Auxillery water temp guage and where to fit the probe 100 series

Submitted: Thursday, Apr 11, 2013 at 01:51
ThreadID: 101623 Views:3193 Replies:4 FollowUps:19
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Hi I have a set of autron lcd guages being fitted to my 100 series 1hz turbo motor and the auto sparky wants to drill and tap a hole in my top radiator tank for the probe/ sensor to be mounted. Is this safe/ common? My car is very reliable and would hate for the radiator to fail due to this mod. The auto sparky says they do this to all the mining cars without any dramas.. Is this ok? Am I worrying about nothing?
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Reply By: bluefella - Thursday, Apr 11, 2013 at 05:56

Thursday, Apr 11, 2013 at 05:56
If it is a low coolant level alarm it's the best place for it, no problems.
AnswerID: 508709

Follow Up By: jacent - Thursday, Apr 11, 2013 at 06:04

Thursday, Apr 11, 2013 at 06:04
no its not its meant to be a engine temp guage not low coolant so I was thinking its prob not the best place? they said something about struggling to find another place to locate it
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Reply By: bluefella - Thursday, Apr 11, 2013 at 07:40

Thursday, Apr 11, 2013 at 07:40
If it's a coolant temp gauge it should have the sensor bolted to the engine, I used a bolt on the housing for the top radiator hose on the head, If it is in the top tank of the radiator and the thermostat fails to open it wont register the heat in the engine, or if you lost coolant the temp. would drop.
AnswerID: 508712

Follow Up By: bluefella - Thursday, Apr 11, 2013 at 07:44

Thursday, Apr 11, 2013 at 07:44
I also have a low coolant alarm fitted in the top radiator hose
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Follow Up By: bluefella - Thursday, Apr 11, 2013 at 07:48

Thursday, Apr 11, 2013 at 07:48
Should have said in the reply "If it's a ENGINE temp gauge"....
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Follow Up By: Echucan Bob - Thursday, Apr 11, 2013 at 11:35

Thursday, Apr 11, 2013 at 11:35
I agree with Blue. Bolt it onto the head where the radiator hose comes out. Do not put holes in your cooling system.

Bob
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Apr 11, 2013 at 12:26

Thursday, Apr 11, 2013 at 12:26
Bob, I think that Jacent has an Autron temperature sender as per photo below which has a 1/4" NPT thread to insert a 'bulb' into a water jacket. Not designed to bolt onto the head. Although with some effort perhaps that could be achieved but with questionable performance.

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Allan

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Follow Up By: jacent - Thursday, Apr 11, 2013 at 14:52

Thursday, Apr 11, 2013 at 14:52
I just went out and had a look and it appears the original temp sender is bolted into the top radiator hose at the head, could this be utilized by connecting both gauges to it? Like tee off it and plug both gauges into the same location? Or do each gauge need to have their respective probes to run independently? My idea of an extra temp gauge is to get a more accurate reading as I have heard the Toyota gauge only moves when temps get very hot! Thanks for all the replies as my car is going back there this week to be finished!
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Follow Up By: bluefella - Thursday, Apr 11, 2013 at 15:06

Thursday, Apr 11, 2013 at 15:06
Hi Jacent
In my opinion two separate gauges are better, the OEM may have different resistance.
In my Toyota I have.
engine saver low coolant alarm
TM2 Digital temp gauge
No affiliation etc.
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Apr 11, 2013 at 15:13

Thursday, Apr 11, 2013 at 15:13
No, for two reasons:
1) The sender bulb needs to be directly in the stream of coolant to read correctly. Installing a tee with the two senders in the tee branch would result in a very low reading from both as they are not now in the flowing stream but in a remote stagnant pocket where the temperature will always be much lower.
2) If you meant to electrically connect the new gauge to the existing sender then no again. Firstly they are unlikely to have the same characteristic and secondly connecting two gauges would 'overload' the sender and cause both gauges to read incorrectly.
Cheers
Allan

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Follow Up By: jacent - Thursday, Apr 11, 2013 at 15:37

Thursday, Apr 11, 2013 at 15:37
Thank you!
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Reply By: pop2jocem - Thursday, Apr 11, 2013 at 08:11

Thursday, Apr 11, 2013 at 08:11
I have re-powered my HZJ75 series with a 24 valve turbo engine ex an auto 80 series. I have had a low coolant alarm fitted to the top radiator tank for some 4 or 5 years and an extra coolant temp gauge is installed in the top outlet housing from the engine to radiator. Because the engine was originally from an auto vehicle that housing has two sensors already fitted. One was to shut off the air con if the coolant temp got too high and the other apparently limits transmission upshifts in certain engine temperature ranges. I removed the auto limit sensor (my vehicle is manual) and tapped the hole to take the gauge sender. I left the original temp gauge connected and both work quite well. With your vehicle I would think you could have the gauge fitted to the top tank, my level alarm has never caused any dramas, or maybe drill and tap the coolant outlet housing.

Cheers
Pop
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Follow Up By: bluefella - Thursday, Apr 11, 2013 at 10:19

Thursday, Apr 11, 2013 at 10:19
Hi Pop

It,s an engine temp gauge so no good in the radiator.
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Follow Up By: Flighty ( WA ) - Thursday, Apr 11, 2013 at 14:09

Thursday, Apr 11, 2013 at 14:09
Sorry bluefella but Jacent has it pretty clear in his post "Header" that it is an Auxillary water temp gauge, not an engine temp.
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Flighty

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Follow Up By: pop2jocem - Thursday, Apr 11, 2013 at 14:45

Thursday, Apr 11, 2013 at 14:45
Blue,
As per my post, the level alarm is in the top tank of the radiator, the coolant temp gauge sender unit is in the coolant outlet housing from the cylinder head.

Cheers
Pop
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Follow Up By: bluefella - Thursday, Apr 11, 2013 at 14:58

Thursday, Apr 11, 2013 at 14:58
Hi Flighty
Have a look at Jacent's first follow up "meant to be a engine temp gauge"
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Follow Up By: jacent - Friday, Apr 12, 2013 at 03:35

Friday, Apr 12, 2013 at 03:35
Hi pop do you think it might be worth getting a housing from a wrecker from an auto trans 1 hz that already has the second hole ready to tap? I spoke to the guy tonight and he suggested drilling and tapping the coolant outlet that the air con cut off sensor is located but the air con sensor is off to the side so not restricting flow and if he tapped this the sensor would be in the middle of the coolant flow possibly restricting flow? Hence wondering about the ex auto motors housing? I thought by paying to get all this professionally fitted it would be a breeze but its turning out to be a drama! End of the day I'm the one who will be stranded in the desert when things fail not the auto sparky so I want things done right!
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Reply By: Allan B (Member, SunCoast) - Thursday, Apr 11, 2013 at 11:17

Thursday, Apr 11, 2013 at 11:17
Hi Jacent,

I take it that this temperature sender has a "bulb" with a 1/4" threaded connection?
Positioning the temperature sender in the the radiator tank is not a good idea. I frankly do not believe your auto sparky is correct about "all the mining cars" etc. He is probably looking for an easy way out.
1) The purpose of the gauge is to measure the engine temperature not the radiator temperature which may not be the same thing. (e.g. prior to the thermostat opening during engine warm-up or in the event of low coolant.)
2) Attaching to the radiator tank is not simply drilling & tapping the tank. If it is a metal tank it is too thin to tap and it is necessary to drill & solder on a threaded boss to accept the sender. If a plastic tank, it will not reliably take a thread and it is necessary to fit a boss with a locknut inside the tank... a difficult procedure. If you elect to fit the sender to the radiator tank you would be wise to have it done by a radiator specialist, not an auto electrician. The outcome of a poor fitment could be disastrous!
3) It would be more appropriate to position the sensor into the water jacket of the engine. There may already be a suitable location available, currently closed with a threaded plug or suitable for drilling & tapping. An engine mechanic could advise you about this and you would be wise to obtain his (or hers, lol) advice.
Cheers
Allan

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AnswerID: 508725

Follow Up By: jacent - Thursday, Apr 11, 2013 at 14:33

Thursday, Apr 11, 2013 at 14:33
The guy who runs the all mine branch it is being done at says he is a mechanic and he is helping the auto sparky with the mechanical side of things, In the instructions it says to tap into a water jacket on block but they said there wasn't a blanked one there and yes it sounds like they are trying to take easy street and just bolt it into the top tank, this was where I was concerned as you say radiator tanks are very thin! I might firm up and suggest the put their thinking caps back on! Thanks
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Follow Up By: jacent - Thursday, Apr 11, 2013 at 14:58

Thursday, Apr 11, 2013 at 14:58
(Head ) not block sorry, it has a oil pressure gauge too ??
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Follow Up By: jacent - Thursday, Apr 11, 2013 at 20:51

Thursday, Apr 11, 2013 at 20:51
I made a mistake, the sensor on the head outlet to radiator is for the air con cut out on high temp
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Follow Up By: Allan B (Member, SunCoast) - Thursday, Apr 11, 2013 at 22:38

Thursday, Apr 11, 2013 at 22:38
Jacent,
You do have one option to measure the engine temperature using the Autron sensor that you have already purchased.
If you can fashion a saddle (similar to a conduit saddle) such that it can be clamped under a stud & nut on the engine block and holds the sensor bulb in good contact with the block then it has some chance of registering the engine temperature.
Be careful to not damaging the sensor bulb as they are fairly thin.
It would also be helpful to wrap the rest of the sensor (hexagon etc) with several layers of silicon self-amalgamating tape to reduce heat loss from this part of the sensor which would introduce an error in the measured temperature.
Cheers
Allan

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Follow Up By: jacent - Friday, Apr 12, 2013 at 03:24

Friday, Apr 12, 2013 at 03:24
Thanks for the idea I will be heading to the workshop tomorrow to sort this out!
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