K-Series Oil Pressure Gauge Sender

[rpaulgreaves]

Hi Everyone,

I'm having a problem replacing the oil pressure gauge sender on my 2003 K-Series 140 X-Power.  It all started with a flickering oil pressure reading, particularly when hot. Occasionally, the reading disappearing to zero!  From all the background I read, it seemed that the sender was a good place to start.

I duly ordered a new unit from Caterham, but, when I tried to fit it in to the oil filter assembly, it would not screw in far enough to clamp the copper washer supplied with it.  It would have needed about 3 washers to close the gap.  Obviously, not a good idea!  The problem appears to be that the new unit does not have a thread cut all the way down to the hexagon section.  This can be seen in the attached photo in comparison with the old unit.

I returned the new unit to Caterham and, apparently, all of the rest of their stock was the same so they have returned them to the supplier. They have now placed an order for a new batch of correctly made units.

I have also tried a couple of other suppliers. One had stock the same as Caterham's.  There was a more promising unit from the other one which had more thread, but it was stiil around 1mm short of screwing fully into the oil filter assembly.

It looks like I need to wait for a replacement unit from Caterham, but in the meantime I wondered if anyone else had had a similar experience with this oil pressure gauge sender and, if so, how did they fix it. 

Cheers

Paul

 

[StevehS3]

Hi Paul, I don’t know if this helps but I bought one a couple of months ago and remotely mounted it via a short hose onto a lower chassis tube. Sorry but I can’t remember about the thread. The hose connection may be a work-around this problem. I am hoping it will last longer by not being directly in water spray, stones and grit etc, and being away from engine vibrations. 

[rj]

The thread is tapered which means that it is not supposed to go in all the way.

(Check that it's the same thread diameter and pitch)

It should no be necessary to use any sort of sealer when it has a tapered thread.

[SM25T]

Senders don't last very long in my experience. Fit an adaptor and capillary hose .... and a mechanical gauge. All for the price of a sender.

[simon_h]

Yes fit a stack mechanical gauge for about £50. All your problems gone!

[rj]

My electric sensors only fail when they're abused mechanically

[Richard Price]

The thread is tapered which means that it is not supposed to go in all the way.

RJ,

I don't think you are correct there. I'm pretty sure its an M12 x 1.5 parallel thread. 

[John Vine]

...away from engine vibrations.

That's the key to prolonging the life of these senders.  But, as mentioned above, a mechanical gauge is so much better.

JV

[rpaulgreaves]

Thanks for your feedback everyone.

RJ, your comment that the thread is tapered did make me check.  It isn't and presumably the sender would not be supplied with a copper washer to seal it if it were.  It would make fitting simpler though if it were!

Sounds like these senders can be troublesome and they are quite expensive. Mine's only done 1800 miles!  I think I'll investigate a remote sensor/mechanical gauge.  Does anyone have any experience of the bespoke Demon Tweeks kit to fit a mechanical gauge and low pressure warning light, complete with all the fittings and hoses, to a Seven?

Thanks again.

Paul 

[paul richards]

Engine vibration is not the problem. Ingress of water is the problem. It rusts the internals. Cut an old one in two and you will see. You can prolong the life of a sender by sealing the gap around the electrical terminal with silicon and also mounting remotely out of all the wet and muck. However still not as good as fitting a mechanical gauge. 

[rj]

I stand corrected regarding the tapered thread 

I'll second that vibration is not the issue.

If you don't want to go the mechanical route you also could use one of the "professional" Stack gauges; those have a by far better sensor and have a configurable alarm output. The problem with the warning light is that if you don't want it to light up at idle when warm it's worthless to protect the engine at speed. You should do something like on the old VWs where there are two sensors: One 0.3 bar and a 1.8 bar. The latter is RPM-gated and only active above 1800 RPM. The Rx00 Stack dashes also have sort of an RPM gate for the red warning light.

[John Vine]

Engine vibration is not the problem.

I'm not sure CC would agree.  I was advised way back that one of the reasons they offered a remote sensor-mounting kit was to address unwanted vibration.

During my nine years of K ownership, I replaced the sensor three times (at least).  None of them showed any signs of water ingress, so something else must have stopped them working.  Of course, this might well have been road debris -- stones, rocks, even assorted wildlife! 

JV

[SM25T]

I sealed one with silicone sealant aroud the body and electrical terminal. Still didn't last long.

[MADMALC]

https://www.lotus7.club/forum/techtalk/mechanical-oil-pressure-guage-part-list    

The last entry is the cheapest way to do the job that I could find.

[Roadsport06]

Mine was rubbish from day one. CC replaced, still dodgy readings so mechanical fitted

[Brian Deacon]

Replaced mine with mechanical from Merlin Motorsport. Easy change and now reads a sensible pressure as well.

[rpaulgreaves]

Thanks again everyone.  Currently researching alternatives to the standard set up as per your suggestions.  I'll let you know how I get on.

Cheers

Paul

[Gnockoff]

I went through a couple of senders in a relatively short space of time before I bowed to the collective knowledge on here and went mechanical. No further issues. I got my set up from Think Automotive who sent me everything I needed, gauge, capillaries and connectors,  for the price of one sender. This was for a K Series before you ask.