Jump to content

Water temp sensor

Chris A

Recommended Posts

Hi all

Bit of a stumper for me but some one out there might know something.

I decided to replaced the existing sensor with one I bought back in April from one of the usual suppliers. The existing one works but I just wanted to fit the new one, the old one came out with no trouble however the replacement wouldn't screw in. As the old one goes in and comes out with no resistance I wasn't going to force the new one.

The new one was ordered as GTR108. There is a physical difference between the two items. The connector on the new one comes out of the centre of the unit, as per photos on supplier sites, the old one has it off centre.

The housing looks to be the original type.

I'm stumped, either the new item was incorrectly suppled, possible but not that likely I guess. The housing is from something else, again possible but highly unlikely as eveerything else is standard 13/60. Third option, for some reason a PO had the thread re tapped and fitted something completely different but does work.


Any thoughts welcome.

Puzzled in Normandy

Link to comment
Share on other sites

Thanks for the tip off.

It did answer a question I forgot to ask initially - the thread size of the sensor, I will now pay a visit to the local John Deere tractory dealer to get a 5/8"" UNF nut if possible. Here of course everything is metric.

My new sensor would only just make contact, not even 1/4 turn. I don't have the tools to tap the thread and I guess nobody else locally would either. Metric rules.

At least I feel that it is just a question cleaning, sorting the threads. I hope!

I'm not pressured as the existing works ok, but don't let the car hear that or it will take great delight in making it fail the next time I go out in it.......

Link to comment
Share on other sites

I did, before attempting to put the replacement sender in, run the old one in and out a couple of times and in the absence of a 5/8th tap, cleaned the threads out with a couple of cotton buds and then a screwed up piece of kitchen roll sprayed in carb cleaner to clear the threads as best I could. As you can see from my post you have to be very careful with this one with your choice of spanner... do not use a 3/4af. Looks ok to start with but if your unit is like mine, the metal will be very brittle and the hex edges will shatter when you tighten it up. Good luck.

Link to comment
Share on other sites

I visit to the John Deere dealer results in me having a 5/8" nut & bolt. One thing about living in a rural area there are as many tractor dealers as car dealers :D

Tried the nut on the new sender, no problems therefore I need to direct my attention to the housing & old sender thread. That is for tomorrow as it is time for my mug of tea and cigar! 

Link to comment
Share on other sites

All fine now :D

Took the old unit out and confirmed the thread pitch with the 5/8" nut.

Cleaned the housing threads with a cotton bud and brake cleaner. There was quite a bit of black gunge - why black? Don't know.

Used the 5/8" bolt to test the threads, went in perfectly.

I used a plug spanner for the mower to remove and refit the sensors, it was n't a perfect fit but as the sensor was only in a little more than hand tight no problems.

Comparing the 2 units ( see photo ) you can see that the old one has a shoulder the new one is sqaure cut which obviously means lining it up with the housing threads is a little more difficult to avoid errors.

Took car out for a spin on my favourite test route, country road virtually no trafic followed by a main road, again virtually no trafic where it can be driven at speed if one should wish, respecting the new 80 Kph limit of course. :rolleyes:

No leaks & it works. Phew!



Link to comment
Share on other sites

just double checked  the AF and they are 3/8 whitworth   or 18mm whichever you fancy

think there you have early smiths with rivet and intermotor or caerbont  (smiths)   ?  fixed terminals  being more modern design

as there's less terminal options these days  from that f the 60/70s


Link to comment
Share on other sites

Just got back from the first trip with my new sensor. Now showing a steady temp of just below 1/2 instead of 1/4. Suits me. Your sensor looks like mine, which has numbers stamped on 2 faces. Don't ask me what, its not coming out out again and the markings are not visible at the moment!!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...