jj_008

iTrader: (8)

My car is having a problem reaching full operating temperature. The factory gauge will swing up and down. When I'm driving, the needle will move up (a little below normal) and when I come to a stop it will go almost to the cold mark (which causes it to idle like crap). With the car in nuetral, I can rev and hold a higher RPM and watch the gauge increase.

I had my cooling system seperated 2 weeks prior, and it was running a little cooler, but now it's all over the place when the outside temp dropped. Does anyone think that my problem is anything but air in the system? Does anyone have a Evo specific way of bleeding the system? The first time I had the system apart, I didn't have an issue.

Thanks in advance.

superz

iTrader: (7)

You either have a faulty thermostat or you have air in the system. I would lean towards a bad thermostat.

jj_008

iTrader: (8)

I guess I will start w/ checking for air first and move to thermostat. Kind of odd that a car w/ 20kmiles would need a new thermostat, but I have seen stranger things. Time to boil some water when I get home

SuperHatch

iTrader: (23)

I don't see how the thermostat would cause this issue. The factory temp sensor is in the t-stat housing, but it is before the t-stat. So if the t-stat is stuck closed, the gauge would still read right, and if it was stuck open the gauge would take a LONG time to reach operating temp, but it would eventually get there.

I think you probably have air in the system or a faulty gauge. I've heard of a lot of evos with erratic temp gauges or gauges that simply don't work at all.

The proper way to bleed the system is to let the car cool competely. Remove the radiator cap and start the car. If there is air in the system the coolant level will drop when the car is running. As it drops add coolant. Once the engine starts reaching operating temp the t-stat will crack open and you will see the coolant level in the radiator start to rise and eventually overflow. Once this happens put the cap on. Fill the overflow resivoir and let the car reach full operating temp (Fan kicks on twice). Shut the car down, the system is properly bled at that point.

If you still have issues, try this again, but it is important for the car to be stone cold when starting this.

- Steve

jj_008

iTrader: (8)

I finally got home and did some work on the car. I popped off the radiator cap and the coolant was all the way full. The overflow tank was low so I add some coolant to it. I started the car and the coolant slowly overflowed from the cap opening. This continued for the entire time I had the car runnning. The fans never came on in the 20 minutes I had the car runnning. The temperature gauge needle never made it to the "middle" either. Even after 15 minutes of running, the coolant was just luke warm and the radiator was cool to the touch. I went inside the car to give it some gas and that immediately caused the needle to drop almost to the cold line and then it slowly climbs back up. I think my sender is messed up or the T-stat is staying open. Any more ideas?

Jim_Patterson

iTrader: (13)

take the radiator cap off completly, turn your heater on high and let the car run for about 5min. This should get all air out of the system that you may have. Other then that Im not sure what it could be.

jj_008

iTrader: (8)

That's, basically, what I did.

SuperHatch

iTrader: (23)

The car was completely cold when you did this?

The coolant strated overflowing the second you started the car?

If both of those statements are true then it sounds like a t-stat that's stuck open.

If you've already done all this, it's fairly simple to check if the t-stat is stuck. You'll have to drain the cooling system, but you don't have to drain it all the cay. There is a drain plug on the bottom of the radiator on the passenger side of the car. If you want to drain it completely that's fine, but you really only need to drain it low enough so you can't see coolant when looking inside the radiator.

Just take the upper radiator hose off and the t-stat housing. It's next to your upper intercooler pipe, there are 3 10mm bolts holding it on. Take a look at the t-stat when you get it apart and make sure it's closed, if not, get a new one.

- Steve

jj_008

iTrader: (8)

The car had not been started in 2 weeks and the coolant started overflowing immediately. I am going to be checking my T-stat in a couple of days. Hopefully sooner if I can find some time.

SuperHatch

iTrader: (23)

Basically the coolant is sucked into the pump and pumped through the motor. the last place it ends up is the t-stat housing. If the t-stat is closed, the fluid is forced through the heater core, turbo, and other waterways ending up back at the pump inlet. If it's open, the coolant still goes through the rest of those places but also into the upper radiator hose and through the radiator. The reason the fluid level is rising immediately is because the coolant is immediately being pumped into the upper radiator pipe. If the t-stat was closed the fuild level would stay even or possibly drop a little when the car is first started. I would almost bet on it being your t-stat.

- Steve

cij911

iTrader: (14)

I too just showed signs of the thermostat stuck open....Odd to me, but all signs indicate that is my problem - car running cold and coolant is swirling upon cold start up (indicating an open t-stat)...

Do you really have to drain the coolant or could you just pinch the upper radiator hose close to the t-stat housing prior to removing ? Thanks!