Oil Pressure Switches - alternatives ?

[937carrera]

OK, so all us flat 4 owners have the same oil pressure switch fitted, whether it's a WBX or an Aircooled. It comes on at a nominal 0.25 bar. https://www.brickwerks.co.uk/brickwerks ... -switches/

Now, that red light is great for telling us that the electrical side is working when we switch the ignition on, but if it comes on while driving, by the time we see it then it's likely the damage is already done and it's too late to avoid an expensive bill.

I was thinking about this after answering a question here. http://forum.club8090.co.uk/viewtopic.php?f=37&t=166272

Has anybody tried fitting a higher setting low pressure warning light, say 0.7 bar as fitted to Golfs and T5 https://www.vwheritage.com/038919081c-o ... n-vw-spare , same M10 fitting. Earlier warning of a problem, but still shouldn't go off on tickover with a reasonable engine, even when the engine is stinking hot.

Those with the DOPS system have extra protection when the engine is above 2000 rpm, this gives additional protection at lower engine speeds as well.

Thoughts / experiences

[bigbadbob76]

Sitting on my desk at work is a 100psi pressure gauge with a built in switch contact on the gauge needle, yours if you want it.
I kept it cos it looked like it would be useful but I'm a hoarder of stuff like that.
You could wire it to the low pressure switch contact wire and set it to any presure you like.
I think it's got a 1/8th bsp thread on the back.
You could even reduce it's sensitivity as your engine wears and you get sick of the light coming on at idle.
I'll send you a pic on Monday if you're interested.

[937carrera]

Many thanks for the offer Bob. In reality I think it would just go from your pile of useful but uninstalled bits to mine

The reason I posted the question was more generic. I see the red light more as being more of a "too late, you're stuffed" light than a warning light. After taking my own oil pressures I'm convinced a higher pressure rated switch could be installed without it going off unnecessarily.

[dave friday]

I'm sure someone posted a two switch design ( on here)..what about a t piece with the low pressure switch and a high pressure switch ( 2 bar?) + a 12 volt led?

[937carrera]

I think that would be adding DOPS functionality to early WBX and Aircooled vans.

I'm just asking about a higher rating for the "low" switch

[T25Convert]

My 2p's worth.

Will probably be fine if your engine is in good condition, and doesn't have rubbish oil pressure at idle when hot.

I suspect that when running full pelt, even if oil pressure drops to 0.7bar, damage is probably also already done (albeit not quite as much) hence the later BOD type setup to try and give that early warning that something is amiss at speed. This triggers at 1.8 bar.

At idle, if it flickers what do you do? First time, you stop and check everything. on the fifteenth time you think, oh bother, its doing it again, but its okay, I have that 0.7 bar switch, so it probably wouldn't be on if I had the original 0.25 bar one in so you ignore it anyway.

Low oil pressure at idle is a cause for longer term concern I think - its showing you a rebuild is on the cards at some point, but not here and now. New oil, thicker grade and a slightly higher tick-over can mask the symptoms for many more miles - i.e. its not a catastrophic thing.

So in short, I'm not sure it will gain you anything. If you are concerned, a pressure gauge would probably be a better investment.

[bigbadbob76]

I see the red light more as being more of a "too late, you're stuffed" light than a warning light.

Maybe not stuffed, When mine spat it's coolant out and I stripped it I was surprised how little wear there was.
I'd had the 0.25 bar led coming on at hot idle for as long as I'd had the van, apart from just after an oil change and for a few 100 miles after that.
When it spat it's coolant I had the led on while driving the short distance to get the van safely off the road and the coolant temp was through the roof, it didn't wreck the engine.
I guess it depends on the reason for the low oil pressure, if it's because you've let the oil level get too low or your filter has fallen off and it's drawing air then you're 0.25 bar switch is going to tell you just as quickly as a 0.7 bar one.
If it's because of wear then my experiences suggest you can run it for a while with the led coming on at hot idle, but not when driving, without wrecking the engine beyond re-buildability.