plz help overheating

[180sxidey]

hi, sr w/ koyo radi & flex dual fan.. the fan is on all time.. water pump is fairly new... less than 10k stock hg w/ gt28rs... haven't tune it yet.... think it s running lil lean.... but never really drove that hard...

one day no issue.. but time to time the temp gage jumps around... it goes over the max temp reading.. so i thought it was some kinda wiring problem.. or something

oh yea.. and my idle went up during cold start... goes up to 2k and gradually.. comes back to ~1k.....

but today i was stuck in traffic and the temp gage constantly stayed way up... noticed no coolant in the reservoir,, so i poured some in... waited little.. but it was still reading.. high.. fu.. it just drove it home... coolant wasn' boilin but it was almost gone again.. i couldn't really tell if there was any leak... but nothin on the floor... but the engine bay was definitely hotter than usual...

i thnk my hg is blown.. but just making sure.. w/ experts.. if it s the hg... inspection for warps required.... before replace em?

i am a noob.. w/ no money... i appreciate any cmts or suggs.

[jdm_master_X]

during cold starts (called OPEN LOOP) the ECU raises the idle to speed up the warming process. it will drop when it starts to warm up so thats normal. the ECU runs on preprogrammed outputs.

anyway, when you add coolant, make sure the car is cold, and start the engine. watch for air bubbles coming to the top of the filler cap on the radiator. let the car run until the bubbles stop forming. maybe you just had air bubbles in the cooling system. you were in traffic, so overheating can occur depending on how long you are sitting. my s13 heated pretty high during bay area traffic.

IF YOU REALLY HAD A blown HG, a cylinder leakdown test would reveal bubbles in the radiator when pressurized air is introduced into the cylinder chamber. i highly doubt you blew it, because it would have run really crappy.

and do fix the lean condition....we dont want another car lost to blown motors...

[180sxidey]

thx jdm masteri just refilled the coolant...and i saw some bubbles coming up to the top...i let it run for about 15 mins.. and no more bubbles i think...but my temp gauge started jumpin up and down again...but after i restarted the car..... it seems to be pretty stable...i will let you know if it fixed the problem tomorrow..thx again

oh.. and the idle did stay pretty high before durin cold start..... like 1500-1800... but it never went over 2000...... but now it goes high as 2200 not sure what s the cause... the whether is still pretty hot down here in soCal... today was over 90 degs...

[jdm_master_X]

yeah that makes sense. ambient temperatures can effect cold start idling. there is an idle air control screw on the intake manifold. your idle should be 750-850, so if its around 1000, either your throttle cable is overadjusted or your idle speed control is overadjusted. tune them down a bit and see how well the idle stabilizes.

how many miles are on your motor btw?

[180sxidey]

hey...it didn't overheat today!! but no traffic..... the engine has about 40k miles... the throttle cable was loose and i tighten it couple of months ago..maybe I tighten it too muchthx master X