KansasCityREPU

iTrader: (9)

I had a rebuilt engine I bought 8 years ago sitting around just recently started it up. There was an issue with water getting into the combustion cambers. The symptoms where that the exhaust was like steam and the water level in the radiator would go down 1 pint to a quart after running for just a few minutes. The overflow bottle had a lot a back pressure also. We looked at what might cause this. I replaced the intake o-rings with freeze plugs and the problem was still there.

At this point I decided another rebuild was in order. So Trochoid, Scott, was kind enough to rebuild the engine at my place (I have a 40x60 insulated all steal barn just for my hobby) about 3 months ago. I just recently got the engine installed and everything back together. We started it up last week and we have the same issue. We are making tons of steam out the exhaust ad the water level in the radiator is going down.

Is there something I'm over looking to get this fixed? At this point I don't want to rebuild the engine myself. If it does require another rebuild, I'll take it to Jesse Prather at Prather Racing in Wakarusa Kansas. They are only 2 hours away. I'm just at a lose at what the issue is. I've been building this car for 10 years and I'm getting tired of it not running.

Jeff20B

iTrader: (13)

If you tear it down again, check for a tiny hole near the spark plug area. I once had a set of near perfect chrome housings that had a pinhole leak from the threaded part of the spark plug all the way into the water jacket. When I look under and around the spark plug casting I found a cavity caused by the PO using straight water. Both housings had this pinhole leak.

Maybe you can try pressurizing the cooling system with compressed air and check if any air is escaping from the spark plug holes. Just remember most compressors are set to 90psi. Your cooling system shouldn't ever see more than maybe 15psi, so set the pressure accordingly.

Of course if you have a problem leak elsewhere in the water jacket, it'll show up this way too as air escaping. Look specifically for tiny bubbles coming up through the threads.

KansasCityREPU

iTrader: (9)

That's a good suggestion pressurizing the cooling system. I did by the Pineapple pressure tester that attaches where the water pump housing goes. I should have used it before I put the engine back in the car. Oh well, to late now. I guess the next step is to remove the water pump housing and use the pressure tester. They say the system should take about 26 pounds I believe. At least this will tell me if there is a bad seal or a pin hole like you describe. I have a funny feeling a rebuild is in line.

RotaryEvolution

iTrader: (30)

+1

but a basic test i do to start with while the engine is torn down is put duct tape across the rotor housing coolant passages at the spark plug coolant passages and the exhaust port passage. fill the passages with water and let it sit for about 5 minutes and then see if there is water leaking into the plug holes or exhaust port.

KansasCityREPU

iTrader: (9)

I did another test today. Filled the radiator with anti-freeze and started the car for about a minute. We had anti-freeze pouring out the exhaust like crazy. We pulled the intake manifold and everything looked good as far as the gasket and o-rings. There must be a massive hole some where internally to consume that much coolant. The overflow bottle was also pressurized to the point that it was shooting a stream of water out the small pinhole in the top more then 10 feet. This means that the combustion camber is pressurize the entire cooling system. We cranked the engine over when the intake was off and a small amount of water was coming out the intake runners in the irons and the exhaust port in the center iron that goes to the intake manifold. Another rebuild is in order. Once I find the culprit I post the results.

Kentetsu

Well, as beautiful as that motor is, I doubt you'd be interested in just dumping in some Alumaseal and curing the issue.

Better to rebuild it and make it perfect.

Good luck!





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KansasCityREPU

iTrader: (9)

Is there anything internally to the intake manifold that can cause water to get into the combustion chamber othet then the manifold o-rings? I've never seen an engine do this before. The amount to pressure the engine was putting into the cooling system was tramendous.

I keep going over in my mind what could cuase this must pressure. I seems like there would have to be a pretty big hole some where to cause this. Keep in mind this was a fresh rebuild that Trochoid and I both worked on and nothing seemed out of place.

To give some more background, I did take off the ACV and powdercoat the intake manifold and put it back on. Could this have caused ther problem?

Kentetsu

Considering the pressure that the engine sees during combustion, I don't think a hole would have to be very large in order to "inflate" the cooling system. A hairline crack maybe?

At least the fact that you have combustion gases entering the cooling system should aid in locating the leak...

Jeff20B

iTrader: (13)

Dude, stop looking at your intake manifold for your water leak. I know solving it at the manifold would make your day but it's gotta be internal at the rotor housing or side plate.

I'd bet 1 forum buck that one of your housings has a hidden hole in the aluminum somewhere. Time to get a high powered light and some time and just tear that sucker down.

Hmm, how long did it take you to assemble the engine last time? Did one of the coolant seals get pinched? They grow after you slather them up with petroleum jelly so I stopped doing that after I crushed one once.

diabolical1

iTrader: (3)

agreed. it sucks, but pull it back apart and track down where the leak is. hopefully it will be as simple as a pinched water jacket seal, but you have to come to grips with the possibility that one or more of the housings could be structurally compromised in some way.

KansasCityREPU

iTrader: (9)

I guess it was wishful thinking. I know in the end it has to be internal. Since I have the external bits about halfway off, I'll just get the engine pulled out and start tearing it apart.

It only took about four hours to assemble the engine once I had everything clean and shiny. I guess in the long run I'm paying for my education.

If it does come down to it, I do have 2 brand new (NOS) 12A rotar housings and about 1/2 dozen rebuild kits. I also have about 10 early used ones that look like new.

bumpstart

the other spot to check is corrosion pin hole around the exhaust port casting

KansasCityREPU

iTrader: (9)

Well, I have a small update. We pulled the motor and it has been sitting a Jesse Prather Motorsports for about a week. I decided to let a pro rebuild it. Jesse's shop was awesome. I'm in no hurry, Grad school taking up to much of my time. He's going to tear it down and inspect it to see what parts we need and why it failed.

KansasCityREPU

iTrader: (9)

Update: Jesse Prather took th engine apart. He found a bunch of grit (black beauty coal slag) from when I blasted the housing and irons. The grit destroyed the brand new rotor bearings and grooved the e-shaft and almost fused the rotors to the shaft. Needless to say, I need new rotor bearings and another e-shaft. This was bad but not the cause of the cooling system getting pressurized and water pouring out the exhaust. He found that the front iron was badly pitted. had noticed this during assembly but thought it would be ok. I was wrong. I'm heading over to Jesse's shop next weekend and I'll take some pictures.

So, the plan now is to use my brand new NOS 12A rotor housings and a set of irons that have been blancard. As luck would have it, I already have a set of irons that Jesse had ground down for me several years ago and not used. I still might powder coat the new irons after they are sonic cleaned. The housings will not get any coating or paint at the recommendation of Jesse.

Lessons learned: NEVER blast engine parts that come in contact with oil. I was warned but thought I could get them clean. Don't believe it, no matter how hard you try, it's not worth the risk.

KansasCityREPU

iTrader: (9)

Since I need another e-shaft, do I need an e-shaft for the year of the rotors I'm using? If so, how do I indentify the year of the e-shaft? The engine currently has rotors and flywheel from a 1981-1982. I have many e-shafts from 1984-1985 12A and the early pre 1979 but not one from a 1981-1982. I like the idea of the 1981-1982 because of the lighter flywheel. I'm not opposed to switching to 1984-1985 rotors and flywheel.

Jeff20B

iTrader: (13)

Shaft doesn't matter. Just don't use a 71-73 shaft even though it may be tempting as those shafts have lightening holes like all 13B shafts. They are the only 12A shafts with lightening holes. Mazda made the original shafts for the 10A that were solid. Then to stretch the assembly for the 12A, they had to lighten the shaft so it would still weigh the same, so their dynamic balancing machine set up for 10As could be used on twin dizzy 12As as well.

Then for the 74 and later engines, Mazda went back to a solid shaft, this time for the 12A and then lightened the 13B shaft so again the same balancing machines could be used.

So don't look for a 71-73 shaft because chances are your counterweight+shaft won't quite match your rotating assembly anymore as they will be lighter together than Mazda intended and you'll need to get them dynamically balanced.

So to answer your question, go ahead and use an 83-85 shaft with your 81-82 rotors. I personally prefer the 83-85 rotors because they are lighter, but you gotta use a heavier flywheel with them. Or you could use a rear counterweight (good luck finding one for an 83-85) and an aftermarket light flywheel of your choice. Or let whatever clutch kit you already have be your guide. If 215mm use an 81-82 assembly or 225mm use an 83-85 assembly. You can also throw on a 225mm disc and pressure plate on an 81-82 flywheel (I've done it, it fits) if you get a bolt set with spacers from Racing Beat or Mazdatrix.

Oh and a word of caution about pitting of side plates. Don't go overboard attempting to clean out the weakened metal from where the coolant seals sit. It's better to just scrape off the old dead coolant seal residue until the surface is flush. That's it. This applies to plates that are in good shape obviously. Like I said don't go overboard. Scrape it off and the underlying metal will support the seals for years and year (never had a failed coolant seal yet). Also don't ever blanchard grind or lap side plates. This is a relic of the 70s when side plates were a hard iron and weren't nitrided. On modern soft iron plates it just causes accelerated wear of oil seals and a premature smoking engine in 20 to 40k miles. It also kills side seals and corner seals quickly. Hopefully your engine will live a long healthy life.