Overheating Problems

Well, I've just rebuilt my motor from the bottom to the top. I've got overheating problems. I should say that the car never gets to the point where the coolant boils and spills out the overflow bottle, but the needle on the water temp guage gets awfully close to "H". I've got heat in the car, brand new thermostat, fan is working, all new radiator hoses, and I cleaned out all the original water hardlines before I reinstalled them. The only thing I've done different is removed the water lines that used to go under the throttle body, but I fail to see how that would affect anything. The car wasn't overheating before the rebuild. Anyone have any ideas?

i was having the same problem in my SE.. turns out now that i've got a blown head gasket..

check this.. http://www.club-s12.org/forum/viewtopic.php?t=6361

this is my old post on it.. but look through it.. it might have some info for ya

hmm maybe a cloged radiator or a bad temp sensor for the gauge...the gauge water temp sensor site under the main water temp sensor that goes for the ecu the gauge temp sensor only has one wire plug while the ecu temp sensor has a 2 wire clip

Well, I don't think it's a blown headgasket, but I'll do a compression test just to make sure. There are no signs of a blown headgasket. As for the temp sensor, I was thinking I might try replacing it first. Of course, it's location doesn't make replacement very easy. I believe the temp sensor is reading correctly, because when the car is hot, it runs a bit differently. Probably because the fan is engaged. I'll have to run some more tests. I wish there was an easy way to get numerical data out of the ECU to see what it's reading for a water temp. I've got a Techtom MDM-100 for my Twin Turbo that plugs directly into the factory diagnostic port and gives me all sorts of real time data. Unfortunately, it doesn't work for the 200SX.

ya datalogging would make life so easy for us.. but oh well gotta use what we have

Just borrowing here.. Im running clost to stock, but yesterday i drove.. well.. pretty hard, but only for like a couple of minutes, and the temp got a little over 3/4..

Is that common, and does it heat up faster/more with that IC sitting in front of the radiator?

Spooled I know this may sound a bit silly, but I have to ask it anyway so don't feel offended. Are you sure that you installed the head gaskests correctly? Meaning "TOP" side up? If you happen to install them upside down you will be blocking coolant passages and still get a good seal for the pistons. Now I'm not sure if this is possible with the VG, but I just need to make sure that this is not the case.

I have known a couple people that have done this with a SBC so I just wanted to make sure that this didn't happen here.

hehe - trust me, that thought did cross my mind, but there is no way to get the left and right head gasket mixed up. They're not symetrical. It's a good thought though. I may take it to a radiator shop just to make sure there isn't any blockage in the radiator that I don't know about. I've pretty much exhausted everything that I can think of.

that's good to know.

What kind of shape is the Radiator in?

I just had mine re-cored ($335.00). FYI.

The radiator looks great on the outside. Not too many bent fins, and no buildup of crud anywhere. Who knows on the inside though. I've been running this car since '99 without incident until I had a failing water pump last year. Every once in awhile, I swear I can hear gurgling in the car though. I'm starting to wonder if I don't have some kind of an air leak in the heater core. There is no evidence of coolant leaking from it though.

If the heater core was leaking at all you would know it. There would be this really nice film all over everything inside the car.

Do you only hear the gurgling sound when the HVAC temp control is moved off of cold? I get that sometimes too.

Ok I know the first part doesn't have to do w/ your post but I wanted to know if you have any pictures of how you modified the MSA headers to fit?

about your post though...
If I just let my car idle in warm weather its get pretty close to the H. When I start driving though it goes down. I just think the stock cooling system ist that spectacular? Later this summer, maybe fall I am going to upgrade to and aluminum 2in crossflow aftermarket unit. They have an assortment of them for domestic sports cars for $200 or less. It will take a bit of work but it sounds like you've done a bit already? So I doubt it would be hard for you. *shrugs* You might even be able to do it for less than a recore would cost?

hehe I'll post up pics of the headers tonight or tomorrow.

As for the stock cooling system, I never once had it go above halfway until the water pump started failing. My previous SE V6 (RIP) I ran at a hillclimb with absolutely no fan whatsoever and it also never got hot, although for the most part, I was moving at a decent pace.

I don't recall if the gurgling noise only happens when the temp control is moved off of cold. Quite possibly, yes, as I'm driving around with my heater on in an attempt to cool the car.

i remember my friends hardbody/pre-frontier would make a sound like it was drinking water near the upper coolant hose after you turned it off i wonder if this is the same noise

Yeah, to me, a gurgling sound can't be good, but I have no idea where it could be coming from. All my hoses, water pump, thermostat, etc are brand new. I'm going to be watching my coolant level a little more closely.

a little late here...but on my CA18ET I get gurgling noises under the hood once I shut the engine off.......on mine it's the coolant flowing out of the rad through the hose into the overflow bottle.

I have the same thing my 87 SE runs hot at idle cools down a bit when you get going. Im in AZ, so my temp gauge is always over 65-75% unless it's a cool night. One time on a cool morning it was rainning and while I was sitting at a light, I noticed the rain drops would hit the hood and turn to steam really quick. It made this errie myst on my hood lol.

Wow, this thread has been brought back from the dead. lol Anyway, my main problem was that my fan clutch was bad. My radiator is in okay shape, although it think there may be some small blockages in it. I installed a Nismo 169 degree thermostat and replaced the fan clutch and now the gauge doesn't quite get to the halfway mark. MorbidPh8, since you're in AZ, the Nismo thermostat might be a good upgrade for you.

I would lose any clutch fan and go to electric only. If your rad is good shape without scale/beny fins then any electric fans are fine.

Save yourself some $$ and just get a Universal Stant 160 t-stat from Autozone or any part store. Just grab a 180 tstat off the shelf for your engine, and match up the diameter with one of the 160 tstats they will have on the shelf. They should be less than $6
I had one of these in mine when I lived in Tucson back in '95, and the needle on the temp gauge barley came off the "C" on 120 degree days with the A/C blasting...I was even only using my clutch fan back then too.
Also you could run a weaker coolant mix with some Redline Water Wetter. Do like 70% distilled water, and 30% coolant along with 1 bottle of the water wetter, and this alone should bring down you temp

I would lose any clutch fan and go to electric only. If your rad is good shape without scale/beny fins then any electric fans are fine.
Yeah, I plan to go the electric route before the next autocross season starts up in Spring. Just haven't had the time or money to do it yet.

If you dont have or use AC, then you could probably just run the stock electric fan with an additional front mounted fan.

Nope, don't have A/C, but also removed the OEM electric fan. I would rather have an efficient puller electric fan anyway.