Sandcast aluminum sump

[dirk489]

Hi guys,
I recently put a sandcast alu sump on my car; I was told not to sandblast it as debris could collect in the pores.
Anyway,very quickly the inside of the engine was worn out.
Would someone know the procedure to handle this?
I am reluctant to just paint the inside with Glyptol paint as I have no idea about adhesion on aluminum.Would etching help?Or a blast with steel balls?
Thanks for response,
Dirk/Antwerp

 

[swall]

Ultrasonic cleaning would be good, if you have access to it.
Would really pop the sand grains out of the pores.

 

[tbuelna]

dirk489,

Sand casting is commonly used for producing engine cylinder heads, blocks, manifolds, oil pump housings, water pump housings, valve covers, oil pans, etc. Residual mold sand causing contamination in production engine lube systems is not a typical problem, even though hundreds-of-millions of engine components have been produced using sand casting techniques.

The most common method of removing the sand from the finished castings is a process call the "wheelabrator". It is a machine that shoots steel shot at the castings to knock loose any debris attached to the casting surface. It is very effective.

The best way to ensure that your casting has an uncontaminated surface, is to perform a chemical milling or etching operation on it. But as I noted, mold sand contamination in castings is highly unusual.

Good luck.
Terry