SR20DET heat issues

[felton local]

I've searched on multiple forums for this but nothing related directly to my problem.
i just finished swapping my sr20det blacktop from my coupe to my hatch. The motor was running just fine in my coupe in the sense of heating.

This is whats happening:
from cold start i can start it let it idle with random revs for however long i want and it will sit right in the middle of the gauge (45 minutes, no overheating). i take the car for a drive and a few miles down the road (driving on a slight incline, winding road) the temp gauge will go to the 2nd to last line before "H" and will sit there for a bit. i turn the heater on and put it in neutral to try and flow air through it. It'll go down just a little bit then i start to drive it again and it goes down a little more at first then shoots back up to "H". i pull over and the overflow is Boiling and whistling steam out the vent. i let it sit for 15-20 mins and turned aroun driving back Downhill. At this point the temp is all good again, i drive it hard and it was doing fine for 7+ miles until i got to a flat area where it went up again to about the 2nd line from "H" and stays the for 1 or 2 miles til i got back. when its hot the radiator hoses aren't completely hard. Also the motor runs good and pulls hard. Although it has died once or twice when i turn the heat on and put it into neutral when it gets hot

This is what i've done:
i replace both heater hoses cause at first they were leaking so i figured now they wernt leaking with new hoses "it's fixed." ...unfortunately not the case. Every time after it gets hot i refill the coolant with 50/50 and it runs fine for a little bit. i swapped the 180sx KM/h gauge that was with the motor so the single and dual wire sensors should match the cluster/gauge. but it almost seems like the gauge is reading wrong.

Today's idea's:
so i was looking at the coupe that i pulled the motor out of and realized that the aftermarket coolant sensor was still just chillin and didnt get swapped with everything else . So ive been looking and looking and cannot find where it was on the motor. judging by the size of the threads on the aftermarket sensor i would think there is a pretty big whole/leak somewhere in the cooling system now but there are no leaks at any point in the running cycle. i was going to try changing the 2 stock temp sensors from my 93 KA along with a new radiator cap before i go pulling the thermostat.


i have dual electric fans , koyo radiator, CX FMIC, t2871, circuit sports overflow tank, and what looks to be a pretty crappy CXracing radiator cap.

Does anyone have any input or ideas? meanwhile I'm going to go change a few things to see if it makes any difference

Thanks for looking, any input would greatly appreciated.

[rican_nick]

other than the coolant from the overflow are you burning/loosing coolant? if not you dont have a leak. If there was a hole in your coolant system as soon as it was pressurized you would have some kind of idea where its at.

The car is overheating if the overflow is bubbling/overflowing so i wouldn't suspect it being a CTS issue.

Thermostat is the first thing i would suspect.

[felton local]

thanks for your reply.
yes every time i go drive like 5-10 miles the coolant level drops down below the fins.
so before i left for a drive i replaced the radiator cap and filled the radiator back up to the top.

Sorry this is long but it is exactly what happened...

on the drive... after letting it idle for more than 25 minutes without fans on i started off. i drove 10 mph for 2 miles down my driveway then got to the main road. dorve it pretty hard for about 5 miles where it started heating up. i pulled over and eft the car running with the fans on. checked the hoses, both were pressurized, checked for leaks, only out of the overflow, sat with it running with the fans on for about 10 mins til it came back to normal range. started driving again, hard but not as hard, a mile or so up the road it was hot again. pulled over left it running still with the fans on Gauge was at the 4/5th line. I turned the car off and left the key in ACC and the gauge was at normal again. started it up and it stayed normal (this is within a minute of the car being at hot). 3 miles down the road it was hot again, at this point i was at a downhill so i put it in nuetral and coast for 3 miles and the gauge stayed at the 5/6th line, then put it into 3rd and drove normal and it started coming down. got to a friends and let it cool off, still no leaks other than overflow still good pressure.
After cooled i had to fill the coolant back up , it was well below the fins. From there i drove around town at 35mph for 10 - 15 miles til it went hot again. after waiting and filling it back up i started back home. same thing happened heated up then i brought 4th to 6000rpms for a few seconds and it cooled to normal til i got stuck behind traffic. heat came back up to 5th line for 4 miles til i got home. i parked and let it idle for a minute or two. temp stayed at 5th line, i turned it off and had key at ACC. and it was normal temp again.

I'm thinking i may not have effecient cooing??? i dont have a fan shroud yet and the electric fans feel pretty weak.

i got a new thermostat and single wire temp sensor. i have a s14 black top water pump but the bolt pattern is a little different so dont know if it will work or not.???

[Slidin' Sam]

Bleed your cooling system. If you swapped everything from one car to another and it is NOW acting up, that is the first thing I would look at. You probably have an air pocket in your cooling system somewhere.

[felton local]

i've bled it multiple times now along with flushing it this last time with the hose for 20+ minutes. i put in a brand new waterpump and thermostat. at one point i found that my heater hose near the firewall was torn, so i replaced all the heater hoses back there with goodyear red hose. it went a lot further of harder driving after replacing the pump and hoses but still heated up and made the overflow boil.
That was last night, Today i went and checked it. when i lifted the release valve on the cap (which i just realized is a 13 lb cap) i heard the overflow bubble, then it bubbled more when i opened the cap all the way. And the coolant was down below the fins again. i put the overflow cap back on, filled the radiator back up, and squeezed on the top hose like 25 time repeatedly til there were no more bubbles when i squeezed. that was with the car off too.

[slider2828]

Your not bleeding enough... Felton eh? My buddy where I used to race motorcycles with used to be there... Man that place gets dark, and mt hermon road really gets watery over night.... kinda iffy there... LOL....

Anyways, bleed it correctly... get a swirl pot, install it, bleed it right.... But check for any water, sounds like you have a leak somewhere....

[daftphunk]

Definitely a leak. Same thing happened to me for the most part. I would drive and be fine and then I would overheat. I was leaking coolant for a long time and even I fixed that and bled the system i still overheated. My coolant would bubble and steam would come out, it was bad.

Anyways I replaced my water pump and that basically solved my problem. Check yours out.

[felton local]

Definitely a leak. Same thing happened to me for the most part. I would drive and be fine and then I would overheat. I was leaking coolant for a long time and even I fixed that and bled the system i still overheated. My coolant would bubble and steam would come out, it was bad.

Anyways I replaced my water pump and that basically solved my problem. Check yours out.

yeah i have new waterpump and thermostat both oem parts. the waterpump is from my 96 blacktop which is considered to be an upgrade.
i also put the stock electric fan back on.

thanks for the responses guys.

[felton local]

so last night i went and drove it around pretty much all night with no problems. after like 10 miles of regular driving and no problems i took it up a steep winding uphill road and pushed it pretty hard. it did great for the whole thing went about 5 miles up the road pulled over everything still was looking good. the only thing was the overflow was spewwing out still but the temp was normal. so i turned around and went back down the road. got back into town pulled over in a parking lot and stopped on flat ground. right at this point my fan fuse blew and the heat started rising. i fixed the fan turned the car off and let it cool. checked the radiator and it was low. next i checked the overflow and it was to the top.. i unbolted the overflow tank and lifted it up higher than the radiator and it al flowed back into the radiator?? this happened one more time after driving around or a while. my fan would die the it would start getting warm. i would check it and all the coolant would be stuck in the over flow till i lifted it up .

I have the circuit sports overflow tank . it seems that my problem is coming from it. it doesn't sit high enough to flow back into the radiator? does that sound about right?

anyone have this overflow ?? has anyone had similar problems?? i would mount it higher but then the hood wont close all the way.

[felton local]

i remounted the overflow an inch or so higher and went and drove it and it still doesnt want to feed coolant back into the system after i drive the car hard and get it nice and hot then turn it off i can hear bubbling in the overflow and can stop the bubble noise by pinching the hose from the overflow to the radiator . its too hot right now to pop the radiator cap so i am letting it cool and also going to check to see if it is infact feeding coolant back into the system when it sits while turned off. but shouldn't the overflow be feeding the system while the car is running??

Also. i noticed after driving it a few miles down the road (pretty hard) after i stopped and turned the car off and left the fan on. within minutes the upper and lower hose were completely soft almost completely squinched together like some one was sucking on them. i have silicon hoses that are some stupid aftermarket ones and the upper one has a bunch of RTV blue looking sealer on the waterneck . but just now when i got back home, after driving hard i did the same procedure and they stayed rock hard.

** during all this my temp is staying normal .

[TwiztedZero]

If you can, test the radiator cap. Your overflow tank does not 'feed' the system while the car is running. If you have been putting all of these parts on, and bleeding the system, and you're still having these issues, test the cap. You said that is a 13 psi cap? You should be running at least a 15 psi cap on that setup.

Steve

[felton local]

i had a 13 lb a 16lb and a oem KA cap and a CXRacing 1.1 bar.. after trying them all out the 1.1bar seems to fix the problem but then i finally got to drive the car around for a few days and now my bov is blowing all kinds of oil out of it.
but the cooling problem seems to be fixed. i think a proper bleeding of the system and the proper parts were all i needed. but hey i have a new thermostat and Waterpump now heh. gotta look at the bright side of things.

[GabeS14]

Bleed your cooling system. If you swapped everything from one car to another and it is NOW acting up, that is the first thing I would look at. You probably have an air pocket in your cooling system somewhere.
Exactley what i was thinking.