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Crank-shaft rattle on start up.

Post by doujoy » Thu Mar 17, 2016 3:52 pm
Joined: Wed Jul 08, 2015 5:45 pm
Posts: 61
Hi to all,

I have been working on a way of stopping that crank-shaft rattle for a week or two and have came up with a way of stopping it, having made up a small one -way ball valve which has been soldered into place in the end of the pickup pipe inside the mesh filter.
Having tested this setup it holds enough oil back inside the pickup pipe to prevent that time lag between the engine starting and the oil pump drawing enough oil to refill the pickup pipe before it is able to supply the crank-shaft and create oil pressure.
The test showed that ball lifted under very light suction and the valve closed as soon as the oil pump stopped and the oil was held in the pickup pipe.

doujoy

Re: Crank-shaft rattle on start up.

Post by doujoy » Fri Mar 25, 2016 10:01 am
Joined: Wed Jul 08, 2015 5:45 pm
Posts: 61
Hi to all,

The final testing of the ball valve soldered into the end of the oil pickup pipe behind the mesh oil strainer in the sump does work well the suction of the pump at slow tick-over was enough to lift the ball valve open and once switched off the valve held oil inside the pipe, so reducing the pump re-priming time and bringing the oil pressure back up much faster.

doujoy

Re: Crank-shaft rattle on start up.

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Post by VDUB384 » Club admin » Sat Mar 26, 2016 9:48 am
Joined: Wed Sep 12, 2012 9:01 am
Posts: 1396
Hi Doujoy,Sounds a good idea,have you actually tried it out with the engine in the vehicle, my only concern is that it could possibably get fouled up and fail really good thought tho, maybe safer cranking it up with your starting handle. :D
Dave
Whilst good maintainece is the best prevention"If its not broken don't fix it."
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Re: Crank-shaft rattle on start up.

Post by doujoy » Sat Mar 26, 2016 12:49 pm
Joined: Wed Jul 08, 2015 5:45 pm
Posts: 61
Hi Dave,

Yes it works very well and provided the engine oil is changed regularly and the oil filter is replaced it will stay free of gunge, it is high enough off the bottom of the sump-pan to always pick up clean oil.
The engine oil pressure runs hot at 43PSI and cold at 50PSI tick-over hot at 23PSI so time and mileage will tell, why no one every thought of putting a 12mm one-way valve inside a 13mm pickup pipe I don't know, but I am sorry if it does not comply with what you see as a cure to an old Bedford problem.
Just like the starting handle Dave it works for me!

doujoy

Re: Crank-shaft rattle on start up.

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Post by Phil Bradshaw » Club admin » Sat Mar 26, 2016 9:35 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3818
What works for one CF owner can be disastrous for others especially those less inclined to maintenance on a regular basis.

Further confounders can arise in diagnosis of lubrication system problems (such as a tired oil pump, jammed pressure relief valve, failed O-ring seals etc. through to the engine having being beyond hope and requiring a rebuild) which should be fixed before diverging much away from original design.

These and similar considerations (e.g. cost of engine removal to replace a stuck valve, the valve itself adding to the potential trouble list) may well have been behind Vauxhall Motors not engineering a valve type fix for the oil pump being so high in the engine and thus much more sensitive to problems affecting priming on start up.

That said, like a number of fixes that by-pass having to find scarce or costly replacement parts the valve idea may turn out good but with a sample of one the idea is, shall we say, in the development stage. :)
  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: Crank-shaft rattle on start up.

Post by Geoffthewelder » Sat Mar 18, 2017 6:12 pm
Joined: Tue Nov 22, 2016 7:49 am
Posts: 7
Hi, don't know if this subject is still open, but if so I can offer good advice from my experience of running for many years my original 2.3 sloper engine. First of all those engines have an oiling system badly designed for start-up, in that the scavenge pipe is very long with the oil pump mounted high up and even inserted into the top of the block with no non-return valve, meaning that the long scavenge system drains its oil when not running and takes too long after start-up to avoid wearing away big ends before getting oil pressure. A 'crankshaft rattle' on start-up means that yours has definitely worn so it definitely needs a grind, then the bad design needs rectifying. I considered a ball needlessly heavy for the non return valve so used a Honda Four cam follower shim (it was many years ago ;) ), which was about 3/4 inch diameter, and my friendly engineer turned out a 2 piece screw-together valve housing, where the lower half had small holes drilled in a circle centered round the circumference line of the shim, and that lower half housing had a seat for the shim turned out round the top of the main inlet hole. Thus as soon as the shim lifted at all the oil had plenty of opportunity to flow past it up the semi-circular holes around and above it. Vertical movement of the shim was limited by the underneath of the upper half housing screwing down into the top of the lower one, and that underneath was castellated to allow oil flow through the castellations into it. The engineer even lapped in the shim to its seat with valve grinding paste, so that after fitting the valve to my scavenge pipe and filling it up with petrol it instantly sealed perfectly, even though it was without any spring. Fitted the scavenge strainer around the valve and had many many years afterwards of completely faultless oiling of the engine, with almost instant oil pressure on start-up and of course absolutely quiet crank bearings, until I eventually sold the engine to an ice cream van owner. Tried to tell her what a valuable improvement I'd carried out but don't think she understood. Can't emphasise strongly enough what a superlative modification this was, and any turner worth his salt could make it and your crank will run for ever.

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