Javascript Disabled Detected

You currently have javascript disabled. Several functions may not work. Please re-enable javascript to access full functionality.

Thermo temp switch

Started by hanra , Mar 11 2012 06:39 PM

Please log in to reply

22 replies to this topic

#1 hanra

Oh My, Don't you post alot

Members
10,941 posts

Name:Brad
Location:Farrrrrr North Qld
Car:1975 LH SL/R 5000, 1967 Morris Cooper S, E36 BMW, Toyota Corolla, Isuzu DMax
Joined: 24-March 11

Posted 11 March 2012 - 06:39 PM

I'm intending to fit a switch that, once the engine is up to temp, it will supply GND to a relay that will turn the thermos on.

What temp switch would be suggested to use?

I was thinking a Tridon brand switch should do the job?

Is this the correct position for me to drill and tap a hole for the switch? Or would I be better off having a switch tapped into the radiator?

Posted Image

Edited by hanra, 11 March 2012 - 06:40 PM.

Back to top

#2 lxsstorana

Forum Fixture

Members
2,499 posts

Name:Mick
Location:Eastwood, Sydney
Car:SS Hatchback
Joined: 23-March 06

Posted 11 March 2012 - 06:56 PM

Hi Brad,

I had a switch fitted to the bottom radiator tank by a radiator specialist in Sydney to activate my thermo's. I don't know if it's the best thing to do but I hated having that crappy set up with a sensor in the top radiator hose and a switch beside it. The new system has worked well for me for the past couple of years. Here's a pic, the switch is in the bottom left of the tank as you look at it and is covered by masking tape.

Mick.

P.S. sorry don't know the brand.

Edited by lxsstorana, 11 March 2012 - 06:58 PM.

Back to top

#3 hanra

Oh My, Don't you post alot

Members
10,941 posts

Name:Brad
Location:Farrrrrr North Qld
Car:1975 LH SL/R 5000, 1967 Morris Cooper S, E36 BMW, Toyota Corolla, Isuzu DMax
Joined: 24-March 11

Posted 11 March 2012 - 07:05 PM

Thanks for that. That may in fact be the better place for it, so it's not seen.

Back to top

#4 _robslxhatch_

Guests

Posted 11 March 2012 - 07:38 PM

Mine is located next to the top hose outlet. Seems to work just fine, It might have been nice to have it hidden in the lower tank. I have to wonder if it would be harder to get the temperature or location of the switch right though.

Back to top

#5 _rob350hatch_

Guests

Posted 11 March 2012 - 07:40 PM

yeah i wouldnt put it in the manifold. what if your low on water and it comes in later than it should

Back to top

#6 _oldjohnno_

Guests

Posted 11 March 2012 - 07:58 PM

I set one up recently using a Murphy Swichgage - basically a temp gauge with an adjustable contact. I like them because you can see at a glance what it's set at and you can adjust them easily from within the cab with a little allen key. I actually prefer their basic industrial look to the flashier stuff but I'm probably on my own there... I usually use one of these for oil pressure too. Not the cheapest way to do it but if you have to buy a gauge anyway it works out ok.
I always put the sender in the normal location under the thermostat housing. If you put it in the bottom tank and something happens to limit water flow (like a thrown belt) the tank temp will be low even though the engine is cooking. Some argue that positioning it lower is better in the case of low water level, but if the water is so low that it's not circulating thru the thermostat then you're in trouble regardless.
Posted Image

Edited by oldjohnno, 11 March 2012 - 08:07 PM.

Back to top

#7 S pack

Scrivet Counter

Members
15,691 posts

Name:Dave
Location:Luggage Point
Car:73 LJ
Joined: 25-January 10

Posted 11 March 2012 - 08:49 PM

I've got the thermo fan temp switch in the thermostat housing (under the thermostat) on my 202. Works fine and in this position it is sensing the engine temp (not the radiator temp) which I think is more important and more accurate.

Edited by S pack, 11 March 2012 - 08:51 PM.

Back to top

#8 _Viper_

Guests

Posted 11 March 2012 - 09:18 PM

I believe it is supposed to be located at the top end (what the radiator shop told me) before it goes through the radiator, as if its in the bottom tank it wont turn on until the water that has been cooled is up to say 85 - 90'c which means the water coming out of the motor could be near on 100'c, That said if its in the lower tank you can just get a sender that turns on earlier to make up for it...

Altho My gemini has one in the lower tank, my temp sender gauge is in the thermostat housing and the fan turns on at around 90'c

Back to top

#9 _oldjohnno_

Guests

Posted 12 March 2012 - 05:47 AM

Yes, definitely in the outlet, and preferably before the thermostat. It's the only way to get a true indication of engine temp and that's the reason all the OEMs have it there. It's risky to have it in the lower tank.

Back to top

#10 _torbirdie_

Guests

Posted 12 March 2012 - 06:21 AM

My 2 cents here.

Looking at all new cars, the fans are triggered by the computer which gets its temp feed from the engine temp sensor, I havent seen any temp sensors on the radiator.

That being said, I have never experienced the fans triggering on new cars from heat soak when restarting on a hot day(dont know how they engineer that not to happen), unlike what happens when we fit elec fans to older cars where the sensor is the engine block or top of the radiator, While to some that may not matter, I find it a little crude that the fans start up when they aren't needed in this situation.

For the reasons above, imho, the temp sensor for our older cars is best in the bottom tank of the rad. It is less sensitive here to the effects of heat soak and will function just fine.

Wont the motor run hotter due to the sensor being colder at the bottom of the radiator? In conditions where you'll be using your fan?no. At standstill there wont be much of a temperature gradient at all across the radiator.

What about on the move? No, at best at speed and with adequate coolant flow there will be a drop of only 2-5 degrees from top to bottom, fan switch on could vary by 5 degrees or so accordingly.....people claiming they need to run the motor at tighter tolerances than that? tell em they are dreaming! Ideal engine operating temp(for power and economy) should be somewhere near full opening of the thermostat.
The idea of elec fans is that they are there to stop the motor overheating in low flow air conditions, not keep the motor at the ideal temp for cruising etc.

Top tank I believe does have problems if the coolant level drops below the level of the fins. This wont be a problem with the bottom tank.

If you put it in the bottom tank and something happens to limit water flow (like a thrown belt) the tank temp will be low even though the engine is cooking.

The fans coming on in the above if you have a eng mounted sensor may cool the outside of the engine, but its not going to really make a difference to the real problem of no water circulating regardless of where the blockage is.

What should be understood and not confused here is that the temp sensor for the temp gauge must go in the engine block.
Yes, its good to have a gauge so you can monitor what is happening, what temp thermostat is opening, how close to overheat it is getting on hotter days so you can pick up problems before they become big problems, but what many overlook is actually keeping or installing a temp warning switch light/buzzer....for the situations where you do throw a belt and the thing could overheat in less time than you periodically check the gauge, same goes for oil

Edited by torbirdie, 12 March 2012 - 06:25 AM.

Back to top

#11 hanra

Oh My, Don't you post alot

Members
10,941 posts

Name:Brad
Location:Farrrrrr North Qld
Car:1975 LH SL/R 5000, 1967 Morris Cooper S, E36 BMW, Toyota Corolla, Isuzu DMax
Joined: 24-March 11

Posted 12 March 2012 - 06:26 AM

Well thinking about it some more, Id rather not drill a hole in the stock manifold, so would it still be ok to have a fitting welded onto the top or bottom tank of the radiator? Ive got to get it re-cored anyways. Thats basically the same as having one of those stupid probes shoved in the upper rad hose??

What temp switch should I look at getting is the next question?

Edit: Ok I just read above!!!

Edited by hanra, 12 March 2012 - 06:36 AM.

Back to top

#12 hanra

Oh My, Don't you post alot

Members
10,941 posts

Name:Brad
Location:Farrrrrr North Qld
Car:1975 LH SL/R 5000, 1967 Morris Cooper S, E36 BMW, Toyota Corolla, Isuzu DMax
Joined: 24-March 11

Posted 12 March 2012 - 08:18 AM

Here is the Tridon Range

http://www.tridon.co...35&G=483&P=2014

Back to top

#13 hanra

Oh My, Don't you post alot

Members
10,941 posts

Name:Brad
Location:Farrrrrr North Qld
Car:1975 LH SL/R 5000, 1967 Morris Cooper S, E36 BMW, Toyota Corolla, Isuzu DMax
Joined: 24-March 11

Posted 12 March 2012 - 09:31 AM

This one might be the go? I mean at what point do you want the fans to come on??? This is probably around the thermostat opening temp to..?? Keep in mind it gets pretty hot up this way to!

TFS 200 Temp Range: 92ºC to 87ºC

Posted Image

Back to top

#14 _oldjohnno_

Guests

Posted 12 March 2012 - 04:29 PM

...The fans coming on in the above if you have a eng mounted sensor may cool the outside of the engine, but its not going to really make a difference to the real problem of no water circulating regardless of where the blockage is.

What should be understood and not confused here is that the temp sensor for the temp gauge must go in the engine block.

You're absolutely right; the location of the gauge sender is critical. And what you say about the fan switch also makes sense - if the level is so low that there's no circulation then whether or not the fan starts is the least of your worries.

Back to top

#15 its Paul

Formerly lx8vd77

Members
1,577 posts

Name:Paul
Location:Gold Coast
Car:LXSS, VUSS, VESSv & the mighty HB
Joined: 07-January 08

Posted 12 March 2012 - 05:55 PM

I think mine is in this range Brad, Temp Range: 87ºC to 82ºC will have to check, plus mine is an alloy radiator.

Posted Image

Back to top

#16 _Ned Loh_

Guests

Posted 13 March 2012 - 07:25 AM

FWIW, my car is set up like this:

- Thermo fan sender in radiator, but not near hot water inlet or the fan doesn't switch off. Found that out the hard way. Moved to mid point of opposite tank and works fine. (Sounds so simple in hindsight).
- Water level switch in top of raditor. If water level in radiator drops it triggers idiot light in dash. (run the same light for oil pressue. Turns red for low oil pressure & green for low water level. Nifty)
- Water temp sender engine side of thermostat.
- Radiator overflow tank outlet hose aimed at windscreen. If there is enough pressure you get a squirt of water on the windscreen.
- Thrown fan belt triggers 'charge' light = pull over and have a look if that comes on.

Works good.

Edited by Ned Loh, 13 March 2012 - 07:31 AM.

Back to top

#17 TerrA LX

Fulcrum Fixture

Members
14,241 posts

Location:Sid 'n' knee
Joined: 31-May 06

Posted 13 March 2012 - 07:46 AM

I wouldn't be having boiling hot water squirting at my windscreen.

Back to top

#18 _double_d_

Guests

Posted 13 March 2012 - 12:36 PM

boiling water on your windscreen will only be a problem if the glass is at a really cold tempreture

Back to top

#19 _Ned Loh_

Guests

Posted 13 March 2012 - 01:35 PM

I wouldn't be having boiling hot water squirting at my windscreen.

I can understand where you are coming from but in practice it's fine. It's an old trick that works well. More chance of saving the engine than relying on looking at gauges anyway...

I should add this is on a race car (& I use the term race car loosely!).

Back to top

#20 _oldjohnno_

Guests

Posted 13 March 2012 - 05:02 PM

Sounds you've got it well and truly covered Ned. I love the overflow idea, it'd get your attention even better in a dirt tracker with no 'screen. I think the ultimate system would be some sort of boxing glove arrangement in the dash. Low oil pressure or high temp would activate the boxing glove, which would energetically punch you in the mouth. Pretty unlikely anyone would cook the engine unknowingly with this setup.

Back to top

#21 _robslxhatch_

Guests

Posted 14 March 2012 - 06:06 AM

Sounds you've got it well and truly covered Ned. I love the overflow idea, it'd get your attention even better in a dirt tracker with no 'screen. I think the ultimate system would be some sort of boxing glove arrangement in the dash. Low oil pressure or high temp would activate the boxing glove, which would energetically punch you in the mouth. Pretty unlikely anyone would cook the engine unknowingly with this setup.

haha , yep , the gauges would get watched like a hawk then.I like it!!

Back to top

#22 _Ned Loh_

Guests

Posted 14 March 2012 - 06:28 AM

Sounds you've got it well and truly covered Ned. I love the overflow idea, it'd get your attention even better in a dirt tracker with no 'screen. I think the ultimate system would be some sort of boxing glove arrangement in the dash. Low oil pressure or high temp would activate the boxing glove, which would energetically punch you in the mouth. Pretty unlikely anyone would cook the engine unknowingly with this setup.

I have the solution for the dirt tracker. FIA, CAMS, and NASA approved.