rb20det over heating and high idle...

[brianb242]

first I'll give you guys my set up.. new water pump oem,ISIS radiator bought from raw brokerage, two 12" pusher fans no a/c condensor, no thermostat, 50/50 premix coolant, adjustable fan relay wired to run both fans when engine hits 180 degrees. I also made sure to get all the air out, opened the bleed screw on the intake let it idle filled it more, drove it checked out ok. when driving just putting around it's fine car runs normal, get on the gas to get on interstate or play around on the back roads, stop and go traffic it runs hot, basicaly anytime the turbo pushing full boost the engine climbs temp like crazy! I am starting to think maybe the car runs lean?? Im in S.C so mid day temps get above 95, I thought maybe the head gasket was blown, did a compression check all 6cyl came to 115psi, I have a service manual but it doesn't give psi it's in kg/cm squared, I don't know the formula to convert it. does 115 sound right? also at night I can drive it hard with not much of a problem but that is when it was only in the mid 60,s at night. also there is no mixture of coolant or oil in radiator or on dip stick.... high idle problem..., after adjusting the tps it's not as bad as it was but it's still about 500rpms to high, checked everything that could cause a vaccuum leak, also did a boost leak check, found nothing! not sure of other info on that to give you guys. all I can say is im pretty freakin aggrivated with this.

[brianb242]

Ok.. So everyone just as stumped as me.......

[s14_sport]

do alittle more searching....theres a couple of huge threads on how e-fans are crap on RB's

[brianb242]

do alittle more searching....theres a couple of huge threads on how e-fans are crap on RB's

Understandable.... Have you seen how thick those radiators are?? Its almost 4 times thicker than the stock one out of a r32. theres no way I can run a the factory style fan clutch. Any one know what the compression should be in psi??

[Yellow4g63]

When I had the electric fans on my S13 RB20 they would run all the time! I had a Pivot fan controller and once it hit like 80 degrees C the fans would kick on and stay on. I had the Flex a lite slim fans as pullers.

had to take off the back plate so they would clear and not rub anything on a automatic aftermarket 240sx radiator. It never really over heated till I started to beat on it then it would.

You could have a blown headgasket on your RB20 Brian. It could be pressurizing the coolant when you build boost, or your radiator just can't keep up, or the fans not moving enough air. I'd prob start with the fans 1st.

[Gabes13]

115 psi is about 8 kg/cm^2 (1 kg/cm^2 = ~14.2 psi) lowest limit in fsm is about 9 kg/cm^2 but there are different factors that can cause low numbers (cold motor/closed tb). The variance between cylinders sounds good but it still may be your head gasket.

Before I swapped my single cam, it had an over heating issue when I would gun it on the highway, and sometimes in the city in 100+ degree temps. Ive over heated it a couple times before but it still ran afterwards. A compression test showed high numbers and no variance between cylinders but when I took the head off, the gasket was toast. I must have lifted the head or something pressurizing the the coolant, like yellow already said.

[brianb242]

thanks guys for the reply's, I didn't like the compression tester I used so im going to give it another try, and yea I did the compression test on a cold engine. the fans aren't anything special just some i bought from advance auto, they worked really well on my awd dsm, I may end up cutting the radiator support to move the radiator foward. so I can get the fans mounted as a puller set up, instead of a push style... I'm thinking they may move more air that way. I'll take some pics of what I got and you guys give me your opinion. as for the head gasket... idk im going to run afew more tests and see. the engine was extremely clean when i pulled the cam covers, so i know it can't have many miles on it. but you never know who had it before, I might just get a full gasket kit with the injector O rings what company ya,ll suggest to buy it from?

[brianb242]

update.... I decided to cut the upper support and move the radiator fwd, then try and run a rb fan clutch, the high idle still has me a little confused, I got it to idle correct for about a week, now when it's cold it idles fine when it get normal operating temp the idle goes up and stays there till the engine is completly cool. I'm thinking a gasket must be expanding and shrinking.