Still overheating....WHY???

[chrismo240sx]

put this motor in about 3k miles ago and it was fine up until about 4 days ago.

When i put this motor in, i put in a new thermostat, temp sensor, radiator, (with cap of course)

I tried bleeding the air out today and it didnt exactly help any.

My old motor blew up because of an overheating problem so i dont need this one to goo.

I parked my car up my driveway (its up an incline) so the front of the car was up. I took off my rad cap, Unscrewed the little 10mm screw on the intake mani and turned my heat on full and let it warm up. I saw a few bubbles coming out then it stopped and no more fluid was coming out at an idle, only if i revved it up so i put the screw back in thinking it was done.

Took it out for a test drive, not 2 minutes in, the needle starting climbing its way to the H line and its really tickin me off now.

So anyone have anything to share? Am i bleeding it correctly?

[chrismo240sx]

anyone, please....could use the help

[positron1]

Still waiting on the bleeder screw jack up diagnosis?

[chrismo240sx]

Still waiting on the bleeder screw jack up diagnosis?

what?

[modulation]

Are you losing any coolant?My first guess would be water pump or stuck thermostat...

If the engine you swapped in was sitting for any amount of time (even a week) the water pump bearing are probably bad, they don't like to sit without coolant.

[chrismo240sx]

Are you losing any coolant?My first guess would be water pump or stuck thermostat...

If the engine you swapped in was sitting for any amount of time (even a week) the water pump bearing are probably bad, they don't like to sit without coolant.

No i replaced a brand new water pump when i put the motor in.

I have no signs of coolant leaks either. For some reason i still think there is air in the system.

And if the t-stat is stuck open what do i do? Buy a new one or can i go in there and do something to fix it?

[modulation]

No i replaced a brand new water pump when i put the motor in.

I have no signs of coolant leaks either. For some reason i still think there is air in the system.

And if the t-stat is stuck open what do i do? Buy a new one or can i go in there and do something to fix it?

I would think the t-stat would be stuck closed so that the cooled fluid from the radiator isn't flowing into the block. If you feel the two larges hoses going to/from the radiator from the block is there a large temp difference between the two? You'd simply replace the thermostat..

If you put your junk up on ramps and the radiator cap was the highest point I seriously doubt you still have air in the system

Is your coolant level staying the same?

[Koukiman654]

Well first off if your thermostat was stuck open you wouldnt have an overheating problem you would have an over cooling problem and second you have to replace the thermostat if it is what is wrong. If you are still overheating and you know there is no air in the lines what about your cooling fans and is anything blocking the radiator??

[chrismo240sx]

so maybe it is stuck closed???

Yea my coolant level stays the same and i have a brand new Mishimoto radiator with an e fan and nothing is blocking that.

Im gonna try to bleed it again in a little bit because when i did it yesterday i didnt keep filling my radiator. Maybe that can be the problem...or the t-stat is stuck closed? IDK

[Koukiman654]

Yea if any air enters it can cause you to overheat but as for the thermostat I thought you said it was new?

[carps13guy]

when i replaced my thermostat i couldnt burp the system either. what i ended up doing is while the motor was cool enough to open up the cap, get a large funnel and fill the funnel with coolant, have someone start the motor, and turn the heater on to level 1 or 2. the point in doing this is that there is air in the system that is not allowing your thermostat to open up. by doing this you should push the air out of the heater core and if you have the funnel filled with coolant, it should suck down a considerable amount of coolant and the air will be expelled out of the top of the radiator. it took 2 times to get all of the air out of my cooling system. but after that, it cooled like a champ

[chrismo240sx]

Yea if any air enters it can cause you to overheat but as for the thermostat I thought you said it was new?

yes it was when i put the motor in...maybe its a bad one? i didnt get it from Nissan so maybe....i bought that, a new water pump, and radiator when i put the motor in.

[Koukiman654]

Well lets see if its a brand new thermostat only thing I can think of from what your saying is that either you still have air in it which try bleeding it some more with the heater going and see what happens and if your cap is off while it is running you can tell when the thermostat opens or not by watching and seeing if the water is flowing through the radiator or spitting at you if that happens then your thermostat is ok unless it has female qualities and has its moments lol.

[chrismo240sx]

yea, ya see what i dont understand is when i put the motor in and filled all the fluids, i bleed the system and it was fine with no overheating problems for about 3 months. So why all of sudden would it start doing it again?

How can air get in there?

[modulation]

It does this when the car is moving steady as well as when you are cruising on the interstate?

Are you sure you're E-Fan is kick on?

[chrismo240sx]

Hey guys, thanks for all the responses and help

I blead the system again and kept filling up the radiator cap and did this for about 30 mins. The needle never moved once it was warmed up.

So after all that, there was still some air somewhere in there!!

Thanks again everyone!!!

BTW...whats the normal line for operating temperature? My needle is exactly pointing to the 3rd line up from the C bar for Cold...pretty much right in the middle.

[modulation]

The temp gauge is worthless, it'll stay there and the coolant temp can be anywhere from like 80-87+C, but that sounds like about where it should sit.

I don't understand though. You think you had air the system the entire time and it worked fine for 3 months but then started to overheat all the sudden?

Did you use your heater or something for the first time in months?

Sounds too good be to true..