Oil Guages

[Kokonut]

Engine :: Perkins 4.107

Can someone tell me please, if the 2 gauges in the image serve the same function or not?

[Wotname]

Well they both measure pressure and have the same scale however to know exactly what they are measuring the pressure of, you will have to trace where their sensors are located.

[kenbo]

Going out on limb here but I believe the one one the left has a sender, i.e. electric and the one one the right may be mechanical, i.e. hard plumbed to an oil gallery somewhere on the engine. Both are labeled oil pressure but as wotname said you'll have to chase the connections to be sure.

[Checkswrecks]

Something is either:
Redundant and possibly adding a potential point of failure or confusion.

Or

Mis-labeled and not engine oil prx.

[Kokonut]

I have uploaded 4 images showing the rear of the panel.

Interestingly, only the top Oil Gauge was connected.

Starting from the top left image, this is looking down the back of the Gauge Panel. You can see a tube with intermittent oil present in it connected to the Gauge. This tube leads to the engine on the next image. I'm presuming this must be the Oil Pressure Gauge then?

I really need to track down a Manual for this engine.

Maybe, the bottom gauge is broken or maybe I can swap the tube over to it? Or, I can just remove the disconnected Gauge and replace it with perhaps, a water temperature gauge.

This now leads me to the 2 images at the bottom row.

The left one shows shows a similar tube with redish fluid inside it. This tube has been crimped, and is not connected to any dial at present.

The only red fluid in the engine that I know of is the water coolant.

In fact, the image on the bottom right shows where the mystery tube connects to on the engine. This is around the top, close to the gearbox. Is it possible that this tube was connected to the bottom gauge, measuring some pressure in the gearbox?

As you would have spotted a mile, I am no mechanic, but I sincerely hope I can amass some knowledge from this forum, plus what I can filter off the web to make sense of this all.

Very much appreciated (as always).

[Wotname]

It's a fair bet the red fluid will be ATF (automatic transmission fluid) and most likely is connected to the gearbox.

Easy enough to tell the different between ATF and coolant. The former is a type of oil and the latter will be water based.

[Wotname]

Originally Posted by Kokonut

........
As you would have spotted a mile, I am no mechanic, but I sincerely hope I can amass some knowledge from this forum, plus what I can filter off the web to make sense of this all.

Very much appreciated (as always).

Although you haven't asked, if you plan on changing anything, I believe all engines need the following (in order of important)

1. Oil pressure alarm - sounds an audile alarm tone and illuminates a light when the oil pressure is low.

2. High coolant temperature alarm - sounds an audile alarm tone and illuminates a light when the coolant temperature is low.

3. Coolant temperature gauge - monitors actual coolant temperature

4. Engine RPM

5. Engine hours

6. Oil temperature gauge - monitors actual oil temperature

1 & 2 are commonly called "idiot lights" and on a boat, they should be combined with an audile alarm.

4 & 5 are often combined in one gauge

There are others but IMO, the first 3 are essential, 4 & 5 is important and 6 is nice to have.

[Orion Jim]

Originally Posted by Wotname

Although you haven't asked, if you plan on changing anything, I believe all engines need the following (in order of important)

1. Oil pressure alarm - sounds an audile alarm tone and illuminates a light when the oil pressure is low.

2. High coolant temperature alarm - sounds an audile alarm tone and illuminates a light when the coolant temperature is low.

3. Coolant temperature gauge - monitors actual coolant temperature

4. Engine RPM

5. Engine hours

6. Oil temperature gauge - monitors actual oil temperature

1 & 2 are commonly called "idiot lights" and on a boat, they should be combined with an audile alarm.

4 & 5 are often combined in one gauge

There are others but IMO, the first 3 are essential, 4 & 5 is important and 6 is nice to have.

Number 6 is interesting. I have an oil temp. gauge in my Corvette but I’ve never had an oil temp. gauge in any of my boats. Just a low oil pressure alarm and an oil pressure gauge.

[jimbunyard]

The connected one is the engine oil pressure gauge, the unconnected is the transmission oil pressure gauge.

Both are what is known as 'manual' type gauges, they 'manually' measure the pressure inside the gauge, usually via an elegant little device called a Bourdon tube. Many people prefer them because they offer a more direct measurement with less intermediary sources for measurement error.

Their downside is if the tube carrying the pressure to be measured breaks, the oil spews everywhere. The routing, installation and support of the tube are also initially more cost and labor intensive.

The alternative is an electric gauge, used with a pressure sensor that is matched electrically to the gauge. The sensor is basically a pressure controlled variable resistor, which is why the gauge and sensor must be matched.

Whilst the sensor can fail and let all the oil out of the engine, this is much less common than the tube failure of the manual gauge.

But the common electrical problems inherent in any electrical system, especially when combined in the marine environment, make many people, including me, prefer a well-engineered manual gauge installation.


Regarding your current setup, the previous owner thought that the gear pressure was important enough to monitor, though in my experience this is a bit unusual on small boat engines. The monitoring of gear pressure could give an indication of potential problems, but (unless you have an automatic transmission) it's a bit more likely that problems will come from worn clutch discs, which will be self-evident, than a worn oil pump. If you have the space though, it's one more layer of defense.

If you don't have the room, and don't have an engine temperature gauge, provisionally, I'd toss (figuratively, I'd actually keep it as a spare) the gear pressure gauge and install an engine temperature gauge. And properly plug the pressure outlet on the gear. And change the nylon oil pressure tube to copper. The two times I can remember having 'line problems', both were with the plastic lines...

[skipperpete]

It’s a little confusing, neither of those gauges should be reading system pressure on a Velvetdrive gearbox , the pressure at the connection point shown in the last pic is normally over 100psi at idle[emoji848]