After buying my 95 Z with supposedly a bad opti I have gotten it to the point where I thought I could drive it, and I can, sorta.


Before I get into this I will let you know what I have done to the cooling system; I have replaced the water pump, cts, low coolant sensor, heater core, put a new thermostat in as well as added a new radiator cap. I have bled the system through the thermostat housing and the heater hose bleeders many times.


With that said when I drive down the road the temp rises to the point of spewing coolant out the radiator cap. When I pull over and let it idle the spewing stops and the car starts to cool down immediately according to the gauge in the dash.


The one thing I'm not sure of is how the fans are suppose to operate. I have read on here that one fan is suppose to kick on at around 226 degrees and the other at around 235 if need be. That is how my fans are operating.


I also read on here that the 95 models were suppose to both come on at low speed at around 226 and kick into high speed around 235 if need be.


Could this be my problem? if so could someone guide me in fixing this? If not I'm open to suggestions as to what to do.


I'm so upside down on this car right now that I'm going to have to get it fixed or I guess I'll be carrying lt1 to work for lunch ! Please help.

 

Under the front of the car, there should be a plastic air dam hanging down (spoiler looking piece) which directs air up and through the radiator while open road driving. Without it, the engine can/will overheat. The fans are no match to the moving air you should have when the car is on the open road. And they're working as they should which explains why the temps go back down when you're idling.

 

have you pressure tested the system?

 

Once again you guys have come thru big time !


I have made it a point to check any and all suggestions that come from here even if I have already checked whatever is suggested.


After further inspection of the air dam 69 mentioned I found that the lower part of the front bumper cover had split and dropped down to where the air dam didn't have much effect. I kinda got it pushed up out of the way of the air dam and took about a 10 mi. drive and wa-la it ran much cooler than before. At least it didn't get anywhere close to red on the gauge until I got on it about a mile from the house and that bumper cover dropped back down.


I will spend time tomorrow making sure that the bumper cover is up out of the way permanently and try to enjoy a little seat time for the first time since I purchased the car in april of 2013


Thanks again for all the help, I never would have gotten this far without it.

 

Here we go again!


So after I made sure that the bumper cover wasn't going to give me any problems I took the car out on a Sunday drive so to speak. Drove about 15 mi. and stopped for about an hour or so, parked on concrete, temp is fine and no evidence of leaks. Drove another 5 mi. stopped for 20 to 30 minutes, temps still ok, drove another 5 mi. stopped to clean windshield and get a pack of smokes, no problems.


I then got into stop-n-go traffic for about 10 minutes or so and the temp started to rise, traffic broke up and I thought being on the open road it would cool down, NOPE! Wound up pulling over when gauge went into red and spewing coolant out of radiator cap.


Took about 20 minutes for me to relieve the pressure without losing more coolant, I then added about 3/4 of a gallon (all I had)and started home with the car still being fairly warm. About a mile down the road the temp gauge drops from a little over 3/4 down to just over the 1/4 mark and slowly climbs back to red just as I arrived home, about 10 mi later.


With the temperature drop on that last leg of the trip home I'm thinking that my overheating problems were fixed and a new problem has arose. Do I have a sticking thermostat? If not I'm lost here.


Sorry for the long post, just trying to get this thing figured out and they say the devil's in the details.

 

cheapest thing you can try to replace cap ,when the engine is cold start it up look for white.smoke ,i had a simular issues after flusing radiator ,could be blocked hose ,that .gunk you never get it all ,an with older cars can couse more harm then help ,well with mine i startrted no.tice the fans not comein.g on when they should not then comeing on early ,i drove the car couse the over heating was not to bad for near 9 months .but it was the head gasket slowly going ,did not have water in oil ,just after start keep cap off ,see if the water shoots out like geyser after about 10 minutes ,then you got problems,i hope its just blocked hose ,but you may want to check them all ,does your overflow have gunk built up in it ,

 

I'm not going to say the cap is not bad but it is a new one. As far as gunk. I have had the radiator off, hoses off, and changed the heater core in the last couple weeks and no sign of anything other than clean coolant. Also none in overflow tank.


I am confident that before yesterday the underside of my bumper being split and dropped down was not letting the air dam do it's job. I got the bumper back up out of the way and had no problem until I got stuck in traffic.


I just pulled the thermostat and tested it on the stove. It passed not once but several times of putting it in, letting it open then taking it back out and letting it cool down. I'm not saying it's good just posting results.


Wondering if I may have a hose collapsing? Is there any way to tell this without heating the car up again? If it is a collapsed hose would it be one of the main (big) hoses coming off the water pump or could it be any of them? It looks like the hose coming off the driver side of the pump has been replaced but the other one as well as the small ones still have the black mesh looking stuff on them.

 

it still sounds like you have air in the system. are you able to get the front of the car up high when bleeding air. there is what is called a steam pipe at the back of the heads, goes from one head to the other. if it gets plugged it will get hot and boil over.

 

Thanks Craby, Maybe I am wrong but wouldn't air in the system have showed up in the 15-20mi before I got into traffic?


I have also wondered about this "steam pipe" Is it very hard to remove this pipe to inspect it?


Thought I was bleeding it good enough but I will have it on a set of ramps the next time that I bleed. Maybe I'm not bleeding it enough, nervous of getting coolant on the opti and ruining it


This is my first 4th gen and I have no idea about where the gauge is supposed to run on these cars. with a 180 thermostat shouldn't the gauge run at about 1/4 (first line) on the open road and a little warmer in traffic?

 

mine runs just over the first mark, assume thats 180-190. yea that is strange it would wait for so long. have you done a pressure test?