overheating problem at idle or slow driving speeds

[dwadia]

My car's temp gauge (which has a 2-month old sensor) rises toward the "H" mark when there is not a lot of air flow from driving at sufficient speeds. This is happening with my dual flex-a-lite fans constantly on, and i am using a Koyo radiator, Nismo thermostat and Redline water wetter, so something definitely isn't right. This only happens sometimes, not when i first start the car cold to warm it up for 5 minutes before driving but i live in NJ and it's like 35 degrees out now so that's not saying much. If i try to let it cool for a few minutes after driving it, especially under boost, it will definitely do it. I'm using a gt3071r at ~14psi, and i understand that i've heated up the engine at that point, but that much? I still don't think once it's parked and returned to idle that the temperature should be rising. If anything, with both those fans blowing it should be gradually cooling down.

Another unrelated question came to mind which was prompted by this problem - how long is it good to let the turbos cool for before turning off the engine after they've been boosting for a while? I'd appreciate any help.

[koukimonster139]

if anything the temp will rise MORE while idling.

not as much airflow
water pump lower rpm

as for the cool down thing, it depends on how hard your boosting for how long and in what conditions. i usually just drive like a pussy when I get a mile from home and let it idle for about 45 seconds in the driveway, then off.

[tiresmokes13]

have you checked for a headgasket problem?

Do you hear the water boil at all or steam?
If not might just be your water temp sensor.

also might try water pump

[sliddinsil8o]

Do you have an aftermarket water temp gauge? Stock temp gauge blows donkey balls...a more accurate temp reading could tell us and you better info.

[koukimonster139]

^^ especially in 35 degree weather i would suspect the temp sensor also

[jrmiller84]

Do you have an aftermarket water temp gauge? Stock temp gauge blows donkey balls...a more accurate temp reading could tell us and you better info.

I second that motion. My stock guage will typically idle at normal temp but it will sporadically rise to it's max temperature. Often it will rise slowly almost like it's actually getting hot. Fortuanately for me a quick thump on the guage and its back to normal. I also agree with the thermostat replacement as well. When I first got my S13 almost a year ago it was one of the first things replaced. Cheap too, like $12 at Advance Auto Parts.

[dwadia]

koukimonster 139: Ok, i was just thinking that since the engine was under vacuum rather than boost that would make the car run cooler at idle (assuming i was boosting it while driving), but i understand your other points and maybe it does get hotter at idle. Still, i don't see why the temp. gauge should be climbing right up to the top. It should stabilize somewhere... right?

tiresmokes13: I don't know of any water boiling and there certainly is no steam. I forgot to mention i'm using a 1.3 bar rad cap. Regarding the head gasket, well, as per my temp gauge my car overheated yesterday due to my fans failing to turn on in heavy traffic (a totally separate problem that i don't want to address in this thread, but as an aside, that's why they are now constantly on bypassing the fan controller). When after it overheated (or at least the gauge said so) i was running on 3 cylinders. First i thought it was a blown HG. I was going to check compression, so i pulled all the plugs and what do you know, they all look identical, light and dry, except one which was wet and dark. So i replaced the plugs and it runs normal again. I should add that i did start the car cold with the rad cap off and the coolant did not bubble at all, something i have heard it may do if the HG is blown. Would there still be a need to check for a blown HG when it's making full power?

The water pump sounds like a VERY good idea to check... but if it wasn't working wouldn't i be overheating even while driving at speed? Anyway, how do i check it?

And to everyone that suspects the temp. gauge sensor or the gauge itself, i want to know, if i install an aftermarket gauge with the sensor placed in the lower radiator hose that goes to the thermostat housing, will this location give me an accurate reading? I was concerned about putting the sensor in a place which only has engine-temp coolant when the thermostat is opened. I actually did buy a gauge, but the sensor is so big i think this is the only place i can fit it without making it a huge job to put somewhere on the other side of the t-stat. What do you guys think?

[sliddinsil8o]

most common place that everyone places it is at the upper rad hose. if you follow that hose you will notice that its in the same path as the stock temp senser

[dwadia]

Ok, so then i shouldn't be concerned about it not having flow when the t-stat is not opened?

[MELLO*SOS]

Have you bled the air out of the coolant?

[Sileighty_85]

Hows the water Pump? Blocked passage ways? My buddies kinda had the same problem turns out he was some how missing one or two of the blades off his pump. Dont ask me how. I guess shit like that happens when you get a 180SX that 20 ppl owned and Dogged on for 15 years

[koukimonster139]

1. The water pump sounds like a VERY good idea to check... but if it wasn't working wouldn't i be overheating even while driving at speed? Anyway, how do i check it?

2. And to everyone that suspects the temp. gauge sensor or the gauge itself, i want to know, if i install an aftermarket gauge with the sensor placed in the lower radiator hose that goes to the thermostat housing, will this location give me an accurate reading? I was concerned about putting the sensor in a place which only has engine-temp coolant when the thermostat is opened. I actually did buy a gauge, but the sensor is so big i think this is the only place i can fit it without making it a huge job to put somewhere on the other side of the t-stat. What do you guys think?


1. not necessarily. at driving speed you;ve got 35 degree air rushing over the engine. only way i know to check it is to pull if off and inspect the blades, bearing, etc..

2. I'd go with upper rad hose.

[dwadia]

mello88: I don't know how to bleed air out of the coolant, but the radiator is basically new so the coolant was fully drained when that was installed. Does that address the bleeding or not? If not, how do i bleed it?

koukimonster139 and Sileighty_85: 1) Ok, i'll see about installing the new water temp gauge with the sensor in the upper radiator hose, although between waiting for the parts and actually doing it, it will probably be a couple weeks. 2) If nothing easier works, it's starting to sound like the consensus is to take off the water pump and check it. And i'm starting to lean in that direction. Just no harm in checking the things that involve less work first. After all, that 35* air that rushes over my engine while i'm driving sits on top of ME while i'm working on this thing in winter, so i'd sort of like to minimize my time outside :hs:

While i'm waiting for the temp sensor adaptor and before i freeze my ass off doing the water pump thing, if anyone has suggestions of things i can check in the mean time (or perhaps radiator air bleeding instructions) i'd love to hear them.

[!Zar!]

Blah blah blah.

It's because you don't have a clutch fan.


As for a run down period, normaly a minute or two is fine. If you have been boosing.

If not, 30 seconds.

[MELLO*SOS]

mello88: I don't know how to bleed air out of the coolant, but the radiator is basically new so the coolant was fully drained when that was installed. Does that address the bleeding or not? If not, how do i bleed it?

It should have been done as part of the radiator install. If there is air trapped in the system, it will cause overheating issues. With the engine cool remove the radiator cap & check if the the coolant is 100% at the top. Now remove the 10mm nut on the front of the intake manifold, to the right of the coolant outlet spout (see pic below). This nut is the highest point of the cooling system, so all the air (if any) bubbles up there. Fill the radiator with your water/coolant mixture until coolant starts to run out of the bleeder bolt hole. Reinstall the bleed bolt and your radiator cap, drive around until warm, cool down and check it all over again...

Bleed screw is visible in middle of this picture, just to the right of the coolant outlet spout: http://locost7.info/files/engine/ka24de/4-95KAonStd.jpg

edit: I don't know whose clean KA that is, but thanks for the pic :)
edit: on SR i think its on the other side: http://www.sr240z.com/srpictures/17.jpg look up the location & process in the FSM to be sure...

[dwadia]

Oh, umm, that's not my engine... I have a redtop SR, and it has a greddy manifold (knock-off i think, but same style) . Does anyone know where the bleeder screw is on that? Also, is it ok if i just drain a little coolant to get it down below the top of the radiator, and then open the bleeder screw, and then top it off again until coolant comes out the bleeder?

Also, i'm 99% sure now that this isn't a water pump issue. I have started my car cold twice today and let it idle, one time for 20+ minutes, another time for ~15 minutes. The temp gauge just goes one-third of the way up and holds there, as i think it should. It's after i drive the car (even briefly) that the gauge wants to climb up when i'm stopped or moving slowly. Interestingly, i just went for a 10-minute drive boosting it hard the whole time, at around 15psi and above 5k almost constantly. The gauge was totally normal while driving (presumably because of the air flow) but when i stopped at a traffic light, it did go up, but no faster or higher than when i drive much more conservatively before stopping. What do you guys make of this :confused:

[aznpoopy]

is your name sam?

you need to bleed coolant after an engine swap for sure, even if this isn't causing your problem. if you have air bubbles it can make the temp gauge spike.

[dwadia]

Were you serious about the name question or was that something that flew over my head? My name is darius...

I would definitely like to bleed it if anyone can tell me where the bleeder screw is. Someone else sufficiently described the method, but it looks like the screw location was for a KA.

[aznpoopy]

i was serious.

i know someone in NJ who swapped in a redtop SR a few weeks ago but i don't know his name on the forum.

unfortunately i don't know sr's that well. if it's anything like most cars you could probably find the bleeder screw by just following the rad hose.

[Flybert]

Fuck the bleeder screw.

Best way to bleed air out of your system is to jack the front of the car up really high and bleed the air out of the rad cap. I usually get a funnel that fits in there and makes an air tight seal when you push down. Then fill the funnel until the water level is higher than the radiator and gives you a good view of all the bubbles that are coming out of the system. Have a friend squeeze the hoses to push air out. Keep running the car until all the air has come out of the system.

[misfitsfreak81]

bleeder screw is on the water neck were the top hose conects. super easy to get to. just dont drop it. i also dont know that this will fix you problem, i have pretty much the same exact setup as you and i bled the system and it still runs hotter than i think it should. hope you get it figured out

mike