Dry Sump Belt sensors?

[philwaters]

Hi, posting on behalf of Steve Foster....

 

Concerns over the freshly fitted belt coming off or being taken out by a flying alternator belt has led us to wonder about rigging up a sensor to indicate it having failed, before it all goes to engine heaven.

 

So what have people fitted? The car is a VX with QED pan and Caterham pump, retaining the standard oil filter housing. I think he is running a 35psi warning lamp/switch already.

 

Any recommendations?

 

Phil Waters

Zetec is in and running wink.gif

[Mike Bees]

I have an inductive proximity sensor (something similar to this) watching the 'spokes' on the scavenge pump pulley. It feeds a stream of pulses to a little box of electronics which lights a lamp on the dashboard when it doesn't see any pulses coming in.

 

Mike

 

 

Edited by - Mike Bees on 28 May 2002 11:06:37

[V7 SLR]

I am becoming more and more focussed on this issue...not because of the number of failures (which appears to be few and far between), but because I now have a relatively expensive engine and this seems such a simple thing to have engineered in by Caterham to begin with.

 

So, I looked at Mike's link which only gets me to a timed-out warning at RS. Any chance you could either email me a piccy Mike, or give me a description of what it was we were supposed to see on RS and I'll go and search for it myself (if they haven't discontinued it), please?

 

I posted a reply today on the Se7ens list to a message PC sent in, and have asked for any piccies he may have. Whilst I believe Mike's solution captures ALL modes of failure (if the pulley isn't turning, there's a problem no matter what caused it), I think it simpler to engineer a switch on the sprung arm that holds the tension pulley. The spring is of sufficient strength that if the belt comes adrift, the tensioner will move to it's fully-open position. It takes a good heave to pre-tension this pulley to refit the pump belt.

 

I just need ideas on how to begin to create a bracket. I have a lot of 3mm aluminium plate lying around at home (front panels off old rack mount computer kit) which could be pressed into service very easily, and there are at least 2 wires spare in the engine bay (not the engine loom though) which pass through to under the dashboard (one is intended as an oil pressure failure light), so I think the connecting up of it all will be easy enough. I just need ideas for the initial design.

[robmar]

V7 when you sort it out make 2 and I will have 1 smile.gif

 

rob

[V7 SLR]

So, you want a Marst-Inc patented aluminum (yankee spelling) bracket then ehquestion.gif

 

It'll cost you precisely NOTHING so there's no comeback if it falls off taking your belt with it. smile.gif

 

In fact I might make just one and give it to you to prove the solution for me. How's that soundquestion.gif

 

I'll have a look into it over the weekend... nag me next week.

[robmar]

sounds fine to me smile.gif

 

you will have to come down and help me 'install' it and maybe stay for a while

 

rob

[V7 SLR]

And the plan was formed..!!! teeth.gif

[Miraz]

I have a oil level sensor in my dry sump tank - in the event of a failure in the scavenge system the oil level will trigger a warning light before there is a drop in oil pressure.

 

Cost was very low - as I nicked the sensor setup out of an old deep fryer.

 

Miraz

[stevefoster]

There is no tensioner on the VX so a micro switch that way won't work.

I will look into using an optical sensor, the type with a channel that the belt can run it. No belt and a signal is made. A few components to trigger a mini relay and bingo light on.

Another way would be to use an optical beam / sensor in one that detects the holes in the pump pulley, light reflected by the pulley or not by the hole. No change and it gives a signal. Farnell's have just the things in their catalogue.

 

My warning light is now directly below my line of sight and shaded from the sun and is a 21W brake light intensity... I must see that no matter how much red mist there is.

[Swiss_Tony]

Steve

I would like to fit a similar thing to my vx.

Do you have any more details?

 

James

 

[EFA]

The time between scavenge belt failure and loss of pressure due to the tank emptying is very very short.

 

Really to trigger off an optical sensor will be very difficult to achieve relaibly, the crud which is inherent in this area of the car easily covering the optical sender or reciever and causing it to not register a belt failure.

 

The resolution to the problem is a pressure sensor in the return to the tank.

 

Miraz's idea is also very good.

 

Reagding alerting of the driver I can say that the indicator needs to be a lamp you regularly reference - in my car it quite often comes on for oil fuel pressure when the engine is idling. I would also personally suggest that the sensor is used to drive a relay to trigger the cars horn or cut ignition.

 

Getting the engine off in a few seconds is critical - if you are on full throttle you have even less time, perhaps only 1 second before damage occurs. (particularly on on systems where the belt drives the scavenge only, as the oil pump then pumps aireated oil into the bearings!)

 

My solution is to set the Stack dash up with proper oil pressure limits and gate RPM so then if you see an alert with an oil pressure wwarning posted you can get to the switch quick. The aviation type ign on/off switch I now have also definately contributed to a fast shut down.

 

I've lost a bet twice with no engine damage in either occaision

 

 

 

 

 

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[robmar]

Arnie - are you sure you want to cut the ignition?

 

imagine the scenario flat out around a corner, dry sump failure of some sort, engine cuts, car is now worse than having lifted, and potntial likely hood for lunching car and driver into barriers is high

 

I would prefer a lunched engine than a lunch car or a lunched me

 

rob

[Mike Bees]

Arnie wrote: "I've lost a bet twice with no engine damage in either occaision".

 

Once at Santa Pod and once at Curborough wink.gif

[EFA]

Now hear this Mr Bees......I was taking the springs in whihc you expressed interest (notice I don't say "yours") to the post office today. Now I'm going to keep your 25 quid instead.......

 

Robmar, if you do lose the lubrication to the bottom end you should not be surprised to find a thrown rod stops the engine rather quicker than cutting the ignition. An engine cutout will certainly ruin the corner, but is not that likely to put you in the armco. (you have to be going flat around a circuit corner when the belt drops off for a start!)

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[robmar]

but arnie that was my popint, flat out around a corner, what if it is ont he road?

 

but it is a fair one you make that a rod coming out is the same effect as cutting the ignition.

 

Do you really think there is only about a 1s delay from belt failure to lunched engine (serious question btw)

 

rob

[Mike Bees]

eek.gif

 

I suggested to Karl once that the M3D could have an oil pressure input and a user-configurable 'shut-down' setting. I suspect that it's near the bottom of a very long list...

 

Mike

[Alex Wong1697456877]

Full throttle at curborough. Alternator belt found near startline later. Oil light comes on about 5 seconds into the run as the tank empties into the engine. Light flashing to lifting off - about 3 seconds. (with 2 bursts of 7000rpm+ having been attained) Time from then to engine off - another 3 seconds. Engine inspected this winter (admittedly from the sump end and not head off) and everything looks ok. Engine seems to be running fine. (touch wood)

 

Very lucky, but I think that there are a few seconds grace before it goes tits up.

 

Alex Wong

www.alexwong.net

www.slipstream-trackdays.co.uk

         _________

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Edited by - Alex Wong on 30 May 2002 11:01:45

[robmar]

Alex - is that more to do with the robustness of the VX Vs a K

 

(BTW I have a K before anyone asks wink.gif )

 

seems to me the only way to reduce this is have some sort of redundancy int he system, dual belts/ pulleys?

 

rob

[EFA]

Robmar,

 

Is if you are hard on the gas near the redline yes.

 

If you are driving more gently or on overrun the you might get away with 15s before you damage the engine - under gentle conditions you might only run the bearings.

 

I basically have a F**king bright LED which gets my attention immediately at the time of any alert/failure. Bottom line is you need something you'll notice very quickly. Anyone who claims they watch their oil pressure gauge to catch events like this is going to find they are wrong when it happens!

 

Fat Arn

Visit the K2 RUM siteid=red>

See the Lotus Seven Club 4 Counties Area Website hereid=green>

 

[Miraz]

Out of curiousity....

 

Does anyone know what the expected flow rate of the oil pump in VX or K is?

 

something expressed in liters per second per 1000rpm would be useful...

 

Reading some of the posts here it would seem that around 3-4 liters per second @ 7000 rpm is not too far wrong.

 

Miraz

[robmar]

Arnie - i agree with the bright light warning

 

must get around to wiring mine up to my redundant shift light on the dash

 

maybe a quick electrical pulse to the drivers arse might get the correct level of attention as well teeth.gif

 

rob

[Peter Carmichael]

If you have a dry sump set up which retains the normal pressure pump, then you have a few seconds grace and if you monitor for the presence of the belt you can switch off in good time. If you have a belt driven pressure pump then the belt failure will immediately lose your oil pressure - you have much less time from first indication to shut down.

 

Wet sump systems, for all their shortcomings, have fewer points of potential failure. This is why dry sump systems are more fuss than they are worth for the casual user.

 

Peterid=blue>

eek.gifSecond loser, Class 5, Curborough May 2002id=red>

[Alex Wong1697456877]

Rob,

 

Mine's wired up to a stack ultra bright shift light and as it's driven by the SPA gauge, it not only comes on but flashes at me. The nice thing about this is you can digitally set the low pressure warning to whatever you want.

 

Alex

 

Alex Wong

www.alexwong.net

www.slipstream-trackdays.co.uk

         _________

/ __ __ /

___ _//__T/__/_ ___

/ (_) (_)/

/`-'/o/ _______ /o/`-'/

/ /// ( VDU7X ) // /

/___/--_________/--/___/

 

[V7 SLR]

A strobe would be good... unless you're prone to fits. Mind you, if my engine grenaded I think I'd throw a fit.

 

Long weekend coming. I'll have look at suitable bracketry. I've also emailed Dave and Karl at Emerald asking what they think of an ECU "interruption", but as I was writing it I thought that an ECU-controlled rev limiter set to cut power is only the same as cutting ignition altogether. What's actually needed is a shutdown and a clutch "in" at the same time to kill the engine completely. If you cut ignition and then coast to a stop, you'll kill the engine anyway.

 

You need a heads-up display which alternates between saying "DIP CLUTCH AND KILL ENGINE" and "IT IS NOW TIME TO EXCERCISE YOUR WALLET MY SON".

 

Edited by - V7 SLR on 30 May 2002 12:19:24

[stevefoster]

ok, back to an inductive pulley registering device.

I have ~6lts of oil (more if I want) to empty in to the engine before the tank runs dry if the scavenge pump belt fails. This must be a reasonable warning time.

As pointed out a belt driven pressure pump looses pressure all at once.

 

RKE reckons ~0.5secs at full chat if you loose all oil pressure.

 

Out of interest does anyone know what an engine full of 6-7lts of oil would run like? Blue smoke warnings? Less power? Other noticeable signs? Would it run fine as a wet splash lubrication system?