EnjoiPugs

I just bought my 88 rx-7. It's having an overheating/ low coolant problem. It was giving me the same problem yesterday. After replacing the filler cap and the thermostat the car seemed to run fine. I even drove it home 40 miles and it ran pretty good most of the way.

Today I went to autozone, about half a mile away. I noticed it was getting a bit past quarter way on the temp gauge. I got there and bought some stuff. On my way back it shot up to three quarters up the gauge and the add coolant light started going off again. I don't know what to try next. I looked at the belts, inspected the rad cap, changed the filler cap, and changed the thermostat. The coolant in the system is a nasty color even though the guy who sold it to me said he just changed the coolant not long ago. What do you suggest I look at next?

Nateness

iTrader: (7)

Look for leaks. If no leaks are detected, I'd look into having the system pressure-tested. Are you missing coolant volume with each time you drive?

Worst case: possible coolant seal failure.

Aaron Cake

iTrader: (1)

Cooling system troubleshooting:
http://www.aaroncake.net/rx-7/cooling.htm

rxtasy3

iTrader: (2)

flush the system and have the rad flow tested, it may need cleaning.

swervin

i took the thermostat out and overheating wasnt a problem. gauge just goes crazy

Rextasee

aaron cake rx7 guru: question-

if you pressure tested a system on an engine with bad coolant seals, where would the coolant leak to? into the chamber? if you cranked it after that would be visible out of the exhaust? is it true that because the methods of lubrication and cooling are different in a rotary, the coolant should never get milky under any component failure and the oil should never really get diluted with anything?

rxtasy3

iTrader: (2)

outside of a poorly operating pcv system, or lack of, causing alittle water to get into the oil from condensation in the filler neck, i have yet to see coolant to get into the oil. bad coolant seals will allow water into the combustion chamber, causing white smoke(steam). so pressure testing with bad coolant seals will leak into the combustion chamber.

Aaron Cake

iTrader: (1)

If you are running without the thermostat, that may be contributing to the issue. The RX-7s uses a bypass thermostat so without it, a major amount of coolant bypasses the radiator.

If you pressure test the system and have an internal leak, coolant will leak into the engine. When you turn it over it will exit the exhaust ports and/or spark plug holes.

It is almost impossible for a rotary water jacket to fail in such a way that coolant and oil mix.

TBelly

Definately do this. Not positive it will help you since I am a noob at cars but I had a very similiar issue in the past with my 87. After changing the radiator fluid and filling it up correctly (by unscrewing the little screw on the side of the radiator) I have not had a problem since.

True2RX7

lol glad I started reading this before I went and blew money on a new water pump. Mine is having the same issue, i'm also having a problem of it not wanting to start after it overheating. I just got the car, and the kid that drove it to my house said it has trouble starting after overheating. I still can't get it started... And when I try I get a strong smell of gas.

Aaron Cake

iTrader: (1)

Sounds like the car needs a basic tuneup, as well as an injector cleaning.

Though a hot start problem can also indicate low compression.

fcs3l0ve

you can try blue devil block sealant. you can buy it at autozone for around $50. i had a fairly similar problem with the car constantly overheating and white smoke coming out the exhaust, it was horrible. i am almost positive i need a rebuild or new engine and im sure my seals are shot with low compression. i added the block sealant and replaced my thermostat and my cooling problems stopped. im planning a turbo 2 swap soon so im just going to drive the n/a with the sealant in until it dies.

diablo_rx7

im having an overheat problem on my 88 gxl. i swapped out the motor fan and installed a 16'' electric fan. it runs cool for about 10-20 mins then jumps back up to half way.

Aaron Cake

iTrader: (1)

It is likely that the electric fan is too small.

Did you do any of the cooling troubleshooting linked to earlier in the thread?

A few words about block sealant as well: It is an option of last resort. While it may do the job, there is no guarantee and it will tend to clog a lot of stuff. For example, the heater core, radiator, etc.

fcs3l0ve

yeah i know the block sealant is a last resort. i have it running in there until the engine dies or when i get enough money together for a turbo swap. it really isnt the best option to go at all but it worked for me for awhile now.

diablo_rx7

umm yea i really dont want to use the sealant... but as far as the E fan i got one of the bigger ones but how big would you recomend? now if i get a bigger fan and it dosent help what could the problem be radiator,water pump,ext....?

fcs3l0ve

umm okay well you dont have to :] it was a suggestion

Aaron Cake

iTrader: (1)

http://www.aaroncake.net/rx-7/efanmyth.htm
http://www.aaroncake.net/rx-7/efaninstall.htm

diablo_rx7

thanks for the e-fan page it helped with a little problem i been having since installing it. i installed it right with relay and fuses and all that just when starting the car it seems to just die out i was wondering if that could be from the fan pulling to much off the battery and alt.