I had the mystery missing coolant for a while..

Replaced both caps just the other day... since then i havent lost any coolant . Just driving around town nothing long distance ( didnt want to be too far from home just incase.)

Today i take it on the highway for the first time in about a year.. everything was fine on the open road... every now and then at a stop light the temp would rise ever so slightly.. and as i was shifting.. in 3rd it would rise the highest but when i shifted to 4 it would drop down to the mid marker..
right before i reached my destination it was about a 40 min drive and im in the city with stop and go traffic.. the buzzer goes off and the stock temp gauge is in the red and climbing i shut it down and i get the steam from the over flow and a coolant pool under the overflow and bubbling from the AST ... Filled it back up drove for 15 mins and overheated again.. filled it up one more time and in another 15 mins same thing. I did make it to a RX7 specialist in ocala "Carlos racing" Carlos wasnt there but they were nice enough to let me leave my car there and he would look at it when he got back..

The car was runing fine other wise.. no smoke or anything just a slightly higher idle sped than in the past

What are the signs for a bad thermostat? which is what i am suspecting from reading other threads. Or is the engine on its way out..

Mods
Greddy FMIC
stock engine 76k
Non seq
Fluydine rad
aluminum AST

 

How much coolant was added during the 1st and 2nd fill after the 40min drive? Are we talking a very small amount or something substantial (1gal)?

Sounds like you may want to check the coolant system pressure.

 

It took about 4 liters of water each time and it over heated.. when i pulled over and shut down it was running out from the over flow tank, then i would purge the ast so i could get the rad cap off

 

You were driving the car with the stock coolant temp gauge going up and down between mid way and red ???? That is a huge no no, that gauge is so innaccurate. If that gauge was moving past its normal slightly below mid way point it is likely you were seeing some pretty intense water temps. Hopefully it will be a minor issue and no major damage was done. However, if it was overheating every 15 minutes it doesnt look good.

 

o yeah i know.. I had a PFC in there for a long time. but i had to put back in the stock ECU the 5 yrs that i had the car overheating has never been an issue.. The car sat outside for about a year its only been recently been drivable.So i am expecting somethings to not work like they did before. I will get a better temp guage but for now my thing is just finding out why it over heated on me.

a stuck thermostat will not pull water from the radiator correct?

the fans kick on and of as normal. and i have a switch to manually control them.
i have let it sit and idle for 20 mins and it seemed ok to take on a road trip but i wasnt till i hit city traffic that it overheated what would be the reason for that?

 

Sounds to me like the dreaded 'O' ring failure symptoms. Same thing I had when mine were going out...exactly.

 

Was yours smoking at all before it failed?

 

yea me too... after a long drive on the highway... temps. hit the roof ... coolant dumping out the overflow... i had o ring failure... coolant pressure check is a good idea

 

that sucks.. i guess i should be excited about the rebuild. but .. im not..
I didnt want to drive it back home luckily i limped it to a rx7 shop. one person was there that was working on his own car but he was cool and let me leave it there.

Pressure test is the first thing im going to get done . do they rent that pump at autozone or anything just incase they dont have it.

 

Wow, that just happend to me to. I feel the same way, I should be excited about the rebuild, but I'm not.

I always knew the day would come, but it hit at such a bad time moneywise.

 

old bump,haha ya i have the same problem too. good thing i have a aftermarket temp guage. it is def time for a rebuild for me too.

 

for anyone new owners reading this....i can say that I have saved my engine on at LEAST 2 different occasions because of an after-market temperature gauge. I have the extra insurance of the fan mod which I almost use on a daily basis if the car is being run hard at all.

the stock gauge should not be relied on.....I have seen somewhere like over 100 degree F temperature change on my aftermarket and not an millimeter of movement on the stock gauge.
ex. on warmup the stock gauge shows normal when my aftermarket reads roughly 120 degrees F and the aftermarket could get up to 220 after warmup without the stock needle moving one bit.

this would be the FIRST mod i would do on a stock car if I did it again....QUICKLY followed by a boost gauge, AST, and dp