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New temperature sender / sensors reading too high?


Colin Lindsay
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Anyone else found this? I bought a replacement sender unit for the GT6 earlier this week, as I'd left the cooling system drained whilst working on other things over the winter and when I rebuilt and refilled the system, the temperature gauge was being intermittent - first there was no heat, then it was normal, then back to zero.... so I fitted the new sensor. On the first drive I brought the car back with the needle in the red, so was quite concerned even though there were no real symptoms of trouble at the actual engine. Took the water pump off, flushed everything, replaced the thermostat, and suspected an airlock so was very careful with the refill, but same result on the second test drive - the needle very close to the red and not in the usual 6 o'clock position. 

This morning as a test I cleaned up the old sensor and replaced it once I'd sourced another sealing washer - this time the needle stayed in the normal position, no trace of overheating. 

So: it appears the new sensor is reading too high. As you can see from the photo it's slightly longer than the old one on the left, so must be a different setting even though it's marketed for the GT6. Looks like I'll have to find a NOS spare, to be sure... but if it happens to you, suspect the sensor BEFORE working on the engine.

DSCF5415.jpg.572ace9328312a3562a66ff0d16aed6a.jpg

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I found this when my original sender became faulty, but in my case I traced the issue to the previous owner having deleted the voltage stabiliser - when I reinstated it, both the new senders I'd purchased read around halfway on the gauge. Clearly the spec of the old one was different as it had indicated fine on the gauge for years!

Gully

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Mif its nos  then from the back of the memory disc you have a two smiths senders

 

Green top is stabilsed gauges   current number  generic GTR108

And red top is for non stabilised gauges being 121997

I might have the colours mixed up but wrong type sender give hot readings

Pete

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Pete - you may be spot on here; I hadn't thought about the stabiliser versions. 

The one I bought is listed as GTR108; no alternative version is listed, but the red top is the one that arrived in a bag, marked GTR108. All the versions of that number on eBay are black tops. I can't find a photo of the other but it's listed as non-stabilised. I may have been sent the wrong version, then.

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Im sure Red is wrong  for stabilised   smiths did  colour them for easy identification but whats produced these days could be any !!

Ie brown was 24v in the hey days wehad the 3 colours on the engine line as all 3 systems were in use in the 60/70s  and green brown  thro the 70/90 s

Had a lot of memebers over the years get the wrong to part number ,  some from Rb.

On the old forum even guys changing engines for over heating ...twas just the wrong sender

Pete

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They are colour-coded and my personal experience of e***y is what you order may not be the one that turns up, sellers not being aware of the difference.  Early doors in my ownership, I ended up "going down a sidestreet" with this, tried allsorts and it turned out to be the voltage regulator... it was probably you who put me right, Pete!

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I'm thinking of get my temperature unit replaced as the reader on the dial doesn't move that much...will compare sizes when I get my replacement and compare it with the old one.

Do I need to empty the radiator when taking the old one out?...sorry daft newbie question.

Nautam

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no need to empty  , just a quick out and in , leave the cap on but relief any  residual pressure first,

you will only get a short spillage , then top up when done.

apart from a maybe different colour insulators the two types are exactly the same fitting and size

its the  innards that  change . 

 

 the two senders operate very differently and cannot be mixed up

what ever colour  the designed resistance and range  for a GTR108 for slow bi metal stabilised gauges and that for the much earlier fast wiggle needle moving iron non stabilised gauges has to be a 121997 

get them mixed and you get a cold engine reading  its  much   HOTTER !

fuel senders from the same   pre stabilised era cannot be mixed either .

pete

 

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4 hours ago, derekskill said:

They are colour-coded and my personal experience of e***y is what you order may not be the one that turns up, sellers not being aware of the difference.  Early doors in my ownership, I ended up "going down a sidestreet" with this, tried allsorts and it turned out to be the voltage regulator... it was probably you who put me right, Pete!

Sadly it wasn't eBay who I got it from, but I was using eBay as an example simply because they have photos!

Went to MOT with normal temperature for the first ten miles, then none on the way home. I have spare sensors in the spares drawer, so will try those and see if they're anyway accurate - they could be Herald versions.

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herald spit gt6 vit bond 2000 std 8  or whatever the senders are the same its just got to match the gauge design

so what one is decided purely on being stabilised or not stabilised 

stabilised the gauge needle moves slowly   after ign.  on

non stabilised fly up to a reading as soon as ign.  on  and wag around on bumpy roads 

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Here's a test: fill a jar with about four inches of Waxoyl.... now try to see your Triumph chassis through it? Can't? Neither could the MOT tester... so despite the Frankenstein weld on the front outrigger it passed. He did give me an advisory about dust on the bonnet, which had accumulated since it sat outdoors all night; otherwise he wanted to buy it and wanted to make out a cheque on the back of the certificate. We're now road legal again! Our first show is next Saturday. I can't resist a photo just to show off!

DSCF5422.jpg.28bee74d629603f50b4f9c003a8cb011.jpg

 

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To be fair, I've seen some very pretty welding that wouldn't hold a matchstick - and some pretty ugly ones that you could hang the titanic on. I know which one I'd rather have. (Ok strong and beautiful is the ideal but ...... )

Lovely looking Spitfire too. 

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It was scary looking, especially as it was really only on three sides. HOWEVER: and that's worth emphasising in capitals - what is underneath was a small rust bubble where the outrigger overlaps the main rail, only through the outrigger centre and I'd be happy, with my own safety on the road in mind, to say that it was unsightly but not structural. It certainly didn't need a new outrigger, although I've bought one just in case. Previous testers advised to have it repaired, but still passed the car. It's currently under about four inches of Waxoyl so almost invisible, but the car can now be taken to a proper welder and have the entire thing done properly.

DSCF5393.jpg.58e6c4fbbc02301fdf4675117df42eaf.jpg

 

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Apologies accepted! I knew I should have posted a bigger photo! I hadn't my glasses on either... and I am NOT depressed over the sender units! Hopping a bit, but not depressed. 

Just bought a laptop that won't run my music recording programme... now THAT's depressing!

(I was just about to apologise to the OP for hi-jacking his thread wayyyy off target then realised .. it was ME!)

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