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Vanagon Nut Samba Member
Joined: February 08, 2008 Posts: 10347 Location: Sunshine Coast B.C.
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Posted: Sat Jun 25, 2016 12:01 pm Post subject: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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So for folks doing an engine conversion on a bus without the L
board installed, but want one (have "we" run out of bone yard L boards yet?),
I think something similar might be made with relays and possibly
repurposing seat belt buzzer but....
If an oil pressure loss causes the "high" oil pressure switch to open, wouldn't
that typically happen at higher RPM's ? i.e. why does the L board also need to
see RPM's at 2K + ?
Looking at the grey switch specs, the upper end bar rating is about 11-15 PSI.
http://www.van-cafe.com/home/van/page_357_241/oil-pressure-switch-grey-.75-1.05-bar.-mounts.html
Neil. _________________ 1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
VE7TBN |
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AtlasShrugged Samba Member
Joined: October 30, 2008 Posts: 1605 Location: Decatur, Ga. USA
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Posted: Sat Jun 25, 2016 12:39 pm Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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The high pressure oil switch is "closed" to ground at its calibrated psi setting..and the logic board fires the alarm when above 2000 rpm if the circuit is open.
My thinking is the modest amount of oil pressure the WBX engine makes when hot running 10psi+ is the warning point..you need that additional warning at 2000rpm. Unlike the 1.9 engine with only a .3 BAR switch..by the time you get down to .3 BAR driving down the road and the warning lamp comes on..you have lost the engine.
For those with some ingenuity..you could make a logic board as a replacement. Relays would work but you need that input RPM feature. |
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Vanagon Nut Samba Member
Joined: February 08, 2008 Posts: 10347 Location: Sunshine Coast B.C.
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Posted: Sat Jun 25, 2016 1:01 pm Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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AtlasShrugged wrote: |
The high pressure oil switch is "closed" to ground at its calibrated psi setting..and the logic board fires the alarm when above 2000 rpm if the circuit is open.
My thinking is the modest amount of oil pressure the WBX engine makes when hot running 10psi+ is the warning point..you need that additional warning at 2000rpm. Unlike the 1.9 engine with only a .3 BAR switch..by the time you get down to .3 BAR driving down the road and the warning lamp comes on..you have lost the engine.
For those with some ingenuity..you could make a logic board as a replacement. Relays would work but you need that input RPM feature. |
Thanks for the reply. Ok, I see. The higher BAR rated switch covers a different
failure mode; it's designed not so much to warn against a pressure loss at
higher pressure operating range, it's built to warn while at highway or similar
speeds. Thus the need for the tach input.
If treated as a separate system, it seems one relay could at least make a
buzzer go off if pressure dropped below the grey switch spec (switch opens, lifts
ground) but the buzzer would go on every time it was energized by 15 circuit.
Was thinking 2 relays might solve that but I'm not quite there yet.
Regardless, it wouldn't work as originally designed. I bet one of those
Raspberry or Arduino things could be made to do this?
https://www.arduino.cc
Neil. _________________ 1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
VE7TBN |
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Butcher Samba Member
Joined: December 05, 2015 Posts: 1285 Location: Right Here
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Posted: Sat Jun 25, 2016 5:46 pm Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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Vanagon Nut wrote: |
why does the L board also need to
see RPM's at 2K + ? |
Because it's German and they rarely do something simple. Heck, some of the new cars have eliminated the dipstick and put a sensor in the pan.
Simple and German sometimes to not work together in harmony. |
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Merian Samba Member
Joined: January 04, 2014 Posts: 5212 Location: Orygun
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Posted: Sat Jun 25, 2016 8:08 pm Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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I guess that's where one might start putting a load on the motor
it must connect to the pulse counting circuit in the tach(?) _________________ .... |
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MarkWard Samba Member
Joined: February 09, 2005 Posts: 17014 Location: Retired South Florida
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Posted: Mon Jun 27, 2016 5:48 am Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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VW started using this system essentially to warn people to check their oil level. VW bought quite a few long blocks under warranty back in the late 70s. This coincided with the proliferation of self serve gas stations. The rpm and minimum pressure was a method that would give you a warning that would not be so intrusive.
On the race car I run a 30 pound oil switch. It is connected to a 1 inch high intensity red lamp. Coming off track it is common for it to be on. It is there only to backup the gauge. There is no relay. The switch completes a ground turning on the lamp when the pressure drops below 30 psi. Very simple. The idea is to hopefully catch a mechanical problem before it gernades. _________________ ☮️ |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22568 Location: NYC/Upstate/ROW
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Posted: Mon Jun 27, 2016 6:34 am Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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I have the best kids in the world, who, as part of driving privileges, have to check any car they drive once a month, under the hood. The other thing they have to do is look under the car before/after each drive for fluid loss.
If you are diligent about keeping oil in it, you can drive with only a low pressure oil sensor and not worry about the high rpm side. _________________ .ssS! |
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?Waldo? Samba Member
Joined: February 22, 2006 Posts: 9752 Location: Where?
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Posted: Mon Jun 27, 2016 8:03 am Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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Vanagon Nut wrote: |
I bet one of those
Raspberry or Arduino things could be made to do this?
https://www.arduino.cc
Neil. |
Yes, I'm sure that would not be all that difficult. I think that if you used an oil pressure sender (variable) rather than switch, coupled to an rpm input you could have it alert you at any time it dropped into an alarming (pardon the pun) condition. You could have multiple rpm/psi triggers rather than just the two of the stock warning system. It would also be easy to add the engine temperature input if desired.
I have been planning on revamping the heater controls as an arduino projectin order to make them function in a more 'normal' manner... |
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Vanagon Nut Samba Member
Joined: February 08, 2008 Posts: 10347 Location: Sunshine Coast B.C.
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Posted: Mon Jun 27, 2016 10:16 am Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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^^
it sounds like you're way ahead of me on that stuff Andrew but my gut told
me it might be possible. Thanks for the thoughts on that.
Mark: cool. Yes. Simple would be best. From my POV, am thinking what could
be made to work with the OEM design of a given "modern" engine. i.e. I'm sure
VW inlines, VR's etc aren't the only engines that use 2 oil switches.
Very interesting insights on self serves and VW's actions.
Abscate: in a perfect world people would check their fluid levels. Being a WBX
owner of late, I've been forced into doing so. I would suggest that at least
50% of the Vanagon owners out there aren't so diligent. _________________ 1981 Westy DIY 15º ABA
1988 West DIY 50º ABA
VE7TBN |
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Merian Samba Member
Joined: January 04, 2014 Posts: 5212 Location: Orygun
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Posted: Mon Jun 27, 2016 11:16 am Post subject: Re: Dynamic Oil Pressure L Board: 2K + RPM Really Needed? |
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you either use a circuit to count pulses (maybe with some conditioning) or convert the pulses into a ramp voltage which you can trigger off of
been a while so I have no idea which would be easier, tho I like to outfit my Glocks with Schmitt triggers _________________ .... |
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