Mk1 return relief oil deflector (inside crankcase)

[camstevens]

Hi All
I have an ongoing issue with oil control in the crankcase. I have stripped the engine, and measured timing side bearing clearances as 0.002" on rear and 0035" at front. I believe they are within acceptable tolerances. Morgo pump installed, and been tested and OK.

What I did notice was something I had not considered closely before; the oil deflector was somewhat loose...judging by the rivets, it had been removed and refitted at some point, somewhat loose on the rivets and not "flat down" against the crankcase. It also appeared to be sitting further than is could/should be from the relief return hole (I could clearly see part of the return hole above the deflector when looking directly at it). This got me thinking...am I looking the cause or contributor to the issue? As a crude test I ran my parts cleaner delivery tube into the relief hole, and could clearly see how the flow through the deflector was beautifully controlled along the crankcase surface towards the scavenge.....but I also noticed a significant abruption loss of flow at the relief return hole, and uncontrolled into the crankcase space.

General thoughts questions;
- has anyone struck issues with this before?
- I would expect at road speeds (55psi +) there to be a fair amount of uncontrolled oil flying around the crankcase. Would/could this cause an issue (I'm pretty sure it would)?
- does anyone know the flow rate of the Morgo return?
- Are the rivets available to better fit the deflector? They appear to be levelled off on the outside of the crankcase (photo below).

PS - the photo of the deflector was taken after I had tapped it back towards the return hole.

Cheers
Cam

[nevhunter]

Babbit Lined Bearings are Meant to run with much less clearance than those figures you have or they will HAMMER out and fail. I would also EXPECT they would Make Audible noise when Pulling hard AND permit TOO MUCH oil to be around. Generally the SCAVENGE Pump should have about DOUBLE the Capacity of the supply Pump. Bubbles in the return line will prove this and Morgo should have Figures for their Pump. The Morgo
Rate would be well above(and More Reliable) than the Plunger and ball set up of the Original. The timing side Bearings in a SQ4 are similar to most Vertical twins. My advised Clearance is free to 'one and a Half thou" on a very good finish Bearing and shaft. Babbit is a soft Low friction coefficient metal that doesn't require a hardened shaft but needs Clean Oil as the dirt embeds into the soft Metal and wears the shaft. Nev

[Mick D]

Hi

Re. the rivets, aluminium or hiduminium solid rivets were the norm in the aircraft industry in the fifties and are still readily available from aviation suppliers. You would need to match the countersink angle as well as the diameter and ascertain the correct length so removal would be required before purchase. The rivets have been set by reaction, not difficult but there is a risk of marking the case, re-setting the rivets is also possible to tighten up the join but again there is a risk of external marking. I'd leave it alone unless you're sure this is the cause of your problem.

Regards Mick

[camstevens]

Hi

Re. the rivets, aluminium or hiduminium solid rivets were the norm in the aircraft industry in the fifties and are still readily available from aviation suppliers. You would need to match the countersink angle as well as the diameter and ascertain the correct length so removal would be required before purchase. The rivets have been set by reaction, not difficult but there is a risk of marking the case, re-setting the rivets is also possible to tighten up the join but again there is a risk of external marking. I'd leave it alone unless you're sure this is the cause of your problem.

Regards Mick

Hi Mick
The deflector is rather loose, but I'm pretty sure I can stick with what's there by carefully peening down the existing rivets with new aluminium washers (with a alloy dolly on the outside to stop them popping out. Cam

[camstevens]

Babbit Lined Bearings are Meant to run with much less clearance than those figures you have or they will HAMMER out and fail. I would also EXPECT they would Make Audible noise when Pulling hard AND permit TOO MUCH oil to be around. Generally the SCAVENGE Pump should have about DOUBLE the Capacity of the supply Pump. Bubbles in the return line will prove this and Morgo should have Figures for their Pump. The Morgo
Rate would be well above(and More Reliable) than the Plunger and ball set up of the Original. The timing side Bearings in a SQ4 are similar to most Vertical twins. My advised Clearance is free to 'one and a Half thou" on a very good finish Bearing and shaft. Babbit is a soft Low friction coefficient metal that doesn't require a hardened shaft but needs Clean Oil as the dirt embeds into the soft Metal and wears the shaft. Nev

Thanks Mick for the really constructive reply. I guess the older clearances of 0.002" were from the days when oil, whitemetal, etc was not of the standard it is now. Cam

[Chris Sealy]

Here is a picture of my Mk1. It looks like one of your rivets isn't doing its job.

[paul.jameson]

I am not quite sure what your problem is with oil but I am working on the idea that there is rather too much of it in the crankcase. A common cause of this problem is the level of the end of the oil return pipe in the sump. Whilst having it too high is an obvious cause of too much oil in the sump, having it too low can also give trouble. This is because the suction from the pump pulls debris such as bits of jointing compound to the underside of the crankcase gauze filter. If the pipe end is too low, you can end up with very little room round the end of the pipe for the oil to flow into the pipe and hence back to the oil tank via the return pump.

See viewtopic.php?p=75133#p75133 for photos of what I mean.

I suppose it is also possible that you may have a leak where the top end of the return pipe goes into the crankcase but that is something I have never known personally.

[simon.holyfield]

Just to add a bit more to the mix - when I serviced the Mk1 last summer I was a bit surprised to get a cupful of oil out of the sump. To cut a long story short, the last time I fitted the sump plate must have been in the dark with my eyes shut because the pickup pipe was bent out of position (upwards and forwards) and the gauze was damaged.

It's a soft copper pipe, easily repaired, and is shown here in what I consider to be the correct position. I do have a Draganfly sump plate, with a drain plug, which may have a bit more vertical distance between it and the pickup pipe (to allow the oil to be drawn up) than the standard sump plate.

[nevhunter]

Oversize Pipes with thinned (HOT) Oil may not Lift the Oils easily OR you may have an airleak/crack somewhere. Babbit was the earlier applications Replaced with Higher Load metals Like Copper -Lead and alutin both having a higher frictional Coefficient and requiring More Oil flow to cool it. ie CLEARANCE. They also have Less tolerance of dirt and should run on a Harder Metal for Best results. Extreme duty is steel backed copper Lead with a Plated Indium Overlay. Nev

[nevhunter]

White Metal, (babbit) Lasts a LOT longer when the Layer is quite THIN. It has to be well tinned to the Metal its In. Thicker Layers Fatigue and large Areas Break out .010" Ten Thou or 1/4 Mil is Enough thickness. You Must bore and centre everything carefully to ensure even thickness IF you do run a Bearing you will get Little shaft damage with Whitemetal as Long as you stop riding it when it Knocks or the Oil pressure drops. Nev