overheating problem/question (searched)

[Gramentz]

I've searched on multiple forums about this issue I'm having. I will try to make this as condensed and specific as possible. I had an SR, sold it, purchased a KA and swapped it back into s14 chassis.

Brand new radiator, rad. cap, and thermostat from advance. I am using the stock clutch fan with shroud. Heater hoses: left-top firewall, right- lower firewall.

Starting the car, the temp takes a while to reach normal operating temp. A short while later, anywhere from a minute to ten, it will start to overheat. Sometimes it will not overheat at idle whatsoever; only when I go for a drive.

At idle under normal operating temp, the heater does not blow hot/warm air; only cool. (I do not have the heater control valve, so it only blows on full.) If it overheats while I'm driving, it will then blow hot/ warm air. It seems to be hit and miss as to when it blows hot air.

The lower radiator hose does not get warm or hot. It feels completely cool at all times. This is why I replaced the thermostat originally, but it did not change the temp of the hose. I bled the system by first removing the radiator cap while the engine was warming up to top off the coolant level. Once the coolant was topped off, I unscrewed the 10mm bleeder while the heater was on full blast (even though it was blowing cold air). I had it loosened for a good 5-10 minutes to let out the air but it still started to overheat it seemed. Every now and then coolant would spit out of the bleeder valve or fizzle out, but no steady surge of coolant.

I am also throwing a few codes: EGR solenoid, Crank Position Sensor, Knock Sensor, and IACV. These shouldn't pertain to my heating issue, right? Only every now and then it will throw the Coolant Temp Sensor code and this is the one I question.

I know the stock temp gauge is not that accurate, but when it climbs and I turn it off, and then back to ACC a few seconds later, the temp reading is different than before. (I.E., between middle and H line, then to normal temp.)

Compression test seemed to yield normal results and two adjacent cylinders did not read abnormally low, leading me to believe this is not a HG issue. Although, when I did remove the spark plugs, cylinders number 3 and 4's spark plugs looked almost as if they were spray painted black and looks rusted/corroded where it seals. These are brand new spark plugs.

I am not sure as to the condition of this engine and its history because it isn't the original. It does sound okay/decent when it is idling though.

Here are my questions: Is the coolant temp sensor code being thrown because the car is overheating? Or is the car overheating because of a faulty/bad coolant temp sensor? The radiator from advance has two extra nipples on the bottom (assuming its for a trans cooler on A/T?), these came capped and I just left it capped and untouched from the box. Do these need any modifications or is this relating to my heating problem? Even if it overheats, the lower radiator hose should still get warm right? Granted, I can take out the thermostat completely to test this, but if there's any other suggestions, I'd like to start there.

Thanks! Really do appreciate it!

[Madmax3]

Have you looked at your water pump. I had one on a 90 Nissan PU that the vanes had completely rusted off so although it was spinning it was not moving any water. I would check that.

[R6_240sx]

Wait did u ever bleed it while the radiator cap was on? If u didn't try bleeding with the cap on along w/ the defroster on full blast hot.

You can check if ur water pump is crapped cuz it won't spin bc its seized or ull see coolant drip out.

[Gramentz]

The water pump looked like it was in good shape. It doesn't leak and none of the fins looks worn down or rusted, etc. I can take it off and inspect if fully though.

I bled the system by unscrewing the 10mm bolt with the radiator cap on. I also turned the heat on full blast even though it was just blowing cold air. I can try it with the defroster turned on.

[Sijonda]

bump...

I got an S13 doing pretty much the same thing. I've been told I have a bad radiator, but before I buy one I definitely want to know where this thread goes.

[Gramentz]

I took the new thermostat completely out and ran it like that for a good hour. Lower hose got warm, heater blew hot air. Put the thermo back in and bled it how I bled it before, and all is good. Maybe it was clogged somewhere and it just needed to circulate....who knows.

[MTX450]

there was probably air stuck in the system....the ka loves to trap air...im working on that issue currently

[Felipe]

Sounds like you have a water flow problem. Check your heater core. Some thing is clogging up the flow. Did you or do you know if they have used some sort of radiator stop leak or sealant? That usualy fuucks up the flow.

[DALAZ_68]

best way to make sure u bled ur system properly is if u were at an incline(hill jacks drive way w/e) with nose up...lossening bleeder valve, start car, let it reach normal heat, then add more coolant till it starts coming out of the bleeder valve...close valve, and ur done...

if ur sensor is malfunctioning then u cant go by what the cluster needle says, best way to know if ur car is really over heating is to have a temp gun handy and see wut it reads,

id say ur best/cheapest solution...rebleed ur system on an incline, better yet open up the lower hose and check ur thermostat, make sure the lil hole on the ''plate'''of the thermo is up not down...

if ur temp sensor is bad then change it...if u wanna test it, all u need is boiling water a multimeter and FSM

u might even have a sedement issue in ur radiator, get radiator flush,

i know u might say ''i was using the same radiator with the sr, not the point, if that is true...sedement might have been in the engine coolant lines ...

another good tip...add a bottle of water weter (find it in autozone or pepboys for like 4-5 bucks) it actually works in keeping ur temp down...

GL and let us know