12v timer for pump

[Brad]

Hi everyone. This is my first post and I'm no electronics expert. Herein lies my problem and would welcome any assistance....

I want to run a small 12v oil pump for approx 15secs every 10mins.
I would like the pulse and the pause to be adjustable/variable so I can fine tune things.
I have located this item from my local electronics store : MK111 Adjustable Timer with Relay Output
http://www.maplin.co.uk/mk111-adjust...y-output-25224

The problem is the pulse and pause setting are not suitable for my needs. Can anyone tell me what component I would need to change in this circuitry and where I could source such a part?

The oil pump is rated at DC12v; 3.6W; 0.3A

Thanks to anyone who can help me with my dilemma

Brad

[piratepaul]

I just searched '' 12v timer'' on ebay and got 458 reults.

[piratepaul]

I just searched '' 12v timer'' on ebay and got 458 reults.

That should say results.

[Pauldf]

You're probably better having two timers, one which when energized delays coming on for 10m, which then switches the pump and a 15s timer on, the 15s timer then resetting the 10m timer (and thus stopping the pump).
Personally I'd use a relay for controlling the pump as opposed to having it run through timer relay contacts.
What is it for?

[Brad]

Thanks for your response. I like your thinking and will give serious thought.
Its to manage an oil leak in an old BMC engine. Oil collects in the bell-housing and gets caught up with the flywheel and causes problems. I have drilled a hole in the bell-housing and want to pump the oil back into the sump. Unfortunately the leak cannot be repaired, so I am trying to manage it with a timed pump that is activated when the ignition is switched on.

[piratepaul]

Hi, one or two bits to add ... what sort of BMC engine, diesel/ petrol/auto/ marine morris minor/ FG ... 4/6 pot etc Tell me more, sounds like an oil seal.
I am into boats which often have BMC diesels... a few mates are expert some are top level engineers, one of the advantages of the boating life is you get to know lots of doctors, lawyers and people in high places top flight engineers are 10 a penny.
i am sure the ol leak can be fixed, it could be reconditioned at a cost but you could prob get the bits quite cheap for diy, must be a bareing or oil seal.
If you must use the pump, use a pump which will not burn out when dry ... wire it to the ignition and thats it.
The amount of oil to be pumped is likely to change with oil pressure, ie toe pressure so the timer will never be set right... perhaps you could work out an air filled coil or capacitor circuit which when the cap or coil fills with oil the impeadance chances which is detected and switches on a transistor which drives the pump... that is a bit tricky to say the least but it could be done.
Tell me more about the engine, I will have a word with the lads... it is always poss to get parts made to spec, even if they are made in China.

[piratepaul]

Another way ... when the pump is pumping oil it draws more current (amps) than when there is no oil to pump... it is poss to detect this and switch the pump off when this happens... a timer then switches it back on in a bit.

[Pauldf]

Or have it falling into a sump with two level switches, the upper switch to turn it on and set a latching relay, the lower one to turn it off.
Or just one level switch which sets a timer to run the pump.
What is the chance of the oil being contaminated by dust etc? Fixing the leak might be a better idea as Paul says

[Brad]

Hi. The engine is a 2.2 diesel BMC boat engine over 60 years old. The oil is leaking from the main bearing into the bell-housing. The 2.5 BMC has a replaceable oil-seal but the 2.2 has a oil-thrower plate as part of the crankshaft casting. Apparently once this starts to wear, oil seeps through. It seems a bit strange as the engine was fully reconditioned a few years ago and has done about 2500hrs since. I've changed from 15W40 oil to 20W50, I replace the filters regularly and even had the engine dismantled and cleaned all the oil-ways in the block and cylinder head but to no avail, and I'm getting fed up crawling underneath to empty the tub I have there to collect the leaked oil.

I've considered the float switch idea but decided it would take too much leaked oil to collect before the pump kicked in and I'm not too keen to have a tub with oil swilling about underneath which why I was opting for a little timed pump that ran directly from the ignition switch.

So thanks for the suggestions re pumping the waste oil as it leaks. I didn't consider contamination would be a problem but I could pass it through an in-line filter en route to the sump.

[piratepaul]

I will see what I can find out about the actual prob untill then ...

You say a small pump 3A... I keep a 60ft gaff ketch(sieve) afloat on a 3A pump the hight from the bilge to the outlet is about 8 ft. (not my boat, I just get to swim in the bilge when there is a prob)

If you put a variable resistor in series with the pump you can adjust the resistance until it just trickles when the engine is on tick over, when you open the throttle the terminal voltage goes up a bit and it pumps a bit faster... rather than the timer control the flow.
I would use a relay to save the ignition.
It is poss to sense the flow of oil in the pipe or other factors such as voltage accross pump or resistor to switch the pump off to save it running dry, but then it prob wont hurt the pump if it runs dry as long as it gets the odd splash of oil.