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2G Overheating need help with cooling

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Turbolence56

Proven Member
68
7
Jul 14, 2021
North_Carolina
Not sure this is the right place to post this, so moderators you can move it to the correct place if needed.

recently bought a 2g 97 gsx with FMIC and FP manifold and turbo.car wants to over heat after driving for 20 minutes or so. I have a/c and have to turn on the heater full blast just to keep the temps in check. OEM radiator, oem fans. I did notice that the over flow tank was empty. Not sure if that’s a contributing factor, though about checking for leaks and seeing if there is air in the system.

drove 4 hrs on the freeway and had to keep the heater on while driving, no smoke, car pulls fine. Just overheats.

also temp gauge rises to middle of gauge extremely quick like in 5 minutes and doesn’t overheat till 15-20 minutes later. I doubt it’s a head gasket as the temp will go back down when off throttle. But at idle it will rise.

any help appreciated, have ecm link so will check logs.
 
What temps are you hitting ?
IIRC, on a 2g you can adjust a setting to kick the fans on sooner. If someone can confirm, please do.
I think this behavior comes with the territory of having a front mount, especially with the condenser in front of the radiator. It adds an extra layer the air needs to go through in order to get to the radiator.
Can start with checking fluid levels, burping the system to release any potential air bubbles, and then a lower temp thermostat. Then look into ducting to direct airflow between the front mount and into the condenser/radiator.
 
thanks for the reply, that’s the plan to do the simple stuff first (check fluids, burp the system, and replace the rad cap and thermostat). I know people go oem but I’m using this car to get to work, can I get a cap and thermostat from autozone or advanced auto? Or is that highly not recommended? Just for the time being.

also the over flow tank was bone dry and moved done to the front passenger side wheel well, below were the stock ic was. This should be filled with coolant all the time right? So when I add coolant I should fill this up first to the low line with engine off. Then fill ad burp system with engine on and heat on high on window defrost mode.
 
Not yet just limped it home yesterday and let it sit overnight. Plan to work on it today. Should I get the stock 1.3 bar rad cap. 50-50 distilled water and coolant mix. Or should I go 70-30. Again I’m going to fill the over flow tank back up as it was bone dry when I got home. Not sure if it has always been dry. Just got this car a week ago and needed to drive it across a few states to get it home. It’s been an adventure for sure so far.

should I change the thermostat as well since I’m in there. Or just top off coolant and add coolant to overflow first before replacing anything.
 
If the 2G calls for a 1.3 bar cap then stick with that.. The weather you get in Carolina should dictate what mixture of antifreeze to use.. I have always used just regular tap water and have had no problems with cooling.. The location of your overflow tank may cause a problem. I believe it works by suction so being at a lower point may change its ability .. but don`t quote me on that.. At this point it don`t seem necessary to change out the thermostat because you say it is reading fine..
 
Also does the overflow tank need to be reputed back to the engine. It’s currently routed as follows. Tube goes from the radiator cap / water neck down to the top of overflow tank (white cap) then another tube goes on the other side of the cap and is open to air. I assume the two nipples on the cap are one way check valves . My question is does the tube that’s just open to air need to go some where or is it just to bleed off when the overflow tank completely fills. I assume it’s to bleed off, but am I also sucking in air? Or is it a one way valve on let’s water air out and not in.
 
It does both over heating at a stop, and on free way and city driving. But the temps are manageable when I put the heat on. Again I have a fmic, new condenser and oem rad and fans. So I know I’m not getting great air flow. But want to check the cooling system first before ducting and stuff. I just took off the rad cap, and I can see that the water neck is empty so I’m definitely loosing coolant or it’s empty some. Will flush and top off. And get a new rad cap. So regular tap water is fine and won’t corrode
 
Just do a flush and tstat first. If the coolant looks dirty, I’d run a cleaner through it. If it’s rusty water, I’d use evaporust. Distilled water is a better option but not a must. As long as you change coolant when you’re suppose to, it shouldn’t rust.
 
I run an air dam behind the FMIC but in front of the BOTTOM of the radiator to "scoop" air up from underneath and up into the radiator. I have used several different things but this one just ended up being part of the car and I used it in a different way. Also, seal any areas where air can "escape" and make it go thru the radiator.
Maybe this will give you some "Options"
Marty
 
+1 for the air dam/scoop. I fabricated one with a 8" x 24" piece of sheet metal. However, you will need access to a sheet metal brake, preferably a hand brake. A shop would do it for you as well if you brought them the sheet, likely pretty cheap.

There are plenty of ways to accomplish this, it helps tremendously.

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For sure :thumb: , but with a FMIC and a A/C condenser, he will need it to get cool air to the radiator.
Top it off, burp it of all air and make sure you have a good cap with 13-15psi and no leaks. Also check that the tube in the overflow is actually hooked up to return coolant from it.
 
Wouldn't be a bad idea to pressure test the cooling system to check for leaks since the coolant level was really low.
 
Last edited:
I found out the issue. Thanks for the replies though. I still plan on ducting and stuff.

turns out I had a hole in what I believe is the heater core hose. It connects to the back firewall and into the dash and also connects to the water neck. I found coolant on top the transmission block area below. I dropped the lower rad pipe though just to flush out the coolant. Coolant was nice and green, so no head gasket issues.

now I got a new thermostat and rad cap. The thermostat in the car already looked good. However when I removed the water neck to check I ripped the paper coolant neck gasket. Couldn’t find anything locally. Would it be okay to just use paper gasket material like felpro. I could just cut my own. Just not sure oem is the best route or not.
 
going back to refilling the coolant do I need to put coolant into the over flow tank? Or just top off the fluid in the system/ radiator. The over flow tank is had to get to since it’s in the bottom passenger fender well.
 
It was ok to make a gasket, either paper or rtv or both. I would add coolant half way up on the overflow then fill the system. I usually run the car with the cap off to watch it flow and add more coolant as needed but you do it however you feel best. You will want to burp the air out so that it is entirely full. Glad you found the "gremlin"!!! :thumb:
 
Yeah thanks! It’s a 6 bolt swap so technically it’s a 1g thermostat and water neck. I put ONLY the permatec grey coolant gasket maker, with NO PAPER gasket on last night. Followed the instructions so finger tight waited an hr then cranked it down. It is messy though. Hope I won’t have any issues as it did move around when I bolted it down. Might have some rtv on the thermostat it’s self. Will that be ok? Or do I need to do both permatec grey coolant rtv and paper? I would hate for this to leak again LOL.
 
The grey is some really good sealant. I wouldn't think it would ever give you a problem. We have had to PRY a blowoff valve off of the intercooler piping before because it was siliconed on with grey rtv. I think it would have held itself in place without any bolts to be honest.
 
Great. Just wanted to confirm. I was thinking of prying it off and placing a paper gasket, but hey sounds like the grey permatex will work great, fingers crossed.
 
The RTV works great... getting an oil pan off can be a PITA because of that stuff. Should hold your coolant just fine!
Try getting an oil pan off after someone has used "The Right Stuff" on it. I tell people to PLEASE do not use it on oil pans because you will bend it all up trying to remove it if and when that time comes. BUT.....it does seal, like forever. OMG
 
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