Hi all looking for guidance Devimead end fed conversion,
I had this done in the early 80s and every time I strip the motor the oil seal is on the end of the crankshaft quill not sitting in the case where it should be!, its a good fit into the case but flush when fitted so no space for a clip,
Always fit the oil seal with the spring facing the outer cover
what I think is happening when the oil is cold the oil pressure is that high its pushing the oil seal out,I checked the cold starting oil pressure and its off the scale when the oil heats up pressure drops
Checked the blow off its the later plunger type all free to move
Using 20/50 oil
Any one had the same issue?

My devinead crank had the quill not central, it’s not the first time I’ve heard of this and this could be causing your pressure drop. Mount a dial gauge and turn the crank over. This will tell you if it is Concentric or not. Mine ended up having another crank which was done properly however that was down to the journals being ground square and not with a radius and not because of the quill.

Hi,


In that case the PRV is not opening at the correct pressure (or not opening at all)
Pressure should not rise above the leak off setting, 60/65lbs/sq in. from memory

I would replace the PRV

John

If the exit from the PRV is restricted the pressure will rise too high working PRV or not with thick cold oil.

+1 with Kommando.
Also if the engine is revved quickly from cold the inertia of the OPRVmay not keep up with the flow and high pressure generated with the very cold oil.
Had that once with a 10000 hp diesel engine in the Eygptian desert.
The pressure surge went to 300 psig and blew up the oil coolers.
They needed to keep the output from the engine going so just kept adding oil.
By the time I got there from UK the oil "puddle" was 5 miles in diameter!
Goes to show that transient conditions can produce effects which are very different from steady state conditions.
Just my two centsworth..

I stick the seal into the housing with bearing fit,doesnt come out without a struggle .

Hi All thanks for the input
Checked the quill and its true
Tried bearing fit and it popped out
The seal moves 4-5 mm out luckily the end of the crank stops it moving any further but I must be loosing some oil pressure no damage to the big ends so far, but not happy with this situation.
The off the scale was probably not that high just looked at the gauge and it only goes up to 4bar so 5bar off the scale 70psi !
when I get the motor back together will let you know how it goes
Ian

How about an annular ring of thin steel with a couple of tabs that could be used to screw it down (3/16 or 2BA countersunk or something similar). Sounds like you could squeeze something about 1/8" thick in there?

Sure I've seen a solution like this somewhere.

Quick search revealed this. Take a look at this thread of Mark's and you'll get the gist.

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=40261

Ray

I'm no great expert on the design of oil seals, but my experience is that if you subject the seal to a pressure that it wasn't designed for, something has to give.
So far the seal has blown out of its housing, if you manage to restrict that movement, maybe the increase in peak pressure will finally force the PRV to fully open and do it's job properly.
OR maybe the pressure surge will blow the lips off the seal.
I've read about a couple of cases of those very expensive SRM oil pumps failing because the drive shaft from the worm gear to the pump gears has mysteriously sheared off.
A case of the PRV not opening and effectively forming a hydraulic lock ?

Hi thanks for the input
I have looked at fitting a circlip my preferred option but the oil seal is 6mm and the recess is 6mm. Even the B25 had a circlip
was also thinking of fitting a radial bearing or a bronze spacer but I like the idea of a retaining washer bit more permanent, that just leaves the pressure will look into the 10/50 oil if needed
Thanks all will keep you posted ,I don't think I can be the only one to have had this problem
Ian

Hi Ian,
I'm not familiar with the A65 and how much metal and space you have to play with.
However, I had exactly the same issue with my pre-unit Triumph. In ~1980 I had the timing cover modified by a local engineer to take the crank oil seal as used in unit Triumphs. This has become a common update, and is done using a retaining circlip just as in the units.

My installation, however, didn't have the circlip. The seal simply pressed into it's recess, leaving the seal flush with the surface of the timing cover. Your situation seems to be the same?
Very soon, I had the seal pop out, and when the next seal did the same thing, it was obvious that a way of retaining the seal securely was essential for such a critical item.
Today, I would take it back for the engineer to recess the seal further for a circlip, as the seal-bearing nose of the crank has plenty of length.
Would your situation permit this? If so, I think it the best way to go, and any good engineer (SRM maybe?) should be able to do it.

In my case, I chose to try a "bodge it and see" approach, much like Brizzo's suggestion.
In a Triumph, the inside surface of the timing cover comes close to the crank pinion nut, so the solution had to be thin.
I used stainless sheet (~1mm or so thick) to make a retaining plate. Then in the alloy outside of the seal, drilled and tapped 2 holes, something like ~M3.
Then loctited 2 bolts in place, firmly bottoming them. Cut the bolts down leaving just enough to play with, allowing for the thickness of retaining plate and nuts.

It was then a matter of assembling the plate/nuts, filing the studs down flush with the nuts, then trial fitting the cover, finding it won't go all the way home. The gap of conflict showed that filing the nuts/studs to ~half the nut's original thickness would get me close, but not close enough. So ended up filing a little off the outer surface of the crank pinion nut as well. As I said "bodge it and see" but I didn't think I could do much damage by trying.

Once I was happy with it, I cleaned up the threads on the studs/nuts, put the nuts back on, and dot-punched the nuts.
When routinely changing the seal a few years later, the studs came out with the nuts (reassuringly), so I cut fine screwdriver slots in their ends before loctiting them back in.
That allowed me to screw them in, and also on later removals, to hold the stud while undoing the nut.

That set up is still in place more than 35 years later. None of it has ever loosened in action. I guess I've replaced the seal routinely 4 or 5 times, and once because the seal split.

By the sounds of it, you may have more room to play with on your bike, in which case such a solution would be a lot less fuss!

Cheers Dave

You could also look into finding a 4mm oil seal that would just about allow the circlip groove to be cut.