SR20DET Over Heating

[Dj_Nizmo]

Need help, of suggestions please. My SR has been overheating for a while now. fans are working fine, no oil and coolant mixing. thermostat is working fine. but it heats up to the point that the coolant resivor fulls up and bubbles and the rad is empty. once i refill it, it lasts about a week and empties agian?.. any thoughts..

BTW, using a Greddy metal head gasket.

[Dj_Nizmo]

I'm using 2 Flexilite 12" fans, they are triggered by a sensor thats welded into coolant inlet on the block. I've also got a fairly large FMIC that is blocking most of the rad. when the car over heats i just drive faster and most of the time i can get enough air flow to the Rad to cool it down. then agian when there is coolant in the rad and its full the fans are enough to keep the temp. low during idle.. i just dont know how the rad becomes empty with no rad leaks, and why it bubbles up. My main concern or worry is that it may be the head gasket. if pressurised air is getting frm the engine to the cooling system that would suck. but with no oil and coolant mixing i doubt thats the problem.

the idots that installed it for me did not mirror machine the block and head so it is weeping a little bit of oil on the outside, but not enough to ever have to top up the oil between changes.

[NISTECH]

the coolant has to be getting out somewhere in your cooling system. either the heater core or heater hoses , bypass hoses, somewhere. if the coolant is being pumped out through the coolant bottle you probably have a t-stat problem, partially restricted ,in backwards something along those lines.

[Dj_Nizmo]

Thanks Nistech, ill definatly check that out.. i figure if its bubbling there has to be air in the system, for air to get in coolant has to get out. i re-checked the hose at the bottom of the Rad and it is slowly dripping.. maybe thats my problem

[mynismo]

i've been overheating nonstop since i got my fmic. just put on a koyo... no probs.

if oil is leaking down though and you are losing coolant, it sounds like a head gasket problem.

[Dj_Nizmo]

mynismo, nice ride man, like the lights. im definatly considering a koyo, the oem 240 Rad is just too small, especially if i wanna crank the boost!.. im starting to lean more away from thinking its a head gasket prob tho. gonna try a new Rad hose first and see how it goes.

[C-Kwik]

I'm using 2 Flexilite 12" fans, they are triggered by a sensor thats welded into coolant inlet on the block. I've also got a fairly large FMIC that is blocking most of the rad. when the car over heats i just drive faster and most of the time i can get enough air flow to the Rad to cool it down. then agian when there is coolant in the rad and its full the fans are enough to keep the temp. low during idle.. i just dont know how the rad becomes empty with no rad leaks, and why it bubbles up. My main concern or worry is that it may be the head gasket. if pressurised air is getting frm the engine to the cooling system that would suck. but with no oil and coolant mixing i doubt thats the problem.

the idots that installed it for me did not mirror machine the block and head so it is weeping a little bit of oil on the outside, but not enough to ever have to top up the oil between changes.

Maybe try putting the temp sensor on the outlet from the block. With it on the inlet, the coolant inside the radiator would be allowed to reach a higher temperature. It could depend on what temp setting the sensor turns the fan on at. It would have to be significantly lower than the temp the fans would turn on at if measured at the outlet though. I'd try to keep the coolant in the radiator as cool as possible at all times. Especially when using a front mount so that you have less chance of overheating for hard long runs.

[C-Kwik]

i've been overheating nonstop since i got my fmic. just put on a koyo... no probs.

If this is to fix an overheating problem that occurs at idle or low loads, then it's a poor fix. It may work, but if you have any ambitions to get on a track, you may want to figure out why it was overheating. Track events can be hard on the cooling system and you'll want it to be in tip-top shape. My KA stayed cool using a FMIC at 6.5 psi in 100 degree weather. Probably even hotter temps at the track. In fact, I have to be going uphill, with the A/C on for a long period of time before I see the temp gauge move at all. In your case, it's possible your radiator was clogged or something, but I definitely wouldn't put a larger radiator in as a fix for a cooling system problem unless the problem was the radiator itself. I'd focus on a larger radiator only if overheating was a result of running hard for long periods where the cooling system just can't keep the coolant cool enough to keep the engine temp under control.

[Dj_Nizmo]

C-Kwik.. sorry, made a mistake in my statement earlier, the temp sensor is on the block outlet not the inlet as stated previously. It's set to trigger the fans at 82c. But im thinking my main problem is the drip in the hose from the block outlet to the rad. right now i'm using a universal flexible hose, its doesnt have the greatest durability because its so flexible. If anyone knows of hose app. that will fit from the SR20DET to the OEM 240sx Rad on a 1989, that would be great, but im thinking that ill have to do something custom for this to work.