found a screw on the crankcase: what is it?

Lorenzo · Aug 29, 2013

dear All,
I found on the front lower side of my crankcase an epoxy patch some time ago. I suspected it was something done from the former owner to fix quickly a crack and in fact I could see some oil just underneath the patch itself.
Once I have taken the yellow patch out, I found a small screw and I am really wondering what is the history of that..

Is there anyone who may have had the same screw over there? What could be the history behind that?
Here below you may find a picture..

found a screw on the crankcase: what is it?

bwolfie · Aug 29, 2013

It's a factory plug for an internal drilled oil galley. There are a few of them on the cases.

Torontonian · Aug 29, 2013

Don't worry about it. It's so they could drill out the oil passage then seal it up with the screw.

pete.v · Aug 29, 2013

The more the merrier. Remove all you can find and clear these gally ways.

Many novices will over look this extremely vital aspect of the rebuild.

I am sure that their have been many failures after a (so called) diligent rebuild due to this oversight. I have remove much ring matter from these tunnel even though mine were intack. Previous owners neglect. I got lucky that time.

Lorenzo · Aug 29, 2013

would you suggest to eliminate the screw and solder the hole?

pete.v said:
The more the merrier. Remove all you can find and clear these gally ways.

Many novices will over look this extremely vital aspect of the rebuild.

I am sure that their have been many failures after a (so called) diligent rebuild due to this oversight. I have remove much ring matter from these tunnel even though mine were intack. Previous owners neglect. I got lucky that time.

pete.v · Aug 29, 2013

Lorenzo said:
would you suggest to eliminate the screw and solder the hole?

pete.v said:

The more the merrier. Remove all you can find and clear these gally ways.

Many novices will over look this extremely vital aspect of the rebuild.

I am sure that their have been many failures after a (so called) diligent rebuild due to this oversight. I have remove much ring matter from these tunnel even though mine were intack. Previous owners neglect. I got lucky that time.

Click to expand...

No, it's just a little pipe plug, commonly call a grub screw, I think. Clear the ways, then snug them up with blue loctite. No big whoop.

Dances with Shrapnel · Aug 29, 2013

I would also lightly stake it in with a punch. Cheap insurance.

pete.v · Aug 29, 2013

Dances with Shrapnel said:
I would also lightly stake it in with a punch. Cheap insurance.

+1 absolutely!

pierodn · Aug 30, 2013

Lorenzo,
in italian language "grub" screw means "grano".

dennisgb · Aug 30, 2013

Was the epoxy over this plug screw?

johntickle · Aug 30, 2013

1972 and 1973 cases have the oil scavenge hole at the front of the crankcase. The oilway has been drilled from the front and closed with a "grub screw".
Blocking the hole inside the timing side crankcase (using epoxy or simply replacing the "grub screw" by a longer one) and drilling one or more holes further back will improve oil return to the tank via the pump.
There are a few options, some involve machining of the drive side crankcase, but this is not strictly necessary.

Lorenzo · Sep 2, 2013

Thank you..
while I have the crankcase open, I have been suggested to repair oil line grub screw with weld repair to blend with moldline and this will now be a non-repairable, permanent fix.
Are there any problems with this?

johntickle said:
1972 and 1973 cases have the oil scavenge hole at the front of the crankcase. The oilway has been drilled from the front and closed with a "grub screw".
Blocking the hole inside the timing side crankcase (using epoxy or simply replacing the "grub screw" by a longer one) and drilling one or more holes further back will improve oil return to the tank via the pump.
There are a few options, some involve machining of the drive side crankcase, but this is not strictly necessary.

pete.v · Sep 2, 2013

If these were meant to be sealed they would have been. This is the only access to these vital areas and need to be inspected and cleared. As with any automotive motor rebuild, vaildating the oil ways and tunnels should be concidered part of a Machanics 101 class.

Do not seal these up. If I end up with these cases someday and the oil tunnels are sealed, I will surely curse the PO.

mikegray660 · Sep 2, 2013

damn i must of missed "Machanics 101 class", i think i did Mechanics 101 - is that the one with the little yellow bus? :mrgreen:

pete.v said:
If these were meant to be sealed they would have been. This is the only access to these vital areas and need to be inspected and cleared. As with any automotive motor rebuild, vaildating the oil ways and tunnels should be concidered part of a Machanics 101 class.

Do not seal these up. If I end up with these cases someday and the oil tunnels are sealed, I will surely curse the PO.

Lorenzo · Sep 2, 2013

you mean I should keep the screw somehow?

pete.v said:
If these were meant to be sealed they would have been. This is the only access to these vital areas and need to be inspected and cleared. As with any automotive motor rebuild, vaildating the oil ways and tunnels should be concidered part of a Machanics 101 class.

Do not seal these up. If I end up with these cases someday and the oil tunnels are sealed, I will surely curse the PO.

pete.v · Sep 2, 2013

Sorry, Lorenzo, I cannot comment right now. mikegray660 has opened up some old wounds. I have locked myself in my basement and I am fighting profound suicidal urges.

On a brighter note,
Yes, keep the grub screws/plugs. They are there for a reason.

If you lose one, they are readily available. 062638 $1.68

Lorenzo · Sep 2, 2013

how would you fix the oil leak from that grab screw?

pete.v said:
Sorry, Lorenzo, I cannot comment right now. mikegray660 has opened up some old wounds. I have locked myself in my basement and I am fighting profound suicidal urges.

On a brighter note,
Yes, keep the grub screws/plugs. They are there for a reason.

If you lose one, they are readily available. 062638 $1.68

pete.v · Sep 2, 2013

These are tapered and are small pipe plugs. I would take it out, clean the threads, apply a thread sealer, snug it up good tight and stake in a couple spots with a center punch to leep it from backing out. But that's just me.

I grant you you, I have cut frame webbing o fit a big carb, drilled holes in the timing side of the cases, added too many reed valve breathers and many more undesirable things to my Commando, but these grub screws are fundamental. Seriously.

Hobot · Sep 3, 2013

Hm, I don't remember a grub plug screw in my Combats but been a few years that close. Just want to mention if you do try to remove it you'd better darn well heat the snot out of the cases first or may turn into a drill out plug w/o a slot left.

found a screw on the crankcase: what is it?

Similar threads