dj-fd3s

so i have a 93 rx7 an when its running the cooling system will keep bubbling but it will hold 15psi for as long as i have the tester on?i think its exhaust gas leaking into the coolant system buy why is it that it will hold psi on the leak down test?

gerald m

If it is exhaust leaking into the cooling system and making the bubbles, the exhaust pressures are probably far higher than 15 lbs. and yet the 15 lbs in the cooling system isn't great enough to make the fluid leak past the problem area .. but it will given time ..Cavitational erosion plays a big part in the cooling system problems with the rotary engine. it happens when the coolant is heated rapidly from the heat of the engine and tiny air bubbles form on the cast iron part of the engine right next to the rotor assembly . These millions of bubbles implode against the cast iron and actually blow a microscopic piece of iron away , eventually you have a weak spot where the gasses can leak through .. and water jackets full of black **** that know one seems to know where it came from .. you can buy additives to add to the cooling fluid to stop this process and it works .. most case industrial equipment had this problem so bad about 20 tears ago that the cylinder sleeves in there diesel engines actually use to develop small holes and leak cooling fluid into the cylinders, they developed a additive to stop this from happening ... just my opinion .

RotaryEvolution

iTrader: (30)

most of the time when the coolant seals fail, they blow exhaust into the cooling system and not the other way around.

dj-fd3s

thanks for the info i wans going to buy a new block from rotaryrebuildstore.com for when i do my gt40 upgrade.
one more quick ? i wanna buy a used 13b for now so i can drive it (need some time to save for the gt40 an the new 13b) whats a good place to buy a used jdm 13b i looked at jdmtigerjapanese. com (1300 for it) but i have not got any good feed back from that place.

D Walker

iTrader: (1)

If all you have broken is coolant seals just have the motor fixed. Long run cheaper than swapping in a JDM motor.

I have seen mixed results from tiger japanese with various customers and would not really choose to use them. Very likely to cost you more time, money, and headache than you care to deal with.

RotaryEvolution

iTrader: (30)

if you're set on trying a used motor, go with Japan2la.

Kentetsu

If you are sure that you want to replace the motor, then you might try adding some Alumaseal radiator sealant to the radiator. I did this to my 12a and its held up just fine for over 20,000 miles so far...



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dj-fd3s

i put some of the radiator sealant in did not help at all! ( did it about 2 weeks ago)

dj-fd3s

is it japan2la.com?

RotaryEvolution

iTrader: (30)

that's his forum name on this site, he's an importer.

Kentetsu

What was it that you used (just curious)?

84stock

iTrader: (5)

Boy you're sure tempting me to try the same on my 12a coolant seal leak!

Kentetsu

One of the many threads on Alumaseal: https://www.rx7club.com/1st-generation-specific-1979-1985-18/dual-fuel-filter-mod-528445/

Radial GT

iTrader: (16)

These are the same symptoms that my engine was doing last fall. All my coolant seals where black in combustion area of the cast irons. The engine had about 76K on its last rebuild, the coolant jackets where DONE! I would recommend just tearing it down and take a look, it is more than likely a really good canidate for a rebuild.

Good luck!

dj-fd3s

i got a new engine an trans on the way thanks 2 japan2la!