Scary carbon build up
 

I have never seen so much carbon build up in any engine i've ever pulled apart. It was almost 1mm thick in some spots, if not a little more.
Any idea what could cause this much build up?
Its a Turbo II engine w/ 80k on it. Running Pennzoil premix (synthetic marine stuff).
Sorry for the crappy pics.
https://www.rx7club.com/attachment.p...1&d=1196320142

https://www.rx7club.com/attachment.p...1&d=1196320142

https://www.rx7club.com/attachment.p...1&d=1196320142

Ok so this is just one side, but others were worse. Now that I look at them it doesn't look as bad as it did in person.

here ya go
not enough seafoam :D

http://farm3.static.flickr.com/2138/...87c09f.jpg?v=0

:shocking:

not enough redlining?

Blame the stock oil injection...

Is yours still intact?
Was the engine exlusive premix since day 1?


-Ted

No stock oil injection is gone as I wanted to run synthetic oil since I bought it (6 months ago) and didn't want to hassle with the syn can/cant be injected and burned debate.

Switched to premix about 3 years ago.

PS I realize the timeline doesn't make sense, but I've been involved with this car for the last 5 years I'd say.

An how many miles were put on it while premixing?

Was the car redlined often as Roen has asked?

Redlining.....THE best way to clean our engines....

Maybe the oil control rings were marginal and were letting the synthetic oil into the combustion chamber.

I generally do a lot of high way driving around 3700 RPM just under the staging point.
Its an S4 TII and I rap out the tach to redline frequently and would do a couple gear pulls for the hell of it, but it only stayed at redline as long as it took me to get there and shift :dunno:

Marginal as in how? The outer rings have a bit of carbon build up, but virtually none in the inner.

The carbon was there prior to you owning the car and converting to pure premix.
Carbon can cake on like that in as little as 10k to 15k miles.


-Ted

It looks like burned ATF.

Interesting. I didn't know it could cake on that fast. Thanks for the info guys

do the gallon of water trick. That will "steam clean" our enigne.


http://rotaryresurrection.com/2ndgen...injection.html

Lol, I'm doing the "wire wheel and scraper" trick while i'm rebuilding the engine. But I just may have to start doing the h2o trick again. Maybe @ 5k miles or so just to keep her clean.

Marginally shot. Hardened control ring insert o-rings not sealing properly, weakened springs, well worn side plates.

The rings ideally wouldn't have any carbon because combustion does not occur there. What I am suggesting is that there was a small amount of oil being consumed over a long period of time from leaking past the rings... which you might have chalked up as regular OMP injection loss, or whatever.

Oddly enough I was actually gaining MORE oil in my oil pan every oil change...I don't know why?
Gas in the oil? hmm....maybe you're on to something.

*goes to highway and redlines car*

gas leaking into the oil also means oil can leak into the combustion chamber (OMP or not). So I see 3 possible causes:

1. Cheap synthetic oil leaving deposits.
2. Cheap gas leaving deposits.
3. Not enough redlining.

If you were getting gas in the oil you would have been able to smell it during an oil change, I'd think.

Scary carbon buildup? WTF? That is completely normal. After just a few hours of runtime, a light film of carbon builds up on the rotor faces. After a couple thousand miles of normal driving you will have about that same amount. I see engines with TONS more carbon than that. This is MILD carbon, and nothing at all to worry about.

I bet the inside of your exhaust has more carbon than that, lol.

REAL carbon buildup son, let me show you it:

http://www.rotaryresurrection.com/2n...e/image017.jpg

http://www.rotaryresurrection.com/2n...e/image019.jpg

http://www.rotaryresurrection.com/2n...e/image021.jpg

http://www.rotaryresurrection.com/2n...e/image023.jpg

http://www.rotaryresurrection.com/2n...e/image025.jpg

http://www.rotaryresurrection.com/2n...e/image027.jpg

http://www.rotaryresurrection.com/2n...e/image029.jpg

carbon build up? ha this is carbon build up

kevin i think you might remember this lol
Btw rebuild is running amazing and almost done with break in. thanks again.

http://i99.photobucket.com/albums/l2...s/engine12.jpg

Well I use Royal Purple for oil. Sunco or Mobil 93 octane and decent red lining

Kevin, like I said, from what I've seen (5 motors pulled apart) this is the worst I've seen and by far the lowest mileage. The others were over 110K this ways 80K. Call me an amateur, but this is my experience.

PS that is some damned carbon covered motor you've got there.

Sorry for misspelling i'm fairly drunk rightnow

That's one way to increase compression..........