn

If your losing coolant and no signs of a visible leak but the heater hoses are rock hard then i'm will to bet your have a blown head gasket and coolant is leaking into the cylinder.

TDGrant

Check your oil filler cap to confirm.