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MG MGA - Help! What's this?

Hi

Giving the engine a good clean befor putting it back into the chassis I decided to take off the sump to get rid of accumulated sludge. I found a 1 3/4 inch long 1/4 inch UNF bolt with split washer lying in the bottom. Long shot I know but does anyone recognise this or where it might come from? I had a good look round the oil pump etc but could not see anything missing. The engine ran fine before removal.

thanks

Barry

B Bridgens

The good news is it is too long to be a wrist pin bolt...
Del Rawlins

Perhaps, "Screw, stainer to pump" AD19 and "washer for screw (spring)" AD21 as on page A8 in Service Parts List.
Bill Haglan

Barry. Is the ruler you are showing in your photo marked in inches? It looks like the bolt is completely threaded along its entire shank and has a shank of 1.75" inches. It is rare to have the entire shank threaded on a bolt of this length. The only bolts, internal to the engine, of this configuration are related to the oil pump. You might want to take a close look at the oil pump and see if there are any bolts missing. My factory parts list shows two bolts holding the arm of the pump to the body of the pump, one of which might be the bolt in question.

But, it has been a long time since I worked on an MGA engine.

Les
Les Bengtson

Oil pump screw?
N McGurk

Hi

Les, the ruler is in inches. It is unusual to have it threaded all the way.
I have looked all round the oil pump and most of the fixings are nuts, the strainer nuts and bolts are there. Most other fixings in the bottom end are much bigger. I feel that I am going to put the sump back on then worry about it evry time I go out in the car. Maybe it fell off the bench when the previous owner was doing some work on the engine.

Barry
B Bridgens

I just had a quick look and I believe it is the longer of the two screws that hold the strainer to the pump, as Bill correctly identified.
N McGurk

Oil strainer mounting screw, prior to (e)GB46045.

(2) HBN0412 -- Screw - strainer to pump
-- 1/4-28-UNF x 1-1/2 long, Hex Head Screw
-- Fin (e)GB46044 except 460101 to 46341
(2) PWN104 -- Washer for screw (plain)
(2) LWN204 -- Washer for screw (spring)

The SPL says "screw", but The Fastiner Decode Book says "Bolt". A "screw" by definition is threaded all the way to the head. A "bolt" by definition is threaded to about 4x the diameter, so a 1/4" bolt longer than 1 inch would have 1" thread length.

In this case, if the screw is 1/4 inch longer than necessary it would protrude inside the screen but would do no harm. Since you found the screw and spring washer, you might look for the flat washer as well. If my memory is still working well, I seem to recall that this is originally a bolt with less than full thread. The screw that you found must be a DPO change.

See CSM MG237: http://mgaguru.com/mgtech/care/csm/mg237.pdf
For the earlier engine, you would be well advised to change the oil pump and pick up screen to the later type.
Barney Gaylord

Hi

Thanks all for the answers and comments. The pump has been changed to the later type , so my guess is that the screw fell into the sump during modification and was not retrieved. I am going to try and convince myself that that is the answer so I don't worry about it any more.

thanks

Barry
B Bridgens

This thread was discussed between 09/10/2012 and 10/10/2012

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