Temperature senders - any experts out there?

RobTwin · Post by **RobTwin** » Thu Sep 14, 06 7:05 pm

Right at the last knockings, I find out the water temp gauge in the dash of the Polara doesnt work! It used to, but in the time since the engine's been rebuilt, something's decided to pack up. And Paul reckon's it's the sender unit.
No problem, you say, just get a new sender. In stock at most suppliers over here, you say. Well, it would be if were a later version ie 1/8NPT.
Apparently

up to and including '63, they were 1/4NPT thread - a size that no one has in stock. Well none of the 6 or so places I've rung today. And the quickest I can get anything from the States is next Monday. Ideally want 'something for the weekend' (ooer) so we know what's going on up front if we use the car for Shakey.

What I was wondering was....
If we were to get the 1/8 version, and fit it with an adaptor (Paul K says he has some), is the gauge likely to read correctly, or, if the sender was made for a different gauge in a different dash in a different car, is it likely to give a false reading?
I'm not sure what the reistance/temp rating of the original part is, and how it compares with the different thread version.

Any ideas?

Ta

Pete · Post by **Pete** » Thu Sep 14, 06 7:25 pm

Bung it in and stop worrying!!

There will be a spare in the Poly motor of mine at Dave Maddres - Alex or Dave may be ableto take it to Shakey.

If you can get over to my place Friday lunch time I will swop it for the one in the '62 Dart if that would help out as a temporary fix....

Anonymous · Post by **Anonymous** » Thu Sep 14, 06 7:32 pm

Rob,go get yourself a 1/4 to 1/8 iron/brass or galv bush.Any plumbing out let will have one.

RobTwin · Post by **RobTwin** » Thu Sep 14, 06 8:13 pm

Adam, thanks. PK says he has adaptors but I'll try a plumbers if not. Dont forget it's NPT not BSP

Pete, if I can get a 1/8 version from Bob Harmans/Watford Motor Acc/A-Z of US Spares.... whatever theyre called.... and use an adaptor, that will be a lot less mileage as a 1st option. As long as it works the same as a new 1/4 part.
I was just concerned that the 2 types may somehow have a different temp rating & therefore give a different reading. Does anyone know for sure either way??

If not, I'll let you know, thanks

charger01 · Post by **charger01** » Thu Sep 14, 06 9:25 pm

I fitted a temp sender out of a series 2 landrover into my 440,hooked up to the origional guage and it works perfect ,reading around 170* when hot,this also corresponds with the reading on the radiator cap I fitted at The Nats from Neil with the built in temp gauge.

MrNorm · Post by **MrNorm** » Thu Sep 14, 06 9:58 pm

I would hazard a guess that it will be pretty similar if not the same.......however you are correct that the sender should be matched to the gauge, so in theory a non standard combination could give a wrong reading if different cars had differently calibrated gauges. But as said I'm guessing it will not be much different.

If you can't find a source (on the web?) to confirm whether they differ then I would connect it up to the loom, earth it with a wire to the engine, and get a pan of boiling water to drop it in. See where the gauge goes to and at least you'll then know where on the gauge things start getting hot (obviously 100 deg C would be OK in the car due to the higher boiling point under pressure)

Kev · Post by **Kev** » Thu Sep 14, 06 10:21 pm

Well if you had one of those snazzy temp gauge in the rad cap jobbies you could set up a little web cam and light under the hood transmitting to your laptop, then reflected as a heads up display on yer 'screen. Yes I know it will be reading in mirror image. But the laptop is on the passenger seat projecting onto the passenger side of the screen. Look in yer rearview mirror.......Hey Presto, your engine temperature gauge.
I am going on Dragon's Den with that one next week, so no copying!

Anonymous · Post by **Anonymous** » Thu Sep 14, 06 10:28 pm

I got mine from Merlin Motorsport in Chippenham Wiltshire.

Pete · Post by **Pete** » Thu Sep 14, 06 10:28 pm

Been on the mad dog Kev?

Kev · Post by **Kev** » Thu Sep 14, 06 10:29 pm

What? Just trying to help a brother!

RobTwin · Post by **RobTwin** » Thu Sep 14, 06 10:32 pm

Thanks Gav & Adrian & erm Kev

It was Bob Harman that put the seed of doubt in my mind about whether the 2 sizes would read the same, but now I'm starting to think it will be near enough, as you say, at least as a temp (ha-ha) measure.
I'll get the proper one ordered and fit it when it comes, but in the meantime, I now think we'll be ok to take a punt on the 1/8NPT version. As long as we can get the correct adaptor

Thanks for the test idea Gav, trouble is our gauge just has C & H - no numbers to indicate actual temp

MetalChuckKey · Post by **MetalChuckKey** » Thu Sep 14, 06 10:57 pm

nick69 wrote:I got mine from Merlin Motorsport in Chippenham Wiltshire.

Where's that mate? I used to live in that town!

RobTwin · Post by **RobTwin** » Thu Sep 14, 06 11:10 pm

nick69 wrote:I got mine from Merlin Motorsport in Chippenham Wiltshire.

Sorry Nick, missed that post.

What typre did you get? A couple of places I spoke to today have the more common 1/8-27 (or 24?) NPT threaded sender, it's the 1/4-18 we're struggling with.

charger01 · Post by **charger01** » Thu Sep 14, 06 11:50 pm

Rob pop down to your local Plumb Centre & like Adam said get a bush.Take the temp sender with you they should have one ,it will be brass more than likely

last minute snags eh?dont you just love these cars

RobTwin · Post by **RobTwin** » Thu Sep 14, 06 11:57 pm

Yep, reckon thats the best plan Adrian. I'll go buy the 'other' sender, take it to a plumb place (i know a few round here in case NPT makes 'em go

) and see if at least the bush i/d fits.
Then check the o/d on Saturday.

Then hopefully, next stop SHAKEY $\:D/$

What else can go wrong......