Oil Gauge (mechanical vs electronic)

[Keir]

Hello all,

While the interior and dashboard is out of my 1982 Turbo Esprit, I'm taking the opportunity to sort out some issues, mostly messy wiring but there's also another concern.

I'd like to replace the oil gauge with an electronic equivalent. The previous owner of my car experienced oil leaking from the gauge input pipe which wrecked the carpet. I know that this is not uncommon. I'm also not keen on the concept of an oil pipe coming into the cabin at all, it seems like a fairly crude and hazardous solution.

Having said that, I have read that a mechanical oil pressure pipe and gauge is very responsive and accurate compared with an electronic system. Can anyone comment on that? Has anyone converted their car to an electronic system? Is it possible to fit an electronic sender at the point on the engine where the existing pipe starts its long journey?

I'd be very interested to hear about people's views and experience of this.

Thanks,
Keir

[ChrisJ]

A colleague at my previous work place converted all of the Smiths instruments in his Jensen Healey with the electronic equivalent - directly from Smiths.

I've not had a problem with any of the gauges in my Esprit and I much prefer them to the crappy VDO ones in my Excel - which bounce all over the place.

[snowrx]

I feel the mechanical responds faster, but I'm sure it depends on the manufacturers design.  Theoretically the gauge could respond immediately, but there is usually some damping in the system to prevent jumpy or vibrating needles (or drivers!).  If you've ever got into a car and watched the gas gauge slowly climb to Full after a fill-up , you've seen this.  

With a proper adapter you can screw the pressure sensor right into the gallery cover where the existing gauge tube and turbo oil line connects near the starter. 

But one advantage of fitting an electronic gauge is you can also fit a SPDT switch and a second sender, and display two items on the one gauge. I run EFI, so I can switch between Oil and Fuel pressures on one gauge and Water and Oil temperatures on another.  Just a plus if you're constrained on dashboard space, which we are in most modern cars.

[The Real Stig]

Will it be possible to add a warning light to the mechanical/hydraulic gauge?

It could save you a lot of money discovering a major oil leak in time (been there, done it).

[snowrx]

Warning light at the simplest just requires a normally closed pressure switch tee'd into the oil galley, specified to open at whatever minimum pressure you're comfortable with.  Some electronic senders also include a second on/off terminal to trigger a low pressure light. 

[drdoom]

This is much easier said than done. Typical oil feed related trouble with the Esprit has been the rapid failure of big end bearings through very momentary loss of supply at the pick-up, when air gulped instead of oil gets blown across bearing surfaces under pressure at the same time the bearings are under load due to hard running. By the time a lamp has shown warning one would have little, if any, time to back off and spare the damage in my opinion. Perhaps if the switch setting is at the top end of the expected pressure range - ~ 65psi - then there might be a safety margin, however the lamp would then be lit at all times except for the upper revs so not really helpful.

Wise practice is surely to keep watch on the oil levels in sump, and in the tank for those running dry sump. Never wind out the motor if there's any doubt as to adequate levels, particularly when cornering hard and especially when turning right.

[Nelly]

My S2 has got an electronic oil pressure gauge and sender which a previous PO installed, so I can't be much help as to how it works but am happy to supply photos if you want o see what it looks like.

[eeyoreish]

From my (recent) adventures with oil pressure on my '90 N/A...

The oil exiting the outlet side of the pump travels down to the cooler at the front of the car then returns to the engine via the filter housing and finally enters the oil gallery where the sender (and Turbo oil feed if you have one) are. Hence the sender is in the last part of the engine to see pressure on startup.

The electronic gauge does tend to have a few seconds delay  (3-4 in my case) in showing presssure at the gauge. The sender is a Lotus specific part (about £80 from SJ) as it also triggers the oil pressure warning lamp, which is set not to illuminate below (I think) 1500 rpm. That's presumably to allow for the short delay in the sender seeing and registering pressure at startup and so as not to cause alarm. The factory sender is oddly 0-10 bar whilst the gauge is 0-7bar which probably doesn't help.

Both my engines are HCs and although the TE has a mechanical gauge I haven't run it yet. However my friend @Kevin Wheeler did say his mechanical TE gauge registers pretty quickly on startup.

Not sure if it's worth the faff and expense of swapping mechanical to electronic, especially of the mechanical variant already works well and potentially gives a more immediate reading than the electronic version.

[Kevin Wheeler]

Just checked. Mine takes about 2 seconds to start to register and a further three seconds to climb to 50-60 somethings on my gauge.

Seems perfectly reasonable to me!