Why old engine blew because...
 

Atkins Rotary just got my old engine and gave the reason why it blew. Carbon Lock. They said the reasons for that are using a poor quality gas, pussy footing the car, oil that wasnt best (I used Castrol GTX), or running rich.

It was a stock '91 TII with a Apex N1 dual exhaust. I auto-xed three seasons on it, liked to see the turbo glow, and changed the oil every 2500 miles. The engine blew at 4000rpm, 80mph, 4th gear, and 8psi of boost on a cold january day.

Not sure where I went wrong with it. I am leaning towards the Castrol not being the best choice and/or it running rich.

Plans for my new engine -
-Run Amsoil sythetic
-Pick a brand of gas
-Tune the fuel with the S-AFC
-Run it harder

The engine builder said he had good sucess from simply changing the oil every six months. I am going to try it. If he recomends it for his engine. What the heck.


Anybody else have any opinions on this?

James

That sounds kind of dumb.
They should have said 'blown a seal', etc.
Mind asking?

I've never heard of carbon lock blowing up engine. Maybe you should get a second opinion. If it's a carbon built up, you may want to try the ATF treatment to loosen up the carbon.

If your engine was running rich, your plugs would have been really soiled w/ carbon and black gunk. I don't think the oil/gas/babying the car caused anything bad. It's not like you let the engine run for 7-10k miles w/o an oil change.

Does it have lots of miles? I am very suspecious, especially if he tells you to change the oil less often, WTF!!

Carbon lock..?? Something HAS to fail, what failed in the motor..??? Ask them and then let me know. It either leaned out, seal finally gave out from wear/use or spmething else..Let me know...

I've never heard of carbon lock blowing up an engine, but regardless, running a synthetic isn't the best way to avoid carbon deposits. Synthetic oils actually burn LESS efficiently than fossil oils.

Man, thats pretty messed up, you sound like you took good care of the car, and the verdict doesn't make much sense based on the way you treated it. Whatever you do, don't run Amsoil, thats the ONE synthetic that caused Mazda to not recommend synthetics because it doesn't burn well. They've probably reformulated it by now, but with so many good synthetics, why risk it?

I have used Castrol GTX (non synthetic) in every car I have ever owned, including 2 different FCs (that I personally put over 130k each on) and an FD and never ever had any problems with oil break down or related to oil breakdown. I typically don't change the oil 'til 3k to 5k miles. I am very very skeptical that using castrol would cause any problems.

The term Carbon Lock is used by some rotary mechanics to mean, a hunk of carbon, pealed off the rotor and jammed or cracked/broke a apex seal. Cheap gas or funky additives to either the gas or motor oil often will cause carbon build up, but some build up is normal for any motor with 60k+ to have some. Besides what he told you, driving cold (not waiting before engine temp is up before driving hard), can also cause it. I think he gave you a generic list of what could have caused the issue, that doesn't mean it was caused by everyone of those things.

On rotaries, the ATF treatment will often help carbon build up.

You never want to use a synthetic oil in an rotary for a motor oil, as that will increase the carbon build up on the rotors as well as coat your exhaust and turbo's turbine. It does not burn off as conventional oils do.

Castrol GTX is what I've always used, and I plan on keeping it that way.

i'm currently rebuilding an import engine which had a blown rear seal(s). i can tell that the engine was running caltex gtx as it leaves a honey coloured coating on everything. it looks as though a build up of carbon blew this engine. however i doubt it was the oil. rotary engines should be redlined often (atleast every second time u take it out), and if u don't it will build up and then break off when u do tharsh it.
but u sounded as if u treated it right, so if it wants it that way always thrash it :)

How much?
 

wankel7, how much is Atkins charging for the rebuild?

have you guys considered doing the oil metering pump mod, so that you can use 2 Cycle engine oil to lubricate your seals which burns a lot better and won't leave so much carbon deposited. That way you can use Synthetic as your main engine oil, and use 2cycle as your apex seal lube oil.

austin-7
 

Instead of 2 Cycle, use MMO if you can find it (Marvel Mystery Oil).

Were you refering to removing the OMP system and adding oil to your gas, or adding a seperate oil injection tank?

-Spencer

I was referring to adding an oil injection tank, I think it would be painful to have to measure and add oil to your tank every time you gas up. I found this link on another thread on the forum, here it is: http://ahura.iwarp.com/2strokepump.htm

Why Marvel Mystery Oil? I've seen it in the auto parts stores, but what is it?

Marvel Mystery Oil is the bomb. It's sold in autoparts stores. It is a additive that you can put in your engine when changing oil or you can put it in your gas tank. It will clean dirty carbs, fuel injectors, etc. I swear by the stuff. Works like a charm

Darril

MMO was original designed to be a Supercharger lubricant, but was discovered to have several properties that made it unique and ideal for rotaries. It mixes easily with gas, is a AMAZING lubricant, and leaves no deposits when burned.

Adding oil to your gas isn't too hard. I use it in addition to the oil injection system. I also add a quart to the engine when I change my oil.

I'm currently working on an oil injection tank mod, and I'll be using MMO in it too.

If you want more info on MMO, PM Denny.

What is the ATF Treatment?