Extremely strange overheating!!!

[nismo dreaming]

ok, car is a 95 240sx, stock ka.

sutation: car overheated to point of warping the cylinder head, the head was replaced with a 93 head that was milled/checked for spec, water pump was replaced, t-stat was replaced, radiator was replaced, coolant and oil was replaced.

problem: the car still overheats, after it warms up, it takes about 10 mins to start overheating, we even ran both the electric fan and mechanical fan, and it still overheats. after the head was replaced, the car ran fine for a week with both fans on, then it started overheatin again, and thats where we are now, this was after about 120 miles of the head replaced.we are also not loosing any coolant, all coolant stays in there.
Modified by jaytheman88 at 3:35 PM 3/24/2006

[onosqv]

have you done the basics?

1) check for coolant leaks2) bleed coolant to make sure no air3) check compression4) if necessary, try leak-down test5) make sure coolant is actually flowing - i.e. when temp goes to warm, you can feel the coolant flowing thru the upper radiator hose.

how-to to do each of above can be found via search...

who did the rebuild/install, do they offer warranty, obviously if they just "fixed" it a week ago, they should have some sort of warranty service.

[nismo dreaming]

1)checked, fine2)mostly checked, some may be stuck in the t-stat cause the burp hole is in the inner ring(the thing that opens and lets coolant out), not the outer ring(the 1 that stops the t-stat from movin out of the housing)3)compression is 160 accross4)were not loosing any coolant or compression5)the pump should be flowing, its a brand new pump thats not leaking

me and my friend installed it, he has done this many times already, engine started fine with timing @ 20deg like stock.

and i did use the search button to no avail.

[DjPantsSpecR]

you didnt say, but is it safe to assume you used a new headgasket?

[Aworkinprogress]

could be your coolant temp sensor gone bad.. went bad on me today. engine was not really over heating just indicating that it was. check it out.

[nismo dreaming]

Yes, we actually USED a new one. The temp sensor should be ok because the engine actually overheats. I know this is complicating, but please, HELP!!

on another note: when the car is at normal temp and the heater is at full blast, air comin out is not hot, or even warm, but if the defroster is turned on, it comes out hot from that 1(takes its time before it gets hot, but it does), that makes the idle rpm go to 1000. I asked a mechanic friend about this and he said it could be a vapor lock?, somewhere in the heater core/system.
Modified by jaytheman88 at 5:52 PM 3/24/2006

[MikeMurphy]

After i replaced my tstat i had very little heat coming inot the cabin. I believe if your heater core is not working then you have a bubble in there.

Did you open up your heater core when you drained and filled your coolant?

[ddgsxr504]

Well after reading your post and coming to an educated conclusion......

CHANGE YOUR RADIATOR CAP!!! IT'S BADDDD! GO OUT RIGHT NOW AND BUY A NEW ONE!!

[nismo dreaming]

Changed the radiator cap about 2 weeks ago. And no, we actually didnt drain the heater core now that i think about it. We just got done pulling off the hose and draining all the fluid out of both the in and out side of the heater hoses. Alot of coolant came out, but were not sure as to if the heater core is broken or not. I am going to try to heater core again tommorow and if no avail, i will go ahead and delete the heater core until i can actually afford one. Thanks for the help.

[nismo dreaming]

Update* After troubleshooting the everything we could think of, we bypassed the heater core in hopes that it would fix the problem. WE ARE STILL OVER HEATING. I am truley, completly, out of ideas as to what else to do. I dont have anouther car and i dont have enough money to have some shop charge me millions to do work that i could have already done. If there are any other tips, please let me know. Thanks.

[Florida240sx]

Is the thermostat opening up? I just swapped engines and the thermo was stuck. You got water in their or do you have it mixed with fluid. Even though your gauge says hot how does it feel? I want to say it's your thermo because that wa smy last problem. Other than that your HG...... You did check the hoses for pieces of paper correct?People often put paper towels/rags in the hose to prevent dirt getting in there.Sometimes we forget and just install

[mattscar]

is thier oil in the coolant? are you blowing any smoke from the tambucho? how is your idling?

[nismo dreaming]

Well 1st, it was the thermostat. The actual problem was that the thermostat that i had bought at orielys was one without the little burp hole at the top so air would just get stuck behind the thermostat and cause the engine to over heat. After takein out the thermostat, the engine ran fine without over heating. Problem is now, the car runs too cold and i have to go and get a nissan factory replacement so that i can run the thermostat again. Thanks to all for such quick and great help.