Main oil gallery to main bearing no3 blocked

[gs.davies]

I’m clearing out the oil gallery on my engine and I’ve managed to get stuck with no3 main. Was using a piece of threaded bar to push white spirit soaked tissue through when it got stuck. I gave a quick tap and it’s stuck solid.

Are the three feeds from gallery to main bearings the same bore? It looks like I probably need to now take it somewhere and have it redrilled...

Grrr.

[gs.davies]

That is to say the threaded bar isn’t stuck solid but the bit of tissue is. Seems that there’s something metallic down that particular bore. Is there some kind of constrictor in that bore?

[Peter Laidler]

Threaded bar eh! What about sliding an appropriately configured anchor plate down the threaded bar then using the appropriate sized nuts to slowly draw the threaded bar rearwards. If it was me, I'd do the nuts up finger tight on to the anchor plate, heat the bar and expand it, tighten the nuts up onto the anchor plate again and as the threaded rod cooled down and contracted, it's slowly pull itself clear. This way you cannot strip the threads due to some metallurgical law of physics (was it ACME's law?).

[imack]

That restriction is the oil pressure relief valve seat.
The seat can be removed by tapping a thread into it and drawing it out with a puller or slide hammer but if you've got tissue around it (the valve seat is kind of hour glass shaped and the oil to the main bearing flows around it) you may draw the tissue into the relief valve bore and jam the seat in the bore.

[gs.davies]

So no3 doesn’t flow straight into the main gallery?

[imack]

A picture speaks a thousand words.

[Peter Laidler]

Can't you pour some methylated spirit into the hole and burn the tissue out

[gs.davies]

Can't you pour some methylated spirit into the hole and burn the tissue out

Well....

I actually did do that but stupidly didn’t realise that there was something in the way by design and so having attempting to run it through with a drill...

It now need replacing.

You live and learn.

[gs.davies]

3/8 UNC tapped, inserted an old head stud and I wound it out. Another disaster avoided