K series - Mechanical oil pressure and temperature guage

[Toby S]

https://www.demon-tweeks.com/uk/racetech-oil-pressure-oil-temperature-dual-gauge-247037/

Hi all

I've found the electrical oil pressure gauge on my 1992 1400 Supersport always to be somewhat erratic and currently seems to be all over the place and would guess the sender may be the problem. I know a lot of people recommend replacement with a mechanical gauge and although saw a "Caterham kit" on demon tweaks for a pressure gauge, I  also saw a dual oil pressure and temperature gauge per link above.

Does anyone have any experience of these - any good or a waste of time

How do you plumb in the temperature bit - through a T piece where the current electrical sender is and take both the pressure and temperature capillaries from there or a sump plug conversion for the temperature bit. Neither seems ideal - the former as I would guess this could affect the readings of one or both, the second due to the exposure of the sump worries me, with the potential for the capillary tube to be damaged/ sliced from objects being thrown up

Any thoughts welcome

[Tazio]

Usually the oil temperature bit is used on dry sump systems where there is an oil temp sensor fitted in the tank.

[revilla]

On engines that I build I usually install a standard water temperature sender on the oil filter housing for use with an oil temperature gauge.

That way you get the temperature of the oil as it enters the bearings.

Theres usually a little plug you can remove with a hex bit and then the standard sender matches the thread nicely.

The oil filter housings do vary slightly, there are several designs with different fittings but there's pretty much always one suitable for this purpose and it's up on the top of the housing where it isn't vulnerable to damage.

[Toby S]

Thanks Andy - that seems a more suitable place.

I've got to do a full oil service anyway (oil, filter and baffle - let's not start on the latter) over the next couple of weeks so I'll have a proper root around then to see if I can see any extra hex plugs on mine.  

[7 wonders of the world]

The ideal place for the oil temp sender is where is registers peak oil temp, so in a DS system this is in the sump trough pre scavange pump.

[Toby S]

Thanks 7WOTW - in a wet sump the only way I can see through to the sump would be through the drain plug, and as noted in #1, both the pressure and temp parts of the gauge in this example work on capillary tubes with I assume the measuring sensors being in the dial itself - although I'm not too bothered with an electrical sensor off the drain plug, a capillary tube off there seems to be asking for trouble in such an exposed area - could become severed and you'll lose your oil (maybe slowly but could happen).

However you have made me think about how accurate the temp reading would be in such as set up - surely there would be some temperature loss in the tube between the sump and the dial especially in winter.

I may be talking balls (I'm an accountant after all and use to that !!), so maybe the ideal system would be a mechanical pressure gauge and separate electrical temperature gauge.

Alternatively I could just stop fretting about the actual reading on my current worry gauge and take comfort that at least it flicks 2 bar between low and high points when revved and it just under reads a bit (I reckon between 0.5 and a bar)

[OldAndrewE]

I can't advise you on your particular engine but a capillary temperature gauge has a temperature sensing bulb that is inserted in the "hot" area via an adaptor and the resulting expansion/contraction of the medium inside is transmitted to the instrument.  The capillary tube does not contain your oil.  In the sump the capillary tube is vulnerable to damage but you will not lose your oil.

The tube to a mechanical pressure gauge does contain oil.

This is an old water temp gauge

[John Vine]

...so maybe the ideal system would be a mechanical pressure gauge and separate electrical temperature gauge.

I agree.  I think the simplest solution would be to fit a mechanical OP gauge, and then follow Andrew's advice for oil temperature (#3).  If you then connect the oil temp lead to the standard water temp gauge via a switch, you can toggle between the two temps on the same gauge.

JV
 

[p.mole1]

Use a mechanical oil pressure gauge and then fit an oil temperature sensor into the oil filter head as Revilla stated.

Then you fit a switch on the dashboard and you use the standard water temperature gauge to switch between water and oil temperature. Just make sure you use the correct sender.

[StevehS3]

Any thoughts on using the sensor fitted to the Apollo tank? Is that a good or poor point of measurement?

[Wrightpayne]

My view is that any oil temp measurement is better than none. Apollo, bell tank, easy clean tank, filter head will all give a fairly accurate measurement.

[revilla]

I reckon at different points in the circuit you'll see small differences, but at the end of the day most of what you need to know is whether the oil temperature is basically under control and whether it's behaving differently to how it has behaved in the past. I've found the temperature gauges not to be that accurate anyway, my own reads about 5°C low on both oil and water, so it's not worth sweating too much over the exact number. A gauge anywhere, once you're used to how it normally reads, will tell you if you're over-cooling in the winter, over-heating on track, running hot because you've over-filled it and the crank is thrashing the oil etc. As Ian says, any gauge is better than no gauge.

[John Vine]

I used the Apollo take-off in my old K.  Seemed to work ok. 

In my R400D (wet sump), I fitted the sender in the big blue sump plug:

Assuming that both senders are identical, one advantage of using a single gauge for both readings is that they are comparable.

JV

 

[StevehS3]

#11 and #12. Thank you - makes sense. I agree it is relative changes to the normal that is most informative. My Apollo kit came with the sensor in the tank and the switch and wire so I will get it done.

[Wrightpayne]

Steve,

If you are sourcing a toggle switch I used an APEM switch. I've changed all of the toggle switches to this brand as a) the switch lever is metal and less likely to get snapped off (though not so good in an accident) and b) they seem much better quality than the originals.

 

Ian

[StevehS3]

Thanks Ian. 

[John Vine]

Re #15:  I used a CC indicator toggle switch to match the other (plastic) toggles.  As it happens, that was an APEM:

JV

[StevehS3]

I want to hide mine under the dash somewhere. Hopefully in a place where it isn't visible but can be reached with the harness on - if such a place exists!

[Bob L]

Andrew,

Did you use a brass washer and / or sealant on the threads of the temp sender.  If yes, what sealant?

Thanks, Bob 

[revilla]

I used a copper washer. Although the thread seemed to match the sender, the taper didn't really go properly tight before it had screwed fully home. You might find otherwise, in which case a little plumbers PTFE tape around the thread of the sender should suffice. See how it feels when you come to screw it in.

[Bob L]

Thanks Andrew