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Tech Talk Technical Discussion About The Nissan 240SX and Nissan Z Cars |
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#1 |
Zilvia Addict
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V-Mount Overheating Issues.
S13sr20det with v-mount.
Issue is as stated, car runs perfect when just doing regular freeway pulls or street driving. Over the weekend we had a two day event and during both days my car would run great and tons of power no power loss, but after a run or two the water temps would start creeping up to around 115+ and drop after about a min of cool down. So i figured it can be a few things, sticky thermo, bad water pump, bubbles, or maybe a bad HG. Also when the car would start to get hot the resivore would fill up then start spewing out and boiling and start evaporating. So got her home changed the oil, perfectly goldish brown no chocolate milk. Flushed the radiator for a 6th time, got all the bubbles out. Opened up the thermo and threw it into a boiling pot of water and it has done its job opened fully and closed fully. It is factory thermo BTW. So only other thing i could think of is if the water pump is going bad? I replaced it four years ago when i got my motor, but when redoing everything my motor sat for almost a year and a half whith out being started or any fluids in it, could that cause a water pump to go bad? I also have not done a leak down or compression test because i dont have either tools. I have heard of guys having warped heads or slightly bad head gaskets. What would you guys say could be the issue? |
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#5 |
Zilvia Addict
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fans not powerfull enough, not enough airflow, radiator clogged, or air still in the system..
jack the front of the car up as high as you can, and run it until you can see water rushing through the radiator.. fill it up, cap it, and turn off the car, you are now perfectly revved.. same exact thing happened to me when i had air in the system...
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#6 |
Zilvia Junkie
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overflow and rad cap will naturally take care of air in system as long as rad cap is highest point of system.
hot pushes air out. cold pulls coolant back in. |
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#7 |
Post Whore!
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Electric fans, what do you have? Single? Push or pull?
Edit also I assume a vmounted rad would not be easy to bleed. Could be air pockets in the system http://www.gtfactory.jp/cms/page.php?11 |
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#9 |
Join Date: Jun 2012
Location: Duluth, MN
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If the system is working properly, fans shouldn't be needed at speed. Airflow through the radiator should be more then sufficient.
Mad could be correct, a swirl pot/pressurized overflow would not be a bad idea. What sort of ducting do you have? Do you have an undertray/splitter? My guess is that you are not getting proper airflow through the radiator. Enough to keep the intercooler from heat soaking, but not enough for the rad. A few things could cause this. Improper ducting letting too much air pass around the heat exchangers. Improper pressure zones slowing or stopping air from moving through the heat exchangers. For the radiators to work, you need high pressure in front, and low pressure behind. If you are not running any sort of splitter or undertray, you may be creating a high pressure zone in the engine compartment. This will make it difficult for large amounts of air to pass through the rad. Just a thought. |
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#10 |
Nissanaholic!
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V mounts sure look cool ... but if your intercooler and rad dont have the same air resistance, it just does not work correctly, unless you shroud them perfectly.
And people never do that. Solution ? Remove fancy V mount and stack intercooler and radiator, with proper ducting. Popular belief is that opening the mouth in the front bumper is better, but you could not be more wrong about that ... Fluid dynamics is not that easy to figure. Basically, you need a small opening in the front that then enlarge to the full profile of your radiator (this makes even more pressure in front of the rad). On the other side of the rad,t needs to go back to a small opening to exit (this creates even less pressure). It works very well. In fact, it is how every plane heat exchanger and turboreactors work. Also, as flatblackIan said, if you removed the undertray... fit it again. The easy way to make ducting is using cardboard and duct tape, then using spray foam on that. Never said it was good looking though, but you can make it look better by trimming and painting it after. |
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#11 |
Zilvia Addict
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For fans I have two e fans. 10 inches each. Rad i am using koyo Sr20det. For ducting i am using thin prices of sheet metal that I got at local home depot and rivited to the ends of the koyo radiator.
Here's how the over heating works. I'll go to track and do 3/4 laps of hard drifting. Then while driving to pits or to line up again you can watch my power fc start climbing in water temps. Sometimes up to 125. I have to keep driving the car slowly to let air pass through the vmount. Until it rapidly drops back down to 80. At this point if my car is spraying water from the system because its put so much back to resivor then its steaming out of the top of the resivor and i have to add more water. Sometimes a gallon depends on how much was lost. |
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#13 |
Zilvia Addict
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it seems like the airflow isnt good, get your garden hose and spray it out, thats helped me before all the fins we full of dirt and debre so air wasnt passing through. and since air is so light its gonna go with the easiest route which would be more through your intercooler than through the radi.... this is just my opinion though, some thing to try
also gotta figure out why your compression numbers decress farther down the line your probably at your difference max between highest compression and lowest. you should try out that leak down test see where there is air escaping |
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#14 | |
Zilvia Junkie
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#16 |
Zilvia Junkie
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think about it....if you are pushing coolant into the overflow then you have a problem. might want to first look into changing the radiator cap and properly pressure check the old one. if it is not holding any pressure, then you are gonna boil the coolant easily.
if the radiator cap is fine, air is all out of the system, you drive for a bit then it happens again.....welll, you probably are pushing air into the system from a fucked headgasket. |
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#17 | |
Zilvia Addict
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#18 | |
Nissanaholic!
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Quote:
It works, and is easier to do than a leakdown test. I dont know the name, i have seen a tuner i know using it (grammar on that sentence looks horribly wrong, sorry if it is) What you need though is one or two cooldown lap after drifting, but i dont know if you can do that during an event (i always do that on trackdays, if i dont the temps skyrocket, not sure there is anything you could do) |
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#19 |
BANNED
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yes PBM's breather tank is the same thing. "swirl pots" are more comonly used with the fuel system to remove are out of the lines, and to help prevent fuel surge. but it is the exact same principle to remove air out of coolant lines....
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#21 |
Zilvia Addict
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I always burp my system 100% before track day, normally do it twice before i hit the track. Because yes i do know that Vmounts can be a bitc* to burp. All the experts ive talked to and the shop that did most of the work on my car saying its 99% nothing to do w/ the vmount because the way it is designed. They are thinking its got to be something internal either HG or thermo.
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#22 |
Zilvia Addict
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Update, i just installed new thermo on monday morning and went out today to test her out and she works perfect, but while burping her for the second time its still getting a steady flow of bubbles. Also i had to add about half a quart of water after cool down time.
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#23 | |
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#26 |
Zilvia Addict
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After further review, just got everything torn apart and it looks as if the drivers side far back head bolt wasnt fully torqued all the way and it caused the head gasket to warp then cause the block to get some wear so it needs to be taken out and resurfaced.
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