E: Engine Twin oil pump fitting

SteveO

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After an hour fiddling in the garage, here's the culprit and it's all down to me. I've caught the edge of the hole putting the OP36 in and dented the sleeve. I've tried to take it out with wet & dry and a small jeweller's round file, but the plunger still jams.
IMG_20191118_143504.jpg
IMG_20191118_143509.jpg

In the other pictures the plunger has been inserted "back to front" to show that it fits. If you look carefully in the last one you can see the groove on the plunger foulling the dented in portion around the hole.
IMG_20191118_143555.jpg
IMG_20191118_143633.jpg
 

SteveO

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It looks really bad in the photos, but it's not as noticeable in real life which is why it took a while to find it. The score caused by the bearing race appears to have no effect and the sleeve isn't bent, I've checked it with a straight edge all round. I think, to be on the safe side, I'm going to have to replace the pump. So now I have two problems; grinding down the bearing race and replacing the pump. This will mean another trip to Kettering, as I think it would make sense to take the case to ensure a push fit with the replacement.
 

Bill Thomas

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I can't see why, You have found the trouble, A bigger hole won't do any harm,
Make sure OP36 is OK.

You still need to reamer the cases out ?.
 
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SteveO

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I don't think making the hole bigger would be wise Bill? This might allow the sleeve to move relative to the OP36 as the plunger operates. I think the hole would then wear and continue to allow more movement in the sleeve until it could turn and block the feed holes which would be catastrophic. What do ther people think?
I'm not sure I need the reamer now, but I need to grind the bearing first anyway, as otherwise it will catch the reamer if I do need it.
 

Monkeypants

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I had some difficulty fitting the oil pump on the 1360 motor.
John McDougall fitted dozens of them but still gave me a forewarning " if it goes badly just stop and go watch TV for the rest of the day. Try again the next day"
I nearly had to turn the TV set on.
These were new Molnar cases. The oil pump housing bore looked like a mirror, as did all of the machined surfaces on those cases.
It measured exactly correct for a very slight interference fit when cold.
With cases heated and oil pump sleeve cold, the sleeve went in most of the way quite nicely then jammed hard.
I tried to remove it but by now the heat from the case had gone into the oil pump sleeve. It was a proper gong show getting the sleeve out.
The problem was that the main bearing outer race was protruding about 5 thou into the oil pump bore space in one spot. You likely wouldnt encounter this problem with original cases.
Had I first used David's method or Vincent Speet's method of checking with a reamer or slightly undersized piece of round stock, the problem would have been avoided.
After using a Dremel to remove a tiny bit of material from the main bearing race, I made a 1 thou under piece then used it with some grinding paste to open the bore just a little.
This was after going back to all five Vincent books to reread the bit on fitting the oil pump.
At least one publication ( Richardson?)
recommended a " light push fit when cold"
I removed enough aluminium from the case so that the sleeve would slide about half way in when cold.
When heated, the cold sleeve now went in easily, though still best to work quickly and get the position right asap.
The bike does wet sump pretty quickly and I wonder if this is due to the relatively loose fit made with the sleeve.
I did read that all new Maughans 2 start pumps like to wet sump, so decided to live with it rather than repeat with another new pump and hope for a different outcome.
Instead I made up a manual oil valve that is operated by the ignition key.
The end result is good, I can leave the bike all winter, turn the oil on in the Spring and go. Best of all, no oil on the floor!


Glen
 
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Bill Thomas

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Just thinking out loud, If it was too hard to grind the bearing, I wonder about grinding a groove where the
Damage is, Most wet sumping only happens over winter ?.
 

Monkeypants

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It was easy to grind the bearing once I realized it was interfering. Because of the angle of the oil pump housing bore, the interference was just at one point and at an angle, so only a tiny amount of material had to be removed from the outer race at one spot. It took perhaps 10 seconds or so of grinding with the Dremel.

Glen
 

SteveO

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Thanks for all this information guys. Bill, thanks, I was overthinking it again. I'll try what you suggest, nothing to lose! But I will make sure the plunger moves easily when the whole caboodle is installed, before fitting the plug!
So far it's only taken about a month to get the mains and oil pump in! I wonder what I'm going to find next...
 
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