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

 

[MikeHalloran]

CNC machine about a mm off the inside, then mirror polish it.
OR
Or shave the inside to clean metal, e.g. with wood chisels and planes, then mirror polish it.
OR
Go back to the original (steel?) sump.




Mike Halloran
Pembroke Pines, FL, USA

 

[WGJ]

Standard practice for porous castings is to have epoxy impregnation (vacuum, usually) - I don't see why this couldn't work to anchor the debris to the inside.

Bill

 

[patprimmer]

I agree with Mike.

Woodworking tools work on aluminium.

Make a good clean surface by whatever method then paint it with a paint rated for use on aluminium in the presence of hot oil.

I would not shot blast it to clean it. I would very carefully clean it with soap and water and a water blaster if available.

I have never had a problem with sand from castings killing an engine when the parts were deburred and cleaned properly.

Did you sand blast it.

Could the abrasion been from another source.

Did you properly clean it.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[dirk489]

Thanks for Your reaction.
It is a copy from an original sump of a veteran Slmson engine.Due to the intricate labyrinth and finned design inside difficult to polish.I scrubbed and went over it with the high pressure water jet.Of course,the sump could have been sandblasted by the casters to get in"clean"
I was amazed how much black rubbish collected in the sump after a mere 150 miles.Crank was damaged as were the piston rings.
I will go the paint way,maybe there is an etching paint for aluminum.
Dirk

 

[patprimmer]

A rinse with a hot or even boiling mildly alkaline solution, like maybe 5% bicarbonate of soda and detergent, then a weak acid rinse in very weak acetic acid might clean it up a bit.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[Nemesis4]

I may be missing something obvious but how does sand from the sump casting get past the oilpump pickup screen and the engine's oil filter? Some cars (like the old Morris Minis etc.) had enormous amounts of metal chips, shavings and assorted rubbish in their sumps and this never got up into the engine's oilways etc. And shave the aluminium sump's interior with woodworking tools?

 

[swall]

Ha! I'm with Nemesis4 on this. Everyone was too quick to jump in with a solution before the problem was identified.

 

[patprimmer]

Ha!

Did you read what I said and the OPs second post.

It is a veteran engine. That means it quite possibly has no oil filter. It might not even have an oil pump.

I also asked if he was sure of the source of the abrasive material.

The working of aluminium castings with wood working tools is not an opinion, it is a fact and I have done it quite a few times, mainly on inlet manifolds and cylinder heads. It is a particularly effective method of removing sharp points and edges from combustion chambers to reduce the chance of detonation, or increasing clearance around a boss to make room for a bracket to fit an ancillary. No I did not use my new or my best chisel, just some old chipped chisel that I sharpened and shaped with a linishing belt.

An old chisel also does a nice first stage on cleaning up a rough as cast aluminium housing in preparation for polishing. I have done it and it definitely works on blowers and inlet manifolds in preparation for polishing.

Just to push the point of suitability of some tools for use outside the original design purpose, angle grinder with a metal cutting blade also works well instead of a spoke shave to shape wood. You just have to sand out the high spots and the burn marks.

A gas torch set to slightly rich burn can make a suitable light source when nothing else is conveniently available.

Have you ever worked on something when you are 1000km from the nearest well equipped workshop and 400km to the nearest general store or fuel supply. It does teach one to make do with what you have.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[swall]

I will admit to having used wood chisels on aluminum castings a time or two.

 

[dirk489]

Hi Guys,
Thanks all for reaction.
Nemisis4: the engine has an oil pump and filter.
I suppose the oil filter overloaded with rubbish and the by-pass opened,letting the rubbish in the galleries.
I was amazed about the amount of rough rubbish inside the sump,have taken some off and a sample of the oil going to the lab for testing to make sure.
Patbrimmer:
I cannot imagine another source of the abrasive material. I always clean my engines thouroughly and with the high pressure water jet to finish.
Casting is very difficult to polish:in those old engines lots of labyrinthlike ways are cast to let the debris in the old oils settle down.The stuff could also come out of the aluminum,as they reused old alu parts(impurities?)
Dirk

 

[swall]

Glad to hear that an oil analysis and debris analysis is under way. Nothing better than data.

 

[patprimmer]

Is it a full flow oil filter.

Does the filter relief valve open during cold start and bypass the filter.

Does it have cam bearings mounted in bores with annular groves to rout oil. If so were the bearings removed to clean the annular groves.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[dirk489]

toatbrimmer:
Full-flow filter.The by-pass probably opened because the filter was obstructed.Alas,the filter was thrown away before the engine came to me.The engine ran fine before the rebore,all gallery plugs taken out and blasted through,but not the cam brgs,as they have the annular groove on the brg side.Bores are still OK,pistons OK,with minor scratches,rings are gone.
I'll keep You posted about lab results.

 

[patprimmer]

I would still knock the cam bearings out to make absolutely sure the galleries flushed clean.

Even when not blocked a filter with a bypass can bypass on start up until the pressure across the filter normalises.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[Nemesis4]

Dirk489 - What kind of car/engine is it? You mentioned "Slmson" - did you mean "Salmson"?

 

[Tmoose]

Do you run an air filter?
Does the crankshaft have any oil galleries closed off with plugs, or are they all through holes?
Do you have any enemies?

 

[Nemesis4]

I have to admit that sabotage did occur to me too. It does happen.

 

[LionelHutz]

That amount of dirt really sounds suspicious to me too just coming from the pores of an oil pan.

You could probably use heat to bake the oil residue out of the pores before painting it. Maybe a motor shop would help baking it and then painting it.

 

[dirk489]

to T.Moose: I have no enemies that would put sand in an engine....
to Nemesis4: Salmson indeed.

Mystery solved! Took the lab some time because they were on holiday. It is SANDCAST SAND.
Conclusion: A high pressure water jet does't take it out.
I talked to someone who cast alu sumps for a main Diesel firm;they blast their castings with glass beads and put some special paint afterwards.He'll get me some of that paint.We threated the sump with glass beads and the colour of the alu went to a much lighter tone.A considerable amount of darker stuff came out and a lot of tiny holes showed afterwards.

Thanks all for Your reactions which put me on the right track!