Relocation of temp sender

[pbaker43]

I decided to replace the fuel pipes in the engine bay, but ‘while I was there’ I ended up cleaning everything all new gaskets painting the rockers and plenum, new injectors and to move the temp sender from its old inaccessible place to another location.
Please note I made the mistake of swapping the location of both devices I should have left the water temp for the ECU in the original location and just drilled and tapped for the new sender..
So at the risk of starting up an old thread, I have just relocated the temp sender in to the inlet manifold next to the temp for the ECU.

When I filled the system and started the engine the expansion tank rattled like an old coffee grinder as the air came out, I then stopped the engine, filled the swirl pot again bled the radiator, massaged the hoses, this I did 3-4 times, before the system settled down, there are a few little air locks still in the system so I am hoping the gauge will settle down.

Before my fans were cutting in at 85°-90° now they are cutting in at 95°-100° hopefully expelling the air locks will correct things, if not I will put the old sender in and see if that makes a difference, failing that I will be back to ask if anyone has some ideas.

[pbaker43]

The old Rover temp sender i used as blank in the bottom of the old location, fitted a treat.

[JonathanT]

so if I got you right, you've removed the temp gauge sender from the silly bit of pipe at the front of the engine and put it in the hole for the rover sender? and put the rover sender in the silly bit of pipe?

[pbaker43]

Correct, I had to drill out the hole where the rover sender fitted and cut down the shoulder with an angle grinder and file, then I unscrewed the adaptor in the old location and screwed in the old rover sender to the original boss. For me I had to fly to the UK with the sender unit and matched a drill and tap for the job as France did not know the type of thread it was, in fact it is metric but a fine thread. If anyone wants the sizes I can forward then…

[Naybr]

A very neat job I'm sure, but I'm afraid I'm failing to see the point of it.

Why not just use the Rover sensor? It works absolutely fine, and is much more responsive. You just need to wire a 180 ohm resistor into the line.

[pbaker43]

So many people complained about the location of the sender unit and seeing they have not taken the route you suggest by using a 180 Ohm resistor I thought I would be different. But you are right there is an easier way as you pointed out,I just wanted to use a standard sensor and show it can be done.

[Ozstyle]

I've seen a thead were an owner used the standard temp gauge sensor in the orginal postion but just removed the brass extension tube (retapped the threaded boss in the inlet manifold to take the sender), this allowed the tip end of the sender to sit in the water flow. Never figured why TVR did not do that, definately something I would do if the inlet manifold comes off.

[Alexdaredevilz]

The brass pipe adapter was full up of crap when I removed it, im suprised I even got a reading

[lotusandy]

pbaker43 said:

, in fact it is metric but a fine thread. If anyone wants the sizes I can forward then…

Yes please, if you could tell me where you got the tap as well that would be great. Thnaks Andy

[Pink_Floyd]

Ozstyle said:

I've seen a thead were an owner used the standard temp gauge sensor in the orginal postion but just removed the brass extension tube (retapped the threaded boss in the inlet manifold to take the sender), this allowed the tip end of the sender to sit in the water flow. Never figured why TVR did not do that, definately something I would do if the inlet manifold comes off.

Me.

[lotusandy]

Pink_Floyd said:

Me.

Looks like the neatest solution I've seen, where did you get the adaptor from?

Andy

[Alexdaredevilz]

lotusandy said:

Looks like the neatest solution I've seen, where did you get the adaptor from?

Andy

Looks to me like the the original, but tapped out and the sender machined down?

[Pink_Floyd]

Alexdaredevilz said:

Looks to me like the the original, but tapped out and the sender machined down?

This is the TVR bodge.

So I removed the brass bit in the middle and then drilled and taped the metal fitting to accept the original sender. Didn't modify the sender.

[lotusandy]

Pink_Floyd said:

This is the TVR bodge.

So I removed the brass bit in the middle and then drilled and taped the metal fitting to accept the original sender. Didn't modify the sender.

This looks like the best way of doing it by far to me, what is the size of tap required & are they readily available?
Do you notice the temp gauge responds much differently, I'm guessing this cures the issues of it incorrectly reading low on motorways etc?

Andy

[JonathanT]

Naybr said:

A very neat job I'm sure, but I'm afraid I'm failing to see the point of it.

Why not just use the Rover sensor? It works absolutely fine, and is much more responsive. You just need to wire a 180 ohm resistor into the line.

As I understand it, the rover sender is not calibrated the same as the gauge, so being able to use the "right" sender is desirable.

[pbaker43]

Hi Lotusandy, here are the details for the tap sizes
On the box (M16x1.5 second HSS B46XEB4)
Stamped on the tap (M16x1.5 ISO2 HSS)
You will need a 14.5 HSS Drill... For some reason the pictures will not load on to the site, I think they are too big.

[Pink_Floyd]

lotusandy said:

This looks like the best way of doing it by far to me, what is the size of tap required & are they readily available?
Do you notice the temp gauge responds much differently, I'm guessing this cures the issues of it incorrectly reading low on motorways etc? Andy

I don't know if it is any better as I am still rebuilding my car after fixing the metal worm.

[Naybr]

"As I understand it, the rover sender is not calibrated the same as the gauge, so being able to use the "right" sender is desirable."

That's why you need the resistor in the line. My experience is that the Rover sensor gives a much more realistic display of what's happening than the TVR one. You can see the engine warming up, the thermostat opens and the fans now cut in at the specified temps so I'm fairly confident it's not far off. These gauges are only ever going to be a rough guide anyway.

Agree that the 'drill and tap' solution is a more elegant job though.

[JonathanT]

Naybr said:

"As I understand it, the rover sender is not calibrated the same as the gauge, so being able to use the "right" sender is desirable."

That's why you need the resistor in the line. My experience is that the Rover sensor gives a much more realistic display of what's happening than the TVR one. You can see the engine warming up, the thermostat opens and the fans now cut in at the specified temps so I'm fairly confident it's not far off. These gauges are only ever going to be a rough guide anyway.

yes but.... AFAIK the temp-resistance curve of the rover sender is different to the temp-resistance curve that the gauge is calibrated for. The resistor will give you an "accurate" reading for one temperature only.

[pbaker43]

Just to inform you guys,
I brought a new temp sender brought from a well known TVR supplier, fitted it and the temp reading was 105° when the fans cut in, I replaced it with the old sender, the fans cut in at 92° as normal. Also the running temps were different the new sender 88° the old one 70°.
The Bible states the fans should kick in at 88-92° I am inclined to think the original is correct, but I could be wrong. Any way I am running with the old sender unit..