I finally got the motor in my '85 GS running, in the most basic sense of the word. This is not the original motor, although it is also from an '85 GS. The motor had over 120K miles on it when I got it, although I don't know the exact figure (dash was gone when I pulled the motor). I was merely promised it ran when the car was parted out (matter of weeks, not months/years). There was no stipulation on how well it would run, as it was only $150.

Here's my list of problems:

1. Surging Idle- Usually symptomatic of a vacuum leak, although I can't find one. Often caused by something else, though. Tach doesn't work either, although I just replaced the trailing coil.

2. Won't run without choke- It will idle for as long as I ask of it, but the moment I open the choke, it dies.

3. Water in the exhaust. LOTS of it.- Clouds of dark steam are coming out the exhaust filling up the garage, and puddles of black water are forming under an exhaust leak under the car. I tried Kentetsu's recommended fix of Alumaseal (thread here: https://www.rx7club.com/1st-gen-archive-71/engine-coolant-seal-repair-maybe-750774/) and that doesn't seem to be doing a lick of good.

1 and 2 could most likely be solved with a carburetor rebuild, but 3 worries me greatly. I'm afraid this motor is a paperweight. Is there anything I'm not seeing here, or not trying?

 

first thing first: compression check when the engine is hot. this will save you lots of headache.

 

I only have access to a piston compression gauge, as I understand those are more or less worthless. Would it be worth it anyways, in this case?

 

you can still use it and it will give you a ball park if you do it with a hot motor...do a search on compression test.

 

Alright, I'll go get one from the shop tomorrow morning, I don't have one at the house.

So you think there may still be hope for the engine, even with the epic coolant leak?

 

Have you taken the intake manifold off to see if the intake water seals are good? It's pretty easy to take the carb/intake manifold/ratnets off as one unit.

 

if you tried kentetsus seal trick and it made no difference then buy a intake gasket set it comes with 2 rubber o rings its worth a small price to pay if that is the issue.

If you do the new o-rings and its still sucking coolant then your seals are bad but the good news is only a strong motor will run with that much coolant in it.
so you may have a good block to rebuild.

Do the steps
1. intake gasket and o rings
a. if it fixes the leak then rebuild the carb
b. if not take the block apart and rebuild.

 

I just pulled the intake manifold, and put in 20mm freeze plugs, new gasket, and Hylomar'd both sides.

Didn't fix it, guess it needs to be rebuilt.

This may be the last straw, this will be the second season I have to sit out 'cause I don't have a running car.