So for those of you who don't know, I had a bit of motor trouble this past year. After my first run through The Dragon at DGRR2011, I knew I had a hurt motor, but I didn't know how bad it was until today.

Symptoms: NO power. I ran it above 7k in 2nd just to get up the hill to Nantahala Village, and was running in 3rd gear above 7k during the Friday Morning Fun Run. I did a quick and dirty compression check Thursday night at the cabin, and found the rear rotor was missing an apex seal. Puff-nothing-nothing-puff-nothing-nothing.

I've had some issues getting the flywheels off of the two motors I popped this year, so when I was in the garage today I hit both of them 3 or 4 times, and to my surprise the flywheel came off of the DGRR motor. Three irons, one rotor, and the e-shaft where salvageable. The rear rotor has some gnarly damage to it, including indentations, a mangled apex seal groove, and a piece of an apex seal embedded into the rotor face. The rear housing was gouged to hell, which I was expecting.

What I wasn't expecting was to find mass chrome flaking (110k motor out of an '85) and a BROKEN apex seal on the front rotor. Here are the pictures:

Front rotor broken Apex seal:



Front Rotor Housing:



Center Iron:



Rear Rotor Housing:

 

Where the apex seal was crushed by the exhaust port and rotor:

Rear Rotor Housing:




Rear rotor:

 

Embedded Apex Seal:


Rear Rotor:


Stuck and Broken corner and side seals (rear rotor):



Found this in the front rotor housing:



Rear Rotor Broken Apex Seal:


RTV found in the coolant passage:

 

More rear rotor carnage (pre-removal):



Pre-opening:


Rear Iron:


Rear Rotor pre-removal:

 

I'll update this thread when I get the other flywheel off and disassemble the motor with a spun bearing. Feel free to request more pictures.

-Jim

 

WHAT THE HELL HAPPENED. is it a turbo motor? I have never seen that kind of damage on an NA.

 

Nope. Stock, non-rebuilt 12a. 110k factory build. It was the original motor that was installed in 6/85.

I figured that I had driven all the way down there and the damage was already done, so I drove the car with two broken apex seals for a couple of days. IDK how they broke, but I was impressed with the carnage.

 

to say the least. the only way you can really break apex seals is detonation caused by neglecting changing the spark plugs.

 

Wow thats crazy. Im surprised it still ran at all after that kind of carnage. Thats insane.

 

Mine had similar flaking and apex seal damage, though not days of driving worth. I popped the seal a couple blocks from my place so I drove it home and parked it. That's some impressive damage.

 

Probably what happened to mine. I was having detonation issues on the way down to DGRR09 because I was running the carb too lean trying to save gas. Finally tweaked it after the 800 mile drive and the car was happy, but it blew up that August. Don't recall how fresh the plugs were though.

 

It had fresh plugs before the drive down. I think that it broke when the motor got a bit warm (got to about 60% of max on the temp. gauge) on the way up the Dragon, and the area around the spark plug holes expanded and closed off the tolerances between the apex seal groove and the housing.

It started to get really hard to start on Saturday morning after a full night sitting in ~30* weather. I had a hard time on the way up the mountain on the Cherahala Skyway, but kept up with and left some people behind on the way down. Not bad for a destroyed motor...

It was either that or twiddle my thumbs while I was down there. I choose to play.

Like I said above, fresh plugs before heading south...

 

looks like a normal 110k 12A to me! apex seals break in those, it just seems to happen. also notice the housings are peeling, so even if you tore it down BEFORE DG, the housings were bad...

 

The rear housing would have been OK if I had torn it down pre-DGRR. Not the greatest, but it had minimal flaking.

 

OUCH! Suprised the irons and main bearings look so good considering all the trash spinning thru it. Silicone must be from the water pump or the intake manifold coolant o-rings. Not uncommon to find it.

 

I was shocked to find good irons as well. The rear iron caught my finger nails slightly, but they were clean otherwise.

 

That is pretty bad. Did you happen to log the MPG on it? I had a blown 13b in my 87 parts car car Blown rear with 1 bad seal.Started and idles fine, but SLOW acceleration (topped out at 55MPH) and I went through 2 gallons of gas in 8 miles, lol. Surprised you were able to drive it very far.

 

I keep meticulous logs of fuel economy.

4/27/2011: 10.508mpg
4/28/2011: 13.834mpg
4/28/2011: 13.378
4/28/2011: 15.929
4/28/2011: 17.038
4/28/2011: 14.023
4/29/2011: 10.914
4/29/2011: 10.355

It had a lumpy idle, started hard, and to get through the mountains I was spinning 7k+ the entire time. Probably the cause of the stuck side and corner seal. I could get up to 65 or 70mph, but it took FOREVER and I had to spin the hell out of the motor and keep it a gear or two lower than I normally would.

 

I think mine was doing 7k in 3rd to hit 55MPH. I wonder if one were to unplug the blown rotor's injectors if it would run as a "proper" 1 rotor in a pinch. The blown seal in my rear rotor probably acted like a vacuum leak ad the computer tried to spray WOT fuel to the rear?

 

Nikki....no EFI....