Range Rover Temp Sender Thread Size?

[Steve_D]

QBee said:

.........................my recently fitted Caerbont oil temperature gauge was shouting “Stop” at well over 115 degrees C. ........................

David Vizard in one of his Chevy books says oil temp up to 149 is OK for synthetic oils 121 for mineral.

Steve

[QBee]

Phew......it was between 120 and 125 on the worst run. This was the one run where I turned the turbo boost up.
I use fully synthetic Valvoline 10w60 racing oil, so you have set my mind at rest.
Thanks Steve.

[ChimpOnGas]

Damn it, my resistor mod gets worse

Today at a true 86c my TVR gauge was reading 98c!!!

New sender should be with me mid week, so by next weekend we'll know if it does the trick.

[motul1974]

..I'm looking forward to the results.

[QBee]

Me too, Dave.
All credit for involving us all in your experiments.
We learn by following them......even if the result is not to do it!

[LLantrisant]

by the way...just in case it makes it easier to search senders: 1/8"NPT and M10x1 are so close...both should fit into a 1/8" thread.

[ChimpOnGas]

Ok the results are in, initially I was concerned the new sender is shorter than the Range Rover sender:



I was also concerned the gauge was not responding but it soon started to move, lets not forget the TVR gauge only starts at 50c so I part warmed the engine from cold start recording 50c on my Canems software before restarting and resuming the test, from 50c where the scale on the TVR gauge starts it appears to follow the digital readings on my Canems software nicely.

https://www.youtube.com/watch?v=KNClgYs-WWA

As you'll see in the above YouTube video I did record a spike at one point but I've run the car extensively now and this seems to have been an early one off anomaly on this very first test.

The second video below shows what happened when I pulled one of my fan relays so the car was only running one radiator fan, from past experience with just one fan operational I know the coolant will rise to 100c and above eventually. The idea of this test being to see if the gauge with the new sender will show an overheating situation which is really the most important function of any car temp gauge.

https://www.youtube.com/watch?v=tSnq2M84Zjo

Out on the road driving the car at speed on the motorway I'm holding a steady 87c on the Canems software and the TVR gauge matches this perfectly, as I reduce my road speed from a 70-80 lepton cruise velocity to the typical M25 crawl of 25 - 40mph the Canems software shows 89-90c



With the gauge spot on again.



So after extensive idle testing and further testing at various driving speeds my confidence in the TVR gauge has completely returned, the new matched 1/8 NPT sender screwed into the inlet manifold as a direct replacement to the Range Rover sender works a treat. In my opinion this matched 1/8 NPT sender is a marked improvement over the original 5/8 UNF sender TVR were forced to fit in an adapter, the adapter is effectively a dead end spur so water contact and circulation around the sender is very poor and so my gauge readings were always rather inconsistent.

I tried to solve this issue by using the Range Rover sender, the trouble is this sender is not not matched to the TVR gauge so like others I fitted an inline resistor which appears to do the trick but as I recently discovered it is not a reliable method of tuning a sender to a gauge, recently with a rad fan fuse blown I witnessed the gauge stuck at 90c when true coolant temp had risen well above this figure which means the most important function of the gauge (to show overheating) was lost.

I'm super happy with the new sender, it's clearly correctly matched to the TVR gauge as I was promised and follows my Canems software readings extremely closely, most importantly the gauge now shows me if my coolant temperature is starting to head towards an overheating situation and gives me plenty of warning to pull over to let the car cool before any damage is done

The sender is available from Caerbont themselves, just call Nial on 01639 732281 and ask for a TT6811-03. I had to buy two as this was the minimum order quantity at £30.19 including VAT and carriage so thats £15.10 each which is much cheaper than buying the original 5/8 UNF sender from a TVR parts specialist. The TT6811-03 is cheaper and works better, being a 1/8 NPT thread it's also a straight swap for what we in TVR circles call the Range Rover sender that sits unused in the inlet manifold.

For more accurate and consistent coolant temperature readings plus the peace of mind an overheating situation can be spotted early I think it's well worth £15.10, and if you can't find a friend to share the cost of two senders Nial did say the TT6811-03 is also used on some Caterhams. Nial recommended I call Redline Components Ltd who are a Caterham parts specialist and will apparently sell the TT6811-03 sender individually, I just went for the two from Caerbont as a local friend and Chimaera owner was pleased to take the second one.

I hope this discovery helps others in the TVR community, I also recommend anyone with the resistor mod on the Range Rover sender gets rid of it straight away as I've proved it's just not to be trusted!

Edited by ChimpOnGas on Friday 28th June 15:18

[bobfather]

Absolutely fantastic Dave. I'll be placing my double order soon. Many thanks for the youtube clips, they demonstrate beautifully how well this works. I'd suggest that differences in heat soak between the new and the ECU senders could easily account for variation during temperature rise. What's important is that they are the same at stable temperature and that they respond rapidly to changes

[ChimpOnGas]

bobfather said:

Absolutely fantastic Dave. I'll be placing my double order soon. Many thanks for the youtube clips, they demonstrate beautifully how well this works. I'd suggest that differences in heat soak between the new and the ECU senders could easily account for variation during temperature rise. What's important is that they are the same at stable temperature and that they respond rapidly to changes

Thanks Bob, glad it helps you and any others looking for a better solution to getting the correct readings on the TVR gauge. I know some claim the standard arrangement works Ok and others say it'll never match the gauge properly but my experience was what TVR gave us was poor, I also discovered in my case adding a resistor to the Range Rover sender was an unsafe and unreliable solution.

I'm super happy with the accuracy of my TVR gauge now, any tiny variance between the ECU sender and the new temp gauge sender are so small as to be considered irrelevant in my opinion, it's also impossible to perfectly compare a digital reading with an analogue gauge but at worse I'd say they are only ever 2c different and as you say Bob the new arrangement responds quickly and accurately while providing a clear early warning of any impending overheating.

As an aside point if you jump to 3.00 mins on the below video you can see scatter spark kicking in, as the coolant temp trips over from 67c to 68c ignition timing drops from 21 degrees to 15 degrees bringing my idle down 150rpm from 1150rpm to 1000rpm. I use this strategy to increase my idle speed slightly during warm up rather than using air, getting shot of the pattern part PWM Bosch idle valve and using a manual extra air valve of my own design with the addition of scatter spark delivered great idle quality and low speed drivability improvements.

https://www.youtube.com/watch?v=KNClgYs-WWA

[Belle427]

I will have the other sender if either of you wants to sell.

[mk1fan]

So, does this apply to the 'flapper' 3.5 versions of the RV8 TVR used in the Wedges?

[asd2001]

Thanks CoG, as you say worth it for the peace of mind. I was quite happy with the resistor solution oblivious that it didn’t actually give a warning when really needed....
Cheers
Andrew
Ps - I don’t tend to comment often but always read your detailed explanations with interest.

[MisterRay]

I can only echo what other people have said. The diligence you have put into this is epic and to then post the proof and all the details of the sender for the good of the community - well I metaphorically doff my cap to you sir! Absolutely awesome

[TVRSJW]

Excellent COG !!! Answers my recent thread about the RR resistor mod !

I’ll buy a spare off someone if there placing an order for two ?? Let me know ??

[ChimpOnGas]

mk1fan said:

So, does this apply to the 'flapper' 3.5 versions of the RV8 TVR used in the Wedges?

This topic relates to a 1/8 NPT sender that's specifically matched to the Cearbont temperature gauge used on Chimaeras and Griffiths manufactured from late1995/early 1996 on.

For the avoidance of any doubt the Cearbont gauge sets look like this......



This sender is not matched to the gauges fitted to earlier Chimaeras & Griffiths let alone an RV8 Wedge manufactured a number of years before the the Griffith and Chimaera models were even conceived, so I'm afraid to say I think its highly unlikely the TT6811-03 sender will work on your Wedge.

Sorry I can't be of more help.

Dave.

[cjrob]

COG - brilliant - thanks for the testing and work you have done with this, anything that increases the peace of mind for less than £20 is a bargain

TVRSJW - happy to go halfs with you, pop me a pm and we can work something out

TVRSJW said:

Excellent COG !!! Answers my recent thread about the RR resistor mod !

I’ll buy a spare off someone if there placing an order for two ?? Let me know ??

[QBee]

Just tried calling Caerbont on the number given above. Eventually spoke to a geezer who wasn’t Caerbont, and was fed up with getting calls.

The number on Caerbont’s website is similar....01639 732200
They are not open on Friday afternoons.

[ChimpOnGas]

My apologies, there was a typo of one digit in my above post that I have now corrected.

For the avoidance of any doubt the number Nial gave me was 01639 732281 and this is his direct dial, I explained there would likely be some interest if the sender worked and he seemed happy to field future calls. Nial was super nice and extremely helpful but it's probably not unfair to say Caerbont aren't the slickest of operations when it comes to selling direct to the general public, they are clearly more geared up for business to business trading.

Caerbont will offer to email you a WorldPay invoice (a bit like PayPal) but we tried this twice and I never received the link, I then discovered Caerbont have recently joined the modern age and now accept card payments but to make this work you need to get to Jan who is the only employee authorised to take card payments! Caebont also dont really operate on Fridays so it's what I'd call a 'retro customer experience' and of course you'll need to buy two senders as thats their minimum order.

I recommend trying Jan between 10.00am & 4.00pm Monday to Thursday but obviously avoid lunch times, tea breaks, natural breaks and forget the leak harvesting season altogether of course . After trying for days just to buy a couple of senders off them I did start to feel I had been caught some sort of 1970's Welsh time vortex but I got there in the end, to be fair to Nial who was really helpful he did say Redline Components Ltd stock the TT6811-03 sender as it's used on Caterhams and they should be able to supply them in singles.

I Googled Redline Components Ltd and got this very basic one page website....

http://www.redlinecomponents.co.uk/

As it's not a proper online shop and my mate wanted a sender too I thought it was just as easy to keep trying to buy from Caerbont direct, but who knows Redline Components Ltd might even work a full week so I guess they're worth a shot

Anyway, I must get back to work as sadly Friday is a normal working day for me

Happy sender shopping chaps, I wish you all good luck with it.

Dave.

[ChimpOnGas]

Check this out chaps.....



Redline work a full week, well kind of... as it's Friday they've just gone down the pub!

[mk1fan]

ChimpOnGas said:

mk1fan said:

So, does this apply to the 'flapper' 3.5 versions of the RV8 TVR used in the wedge

Sorry I can't be of more help.

Dave.

Do you have the specs of the sender - can compare to the wedge ones as 'we' do use the port you're rellocating to for our temp sender and have similar issues.

Cheers.