K Series Coolant Sensor Thread

[RyCliff]

Hi All, 

I've been a real wally and thrown away the old water temperature sensor on my k series before checking the new one fits... And the new one has a different thread to the old! New one I've got is an MEK100060, which fits in the loom but not the coolant rail (thread is smaller on the sensor). Is there a reducer I've mistakenly thrown away?

Very annoyed with myself, schoolboy error. Even spent 30 minutes going through bins to no avail trying to find the old one. 

[Jonathan Kay]

What year is your Seven?

I haven't heard of a reducer.

Andrew's description of the different sensors and the history, incluidng MEK1000060.

And I've just bought a new sensor for the gauge from Redline... I'll look for some numbers.

Jonathan

[RyCliff]

Mine's a 1996, one of the Road sports so has the forward facing air inlet plenum on the opposite side to the coolant rail. 

I'm wondering if it was in a sensor probe pocket and I've thrown that out too.

The old sensor was black but had a central locating point on the housing so I assumed it was the brown. https://www.caterhamlotus7.club/forum/techtalk/k-series-coolant-temperature-ecu-sensor-types-what-have-you-got

this is the page I used to decipher which probe, though it says both have the same thread anyway

[Jonathan Kay]

K Series Coolant Temperature ECU Sensor Types - What Have You Got?

Jonathan

[RyCliff]

Yep that's the one. Though just measured up the thread on the sensor I've been sent by discount mg rover spares which has a thread OD of 10mm. So either the linked page is wrong or my posted part. I'll give them a call in the morning 

[SLR No.77]

Ryan, there are two coolant sensors in the water rail, one for the ecu and one for the gauge. IIRC the ecu sensor is the larger diameter thread, have you mistakenly bought one for the gauge?

Stu.

[SM25T]

Should have gone to Redline 

[RyCliff]

Yep definitely the larger sensor Stu, 2 wire connection whereas the gauge is a single wire probe.

Decided to check the new one with a caliper this morning and the thread OD is 12mm, so I guess it is correct. Hopefully a call to Chris at Redline might shed some light. 

[RyCliff]

 

I've found a picture of the old temperature sensor on the car before I binned it. Looks like it was a much smaller thread than M12 of the replacement but with a bushing to take it down (that I've removed thinking it was part of the sensor). No luck from Redline on identifying it. I've got a Stack ST700 rev counter with temperature readout but this doesn't look like the stack sensors. 

Starting to tear my hair out with it now! 

[OldAndrewE]

A wide variety of adaptors is available e.g. from Merlin

Gauge Fittings, Accessories and T Pieces from Merlin Motorsport

You just need to identify the two threads

[anthonym]

I thought this sounded like a Stack and ECU thing. One each. My car is only 4 years newer and has this Stack ECU split. so I'll see what I can find

[anthonym]

Are these relevant? 

[RyCliff]

Thanks very much, looks like this is the much newer submarine arrangement. I've ended up dropping my coolant rail off with Oakmere to see if they can identify the thread.

Interesting that my gauge sensor has a single wire and is earthed through the rail whereas the above has a wired earth. Presumably this gives a better reading. 

[SLR No.77]

Ryan, if memory serves me correctly it was around '96 that the gauge sensor changed from being a single connection earthed via the coolant rail, to a twin connection earthed through the loom.  In Anthony's install above there's a threaded rod that's part of the submarine tube to enable it to be earthed for earlier gauges, it'll be on the rear so can't be seen in Anthony's photo.

The ecu sensor has always been a twin connection.

Stu.

[TomB]

That likely correct - mines one of the last before the 96 changes, has a single earth, VDO gauges.  The 96 changes were quite substantial, wiring, chassis, suspension, Caterham gauges etc.    

[Mechanical Moz]

My 1998 car has a single wire gauge sender, both senders in the water rail above the exhaust primaries.

[RyCliff]

Mine is the same as Mechanical Moz.

Looked more closely at the rail and it looks like for some reason someone had welded a slightly larger boss on then bushed it down. Once I've worked out the thread of the boss I should be away... Also need the radiator from Radtec to arrive! 

[TomB]

Hows the replacemtn wing coming along?  Any other damage after the off? 

[RyCliff]

Not going too bad thanks. Managed to get a new wing from Oakmere and have had both resprayed. Had a load of leftover paint from the garage so using that to tidy the old rivnut locations up before bolting the new wings on.

No further damage from what I've come across with nose cone and radiator off. Once the new rad arrives I'll be able to have a run out and check for anything unusual. There were some knocks on the drive home but given the number of cable ties holding things together I can't tell if any were to concern over! 

[Wrightpayne]

RyCliff,

 

This is my '98 K. I think the boss on your water rail looks standard and has been bushed down to take a different sender? Looks about 20mm OD (ruler in shot!)

Mine also has the single wire temp gauge sender.

 

[RyCliff]

Thanks Wrightpayne, yep the boss looks to be the same, will double check when I pick mine back up from Oakmere tomorrow. 

Interesting though as the only senders sold for the k series are all M12 threads as far as I've found but can't see an obvious reducer on yours. 

[Wrightpayne]

I'll get the mirror out later and check for part numbers!

[Wrightpayne]

My (paper) parts catalogue says GTR206 post '96 chassis.

[revilla]

For the ECU sensor, it should be MEK100060 for the brown EU2 sensor and MEK000030 for the black EU3 sensor, but they're both the same M12 thread.

PS: I've only ever seen the single-terminal temperature gauge senders, even on later cars,  e.g. mine is a 2003 and has the single-terminal sender.

[RyCliff]

GTR206 looks the same as the brown EU2 sensor Revilla references. Seems to be an M12 thread as well based on these GTR206