Cold lower radiator hose okay?

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onecrazyfoo4u
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Car: 03 Type S

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I recently change out all my coolant system....3-row radiator, hoses, water pump, thermostat, and still have the stock clutch fan. Ever since then, my lower hose and lower portion of radiator is always luke warm after a good 30 min. drive. The upper hose and upper portion of the radiator will be nice and hot. Off my autometer gauge, I never get over 195-200 deg, but my stock gauge will be on Hot by then.

I think the stock gauge is just crap, but why doesn't the lower hose or radiator heat up like the rest of it does? Just seems wierd to me. Also, the thermostat I used didn't have a hole in it, jsut a tiny ball/pin assembly that opens and closes, could this be the problem?

Just asking because I have to take a long trip here soon, and I'm wondering if I need to fix anything. Thanks!


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srdub-t
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Car: white 91 SR22 powered coupe 240sx, 95 black c36 amg

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usually when the lower hose is cold it means that ur thermostat isnt opening.

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onecrazyfoo4u
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Yeah, I figured the thermo wasn't working right, even though it's brand new. I think I'm going to drill out the ball/pin thing, so it's just a hole to let water flow in. Would this be okay or cause any problems at all? That's how the thermo was that I pulled out, when I changed them. Thanks!

Emperor_Tha
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Joined: Wed Nov 22, 2006 12:56 pm

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well the lower hose should be cold even at idle since u still have the stock fan. Even if its cold after 30 mins it means the thermostats is working. Remember if both hose are hot thats no good means that the thermostat is stuck closed.

Its ok to drill a hole in it, its purpose is for air to bleed out the system as I was told.

U can just drive with out it but it will just take longer to warm up especially with a stock fan

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srdub-t
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Car: white 91 SR22 powered coupe 240sx, 95 black c36 amg

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you could just take the thermostat out and run no thermostat

grenade180sx
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DO NOT TAKE OUT YOUR THERMOSTAT!

its meant to be there for a reason. did you install it correctly? yes thats right you can install a thermo wrong. the ball pin needs to be at the top.

running your car without a thermo is a bad idea. you need to get your car up to temp. running a car colder then factory operating temp can Damage it.


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onecrazyfoo4u
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Car: 03 Type S

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Yeah, it's installed correctly, ball/pin thing up top and spring facing inside the block. I think I'll just pull it and drill out the pin thing, so it's like my old thermo that I pulled out. The lower hose isn't cold after half hour of driving, just luke warm compared to the rest. But I guess that's how it should be, so thanks guys!

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240_SeX
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Car: 1992 240SX SE

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Is your rad clogged??? This could cause the lower hose to be cold. do you have coolant flow?? maybe a bad water pump? Use an infared non-touch thermometer and test different points accros your rad, there should not be a drastic drop in temp or any cold spots

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onecrazyfoo4u
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No, my radiator def. isn't clogged, it's brand new aluminum one. And there's no cold spots on the radiator. You can just run your hand across the fins and it gradually gets cooler from top to bottom. The top is hot, and it's kind of warm at the bottom. I don't know, just think the thermo needs to flow better is all.

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240_SeX
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Car: 1992 240SX SE

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How about coolant flow? maybe try removing your thermostat and leaving your upper hose off, put a drain bucket under the car and start it up to make sure there is flow. This will rule out the water pump. If that =s good i would just replace the thermostat, maybe you got a bad one if its new maybe they can return it? if not they are fairly inexpensive the pn is 21200-53J00.

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srdub-t
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Joined: Wed Dec 20, 2006 4:59 pm
Car: white 91 SR22 powered coupe 240sx, 95 black c36 amg

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try bleeding the coolant system, you prolly have a PITA air bubble in there, this happend to me a few times.

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onecrazyfoo4u
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Car: 03 Type S

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Yeah, I might try checking the flow out of the upper hose like you said. And there shouldn't be air bubbles....I've bleed that thing many times. It's stupid that there's not a perfect way to bleed it, everybody says something different.

Is it okay to have a thermostat with an open hole instead of the ball/pin valve thingy? Does everyone else's thermo have that valve thing, or is it just me? Just wondering if you guys have holes in yours also?

FXDodger909
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Joined: Thu Nov 10, 2016 2:14 pm
Car: 2006 Infiniti FX35

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What would happen if you drive without a Thermostat on a FX?????????????


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