I just purchased a 1979 Rx7 with only 35k miles on it. It's in really sweet shape for the age but I knew that it likely had a coolant leak. The previous owner reported white smoke coming out of the exhaust when he first started it up.

It had been setting for 2 years and I just fired it up for the first time last night. When I first started it, it blew all kinds of nasty stuff out the pipe including mice nests. After running it until it was fully warmed up, I shut it off and let it set a minute. When I restarted it did blow white smoke then ran clear. When I shut it off again, I noticed smoke/steam coming from the exhaust side of the engine. It sounded like water boiling in side the exhaust pipe.

I suspect a leaky seal somewhere on the exhaust side or maybe inside the engine. I would like to hear from others and their experience with this. I know I'm probably looking an engine replacement or rebuild. I'm inclined to rebuild it myself so I'd like to hear from others on that subject too.

This is my first time owning a Mazda and I'm looking forward to fixing and running this baby for a long time.

Thanks,
Phil

 

Jim,

I have the almost identical situation! Very cusirous to hear response! I just bought a white 79.

 

The intake o-rings may be leaking. The coolant circulates through the intake to temper the fuel charge. The rubber o-rings break down eventually. Repair requires removal of carb and intake.

Welcome to the forum and the Darkside. In my sig line is a link to the online FSMs, carb manuals, etc. Download whatever you need.

 

I took your advice and removed the card and the intake manifold. The o-rings were shot. They were brittle and it looked like pieces were missing. Another tell-tale sign that fluid was leaking was the manifold gasket. Usually these gaskets are hard and brittle. The end parts were hard but the middle section was soft and broke apart easily. So it's off to the parts store to get a gasket and some o-rings.

Just some additional info...taking the carb off was not too hard. I took pictures and made sketches of all the hoses. The intake manifold was a little hard to get off because the bottom bolts are a little behind the thermal reactor. I removed the shield from the reactor and tho9ught I may have to remove the whole thing. But with same fancy wrenches and some patience it came off okay.

Thanks for the advice. I let you know how it all turns out when I get it all back together.

Phil

 

I bought a wobbley socket just for the 2 middle nuts on the SA intake manis. Makes life much easier.

 

Phillip,

Defintely keep me posted. I will begin tearing into it tonight. Also, do you think one of the regualr auto parts stores will have the O-Rings?

Tnx

 

I just ordered the gasket kit from NAPAONLINE.com. Part number BA0374754. From the picture it looks like it comes with o-rings. GREAT! I was going to go to my local hardware store with the intake manifold in hand and try to match it up. Now I'm going to wait and see what arrives in the UPS truck.


Phil

 

I buy o-rings at the autoparts store, they usually have an o-ring kit under the counter. For gaskets, buy a sheet of dark gray gasket paper and make your own.

 

We just did this 2 weeks ago on my 85GSL and here are the higpoints:

-didn't have to remove carb from manifold, but care required.

-Rotated carb/manifold 90deg upward over top of engine for access.

-manifold has 6 fasteners, some require wobble extensions and/or Ujoints

-ORings from mazdatrix were ready, but Tru Value 1 block away has them too

-cleaned metal gasket surfaces nicely.

-had gasket ready from mazdatrix

-used mazdatrix hylomar gasket sealer, blue permatex usually works OK

-cleaned Oring receiving surfaces nicely; no burrs or dirt

-wouldn't start immediately;
-checked carb floats visually:OK. Didn't wanta open them up
-fuel flow OK from pump to carb
-accelerator pump OK: saw gas squirt when ***'t pumped pedal
-started running on one rotor: checked timing OK
-manual choke wouldn't stay out
-carefully examined vacuum hoses and diagrams: hadn't properly marked all
-85 hoses slightly different from 83
-didn't have to replace any hoses, though I had them ready
-clear thin tubes from OMP to carb fractured then replaced.
-Haynes diagrams helped rectify vac hose problems: must be exact, close doesn't count



Some people replace the Orings with freeze plugs that block the holes and prevent future leaks.

Same overheating that burned manifold ORings probably burned 4 Orings under beehive.

I managed to postpone this job for a year with the Temporary Water Seal Leak Fix that Paul Yaw initiated that uses Colloidally suspended copper flakes from the autostore after extensive cooling system cleaning and degreasing.

It's working good, as evidenced by the residual pressure in the system when I loosen the radcap to test it in the morning.

 

bliffle

How did u take the intake manifold off with removing the carb? If I can get away with that, would save much time!

Thanks,
Loco

 

Loco,

I would recommend taking the carb off. Flipping the whole carb/intake assembly up over the engine will likely cause something to break. There are lots of vacuum hoses and if yours is like mine, most of them are brittle and need replacement anyway. You've also got the oil metering lines attached to the carb. These are a clear plastic and are very easy to break especially with age. Once the vacuum lines, oil metering lines, and cables(throttle, choke, hotstart) are removed, the carb comes off easily after removing 4 nuts. The nuts on the left hand side are difficult in that you cannot get a very good turn on the wrench, there is too much stuff in the way, so it takes a lot of patience.

Taking it off completely allowed me to get everthing cleaned up real nice while I wait for my gasket to arrive.

Make real good diagrams of all the hoses, take some pictures if you can, and go for it.

Phil

 

Thanks Phil!

Great advice. I am headed to the garage right now! I found a lot of oil in the rear rotor through the spark plug hole though, the rotor oil seals are porbably gone. We'll see....

 

Bad rotor oil seals are a separate problem, tho the cause may be the same. Some guys have used "Lucas Oil Stabilizer" additive with some success.