DiamJim

My 1985 RX7 GSL 12A with a 150K miles is blowing what looks like oily water from the exhaust and running hot. The car initially ran hot from a bad heater hose. I replaced the bad heater hose and it ran hot again. I changed the thermostat and it over heated again. I brought a new radiator and it ran hot again. I changed the oil and test drove it and it ran hot again. The car smokes with white and gray smoke. Thank you for your analysis and thoughts!

I'm running a Weber knockoff 48 DCOE FAJS side draft carb. I've had this car since 2005 and love it more and more each day.

Ckforker

Is there water in the oil? Not sure what intake you have with that carb, but the o rings may have failed and water is getting in that way.

Worst case scenario is coolant seals have failed.

I'm sure others will add more detailed information.

t_g_farrell

iTrader: (1)

You don't mention if its losing coolant? Are you having to top off constantly? If so it could be as Chris has suggested or you could have coolant seal issue. Last resort is to try a leak stop product but that will just buy you some time. You may want to do a compression test too.

DiamJim

Since it been running hot and the temperatures here has been in the low 40, it has been hard to start which goes with the 48 DCOE with no choke. When I changed the oil, I did not find water in the oil like I thought. The coolant system is not keeping the engine cooled. The overflow coolant reservoir keeps overflowing when it runs hot.

mazdaverx713b

iTrader: (91)

Where on the gauge is the needle sitting when you say its running hot? Are welcome talking overheating?

The oil water from the exhaust is likely a water and carbon mix. You are likely not losing oil through the exhaust.

I would do a cooling system pressure test at this point and ensure you haven't lost a coolant seal. I would suspect loss of a good seal near the exhaust port if the coolant is heating up rapidly.

Ckforker

Another reason may be the impeller has broken off the water pump. If you start the car without the cap on, once it warms up a bit, you should start to see coolant move across the radiator.

Did this happen suddenly, or gradually?

DiamJim

Each time it runs hot the temperature gauge is beyond max out. Each time it runs hot, I have to add water. When the heater hose went bad it ran extremely hot and it been running hot each time tested on a one mile test. After adding new thermostat, water pump, heater hose and new radiator, it still run hot.

DiamJim

Based on Ckforker's suggestion, I filled radiator up and left off the radiator's cap and it blew water out of the top radiator as I crank the engine cold. I must have a blockage???

JNew

Aaron Cake has a good cooling system overview and troubleshooting guide at https://www.aaroncake.net/RX-7/cooling.htm. The very last section describes your problem perfectly: Constant Violent Overheating (Coolant Gushing Out Of Overflow Bottle, High Temps, Car May Spew Clouds Of Steam).

Unfortunately, he says that "this almost certainly indicates a failure of the coolant O-rings. Combustion gasses are being forced into the cooling system, over pressurizing it and causing coolant to be ejected as the gas bubbles force their way out of the system. Normally, the car will also emit clouds of sweet-smelling steam from the exhaust. The only cure is to rebuild the engine to replace the damaged seals."

Based on the fact that your rad is blowing coolant out the top on just cold cranking, it seems your engine is trying to use your cooling system as part of its exhaust system.

DiamJim

JNew, Thank you for a definitive definition of what's causing the issue.