Hey guys, I just bought a 79 SA last month, car ran great no cooling problems engine and trans seemed solid. About 3 weeks ago I noticed when driving to work, about 26 miles highway, the temp guage started climbing and i could smell coolant. Popped the hood and the overflow was completely full, Thought maybe it was a bad thermostat (going out on a limb assuming that as a Japanese engine it is reverse flow) replaced the thermostat drove it for about 30 minutes around town no problem. Drove it to work next day temp started climbing, It seems to only do it when running above 3000 rpms constant.

 

Build Threads probably isn't the place for this question

When the engine is cold try removing the radiator cap and starting the engine. If the coolant overflows you may have water seal failure which will need a rebuild to rectify.

 

I was hoping to not hear that, the engine supposedly has 50,000 miles on it out of a 83 rx7. As soon as i get my new radiator in I will give that a try though

 

Whoa, wait a minute, lets diagnose it first. It could be something simple like a clogged radiator.
Sounds like airflow may be restricted at highway speeds or higher rpms. If it stays cool at idle
then its some sort of inefficiency which can be caused by a number of things.

Try hitting the radiator from the engine side with a good spray from the hose. It could be trash is blocking
the airflow. Also open the radiator as suggested and see if you see some good flow happening
when the engine warms up. Make sure to open it cold and then start it up and let it run. If the
flow looks non-existent or way slow it could be the radiator internally is clogged or the tstat
is not opening all the way. You can check the tstat by grabbing the upper hose and seeing
if it gets hot when the engine hit operating temps. If you feel the hose get real hot quickly you
know the tstat is opening.

Lets not jump to the "OMG I need a rebuild" hysteria too soon.

 

Thanks t g farrell, right now i am waiting on the new radiator to get here from wherever they hide all of the replacement parts for FB's. The old radiator looked terrible when i drained it, coolant looked amazingly clean though, so I decided to go ahead and revamp the cooling system. New thermostat and water pump although the old one didnt look that bad off. I am really praying that the radiator is the problem, so I dont even have to worry about fighting with a rebuild right now.

 

Finally got the radiator in, after cutting some hose to fit the outlets, that puppy is installed and good to go. I let it run with the cap off and after the thermostat opened it did start to overflow but there were no bubbles. I still have to tap out the holes in my hood so I can get that back on and really test the cooling system

 

replaced the radiator, water pump, thermostat, you name it. Turned out the problem was the fan clutch. It was shot and not turning properly. Changed that and no more problems.