I am picking up a s5 n/a in a month or so with a blown rear rotor and only 79,000 km. I have seen the damage my engines suffered when a 2 piece seal blows, however I am wondering if the rotor and housing "may" have survived the stock 3 piece seal failure?

 

Maybe, maybe not. It's sort of a crapshoot either way. But generally, any stock apex seal failure means damage to at least the rotor housing unless you are incredibly lucky and it was immediately swept out of the exhaust port. Unfortunately, the stock 3 pieces seals tend to "roll" out of the slot when they go, causing big damage to the housing and the rotor.

 

most likely you will need a rotor and housing with the stock 3 piece seals on an original engine.

 

Start hunting for a S5/S6 housing and a S5 N/A rotor with "c" weight.

 

on a side note, the non turbo cars have little room for the debris to get spit out of the exhaust which is why i said what i said. although it is rather uncommon for non turbo engines to spit a seal, it could just be carbon locked and jammed up the rotors, in which case you may be able to revive the engine with some MMO/ATF and a water treatment.

only way to tell if it did spit a seal is to inspect the seals through the exhaust ports or spark plug holes. it's usually pretty apparent that the motor half is trashed without tearing the engine apart.

 

The current owner had a dealer diagnose it 12 years ago and it lost compression on the back rotor. She still drove it about 40 miles in that state before having it towed to the dealer. She bought the n/a base model new in 1989 and chose it over the TII because the power of the TII seemed like too much for her. I am hoping to get lucky and do a MMO revival and discover a stuck seal getting free do to a driving miss daisy easy driver carboning things up...the car is in amazing condition!!

None the less, I have a spare S5 with good compression in my garage.

 

I am not holding much hope on rotor and housing survival. Worst damage I've seen was when my bridge snapped off and scraped things up real good!

 

Second question then, anyone have the same symptoms and have success with mmo due to simple carbon build up?

 

Just use carb cleaner. MMO is just "wax mud" according to the datasheet. Letting diesel fuel sit in the chamber also works very well.

 

i use MMO all the time on engines that are siezed or have 0 compression due to stuck seals. once running though i use carb cleaner to decarbonize severely carboned up engines as water usually is for light stuff. carb cleaner along with the MMO helps break up carbon in the siezed motor cases.

MMO is a lightweight detergent based lubricant, very similar to hydraulic fluid and transmission fluid which is why i don't suggest using it as a premix. it is a good for decarbonizing parts, which is why so many old school mechanics use ATF to flush piston engine crankcases.

 

It's funny though, how ineffective ATF actually is on carbon. Years ago I tested a bunch of these products on carbon'ed up rotors and ATF was about the worst. WD-40 worked better, as did PB Blaster. The best was carb cleaner and diesel fuel. I didn't test MMO though. It is a bit harder to find in Canada.

Guess I should dig up the pictures and post the comparison to my website.

 

i have never tried ATF inside the chambers but i do know it works inside the engine. did you heat it up or just set the parts in it and let them sit? most detergents only work when agitated and heated.

 

I just let them sit. I figured that's how most people would be doing these "treatments".

The ATF also turned the coolant o-rings and oil o-rings to jelly.

 

Good info in here. Show some pics when you tear down the engine if you can. I am really digging your s5, looks clean.

 

So the car has also been sitting for twelve years?

 

Just broke down 3 engines yesterday: 1S5 and 2S4's.

The best/worst was an S4 Mazda reman where then in the aux acuator sleeve rattled loose and got sucked through the motor. It bent up the intake port as it came through and grinded against the rotor. It might have actually broken in half as the rotor looked like it had been shot multiple times w/ a .22. Sucks cuz it also ruined a sub 20k housing....

 

Yepper

 

that's why i try to avoid the ATF without dulluting it, it just doesn't mix well with most engine seals. i assemble engines with MMO, have let one sit for almost a year before starting and none showed any ill signs of the MMO eating away at the rubber seals.

my REPU sat for almost 25 years, was carbon locked and MMO worked it loose like a charm, had multiple cars given to me also that MMO loosened the stuck seals on. i don't swear by MMO by any means but i have never seen it harm any motors while bringing them back to life when most people would have written them off. carb cleaner and 2 stroke oil would probably work equally as well but i prefer the thinner MMO since it can work into recesses better than 2 stroke oil and lubricate better than carb cleaner can.

 

Sounds like it will be MMO for me...

 

Well, I bought the Amsoil Powerfoam. The car arrives this Saturday so we'll give the Amsoil a test.

Step 1: I am going to spray both rotors down through the spark plug holes and just turn it over by hand.

Step 2: Turn the engine by hand both directions daily over 3-4 days

Step 3: Compression test

Step 4: Assuming lost compression in one of the rotors still, fire the bitch up and warm it up real well.

Step 5: repeat steps 1,2

Step 6: cross fingers, say a prayer, apologize for all my discretions (this could take a while), and do another compression test

Step 7: compression or no compression, fire the bitch up, warm it real well, maybe drive it and see if I get lucky loosening up any seal restricting carbon.

Step 8: If all fails, pull the engine and install my spare.

 

Sounds like a game plan to me.

 

Try this for a carbon remover. Most auto parts stores sell it. Around $12.00
Mazda dealerships use the same product (renamed) for decarboning the Renesis.

 

Just use Zoom Zoom Cleaner to clean it.