Coolant leak from motor block after overheat
 

I had an overheat problem on the highway, and I think it may have been pretty severe. There is brown color on the surface of the motor which looks like the casing got very hot. It was low on oil too so I think a lot of the oil was burned when it overheated. I check the oil every fuel stop so I'm pretty confident the oil level was good when I was driving it. The coolant level sensor popped out and steam came pouring out, which was when I noticed it was overheating and I shut the motor off immediately. Unfortunately I think the damage may have already been done...

I had the radiator repaired because it did have some minor clogging and a few leaks at the top. I replaced the thermostat and coolant level sensor. Refilled the radiator and without even trying to start the motor it was already leaking coolant from the block.

Here is a video of where the leaks are at.

http://www.youtube.com/watch?v=L-DXE97AhTs


So i'm hoping some of you experienced players who have rebuilt motors has a good idea of whats wrong here. Think i'm screwed here? I'm assuming already the motor will need taken apart so it might as well get a full rebuild. I don't really have the time or money to do it so i'm probably going to have to sell the car. But getting a good idea of what is needed would be helpful.

Any feedback would be appreciated...

Yep she's toast, if your lucky you just blew out some coolant seals, if you're not lucky you may have some warpage concerns....

If you're lucky, you only toasted the water jacket seals. That leaves rebuildable parts.

If youre unlucky, you warped or collapsed your rotor housings.

Considering you're looking at a rebuild in either of those scenarios, you might consider asking Kentetsu to recommend some stop-leak that he had fair success with, but that's a pretty heavy leak rate you're showing.

Keep a very close eye on your oil, though... that area of the housings is very close to where oil passages to the pan are. If you're leaking water into the oil, your only hope is an immediate rebuild, or you'll wreck every rotating part you have.

You don't want to overheat rotaries.

if it got too hot, too fast, you may have warped the housing.

It's probably warped :( It was about 95 F outside that day, I was on the highway doing about 80mph... so yeah... It was very sudden, there were no warning signs.

Now I gotta decide if I should sell the whole car or attempt a rebuild. I don't have much mechanical knowledge, time, or money... Most technical task i've accomplished was replacing the clutch and PP in the RX. I could probably do this, but i'm not sure if I want to because i'm afraid it will sit for way to long and never get finished.

Wow, I eat jobs like this for breakfast. I'd jump at the chance to do a quickie tear down and see what's usable. Then turn around and have it back together in a week. Wouldn't be the first time.

These 1st gens are easy to work on. Try this on any newer car and tell me you don't hate your life.

Main issue ur gonna have when u tear it down is NLA parts being warped (ie rotor housings) ur lookin at a extra 400$ for a good set from a user on the forums. ive never rebuilt a rotary but ive ripped plenty of em apart and they dont seem like they would be too hard to rebuild with a little bit of patience and a dvd tellin ya whats up. If i were u ide pull the block and tear into it to see if ur motor is warped.. worse comes to worse u sell the car as a roller.. ur gonna get the same amount of $ with a roller or one that the motor is completely toast.. ur just savin the next guy the motor pull lol.

just my .02$

Depending on where you live and what smog regs you live under, if a teardown reveals the housings to be unuseable, you could likely swap in a use 13B fairly economically. Depending on which parts are salvageble, selling them off may get you part-way there.

Rotaries are not hard to build compared to other engines. You need to pay attention to details like keeping track of which rotor seals came out of which specific slots on which rotor, but for the most part they are pretty straight-ahead work.

Did my first re-build in the garage of the guy I was renting a room from, and the only reason it took a month was me scrounging for parts money. Actual work time was a couple weekends and 5 or 6 evenings, and she lighted on the first crank.

My friend and I have a joke about our RXs that is "Instead of putting a coolant overheating light, Mazda should have just put a 'Replace Engine' light."

Based on the video, I say it's warped. Looks like water is comming from both sides.

v8 swap

you didn't

Heck, that leak ain't nothin! Grab a bottle of Alumaseal (Brand name, don't try anything else) and dump it in the radiator, then let it idle for a bit and see what happens. A leak like that should take about 20 minutes or so.

Worse case scenario, it doesn't work and you need to replace or rebuild your motor. Mine was blowing coolant out the exhaust faster than I could pour it into the radiator. That was over 30,000 miles ago. :)




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