Combined oil temp & pressure gauge

[TomB]

While I’m finishing a few bits off from my rebuild due to the obvious enforced delay, my mind has turned to wondering about fitting a combined oil / water temperature gauge in place of the standard water only gauge. 

My car is 1996 VDO gauged K series. I have a dry sump with a twin terminal pressure sender for the standard gauge and oil pressure warning light on the dash. 

Some searching here seems to suggest that the more common is a combined oil temp/ pressure gauge. I guess this is good as it gives a single instrument  for the key oil parameters. 

I’ve also read a bit about fitted a toggle switch to flick between oil and water temperature on the standard temp gauge. I guess this is the cheaper option. But how do I fit a oil temp sender  and where? I’m not up for taking the sump off and drilling tapping a new hole. 

So, please tell me about your set ups and what you’ve done to achieve this. 

Cheers, Tom

 

 

[7 wonders of the world]

Depending which DS set up you have you should have access plug on the sump pfor the gauze etc drill and tap this a it puts the sender in the oil stream in the hottest place.

[SLR No.77]

The usual location for the temp sender on the K-Series belltank is the near-side (left side) of the tank towards the bottom, IIRC it's not far off level with the end of the passenger footwell. Easy enough to take the signal from this to a toggle switch on the dash.

Stu.

[7 wonders of the world]

The problem with hve the sender in the tank is you never see the peak temperature - which makes it a little pointless, 

[TomB]

Is that a predrilled & closed of hole, or is it a drill & tap job? 

[SLR No.77]

For a non-competition application it's a perfectly sensible location to put it though ... there's already a threaded hold to take the sender. If looking for absolute accuracy then yes there are likely better locations, but pretty pointless without a better gauge as well.

[7 wonders of the world]

Is there not a sump plug for the strainer though.... minimal effort to do the job properly

[SLR No.77]

In the K-Series dry sump there is no access or sump plug for the gauze. The gauze is contained in-line in a sleeve which is part of the scavenge outlet, hence the sender being fitted directly into the tank.

[Wrightpayne]

The bell tanks, as Stu suggests, are usually tapped already, with the same thread as the water temp sender on the K.

My car currently has the easyclean tank. A seven acquaintance, who is a professional fabricator, made and welded in a boss for me.

 

[7 wonders of the world]

I realise the tank is usually the easy option however its not the correct place, I didn't know the OE K set up has no plugs - I ran a Pace (which doesn't either) when I had my K series which I tapped the trough in the sump prior to fitting.

I know its a pain popping the sump off but since we have time on our hands I'd be doing it properly.

[sjl1]

Using a dash switch to flick between water and oil temps is a cheap and easy job which works surprisingly well, saves having to but an expensive replacement dual gauge and doesnt spoil the look of the dash.

[JonL]

Not sure if you found this thread from Andrew Revill, but it may be useful. 

https://www.lotus7.club/comment/2179893#comment-2179893

and this one

https://www.lotus7.club/forum/techtalk/water-oil-temp-gauge-switch-mod-advice-needed?page=1

I am just planning on doing the same thing myself, although I have an apollo so my temp sender is in that. 

[Wrightpayne]

Neil,

I understand what you're getting at, however, I thought the senders work by being constantly submerged in oil. How much residual oil is around in a dry sump when the pump is doing its utmost to evacuate everything?

I think if you're going to the nth degree of temperature measurement, the standard Caterham senders and gauges probably need upgrading too.

I'm happy with my set up - yes it might be a few degrees out but far far better than nothing and a much better indicator of when the engine is up to temperature.

Ian 

[MADMALC]

W has a very good point. The gold pump on my SLR was so good that I lost no oil from a large crack in the sump for the 50 miles to home after hitting a cats eye (no animals were hurt in this process). On turning off the engine the oil ran out immediately.

If you treat the readings as 'Bananas' then you will get a 'normal' reading for both oil and water temperature and any variations will for most road going situations indicate what is occurring with sufficient accuracy so as to be useful. 

[TomB]

Morning all - Ive just stuck my head under the car, and it looks like the only point I have on the bellhousing tank where I could put a sender is the now plugged, old inlet into the bell tank, just below the tower.  My system is an older, 1995 era system, so I suspect it might not have other sender drillings.  

This location might not be ideal, but would give a good indication assuming the sender was under the oil level when running.  Im not sure the thread on the dry sump inlet port vs the VDO water temp sender.   

Assuming I can get a VDO temp sender to fit in here, is it a relatively simple case of running a wire to a new indicator switch (or headlight dip flash switch), linking the common earth between the dial and new switch, and tapping the instrument wiring?     

[7 wonders of the world]

If you place the sender in the low part of the trough, usually near the pick up in the DS pan it is submerged as all the scavenge oil goes via this and this offer an instant reading of peak temps.

Understand what you mean re CC gauge accuracy however placing the sender in the wrong place is hardly going to aid this.

If your not really bothered if what is being shown on the gauge is meaningful then why bother - seems a cosmetic exercise really..?

I use a  DD2 dash with VDO senders,which is more accurate based on comparison with an infa red thermometer on both oil and water temps.

A DS will mask a leak as it will merely pull air thro the crack, the leak only becoming evident after you switch off, unless of course its a full on puncture wound     , you may find your catch tank if you run one has more work to do during this period though

[Wrightpayne]

Accurate enough for me!

[SLR No.77]

There's more than one reason for measuring oil temperature, and particularly in a road car ensuring the oil is up to temperature is a key reason. Siting the sender in the bottom of the belltank is ideal for this.

Stu.

[MADMALC]

Me too. Was going to write more but !!!!!!!!!!

[7 wonders of the world]

Malc dont hold back on my account......

Stu agree ideal for that purpose - but nothing more

Personally I prefer to do things properly, but each to there own,  at least the OP has been given the options now   

[SLR No.77]

One day when I get chance I'll plumb an additional sensor in to the sump/gauze filter outlet and see how different the reading is ... 3 way switch needed!

[TomB]

Ive got a few options, certainly! Putting in a new sender somewhere and some relatively light touch wiring mods appeal over the expense and complication of a new gauge and senders.  Ill crawl under the car later and see if I cant find anything more obvious in the bell housing area for a sender.  There is also the oil filter housing area, with another potential off take for a sender. 

How do you tap into the temperature gauge wiring?  Small scotchlock things?  

[Wrightpayne]

Connections - no need for scotch locks.

Original sender female spade onto one switched connector of switch, make up new lead 2 x female spade - common of switch to gauge and new sender lead to other switched connector of switch.

I think its a 2 position headlight dipped / main switch you need with 3 connectors on the back. I orientated / located mine so when the switch was over towards the oil pressure gauge its oil temp.

 

[TomB]

WP, that makes sense, I think I was mis-remebering that there was a plug for the instrument, not individual spades/ wires.  

[SLR No.77]

Tom, mine has one of these from Polevolt (pt no. RKS14):

 

Spotted one in Bricol's car years ago and decided it looked much tidier than a toggle switch.

Stu.