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Rb20 Cold Start Problem/ Overheating

freestyleMX

By freestyleMX,
in Engines & Forced Induction

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freestyleMX Community Regular

freestyleMX

Posted
Posted

im sure this topic has been hit upon before but i have not found one that specifically covers my problem..

so first off my car r32 gtst

mods.

25 turbo

split fire coilpacks

cooler

exhaust

nistune

alloy radiator

thermo fan

catch can

problem #1..

my car has been pushing water bubbles into the radiator overflow bottle after i turn it off after a normal drive. and if i go for a hard drive and push the motor a bit say straight after pushing it i pull into a car park leaving it idling the temp on the stock gauge will go up into the h. so i turn the car off (normally not good idea i know) and then restart it a couple mins later. when i do gauge reads normal (halfway) my theory is theres an air lock and when the gauge is reading hot its just cause theres no coolant in the pipe that has the sensors in it..? the car runs fine while all this is happening btw!

problem #2..

in the mornings when i go to start my car it will run on 4 cylinders for maybe a min then pickup one then a few seconds later pickup the last and run normal. (this problem has only just started maybe a month ago)

now for all you that will ask no normal signs of a BHG water doesnt have oil nor does it have bubles while engine running oil is black with no signs of water. havent had a chance to do a compression test as my mate has my tester atm

so just to clarify car drives fine engine runs great outside of these problems even on a warm day giving it a bit it still wont get past halfway on the gauge..

and please no smart throw it away get a 25 etc comments i like this motor and just want to get it running sweet!

but im stumpt hopefully someone can help me out here

thanks

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https://www.sau.com.au/forums/topic/380326-rb20-cold-start-problem-overheating/
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SargeRX8 Grand Master

SargeRX8

Posted
Posted (edited)

Why not open your bleeder valve while the engine is cold and running and let the air bleed out? Physics has it the air will rise to the highest point, which I think is the bleeder. There is also another technique which involves cutting the bottom off a coke bottle and filling it with coolant and placing it into the radiator and sealing it and leaving the bleeder open. Gravity will help pull the water in and the air should bubble out.

Do this while running your heater because if there is air in the heater core and you don't have it all on it won't come out.

Heater on max, open bleeder and let engine warm til water starts pissing out. You can tell when you have air coming out and then water pissing out. Be f**king careful. IF there is alot of air in there and it gets into the head you can warp the thing(worst case). Ive also heard, in cars in general, when you overheat it can often cause the headgasket to fail. Maybe you had air in there and now its heated its fried your gasket hence your failed wet starts in the morning. Compression test up in this bitch. If you get two low readings between two neighbouring cylinders, more than likely a blown gasket.

Edited by SargeRX8
freestyleMX Community Regular

freestyleMX

Posted
  • Author
Posted (edited)

update..

ok so took out the plugs this morning. all the plugs looked a coppery brown color all consistent with eachother. looking into the bores cylinders 1 and 2 had a light layer of oil on them where as all the others were a dry black.. i noticed the car has been using a bit of oil as of late. i have a dual catch can setup and have noticed that enough oil have been getting past my first catch can and accumulating in my second can as of late when going for a hard drive! i'v heard that rb20's crack ring lands? just an idea as its only between cylinders 1 and 2 only...

Edited by freestyleMX
freestyleMX Community Regular

freestyleMX

Posted
  • Author
Posted

What SargeRX8 said RE; the bleeding, plus the radiator / part of the cooling system is probably blocked with gunk.....Perhaps time to get the radiator flow tested...

i did what he said in regard to bleeding it yesterday but still no difference..

freestyleMX Community Regular

freestyleMX

Posted
  • Author
Posted

I'm no mechanic but what about thermostat or water pump My mate had these symptoms on a wrx and water pump was the issue I could be totally wrong but worth a shot

brand new nissan water pump maybe 3 months ago and tested the thermostat in boiling water and is working

Wheezy Mentor

Wheezy

Posted
Posted

no and no new nismo cap have been loosing water its been spitting out the overflow

That is probably because of the overheating due to loss of too much water. If it's not on the ground and comp is not too bad, time for a leak down test.... Although I have never done one myself. There are others on here who could point you in the right direction.

GTScotT Grand Master

GTScotT

Posted
Posted

Do a CO2 test on the radiator, if it gets a high reading it will confirm its a BHG.

CO2 tester measures CO2 component in the coolant, it will tell you if you are getting exhaust gas into the coolant.

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