Cooling and the Otter

[Overhere]

HI, I'm a new Chim owner and have been reading Steve Heath's guide, the single best investment I've made since buying the Chim.

My question I'm looking for opinions on is in Chapter 7, cooling, we all know Chims are known for overheating and chapter 7 is great info on this subject. What I've noticed is that from the factory that otter switch is a 90 degree switch, but my fans come on just over 70 degrees.

Seems this would be good for a car spending a lot of it's time in heavy traffic or hot weather, but Steve's diagram on page 141 shows the "sweet spot" of running temp at 70-90 degrees.

Even in the awesome weather we've had over the last month or two, commuting, long country drives, heavy fast drives and in occational heavy traffic, my engine rarely goes over 75. I wonder if this conversion is overkill as Steve says that when the engine is at the lower end or below 70 the ECU is not running the mixture at it's most efficient.

Appreciate any thoughts or comments.

Thanks

Jack

[2 Smokin Barrels]

Overhere said:

we all know Chims are known for overheating Jack

Do we?

[2 Smokin Barrels]

...generally speaking, a well maintained car will not overheat if all is well..

I've found all of mine have worked well, each operating in an apparently different manner..I always put this down to variability of temperature guage readings. (i.e. callibrated differently)

In 200,000+ miles, the only overheat I ever had was when the otter switch was bust, and I didn't notice soon enough!

[2 Smokin Barrels]

If the car seems to run ok, and returns expected mpg etc I'd not mess with it.

[david beer]

I see you are a serp, so you can use the spare temp guage sender on the head and set up your guage. It sounds like your origianl temp sender is on its way out.

[stringbag]

I'll second that.
Mine took ages to indicate anything on the temp guage (still reading nothing when the thermostat opened), but seemed to be faily accurate when it eventually warmed up.
Changed the sender to the spare one, bit of adjustment on the variable resistor to callibrate it and bingo, now indicates within 30secs of starting, and seems to react to engine temp changes far more quickly.(thanks David!)

>> Edited by stringbag on Wednesday 14th September 09:29

[k4trv]

Overhere said:

snippity........ What I've noticed is that from the factory that otter switch is a 90 degree switch, but my fans come on just over 70 degrees. Seems this would be good for a car spending a lot of it's time in heavy traffic or hot weather, but Steve's diagram on page 141 shows the "sweet spot" of running temp at 70-90 degrees............. Appreciate any thoughts or comments. Thanks Jack........snip

In my humble opinion, you have based your comments on the most inaccurate gauge, maybe second to the fuel gauge, in the car.

Go with the suggestions that if it ain't broke.....

What "other" indications do you have that your car is super-cooled?? Mayonaise in the rockers ?? Very heavy fuel consumption (more than TVR norm that is), Smoking (black, not steam) from exhausts. Sulphurous smelling exhaust. Sooty plugs?

You probably have a fine dam running car - don't mess with it !! The Bible's great but I have hidden it to stop me reading more into ownership/handling/performance and changing things !! I know it's part of the TVR experience..........

Have fun.

Trev McM

[kenny chim 4]

david beer said:

I see you are a serp, so you can use the spare temp guage sender on the head and set up your guage. It sounds like your origianl temp sender is on its way out.

This just may be the answer to a new problem I have!

I had to replace the (cracked) swirl pot last week and sourced a replacement from TMS (bespoke part- not Landrover). When I collected the car yesterday from the good indie I use, they pointed out that the new pot had no facility to screw the temp guage in and so they just adjoined the wires!

Now, with winter coming on, and being a daily driver, I do not want the fans on from start-up.

So, if you'd be so kind David or Stringbag, where is the spare located on the head- and how do you wire it up to bypass the swirl pot one? (preferably in detail for a numpty thanks!)

Incidently, part of the work done over the last couple of weeks involved me getting hold of a new or recon'd gear box. TVR Parts came up trumps getting me one from a written-off Chimaera with only 10k on the clock! Hope it didn't belong to anyone on here. (Should we carry Donor Cards?).

Any responses welcome to my thermostat prob...



>> Edited by kenny chim 4 on Saturday 17th September 21:23

[GreenV8S]

kenny chim 4 said:

This just may be the answer to a new problem I have! I had to replace the (cracked) swirl pot last week and sourced a replacement from TMS (bespoke part- not Landrover). When I collected the car yesterday from the good indie I use, they pointed out that the new pot had no facility to screw the temp guage in and so they just adjoined the wires! Now, with winter coming on, and being a daily driver, I do not want the fans on from start-up. So, if you'd be so kind David or Stringbag, where is the spare located on the head- and how do you wire it up to bypass the swirl pot one? (preferably in detail for a numpty thanks!)

Sorry, but you're confusing the temperature sender with the otter switch. They're completely different beasts, the temp senders are nothing to do with switching the fans on.

You need an otter switch. Swapping a tank with an otter switch for one without an otter switch was a bit of a cock-up, I'm surprised you've been left to put it right on your own. You have a couple of options: the easiest one is to get a wax cannister type otter switch and put the wax cannister somewhere hot - either inside one of the hoses, or strapped to the outside of a metal pipe or tank. Mod-Wise use these, and perhaps they would sell you one. I have two of them on the V8S. Alternatively, you can get an aftermarket sleeve fitting that has an electronic adjustable otter switch built in. This would require significant changes to the wiring loom, though.

[stringbag]

What GreenV8s said.
Basically the later cars didn't have the otter switch on the swirl pot, TVR moved it to the Rad. You have obviously got a newer swirl pot.
All the Otter switch does is turn the fans on/off. The temp sensor is in the Engine block. (there are two of these as well, one for the Guage and one for the ECU.) Just to confuse things more for you.
Have a word with David and get the fans thing sorted first(he is Mod Wise). His adjustable cooling kit basically replaces the otter switch.