Overeating KA, fluctuating temp gauge

[Ollie]

When I drive my dohc ka it heats up normally after about 10 minutes of driving and then the temp gauge keeps going up to H and then it goes back down to normal and then back to hot again and back and forth. Is my temp gauge messing up or is it something else? Maybe air trapped inside? Anyone have this issue before? I searched but couldnt find anything similar to my problem with the gauge fluctuating like this.

Any help would be greatly appreciated.

[Z U L8R]

yeah, sounds like there's an air pocket in there. burp your cooling system via. there's also a bleeder screw on the intake manifold right by the upper hose, it's a 10mm nut with yellow sticker and japanese writing on it.

open that until you get just coolant flowing out with the radiator cap off (don't do this on a hot motor, duh) and the engine idling.

also get a new radiator cap because it should be letting out the air pockets when it heats up, then sucking back the coolant in the resivoir when it cools down.

gl

DAVE

[junn]

yup had exact same prob when i had my ka....ended up being air pocket

[SinGarage]

That would also be the first thing I would do. Second is check your temp sensor that goes to the gauge per FSM. They seem to be also very notorious to go out. Just happend recently on an S14 I just worked on. Bled it quite a few times and it was still doing that. Then checked the resistance on the sensor and it was bad. I think $18 bucks at autozone.

[240_fun]

How to get air bubble out of your 240 (http://s8.zetaboards.com/240SX_Family/topic/8174283/1/)
DO IT

[Ollie]

Okay so I tried bleeding it a few times. At first it seemed to be working but it kept overheating. Then it seemed like the bubbles wouldnt stop coming out of the bleeder screw and I couldnt get an even flow. Now I tried again and no coolant is coming out of the bleeder hole at all. It was blowing out smoke/hot air.

Anymore help??

[Z U L8R]

if it's blowing out hot air right away when your motor's not even warmed up then you have a blown headgasket. you should have about 2 gallons of coolant/water in the system.

once the car warms up see if you have heat coming out of the air vents. if not, there's not enough coolant in the system and you still have some air pockets.

best of luck

Dave @ Pro Auto Care
770-980-0033

[ericcastro]

shove your a garden hose into the radiator cap, open that bleeder and get that thing filled up!!
lol

really thought.
are you leaking coolant anywhere?
have you been working over a gravel driveway and not seen a leak?
is there alot of smoke coming out your exhaust?

[Ollie]

if it's blowing out hot air right away when your motor's not even warmed up then you have a blown headgasket. you should have about 2 gallons of coolant/water in the system.

once the car warms up see if you have heat coming out of the air vents. if not, there's not enough coolant in the system and you still have some air pockets.

best of luck

Dave @ Pro Auto Care
770-980-0033I changed the thermostat and bled the system. At first it wouldn't blow hot air at all, then I got some more airbubbles out and the temp gauge went back to normal and the heat began to work. I thought it was good then I drove it for a 5 mins and it started overheating again. This time the gauge stays hot instead of fluctuating like it did before.

shove your a garden hose into the radiator cap, open that bleeder and get that thing filled up!!
lol

really thought.
are you leaking coolant anywhere?
have you been working over a gravel driveway and not seen a leak?
is there alot of smoke coming out your exhaust?
That's pretty much what I did and I thought it worked.

I cant tell if I am leaking coolant. First I was over gravel and then i was working over snow/ice. Ive been working in the freezing cold, it blows.

I had someone take a look and help bleed the system and they said if it starts to overheat again it's probably the waterpump. The car's got 135k miles.
What do you think??

[Marc240]

Headgasket? Did the same thing in my buddys honda.

[CrazyRob]

any leaks? what fan? did you do a block test?

[Ollie]

I'm going to check for leaks again now.

The motor is totally stock. I havent done a block test but I think Im going to bring it in soon for a test.

It doesnt overheat when idling, only when hitting the throttle.

[AWDJosh]

it starts to overheat when sitting still then cooling as you drive you may have a failing waterpump.

BUT like everyone else stated replace that temp sensor if it keeps overheating after all of this then you sir may have a BHG. =[

[240_fun]

BTW i ignored an air bubble in my KA till yesterday (just kept opening the bleeder but not rly trying hard to get rid of the bubble) and my upper rad hose popped. just saying

[Ollie]

Just drove the car. It ran completely normal. Didnt overheat at all. Only thing is the heat was warm, not really hot. Car warmed up normal and the gauge stayed in the middle the whole time.

[jza240sx]

Just drove the car. It ran completely normal. Didnt overheat at all. Only thing is the heat was warm, not really hot. Car warmed up normal and the gauge stayed in the middle the whole time.

what was your problem?

[Addicted2Kouki]

hungry overeating KA!?