Unforseen Damage: Wrath of the Thrust Bearing
 

Months upon months after the rebuild, I've finaly decided to clean things up. I found most of the components that were badly damaged by the fall of the thrust bearing sometime a few years ago. Since that day, I remember the main pully, always having a "wobble" look to it as the engine idled.

I installed the thermal pellet several years ago. The car ran fine, but I remember there being a leak at the seal that prompted me to reseat the thermal pellet, the second time forgetting the proper procedure to insure the trust bearing doesn't fall. The engine was already on its last leg, burning plenty of fluids. But that day, the thrust bearing did fall, and begin to cause damage, and plenty of it.

The car started to eat alternator belts like nothing, several every year was not uncommon. The waterpump went out twice, but who knows if that is related.

I worked with project84 who has rebuilt several rotaries. This was his first S5 block. Things didn't add up well on the breakdown though. The dificulty in breakdown was far more than it should have been. Especially regarding the eshaft and the bearings/gears associated with it. Anythign that should have "slid" off the eshaft required a swift smacks from a rubber mallet. The front weight required even more force however-- solid mallet.

That event some time ago that dropped the thrust bearing had caused the bearing to eat into the raise, somehow attempting to eat its way into the block.
The damage did not stop at the bearings however, the end of the eshaft became bulged, the rotor bearings were severely warn, the two front bearings were toast, and both counterweights were warped.

I don't know what the estimated cost of the damage is, I threw away most of the reciepts. But I needed two new rotor bearings, (plus the metal shop to remove/install), new front weight, used (replaced) rear weight, new bearings/raises for the front assembly.

Coincidentaly, the most irritating thing to stop a rebuild only minutes from completion is the front eshaft key, which had to be pounded out. The local mazda dealer was nice enough for free overnight shipping of a $2.00 part however.

All said, a costly mistake. The one thing that we were able to salvage was the eshaft. Some emery paper was able to take the slight bulge off of the lip.

Just a forwarning for you all when you work with the front pulley. Don't make the same mistake I did, its costly, and will force you into a rebuild that much sooner.

https://www.rx7club.com/attachment.p...d=215232&stc=1
https://www.rx7club.com/attachment.p...d=215233&stc=1
https://www.rx7club.com/attachment.p...d=215234&stc=1


https://www.rx7club.com/attachment.p...d=215235&stc=1


Edits for the noobs: The rotor bearings (big round things) are a slight discolored on the outside due to oxidation from being in the garage the last half year. The inside of the rotor bearings however should appear to be a silver/nickel color. They should *NOT* be copper colored. The remainder of the pictures shold be self explanatory.

one word...

ouch....

actually it looks like you got off easy, the damage could have been MUCH more severe.

picture this:

bearing material makes it way to rotor bearings and begins to tear them up, added material in the oil as well and bearing chunks floating around make way to the oil pump and severely wear it out losing most oil pressure and pumping even more metal through the engine. this process can go on until you lose basically all oil pressure, cook the bearings until almost siezing, lack of lubrication to the oil seals can score the iron housings until they are virtually garbage, spun rotor bearings, scored e-shaft spun stat gear bearings... you get the picture and it only takes a matter of a few minutes do.

granted this amount of damage is a bit over the top, i have seen it in engines that were run dry of oil but i can see the oil pump failing if enough debris is pulled in.

we've all seen the pics of tossed apex seals and rotor housings, that is nothing compared to lubrication system failures.. i have torn down motors where virtually nothing was salvageable.

I do agree without a doubt. The car ran "fine" while the damage was continuely occouring. I never thought a small mistake could lead to such damage.

Image what this would look like after another year, or two of not being replaced. The bearings would probably have warn to the point that the e-shaft would have such great wobble that the rotor bearings would accelerate wearing. Augh, indeed, the damage could have been far worse if the coolant passages hadn't broken away:

So, for the noobs out there, what would be your advice as to how to keep the thrust bearing from falling while working on the front pulley?

Kenteth, do you think you can repair that iron?

you got lucky...

push the clutch in, keep it pushed down the entire time.

before removing the e-shaft pulley make sure to push/tap it back removing any back-and-forth play, basically push the e-shaft into the motor, then work on it and dont tug the e-shaft forward.

thats how i did it when i had to re-seal the front cover on my 88 n/a's fresh reman.

kevin.

I used a 3foot 2"4. I pushed the clutch in with it and then held it in place with the seat.

Haha, little JB weld, maybe some weld flak. $15 + ship and shes yours.

Bump incase there are newbs out there in the last few years

Thrust bearing failures rarely end well.

http://www.aaroncake.net/rx-7/damage.htm

Here's a misaligned pulley, the first hint at something wrong.

http://www.aaroncake.net/rx-7/damage1.jpg

There is more metal in this oil pan than one would want to see.

http://www.aaroncake.net/rx-7/damage2.jpg

The friction of grinding metal ruined the entire front stack.

http://www.aaroncake.net/rx-7/damage3.jpg

What is left of the inner thrust bearing.

http://www.aaroncake.net/rx-7/damage4.jpg

It took quite a bit of effort to remove the stationary gears.

http://www.aaroncake.net/rx-7/damage6.jpg

The bearings had to be torched off of the e-shaft. Every bit of the rotating assembly was trash.

http://www.aaroncake.net/rx-7/damage9.jpg

So I made a lamp out of the eccentric shaft and stationary gears.

http://www.aaroncake.net/projects/eshaftlamp1.jpg

Hey Aaron-

Thanks for helping us see the light.

-Jack

Bringing this back to life.....and it's been close to 15 years since I rebuilt a 13B.

Just a quick back story so you know where we are with it, my son needed a new engine or a rebuild on his TII. We came across a supposed half bridge with receipts on fresh internals, pictures of good porting, etc... and for the price, he decided to risk it. The starter we took was an older spare TII and when we connected it, the starter would barely turn over. The assembly moved as it should by putting a 19mm on the front and turning with a ratchet. We had a rotary engine compression tester with us but the starter wouldn't spin the engine. In short, the starter was no good. My son decided to take the risk since there was documentation and turning by hand sounded solid pulses coming from each face. Got it home, hooked up a good/new starter and began getting inconsistent compression results. There would be consistent two solid reading on each rotor with a significant drop on a single face. It even seemed that it would not even be the same face while trying multiple times, plus readings over 150 psi sometimes down to 60s on a single face. Apex seals are visible through the exhaust ports and all are visibly good and have spring back. Internals look new, rotors look great, everything you can see prior to opening the keg visibly look great. It puzzled me, to say the least. We decided to take a chance and drop it in the car. We needed to swap our pulleys over to the Gilmer drive we use and, upon doing so, the front pulley needed to be removed. It wouldn't easily come off by hand, so I put a pry bar behind it to add a little pressure, and that's when I found it. Seller got me, or so I thought. I forgot to check the front to back movement before purchase, so it's on me since I didn't check it. The assembly moved right at 3mm when very little pressure was applied to get the pulley off. Dang it! Speed it up, took the cover to discover the needle/thrust bearing behind the bearing housing plate was disintegrated and no spacer at all.

The story we were told was the seller built this engine, installed it, cranked it to dial in the timing, brought it up to temp, revved it a few times, but it was ran for a total of less than an hour. What I see through the exhaust ports support this. Before finalizing the build of the Datsun truck the seller installed this engine in, someone made him an offer to trade vehicles. He kept the engine and accepted the turbo Honda (sad) for the trade. He kept this engine for a few months and decided he wasn't going to do anything with it and put it up for sale. That's where we come in and now own it.

I say alllllll that to ask if I am thinking correctly that the amount of "slop" in the assembly could result in erratic compression loss like we've seen with the rotary compression tester? Everything spins like it should by hand. We really don't want to open the keg if we don't have to. What are the thoughts of you folks that do this more often than I?

I've been owning and working on these things since 1986. I've owned many rotaries and built a few engines myself, albeit it has been many years that I mentioned already.

Help an old rotary dude and his son out.