19 replies to this topic

[JonBooth]

Hello,

I know this has been asked before but I just wanted to get everyone's opinion on oil pressure gauges. Are they really necessary (I know if you rely on the warning light, the engine may already be dead)?

Another question is whether to go mechanical or electrical. Both have advantages, the electrical has the added advantage of not having to plumb a pipe into the cabin but are generally not as accurate. The biggest problem I can see with the mechanical ones is that it must be a bit of a nightmare if you ever need to remove the dash.

Any thoughts would be great. Thanks in advance.

Cheers,

Jon.

[Carlos W]

An oil pressure gauge is probably advisable and could save you from an expensive bill!

I'm sure I've read about oil pressure switches which make the light come on at a higher pressure possibly preventing damage but a gauge shows the oil pressure being too low as well as too high and too high can do damage as well

[Wise Old Elf]

I have always use a mechanical gauge. Its only one pipe.

http://www.ebay.co.u...=item43b6e86130

[Badboytunes]

Id have one all day long. Mechanical ones are not that dificult to fit and posed no problems when removing the dash.

[mattbeddow]

Ditto getting a mechanical one. So long as you dont run the engine with the dial off, the pipe shouldnt pose a problem when removing the dash.

But dont do what i did, take the dash off the fix a loose wire to the rev counter, start the car to check its fixed and forget to reconnect the pipe to the guage, oil all over my brand new carpet

[leroy26]

is it generally easier to plumb in a mechanical one than a electric?

[Gremlin]

I've got mechanical, its just one pipe screwed onto the back, and it just replaces the switch in the block. If you leave yourself plenty of slack, when you take the dash off, it will just take up the slack, you can always unscrew it which isn't a problem. Also if you pull the wire to the old switch, you have a good 12v feed which in use for a light for example, the warning light in the dash is on, but say there's a problem and it shorts, the light goes out, which is handy :)

[mattbeddow]

Alternatively, get a t-piece (i think thats what its called) and then you can keep using the switch as well as the guage

[dklawson]

is it generally easier to plumb in a mechanical one than a electric?

I would not say easier, I would say "different".

First, it is no harder to remove the dash where a mechanical gauge has been fitted than electrical. In both cases you would need to pull the dash forward enough to disconnect the gauge (spade lugs and a lamp on an electric installation, a small fitting and a lamp on the back of a mechanical installation).

In both cases you will run "something" (wire or oil line) from the dash to the engine. As mentioned by Mattbeddow, on the engine block you will either replace the existing pressure switch with the electrical sending unit for your guage OR with a pipe fitting for the oil pressure gauge. You can use a "T" to run both the existing warning light and the gauge. Keep in mind that you will NOT connect an electrical gauge to the pressure switch. You MUST use the appropriate sending unit for the electrical gauge.

With the electrical installation you have to source a 12V supply for a light, power for the gauge, and an earth for the gauge. The sending unit wire is generally easy to run as it will be very flexible. There are a few Smiths electric oil pressure gauges. If you opt for one of those, the required power will not be 12V but 10V. This means you would connect the gauge to the output of your existing voltage stabilizer. That can complicate things. Aftermarket electrical gauges will have an internal voltage stabilizer and will be easier to install than Smiths.

With the mechanical gauge you will have to supply lamp power and an earth but no other electrical connections. There are at least 3 possible method of plumbing the gauge to the block. There are inexpensive nylon tubing kits, copper tubing kits, and stainless braided hose kits (listed in increasing cost and preference). The nylon kits work OK but the plastic hardens over time and is easily damaged. The copper kits last a long time IF you loop the extra tubing into a spring shape to absorb engine vibration between the block and firewall. They are obviously more robust than the nylon and only cost a little more. The braided hose kits are really nice and very durable. Typical construction has a PTFE tube inside a protective stainless overbraid. They are as flexible as the nylon and more durable than the copper. However, they will cost quite a bit more.

I prefer mechanical oil pressure gauges for a couple of reasons not mentioned yet. Mechanical gauges respond faster. Some (but not all) mechanical gauge have more degrees of sweep. While the needle of an electrical gauge may only move 90 degrees across the gauge face, many mechanical gauges will have a needle that sweeps 270 degrees around the face. This allows for larger and easier to read scale graduations.

Regardless, an oil pressure gauge is very reassuring (to a point). I do want them in my car I drive but almost everyone who installs one for the first time then starts asking if their car's particular oil pressure is "OK" or if they have too much or too little oil pressure.

[JonBooth]

Thanks for all the replies, I think I will go for a mechanical one.

Cheers,

Jon.

[wardyxxx]

Where did you guys feed your mechanical pipe through?

[dklawson]

Since my car is a Mk1 the oil pipe/tubing is easily fed through the large hole in the firewall and directed over/behind the dashboard to the gauge. I don't know how this is handled with dashboards on later cars but I would assume the feed path would basically follow the same route as that of the speedometer cable until the tubing is inside the passenger compartment.

[wardyxxx]

I'm not even sure where the speedo cable passes through the bulkhead on a 96....

[KernowCooper]

I used a stainless braded hose on mine as its far better construction than the cheap nylon pipes are more resistant to damage, and I'd also get the 22psi oil switch far safer as you cover both ways then

[MiniLandy]

The 22psi switch has been out of stock for ages now.