RB20DET over heating terribly bad!! please help

[slowrb20]

I have an rb20det in my s13 and ever since i put the bigger turbo on and the fmic and upd the boost to 10psi it over heats within minutes. Its building pressure in the radiator and boiling out the overflow. first thing i thought was the thermostat but i took the cap off the radiator and waited for it to open and it circulated through. Second thing i thought was the fmic was blocking the radiator and with the turbo and fmic and at 10psi the little ka radiator just isnt big enough? it over heats pretty quickly and even if i dont rip on it if i just let it spool it over heats. the heater core is eliminated and i have one electric fan on it. Any ideas on what it could be?mods to the car are in my sig

[Kansei240sx]

What kind of fans are you using to keep it cool?

[slowrb20]

just one single 8nich electric fan.

[Cjmartz2k]

with a fan shrowd?

[mello88]

just one single 8nich electric fan.

Overheating sucks =/. Here's some suggestions that might help you.

-You might have air in your cooling system, bleed it properly per the FSM. Any air in KA, RB, SR, CA cooling system will always cause overheating issues.. Refill with 50/50 premix and some water wetter.

- Make some ducting for your radiator so the air doesn't just flow around it.

-Your little 8" fan probably doesn't have enough CFM to keep the radiator cool when you're under 30mph. Ditch it and go with at least a 12 or 14 single, or even better dual 10s, 12s, 14+10, etc.. You didn't say if you overheat after the run or if you'll overheat at highway speeds. If it's only at slow speeds it's probably your fan, if it's all the time (or above 30mph or so) it's probably air/radiator/waterpump/thermostat/etc..

-The stock KA radiator isn't the best for cooling the RB.. Might be time to upgrade to a Griffin, Koyo or Mishimoto radiator. Might want to research those brands/rads a little before u choose some have better reps than the others.

-When was your water pump last replaced? Many stock/oem pumps are pretty rusted/rotted away by the time the engines get over here. If you didn't replace your pump before you put your motor in, you might consider doing that sometime soon.

Thats all for now, GL...

[slowrb20]

it overheats at all speeds. there is no fan shroud and thanks a bunch for that info. i mean it over heats ridiculously bad. im going to try bleeding the coolant system because its not the water pump because its flowing fine. and its not the thermostat. also the fan isnt directly up against the radiator. would that make a difference? anybosy have a cheap radiator there trying to get rid of it?

[mello88]

my ka would overheat if the altima fans got more than 1/4 away from the core. get it super close! also sounds like there might be some air in the system.... which will always make u overheat, try bleeding and fixing your efan that might do the trick

[rb25drag]

Well I had the same problem with my rb25, it kept throwing my coolant into the over flow jug, I finally had to upgrade to a R33 aluminum radiator and 2 12" pusher fans. it seems to stay cool now. 180*, I wouold say add another fan, Some custom shroud, If that doesn't work then its time for a Radiator upgrade.

Also Try some Be Cool Fluid, it mixes with your coolant and does a really good job to keep it from overheating. My cousin races Dirt track cars, We kept having a overheating problem after about 10 laps of WOT, Well we put some of the Be Cool liquid in it and never had another problem. You can find it at a local parts store.

[slowrb20]

ok another question? can someone give me a step by step on how to bleed my coolant system? thanks

[ItzGenX]

Are you sure it isn't a blow head gasket? You can get a tester tube to test if your coolant has any exhaust gases in it.

[slowrb20]

no white smoke? no smoke at all? isnt that the leading sign of blown head gasket? maybe im wrong? but thanks for the input.

[Coolwhip]

Take off your radiator cap, fill it up, turn on the engine and see if it shoots coolant up and out of the filler neck, like if someone has a straw and blowing bubbles into the system.

If so, blow head gasket, lifting head, or a crack. You might have compression leaking into the coolant system and would never have mixed with the oil.

if you still are weary, compression test the motor



(btw this was not the way you bled it, its diagnoses)

[ItzGenX]

no white smoke? no smoke at all? isnt that the leading sign of blown head gasket? maybe im wrong? but thanks for the input.

Blown head gaskets have many more signs then just the white smoke. When you get white smoke, it just means you are burning water (water leaks into the cylinder and burned and turns white (burned glycol+steam=white). Many times, you can have the opposite effect, in which case, the combustion pressure in the cylinder is enough to leak past the gasket and into the water jackets. When the combustion gases get into the coolant, there aren't any smoke signs out the tail pipe. The main symptom for this situation is a constant bubbling in the coolant if you leave the radiator cap off (even if not fully warmed up, you will see bubbles). Then there's two more things a blown head gasket can do. Those are oil in water or water in oil.

[slowrb20]

ok ill try that first thing tommorrow. thanks guys

[nissandrftr88]

U

ok another question? can someone give me a step by step on how to bleed my coolant system? thanks

Unscrew the bolt from the top rad hose on the intake,fill radiator up and squeeze upper hose until you see water come from the hole.Tighten the bolt back up,crank car and add if needed.some times this needs to be done at about a 45* angle.

Also are you sure the thermostat is good,mine was doing the same thing.It would flow but it was sticking halfway open and not letting enought through causeing it to overheat.

[lilskyline240]

your best bet would be to get a new radiator. the Stock KA radiator does suck unless you have a good radiator shroud and good fans. Im running a mishimoto Radiator with a single 12inch pusher fan that i got off a 7mgte supra with no radiator shroud and i hold a temp perfectly. Also if you can hook your heater core back up because that is a way you can disipate heat. it acts like a second radiator

[slowrb20]

The heater core exploded in my passenger seat lol and autozone wants like 200 bucks for a new heater core and theres no junk yard within 100 miles that has a 240. and would it harm my car in any way to take the thermostat completly out to see if that fixed the problem?

[Yellow4g63]

The heater core exploded in my passenger seat lol and autozone wants like 200 bucks for a new heater core and theres no junk yard within 100 miles that has a 240. and would it harm my car in any way to take the thermostat completly out to see if that fixed the problem?

Loop the hoses going into the firewall back into themselves and that will cut out the heater core. You won't have a heater till you replace the core tho.

[onepuff]

I hope you already have the heater hoses looped otherwise there's probably not much coolant in the engine.

Don't bother removing thethermostat it will just take a little longer to heat up, but once its heated up it wont make a difference. Just get some real fans with shrouds and some ducting for the radiator.

[nissandrftr88]

would it harm my car in any way to take the thermostat completly out to see if that fixed the problem?

Wouldn't hurt it at all,I took mine out and cut the valve off and put it back so it's not completely gone but it can still slow a lil bit of the water coming in.

But you can also take it out and put it in some water and see what temp it opens at and see if it opens all the way.

[DriftX]

The heater core is your problem.

Coolant systems work under pressure. More pressure, the hotter is has to get to boil.

Every lb of pressure that a coolant system adds, raises the boiling point 2 degrees. So a 13 lb cap adds 26 deg, so 212 plus 26 = 238.

Now you say your loosing coolant at the heater core. If you have a hole in your cooling system, the system is barely if at all pressureized.

One 8in coolant fan is not going to handle a cooling system in an rb, espeically one that is leaking.

Sorry to get all technical.

[slowrb20]

lol im not a genious about cars but you guys can give me a little bit of credit. the heater core is already elminated and the lines arent kinked.

also the ehater core has been gone for months with no over heating problems at all? why did it start now? im going to try taking the thermostat out and bleeding the system and hope for the best. thanks for all the helo guys