Author Topic: Partial seizure  (Read 2582 times)

Online bsa-bill

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Re: Partial seizure
« Reply #15 on: 23.07. 2014 14:24 »
Quote
Ok, so my take may be a little different to others,

yes - probably because you thought about it more than some of us (ME) - I'd think a lot of partial seizures are after a re bore and new pistons which is the way I was thinking, not so much in the way of no oil circulation.

So good point John
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

beezermacc

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Re: Partial seizure
« Reply #16 on: 24.07. 2014 09:14 »
mate has a Super Rocket with an SRM engine. Occasionally it would nip up, particularly when going up hill or on a very cold day. The problem was caused by their anti wet sump valve which they fit behind the oil pump which was restricting the oil flow to a dribble. After finding the problem we stripped the top end and there was little or no damage to the bores but the pistons needing cleaning up. Our concern was the bottom end but there was absolutely no play on the conrods and no scufs on the cam lobes so my mate 'got away with it'! If you don't strip the top end you're always going to have nagging concerns........

Offline ben

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Re: Partial seizure
« Reply #17 on: 26.07. 2014 10:27 »
Hi Morris,

thanks, yes, Belgium is an incredible country. Esp the two language thing. We are situated in Maastricht where I believe the biggest BSA meet ever was organised a few years ago. Belgium is where I ride around. I agree with dumping the tap. I'm in semi-denial about damage to the big ends, but will have to check it out.
Cheers
Ben

Online chaterlea25

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Re: Partial seizure
« Reply #18 on: 26.07. 2014 21:23 »
Hi beezermacc,

Quote
mate has a Super Rocket with an SRM engine
Quote
The problem was caused by their anti wet sump valve which they fit behind the oil pump which was restricting the oil flow to a dribble.

The only way I could see this happening is if the wrong sized ball (too big) was fitted ?

The SRM modification is not an "anti wet sump valve" as  sold by others as an addition which is fitted in the oil line from tank to engine
It relocates the ball valve only accessable when the crankcases are split to behind the oil pump
This means it is on the pressure side of the pump
There are hundreds if not thousands of SRM modified engines running with this mod
Including mine which has well over 20k miles up on it now,
Several engines I have built for customers incorporate this modification and all are fine
How come all the A65s which used the modified system havn't siezed??

John


1961 Super Rocket
1963 RGS (ongoing)

beezermacc

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Re: Partial seizure
« Reply #19 on: 27.07. 2014 07:19 »
Whether the ball wasn't the right size or the engineering wasn't quite right, I don't know, but this mod was definitely causing the problem. From experience I know what the return flow should look like. Before taking the ball and spring out the return flow was a dribble, after taking it out the flow became normal. Like John I was surprised. We even put the ball and spring back, just in case disturbing the pump and gasket had resolved the problem but, no, back to a dribble again.

Online bsa-bill

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Re: Partial seizure
« Reply #20 on: 27.07. 2014 09:18 »
I'm reminded of the great man - ball - spring - spring - ball

so hoping not to be disrespectful beezermacc but it did go in spring - ball - pump not ball - spring - pump

fire proofs donned
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline duTch

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Re: Partial seizure
« Reply #21 on: 27.07. 2014 10:57 »

Quote
This means it is on the pressure side of the pump

 John, I'm not totally familiar with the A65/50 setup or the modification, but unless I've misunderstood, wouldn't it be pushing oil in the same hole under/from the same pressure side of the pump..?

 Bill I think I know what you mean, that if the ball was in the wrong order, could be actually blocking the feed hole further in...? But as you say a bit hard to do it wrong!

 Beezermacc- maybe I'm off track, but is it possible is the wrong spring- too long/soft (wire too thin)/short/stiff (too thick), or the hole not drilled deep enough, which could give the spring excess pre-load..?
 Just som ethoughts
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beezermacc

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Re: Partial seizure
« Reply #22 on: 27.07. 2014 11:19 »
Regarding the SRM anti wet sump valve - this is probably another thread..... but on all the SRM engines I have had dealings with this mod works well. SRM drill the crankcase at the back of the oil pump on the feed side, a light spring is dropped in the hole with a ball facing out (against the back of the oil pump). When the pump starts to build up pressure the ball is forced away from the back of the pump and the oil passes around the outside of the ball, just like the pressure release valve. I have no idea why it didn't work on this occasion and, as we were short of time, we decided to remove it altogether and fit an outboard valve [I know not everybody likes them and I don't want to open up that old wound!] which works fine.

Online chaterlea25

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Re: Partial seizure
« Reply #23 on: 27.07. 2014 22:31 »
Hi All,
beezermacc,
If the feed from the pump was restricted by any blockage then the oil will flow through the PRV and will return to the tank as normal
If this did not happen the worm gear drive would be destroyed

The only way the flow will be reduced is if there is a restriction in the oil flow from the tank to pump

Seeing a "normal" return to the tank is no guarantee all is well in the engine  *roll*
oil can leak from the pump or main bush and anywhere else it can, then drop to the bottom to be returned as normal

John
1961 Super Rocket
1963 RGS (ongoing)

Online Butch (cb)

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Re: Partial seizure
« Reply #24 on: 28.07. 2014 09:27 »
I fitted an anti wet sump valve to mine, and then suffered a seize at 250 miles from the rebuild. Crank had picked up on the timing side bush. Solid. I had Roger at Cake Street pull it all down and sort it - he reckoned it was assembled with just too little clearance there. My theory though was that the oil below the valve had drained through the pump and then it failed to prime on the next start. I didn't check the oil return before setting off, but on that theory this would have shown OK - for a while at least. It seized less than a half mile from my house so wouldn't have been hot and bothered at that point.

Warning - observations made by this member have a 93% unreliability rating.

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beezermacc

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Re: Partial seizure
« Reply #25 on: 29.07. 2014 21:51 »

If the feed from the pump was restricted by any blockage then the oil will flow through the PRV and will return to the tank as normal
If this did not happen the worm gear drive would be destroyed

The only way the flow will be reduced is if there is a restriction in the oil flow from the tank to pump

Seeing a "normal" return to the tank is no guarantee all is well in the engine  *roll*
oil can leak from the pump or main bush and anywhere else it can, then drop to the bottom to be returned as normal

John
I'm always willing to learn! But can you explain how the oil gets to the PRV if the SRM anti wet sump valve is blocking the pathway from the back of the oil pump to the crankcase? For information there was no blockage from the tank, obviously this was the first thing we checked, with the oil pump removed oil poured into the timing chest via the entry hole in the crankcase at the back of the oil pump. I accept that a 'normal' return does not prove that everything in the engine is OK, however an 'abnormal' return suggests something is seriously wrong. Having seen 'abnormal' return with the anti wet sump valve fitted and 'normal' return without it fitted is it reasonable to assume that the anti wet sump valve was the cause of the problem or would you be looking for something else, if so, what? At the moment my mate is happily riding his bike around and it isn't seizing up like it used to. Do you think we should get the spanners out again?

Online chaterlea25

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Re: Partial seizure
« Reply #26 on: 29.07. 2014 23:57 »
Hi beezermacc,
Yes you are correct, I thought about this after replying, but I would still expect rapid damage to the oil pump drive gears if the outlet from the pump was restricted for any length of time
Maybe given more time and a detailed examination of the pump and outlet oilway would reveal the cause of the issue
I just do not trust those ASV's in the feed line *eek* having seen the damage that can result

John
1961 Super Rocket
1963 RGS (ongoing)

Offline kiwipom

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Re: Partial seizure
« Reply #27 on: 30.07. 2014 22:29 »
hi guys, just a picture of a 73 Gold Star for sale in nz,  notice the oil line valve? cheers
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Re: Partial seizure
« Reply #28 on: 31.07. 2014 07:52 »
That's a full seizure waiting to happen.
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Offline Flatboy 1950

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Re: Partial seizure
« Reply #29 on: 31.07. 2014 08:59 »
I had a 1970 B44 VS and rode it for 14 years ...... never , ever wet sumped !!
Bust a few cam plate leaf springs in the gearbox but always got home ... stuck in 4 th. gear !!