UNDERheating!!??

[#1gun]

so here is the story. i have a 92 240 and it is all stock except suspension and full exhaust system but that doesnt matter. my heater wont blow hot air, and my gauge says cold all the time. my thermostat is new as of last fall and there is no leakage or anything. its like my cooling system works too good lol. but seriously any ideas?

[ShaunakaRichard]

Make sure that coolant is flowing through your heater core. It'll be the two hoses attached to the firewall on the passenger side. And also make sure that the thermostat control is functioning properly. Could be stuck on the cold side instead of the hot. In mine the pull wire in the thermostat control came out so turning it from cold to hot really was doing nothing. Something to think about.

[ShaunakaRichard]

and as to the temp gauge it could be that it simply isn't working. Or the sensor on the motor isn't any good. The oem shop manual will have instructions on how to test them. You can find them around the internet for free download.

[That Guy1]

And I see youre in Indiana(cold). If you have headers and not a manifold. your car wont ever get to temp in the winter. I live in cincy and I can hardly get there with a ka24de-T.

[johnnyballs180]

it's cold and i'm lonely, so i've been posting all over the place. I think ShaunakaRichard was talking about the factory service manual (aka oem shop manual??), so that's the link here on NICO below. and then a couple possibley-relevant links on NICO about the coolant temp sensor and thermostat.i hope this helps?

http://www.nicoclub.com/FSM/

zerothread?id=254375

zerothread/306630

zerothread/253879

[the converted]

And I see youre in Indiana(cold). If you have headers and not a manifold. your car wont ever get to temp in the winter. I live in cincy and I can hardly get there with a ka24de-T.

Never thought a header could take all of the heat out of the engine Double check the thermostat, and make sure there are no kinks in the hoses that feed the heater, and check that the mix valve opens and closes when you move the heater from hot to cold.

[Rex]

It's possible the thermostat has "failed" in the open position. If that's the case, the motor/coolant will never "get warm" enough to create any heat.

When was the T-stat last changed?

[SullivanRacing06]

do u still have the stock clutch fan or electric fans? damm, every one in the rb forums wishes they had this problem

[SullivanRacing06]

install a aftermarket water temp gauge in your upper rad hose n see what it reads!

[#1gun]

ok about the thermostat, i changed it last year around this time because of the same problem(this was before i put the header on btw) and it didnt seem to fix it

the temp gauge was working a few weeks ago when it was unseasonably warm a buddy of mine said maybe an air bubble is stuck but i opened the bleeder bolt near the intake mani and it was fluid all the way up. i did this with the engine off then started it with it open. some fluid came out and leveled of then i put the bolt back in with it still running

while doing this i also looked inside the rad and it looked like the coolant was flowing through. not very fast though.

and i still have the stock clutch fan. after typing all this i realize it must be the therm not closing. right?

[#1gun]

oh and exactly how do you bleed the coolant system? im not a noob but i have never heard of that until i was searching trying to figure out my problem

[ANVIL]

open up that bleeder valve and let the car idle for 10-15 minutes. make sure you have the heater all the way hot, and on the highest setting. another way is doing it with the radiator cap open instead of the bleeder valve. helps out a little to have it on a hill/driveway/ramps too, where the engine sits higher

drive it around and see how it does. it could take a few times of doing this before you get all the air out

[#1gun]

hey thanks i will try that and if it doesnt work i will just get a new thermo and try again.

[#1gun]

And I see youre in Indiana(cold). If you have headers and not a manifold. your car wont ever get to temp in the winter. I live in cincy and I can hardly get there with a ka24de-T.

is this true? i thought if anything it would make the under hood temp go way up. but i dont know. can you elaborate?

[the converted]

It's wrong.

[Rex]

If the T-stat is not "old", then I bet you have an air pocket/bubble. Is your overflow tank up to the full cold line? Make sure it is and try this ...

Park car with nose up hill. Use ramps or a good incline. Let car get warm (as it can), turn on heat full hot and listen for gurgling. You need to make sure the air can go "up" and then has something (coolant overflow) to be replaced by while it's cycling.

If you take the radiator cap off (while cold) does the coolant come all the way to the top?

[#1gun]

ok i was just outside freezing my ace off while doing this. first off when i take the cap off the coolant is at the bottom of the opening. seems fine. i put some coolant in the overflow tank. topped it off to the line. now , i started my car and let it run. no gurggling. a few small bubbles when i squeeze the hose. i put some water in to bring up the level. turn on heat on defrost full blast full heat. wait about fifteen mins and check the air coming out. still cold.WTF. ok now i am starting to get cold and thus getting pissed. i squeeze all the cooloant lines i can find in hopes of releasing some more air bubbles. nothing. so i look over and see that my fan just kicked on. what? i never noticed i have a clutch fan and an electric fan . so i pull out the relay and it goes off. cool. should start getting warm. ten more mins nothing, still cold. now i am baffled. so i just stand there looking at my running engine pondering what the h$ll can be going on and notice a sound coming from the bottom end. kinda like metal on metal. so i instantly turn it off and check my oil. NOTHING!WTF! i just changed it a feww weeks ago. and now i am on my way to get some oil. ill check back when i get back. someone please give me an idea on whats going on

[#1gun]

update. i put some oil in and tried to warm her up again. this time with cap on.ten mins later nothin but cold air.

i am stumped on why its not getting warm and where the oil has gone, no leaks or oil anywhere under the car(actually its probably the cleanest its ever been lol) so any ideas will be greatly appreciated. i will check here again in a while, hopefully someone has something.

ha ha i am going to change the name to "the ice box"

[IanS]

Are you still using the belt driven fan?

It is possible that your fan clutch is siezing, this is not allowing the fan to freewheel when the engine is cold.

With the engine off and cold the fan should spin freely, if it has a lot of resistance, the clutch is bad.

I would suggest removing the fan and running the car, if it still wont warm up, you have other issues.

[SullivanRacing06]

good idea, yea if the stock clutch fans clutch is worn out or locked up, your stock clutch fan could be spinning allot faster then what it was designed to. its attached to your water pump pulley with 4 10mm head bolts, remove the fan, tighten up thoes bolts n see if it builds ne heat

[scooz14]

the fan shold spin freely with a cold engine. if not, replace the clutch

[#1gun]

thanks for the replies. i just checked the fan it spins freely. well not like freewheeling or anything but it is super easy to spin. would you suggest removing it anyway to see if it warms up, or move on to something else?

actually i will just remove it and test it. RESULTS COMING SOON!

[#1gun]

i am truly baffled now. i took off the fan, electric fan is still unhooked from yesterdayand i let it run for about 5-10 mins. still cold. so i took it for a drive for about four and half miles with my hand feeling the vent the whole time and watching the gauge. still nothing on either. so i figured maybe my gauge is broken and my heater is clogged. i pull in the drive and pop the hood, put my bare hand on the valve cover. COLD. i start checking the hoses and they are like luke wrm so i am absolutely dumbfounded.

maybe i should drain the coolant just kidding

[Chaotic_Warlord]

i am truly baffled now. i took off the fan, electric fan is still unhooked from yesterdayand i let it run for about 5-10 mins. still cold. so i took it for a drive for about four and half miles with my hand feeling the vent the whole time and watching the gauge. still nothing on either. so i figured maybe my gauge is broken and my heater is clogged. i pull in the drive and pop the hood, put my bare hand on the valve cover. COLD. i start checking the hoses and they are like luke wrm so i am absolutely dumbfounded.

maybe i should drain the coolant just kidding

Seriously dude? Not to insinuate anything but you seriously need to run longer than that. I have a 95 S14 with a stock engine but have a full exhaust header back and it literally takes my car close to half an hour to warm up when it's cold out. Go out for a nice cruise, get some stop and go along with some highway miles in there for good measure. take like an hour like cruise just for good measure.

If you are still cold then you have a severe air pocket in the system. Either that or your Thermostat is frozen or stuck in the open position. I had the exact same problem you are having and finally replaced the T-stat for the second time in a year. Make sure you get the proper heat range, don't go and get something meant for a track car if you aren't tracking it regularly and if you live in a cold climate. T-stats are one of those finnicky parts that you can get bad from the factory or go bad fast.

Also check the cable that attaches the heater core to your heater unit in the dash, since it's a cable it may be stuck in the cold position, I have to physically move mine every winter because its sticks. For peace of mind replace your temp gauge sensor, it's in the front of the block by the water pump. If you replace everything and are still having an issue take it to a mechanic and have them run a diagnostic, if you are under heating you're ECU will cause you to run rich to try to get the block up to temperature. Under heating will cause you have horrible gas mileage and your timing may get thrown off because the ECU will do what it can to prevent you from having a detonation problem or worse yet cracking the block from the friction and improper oil viscosity.

So my tips to you are as follows:

1) go for a decent drive allow your car a decent period of time to heat up2) replace your T-stat yet again (flush the coolant system in the process you may have a blockage somewhere)3) properly bleed your cooling system

If you still have the same under cooling problems or think you are:

1) replace your temp gauge sensor2) check your heater cable

If you still have the same problems take the car to a shop and run a diagnostic, it could be a serious problem. Beyond all that I have no freaking clue

[#1gun]

Chaotic, thank you immensely. i will do this tomarrow since im off and report back with my findings. btw my thermostat is oem

[#1gun]

alright i didnt replce my therm yet but i did get my car to get warm. i took it down to the local high school and slid around in the snow for about half an hour and it warmed up rather nicely. stayed that way the whole time until i left to go back home which is about 1.5 miles away and about a quarter of the way it just went down. it was back under C by the time i got home. so my conclusion is... my thermo, even being farely new, is bad and is stuck open. there is my expert thinking. i will actually change my therm tomorrow and hopefully fix this shizzle. any comments or thoughts are welcome.

[nuts510]

I know being cold all the time is aggravating plus it will sure make you burn more gas. Quit fighting with it go buy a OEM Nissan thermostat for your car and install it after you have installed it removes the air bleed screw from the upper radiator housing it's a little 10 mm headed bolt. Fill your radiator back up and then continue to slowly and I mean slowly add antifreeze and until you actually see it come bubbling out the bleed screw then reinstall the bleed screw with the radiator cap off allowing the car to idle until it reaches operating temperature this band when the gauge is in the center not just starting to raise then topped or cooling system back up reinstall the radiator cap and go see if you don't have some heat now I bet you you will the problem with thermostat on these silly things is not only does it open for the radiator but it also closes off a highly set allows for recirculating and a lot of aftermarket ones don't do this right. Try it but use a Nissan thermostat

[SullivanRacing06]

if you wanted to do a lil mod, eliminate the factory clutch fan and wire a fan controller in on your stock electric fan, ull gain ppower n itll stop air flow thru the rad untill the electric fan kicks on, just a idea

[#1gun]

i have heat! whoever said it was air you were right! i drained the fluid and took out the therm and tested it with a pan on the stove and it opeened at exactly 170 which is oem. so i put it back in and filled the fluid on an incline and bled it. and now i have heat, still no fans in though. it works, i'll put the relay in when it gets a little warmer outside but for now its good. thanks for all the help fellas