Well... I can only say that it was very strange to see it happen in one weekend, could be batch related or something else. Before that weekend I have not seen any issues.

I run Runnertime or sometimes an own mix with my engines

Here is a pic of my OS zac project...super clean
I know the previous owner used maxima fuel on both engines yet the IDM was dirty - I can't work it out

Marko, a lot of us ran Maxima at the worlds and it was fine, I liked it.

Depending on the weather, humid days can cause poor combustion, our engines are much cleaner running in Victoria than Brisbane.

Nitro engines need cleaning, the residual castor can look like rust, but more often the fact we pack O2 in the fuel makes it oxidising. Keep them well maintained (as you are) they dont have to be polish clean, but they do need the castor buildup removed regularly and stored free of methanol.

Your goal is to keep the bearings clean and prevent failure. Once a bearing goes, then everything starts going downhill.

thanks for the feedback mate - much appreciated.
do you run afterrun fuel or afterrun oil?

I do what you did with a little less attention to detail after each meeting. It means there's less build up over time and it takes me less time if I do it frequently. I personally don't like flooding my engine with oil, if I have to I will but it's not my preferred method.

You can burn off the methanol and nitro to prevent oxidation then what your left with is an oily residue and that's what I want to reset each time we run the engine, the residue is essential, yes.

So u use afterrun fuel?

No, I take my engines home and clean them.

Understood. Pulling them apart after a meeting isn't a big task anyway...makes sense

which not many cbfd to do.. expect those of us that are more.. meticulous .. satisfaction of knowing that you have done well to keep an engine clean and well managed..

Stripping down an engine and cleaning out all the residual oil with brake cleaner after every meeting isn't good for the life span of an engine, unless you're prepared to run the engine rich for a tank before each race to oil it up properly again.

I check for play on the bearings and replace as required, change rod at frequent intervals, this is all the maintenance you need.

If your fuel is rotting the bearings then you're running poor fuel, switch to Meccamo or Runner Time, yes it's expensive but your engines will last much longer.

id agree not to use brake cleaner and never have.. stick with something as good as a tiny amount of afterrun fuel to line the engine with oil and burning the excess nitro left after a days racing.. and your safe to leave it stantding for a week or 2....