ET: Engine (Twin) Maximum temperature for baking castings

[Cyborg]

Maybe a dumb question or discussed elsewhere, but….

What would be the highest temperature that would still be safe for baking things like cylinder heads? Object being to force out and or burn off oil. This was in the oven for about 90 minutes at 300-325 F. It was cleaned several times before baking.

 

[oexing]

200 degrees C is a typical temperature for fitting valve seats, so 250 should be allright for a few hours, not less, as you want oil to turn to smoke. This can be done to oiled brake linings, keep them at 250 degrees for some hours and they are fit for purpose again. No solvent will do this as it will not clean all pores.

Vic

 

[Cyborg]

Hmmm. More smoke and stink from the garage….The bride will love that. I may get banned from the kitchen.

 

[bmetcalf]

Would time in a vacuum chamber be useful?

 

[Vincent Brake]

And in a solvent filled vacuumised can??

 

[Vincent Brake]

But i think he is asking about the precipation hardening of alu castings, i think google is ur friend here

 

[Cyborg]

Would time in a vacuum chamber be useful?

A vacuum chamber is on the short list. I’ve been looking around for a pump that is decent quality. Not interested in buying anything from China anyway until they modify their position on the invasion. There have been several times when I could have used a pump.

I did wonder about this https://goodson.com/products/cps-32-seal-all-polymer-sealer or something like it and use a vacuum to draw the air out and impregnate with sealer. I don’t think (although I don’t know for sure) there are any issues in the ports, so I was more concerned with getting the paint to stick.
There is a company in the UK that specializes in these things, but their website doesn’t say anything about what they use.

 

[Cyborg]

But i think he is asking about the precipation hardening of alu castings, i think google is ur friend here

Basically trying to find out what is high enough to burn off most of the crap without getting myself into anymore trouble than I’m already in.

 

[Magnetoman]

Would time in a vacuum chamber be useful?

I'm not sure vacuum would help very much. Ignoring the vapor pressure of the oil (which can't be ignored), at the left of the figure is the situation with oil at the bottom of a cavity in the Al. Next is what it would be if the oil somehow could be magically caused to rise above the bottom, leaving behind a pocket of vacuum under it. The atmospheric pressure above would inhibit this from happening. Next is if this were done in a vacuum, showing there wouldn't be a pressure difference to push the oil droplet one way or the other. And finally, taking into account the vapor pressure of motor oil at 290 ℃ (an old oil deposit would have an even lower vapor pressure since the volatiles would have left it long ago).

Given the capillary force also at play, I'm not sure the additional help from the vapor pressure of the oil along with the vacuum would make much of a difference.

 

[greg brillus]

I never heat crank cases in the oven more than about 170 celcius....... any more and you risk annealing the alloy.......just like welding.