Coolant level sensor

[Zaphod]

I have a nice new alloy twin filler header tank, which has no level sensor (Not that I expected one!) how to I transfer it from the original?

[Pete Boole]

I think they just poke through the grommet - very simple. I'll dig mine out - it may still have the sensor attached.

Pete

[Tanz]

Yes, it just pushes through a rubber grommet. Just painted my tank and the sensor just pushed out. I put a bit of sealer around it when I pushed it back in.

[Zaphod]

Yes, it just pushes through a rubber grommet. Just painted my tank and the sensor just pushed out. I put a bit of sealer around it when I pushed it back in.

That worked!. I had some progress today, the car starts, the tappets are quiet and the clutch works. However the oil pressure gauge reads zero, this is annoying. It's got a new sensor, (a VDO 10 bar one) which has two terminals, does the second terminal need to be earthed? the terminals are 'G' and 'WK' but as I recall when earthed the reading is zero, when disconnected the reading is FSD so that would indicate that the sensor earths through the casing

[Alan_M]

However the oil pressure gauge reads zero, this is annoying. It's got a new sensor, (a VDO 10 bar one)

The Excel had either a 0-5, or 0-7 bar gauges and need the matching sender, so could it being a 10bar sender be the problem?

[Pete Boole]

ISTR that "G" is gauge and "WK" is the warning light.

Pete

[Lotus-e-Clan]

The sensor SINKS the gauge to earth via the internal rheostat - but sensors are not all wired the same way around internally...

Some senders provide zero pressure at low resistance (as for Excel), others provide zero pressure at high resistance.

IIRC this applies to VDO too (or so called VDO-compatible sensors) I think I have a discarded high-resistance-at-zero sensor in my tool box that I bought off eBay years ago. In the end, I bought a proper one from SJS when they had them in stock about 5 or 6 years ago.

Because the gauge shows FSD with the sensor disconnected, then, with the engine not running, ignition on, the disconnected sensor should show LOW resistance between terminal and case. When reconnected, engine running, the resistance should RISE with increasing oil pressure.

[Zaphod]

Ahh,
So I may have it wrong.. however this does not fill me with confidence, as the guage reads zero when the ignition is on, if it was the warning ligh it should read FSD if my understanding is correct and then go to zero when started?
(I seem to recall when disconnected it reads max and when earthed it reads zero). If the rain stops for long enough today I will swap rerminals.
As I defiantly have oil flowing (it came out of the inlet cam cover that I had not tightened up yesterday!) if there is no oil pressure I can only imagine the oil pressure relief valve is stuck partly open, but I can’t see one in the service notes..

[Zaphod]

So.. I have swapped the connector to the other terminal on the pressure sender… still zero at idle, however if you blip the throttle the needle moves but stays in the red. Question is, do I have zero pressure of a duff sender? There are no untoward noises. I am fairly sure I can discount a bad earth as they would result in a constant 7 bar reading

[Alan_M]

Use a mechanical diagnostic pressure gauge. This will give you a true indication of oil pressure.

Something like this - https://amzn.eu/d/cPCMNIH

[Lotus-e-Clan]

So.. I have swapped the connector to the other terminal on the pressure sender… still zero at idle, however if you blip the throttle the needle moves but stays in the red. Question is, do I have zero pressure of a duff sender? There are no untoward noises. I am fairly sure I can discount a bad earth as they would result in a constant 7 bar reading

Wrong sensor I still think.

For incompatible sensors that are wired backwards internally, expect the Excel gauge to read zero/low pressure when the oil is stone-cold. When the oil is hot,( i.e. the actual oil the pressure in the engine will drop as you would expect), the Excel gauge needle will rise IF the sensor is wired backwards internally.
The added complication is that it's a 10 bar sensor rather than a 7 bar, so you won't expect the needle to rise to anything sensible on the Excel gauge even when the oil is hot (75 - 85 C)....and to get the oil hot you must drive it, revving on the drive doesn't put much heat into the oil. iIf it even gets to 40C oil temp just idling on the drive, that would be it, so you won't see much oil pressure rise with a backward wire sensor.

[Zaphod]

Looking for a 7-bar sensor seems a fruitless task! I seem to recall reading that the sender was a 10 bar one anyway. I have put the car back in the garage and am awaiting the arrival of a mechanical test gauge, that should tell me if I need to acquire the correct sensor or pull the oil pump to bits. I really hope you are right!

[Hawaiis0]

Hi I have a new 5 bar one if you want to try a diagnose fit .

https://www.merlinmotorsport.co.uk/p/vd ... 081029001c

[Zaphod]

That would be marvellous! The car is a bit different to when you last saw it!

[Alan_M]

If you can’t correct sender and you confirm pressure is correct with mechanical gauge, then I believe you can use this to match a different sender to the gauge.

https://spiyda.com/fuel-gauge-wizard-mk3.html