Blown engine (19/8/2018 update)

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dynodave said:
While any blow up can be unique, I seem to have seen this similar blow-up scenario on several local club members bikes/ norton heavy twin.
Fresh rebuild, sometimes big bux...new tight crank clearances coupled with a worn oil pump.
Journal gets hot because it's not being adequately cooled by the oil , metal scores-melts-seizes- big end snaps
Did your rebuild have a new pump or a "competent" testing done.
I did similar on my 1970 command at 105mph with resultant rear wheel lock up. luckily I did not dump the bike and lived. (obviously)
45 years later , I know better now.
I test pumps for local club members on my pump rig, and feel I have saved at least a few from a similar fate.
Click to expand...

Not a new pump i'm afraid, rebuilt it myself flatting the body as per the workshop manual.
after reading the pages linked to here it could be possible that it was barely coping so when a PCV valve was installed, it was too much and failed to supply
 
Adam_R said:
Not a new pump i'm afraid, rebuilt it myself flatting the body as per the workshop manual.
after reading the pages linked to here it could be possible that it was barely coping so when a PCV valve was installed, it was too much and failed to supply
Click to expand...

And to just to confirm its definitely buggered now :/
 
swooshdave said:
Why would the PCV valve affect the pump?
Click to expand...
Im sure i just read this in a post but cant find it now,
is it possible that the pressure within the engine changed due to the PCV valve?
if the pump were to be "just" functioning could a change of conditions cause it to not be able to supply?

Im aware i'm clutching at straws, as much as id like to find the route cause, i know how very unlikely that is.
 
Adam_R said:
Im sure i just read this in a post but cant find it now,
is it possible that the pressure within the engine changed due to the PCV valve?
if the pump were to be "just" functioning could a change of conditions cause it to not be able to supply?

Im aware i'm clutching at straws, as much as id like to find the route cause, i know how very unlikely that is.
Click to expand...

Hi Adam, with a PCV fitted after a few strokes the pressure in the cases is reduced to a very slight vacuum, so I doubt it would affect the oil delivery, unless you had some other problem e.g. the timing cover to pump seal (but that is me clutching at straws).
 
cliffa said:
Hi Adam, with a PCV fitted after a few strokes the pressure in the cases is reduced to a very slight vacuum, so I doubt it would affect the oil delivery, unless you had some other problem e.g. the timing cover to pump seal (but that is me clutching at straws).
Click to expand...

Ive been clutching at straws since this went bang, Id much rather put the energy into rebuilding and making better
 
cliffa said:
Hi Adam, with a PCV fitted after a few strokes the pressure in the cases is reduced to a very slight vacuum, so I doubt it would affect the oil delivery, unless you had some other problem e.g. the timing cover to pump seal (but that is me clutching at straws).
Click to expand...

Yeah, that's what got mine. The seal fell out when I put the cover back on. It ran for several days without the seal, only a sprint down the freeway did it in. Something as minor as the PCV wouldn't have much affect.
 
swooshdave said:
I don't how I can ask this without sounding dirty but can you tell us more about your pump rig?
Click to expand...

simple in concept, 2 different pieces of equipment
1A. a set of blown up (cracked ) combat cases.
A machined shaft to replace the crankshaft and oil pump drive gear (3 or 6 start)
A motor coupled to dummy crankshaft driven by variable power supply to vary motor/shaft speed
photocell optical tachometer
1B custom modified cover.
drilled to accept 100% of test oil pump output into flow meter and pressure gauge
secondary drilling to allow flow and pressure reading for over pressure valve if selected
metering valves to simulate restriction like crank and rockers
Blown engine (19/8/2018 update)


2 A motor/pump to blow oil through a stationary pump. either feed or scavenge sides.
shows propensity to wet sump as measured again by variable area flow meters.
biggest testing consistency problem is viscosity variability based upon changing oil temperature
second problem is setting up and doing tests is time consuming

Blown engine (19/8/2018 update)


I have in the past tested 2 brand new AN pumps, one from BSA Regal, one from Andover/Siefert

A good pump with 3 drops of oil in the feed side will suck a vacuum that will collapse the tygon 4040 lines.
So yes, just before you put the timing cover on, stick an oil can into the pump output and give it a shot......I would NEVER kick a bike over to "prime the pump".

Even shop recommended reconditioning can still leave you with a poor pump. Sometimes it helps a bit.
The pumps have 4 wear modes, yet the shop manual reconditioning only addresses only 1.
 
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So @dynodave what is your recommendation for dealing with an oil pump? Try to refurbish? Buy new and hope it's with specs?

Of the pumps you have tested what is the success/failure rate for new vs. old pumps?
 
Thought I had better update this, the engine has been rebuilt, and is currently being run in.
The crank was saved
Blown engine (19/8/2018 update)
IMG_2076 by Adam Rodger, on Flickr
The barrels were deemed OK to use again with a hone.
and more importantly, the cases were welded without distortion!
Blown engine (19/8/2018 update)
IMG_2368 by Adam Rodger, on Flickr
Blown engine (19/8/2018 update)
IMG_2369 by Adam Rodger, on Flickr
Blown engine (19/8/2018 update)
IMG_2374 by Adam Rodger, on Flickr

As it happens I found another set of cases, I've saved them as a spare set. Opting to use the repaired ones.
so all in all a happy ending.
 
Good to know, thanks for posting. I kind of got started with " all things Norton" when I came across a old 750 engine at a junk yard in Houston, back in the early 80's. My big brother still had his '70 750"S" model, so I bought that blown motor for 10 bucks, figuring that if nothing else, the head could be worth it. Well that "spare parts" engine stayed in the back corner of my garage, years after my brother sold his "Snortin Norton". After seeing an article in a cycle magazine about Kenny Dreer, I said to myself.... "Shoot, I still have that old engine..... I can use the internet now to help me rebuild it, then build a bike around the motor"..... Even made a long distance call to Steve Maney, however he "set me straight on what I could do and couldn't do with that old head" lol. I ended up getting a MKIII from an old ad on the INOA site. Funny how things work out.....gosh, didn't mean to go off like that.... Glad your rebuild went well. Cj
 
Thinking the timing cover oil seal wouldve caused it , too .

No Way should itve been that grubby inside .
Sever discolouration of the rod lower ends also indicates long term roasting .

Would it pumping the majority of oil into the timing cover have got the coke in the cases ? ? .


Blown engine (19/8/2018 update)


THE OUTER ( ONLY ) of this TRIUMPH Pre unit Oil Pressure Indicator , fits the inner Commando Oil Pressure Relief Valve .
And you cant even kick the protruding button into gear , as on a Triumph .

The Wee Thingamy with the Cross , there , protrudes around 5/16th inch , full pressure .
Idle Barely , Inadvertantly leaveing the seal out at a Timing Chain Adjustment ,
had it go no further than half out .
Obviously saved our bacon .


You need to lean right , to view the indictor , when seated . look & see Std Norton one from the seat , to check the move .

Ordinarilly we coffe racers in NZ CRACK TESTED the Crankshaft as a first order of overhaul .
 
the timing cover oil seal was in place during the teardown, I've put it down to a pump failure. The actual issue, I will probably never find out, so I've stopped guessing.
I felt it important to update the thread as so many are left with missing endings.

Thanks, Eddie, but aside from rebuilding the work was done by a good friend. without his encouragement and positive approach, this would more than likely still be in bits.

Adam
 
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