I'm in the process of converting to Evans. Right now I'm just flushing the system with Sierra. I bought new AST and filler caps, upper and lower rad hoses, AST hoses, thermostat and coolant level sensor ($53 ouch!). I emptied the rad and the engine block, put in all the parts and refilled.

I knew there was air in the system so I wanted to burp it, I used the big yellow no-leak funnel I found in another thread (bought in PepBoys for $12.99) to let air escape. Well, it didn't quite work like I expected. I kept a close eye in the temp gauge while the car idled with heater at full blast and it started to go up from the center normal position!!!! I shut her off, let the fans blow like mad but they were blowing coool air so the pump wasn't pumping!!!

I squeezed the upper rad hose a couple times and saw some bubbles I restarted the car and temp went slightly down then up again... shut off... I was using the funnel in the filler cap so I decided to try using the ast instead, got more air out but still the pump wouldn't move water through the rad. The thermostat was open as the thermostat housing was hot but the coolant wouldn't move...

After a lot of frustrating tries, a dead battery from the fans running full all the time and many squeezes of the upper rad hose I couldn't see any more air bubbles... I took the funnel out, replaced the caps and tried again... heat rises again!! I tried a last time without using the funnel and finally the water pump would move the coolant! Temps inmediately went to normal, fans started blowing hot air (the heater vents too) and the idle settled at normal 750rpm (it was higher when hotter)

I let the car idle for a couple minutes watching the temp gauge and the car's behavior... normal temps, normal idle, normal fans on-off operation and the coolant light didn't come on. phew!!

Why did this happen? Did I have an air locked water pump? How will this affect my car, the temp gauge pointed at 10 instead of normal 9 (as in an analog watch) but it never got to the white hot line on the gauge.

 

Two possibilities

1. My second gen just had a similar incident. Car had been running perfect temps then next morning, temps climbed and the heater core blew nothing but cold air. Brought her back home let her sit. Check T-stat, it had locked up. Less than 2500 miles on a brand new OEM stat. BTW T'stat was hot but upper radiator hose and radiator were ice cold

2. Airlock somewhere in the system pre-waterpump

 

Seeing temps like that wont really hurt you. You have to get it to the H to do some damage.

 

do you think I should get the brand new OEM T-stat out and boil it to check if it opens? Car seems fine now...

 

anyone else?

 

Sounds like it should be okay. I would definitely invest in a new T-stat.

 

T-stat is brand new direct from Malloy

 

when you use the no-spill funnel... keep it on the car while it's running then wait until the theromostat opens. This is when the coolant will circulate throughout the system and let the airbubbles escape through the funnel.

if you're shutting the car off too early the trapped air bubbles will not go anywhere.

 

I was kind of worried when I converted to Evans NPG+ also. My coolant temps kept wanting to go high until I had pumped out enough air and enough coolant in. This involved squeezing (pumping) the radiator hose, turning the car off and on, and adding more coolant as needed. About 3 times turning the RX-7 on and off (to let it cool) and I haven't had to add a drop of coolant and my temps are normal. Note that I have an Aluminum AST and Fluidyne radiator.

I wouldn't wory much about your car getting a little hot at idle. I think your thermostat is Ok and I wouldn't replace. You don't want to have to burp your system agian do you? The nice thing about NPG+ is that you probabely won't have to for a long time.

 

That's how I did it, I had it there all the time with extra coolant about halfway full. Thermostat opened and some bubbles came out but it just wouldn't circulate. I wasn't after I took it off and put the caps back on that it finally circulated. I'm gonna check again this morning to make sure everything is ok...

 

Did you unhook the coolant line from the the throttle body while filling? If not, you will have a hell of a time getting all of the air out of the system.

Sonny

 

Did this ^^^ today after draining the Sierra to put the Evans prep fluid in. Works perfectly! As soon as the prep fluid started coming out of the TB hose I put it back on, finished filling and started the car. No overheat this time everything was running smooth and with the no drip funnel the remaining air was slowly venting out. I let it run a few minutes and tomorrow will drain the prep fluid and finally fill it up with Evans NPG+