After Market Temp Guage.

Submitted: Monday, Feb 20, 2006 at 23:56
ThreadID: 30993 Views:2165 Replies:7 FollowUps:32
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Ok, been thinking about this for a while now because I don't trust the factory guage, it's SO slow to respond and who knows what a little bit above half on the guage really is anyway! So I'd like to put a good quality guage with METRIC readings on it so I can monitor the surf's temp more accuratly and see what the old girl is actually going through while we're tearing down the beach on a 40c day.

My question is:
1. is it better to go electric or mechanical or does it make no difference.
2. Is there any other way to fit a second temp guage without drilling and tapping into the thermostat housing? I really don't want to do that if I can help it, because it looks like a mongral to get off, might have to remove the power steering resivour to get to the bottom bolt, and just thought there might be an easier way.
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Reply By: Truckster (Vic) - Monday, Feb 20, 2006 at 23:59

Monday, Feb 20, 2006 at 23:59
I got a mechanical VDO gauge here if your interested :)

I went elect as the cord wasnt long enough for the GQ.
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 00:09

Tuesday, Feb 21, 2006 at 00:09
Cool, wadya want for it?
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Follow Up By: Truckster (Vic) - Tuesday, Feb 21, 2006 at 00:10

Tuesday, Feb 21, 2006 at 00:10
paid $50ish.. $25+ post? or ono.. its sittin there in the box still never used
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 00:16

Tuesday, Feb 21, 2006 at 00:16
Yeah cool, it's got celsius on it yeah? If so that sounds cool, so what's that $30 bucks delivered? Just email me jeff at smokinghat dot com dot au.

So now I got the guage, where do I put the sender!? ;-)
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Follow Up By: Truckster (Vic) - Tuesday, Feb 21, 2006 at 00:26

Tuesday, Feb 21, 2006 at 00:26
I'll get photos and VDO Part # for u to make sure its what you want, dont want to send it and it not be the right thing.

mail me off here if u like

fu_kew
at
hotmail
dot
com

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Follow Up By: Member - Roachie (SA) - Tuesday, Feb 21, 2006 at 08:29

Tuesday, Feb 21, 2006 at 08:29
I've put my sender unit in the top radiator hose. I got an engineering shop to make up a short piece of stainless steel pipe, add a collar to each end and a lug half way along. I then drilled and tapped a hole the right thread pattern to accept the brass sender unit of the VDO gauge. Need to earth the gauge to neg battery terminal (or body etc).....too easy. Cut a section out of top hose and insert the new section into it. I carry a full set of hoses/belts anyway, so if there is ever a problem with split hose etc, just need to change things around as you normally would.
Works real good.
Mine is a VDO gauge in celcius.
A word of caution......you'll find the VDO gauge will reflect the TRUE water temp. On my GU, this means watching the water temp vary quite a lot. When the Nissan gauge hits it's "normal" position of just under half way, the VDO gauge is only up to about 50oC. The Nissan gauge will sit at this point whilst the VDO gauge goes from 50oC up to 105oC, before it decides to move up to around half way. From that point the Nissan gauge will go to almost 120oC with the Nissan gauge just about to enter the "H" zone (although it has never got right into the hot zone yet).
As for the idea of oil temp gauge.....I have one of these fitted in the sump and it is good to know what is going on there as well. However, it is very slow to rise and fall, so I would have to say that it is not necessarily a good "substitute" for a water temp gauge. BTW, don't discount the idea of also fitting a Engine Saver Low Water Alarm!!! The water temp gauge will not tell you if you've blown a hose or something and have lost all your coolant!!!!
Cheers

Roachie
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Follow Up By: Exploder - Tuesday, Feb 21, 2006 at 19:34

Tuesday, Feb 21, 2006 at 19:34
Jeff, if you want to go with Roachie’s installation RE: the temp sender in the top hose with a Stainless tube insert housing the sender let us know the ID size of the top radiator hose and the size/Type of thread you need taped in it and I could put one together for you at work for $0 Probably. It would be 316, or 2205 Marine grade S/S so it will never corrode.
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 20:13

Tuesday, Feb 21, 2006 at 20:13
Exploder you are a legend, i might have to take you up on that one!! Thanks Mate.
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Follow Up By: Exploder - Tuesday, Feb 21, 2006 at 21:28

Tuesday, Feb 21, 2006 at 21:28
No problem, Hope we have the right sized tube, May need to be CuNi but that’s ok just more corrosion resistant or S/S Hydraulic line.

When you get around to it just Post the
1. the ID of you top radiator Hose
2 .The size and type of thread on the sending unit fitting, hopefully I will just be able to use a toe nipple to keep it easy.

And I will let you know what I can do

I take it you just need a strait peace about 100mm long and you will cut 35mm out of the top hose and slide it in, I will flair the 2 ends a few degree to illuminate the possibility of it slipping off the hose when under pressure, and just drill a hole in the middle and Tig weld the Toe nipple over the hole to take the sending unit.

Is this the sort of set up you had in mind?
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 21:37

Tuesday, Feb 21, 2006 at 21:37
Bloody oath, sounds awsome. I'll let you know ASAP. Thanks again!
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Follow Up By: Member - Roachie (SA) - Tuesday, Feb 21, 2006 at 22:41

Tuesday, Feb 21, 2006 at 22:41
If you're gunna use the VDO gauge, I think you'll find the thread size is 1/8"NPT.
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Reply By: V8 Troopie - Tuesday, Feb 21, 2006 at 00:18

Tuesday, Feb 21, 2006 at 00:18
If I were to add a temperature gauge it would be one for the oil temperature. This, IMO, would show engine operating conditions better than monitoring the efficiency, or lack of, of the cooling system.
The average 4WD engine is a fair size thermal mass which cannot change quickly anyway, the coolant temperature, being rapidly pumped through the engine, only shows heat as its being transferred from the block to the radiator. This is not necessarily the operating temperature of the engine.
Klaus
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Follow Up By: Member - Reiner G (QLD) 4124 - Tuesday, Feb 21, 2006 at 00:42

Tuesday, Feb 21, 2006 at 00:42
smart thinking Klaus........ no need to know really what temp the water is if the oil gets to hot that will kill the engine.
I have seen in a 4 cyl racing car they had gauges of each cylinder head temperature.......makes a lot of sense.

Reiner
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Follow Up By: Member - Oldplodder (QLD) - Tuesday, Feb 21, 2006 at 09:19

Tuesday, Feb 21, 2006 at 09:19
Run the head temp guage on the beetle.
Being air cooled, no water temp to monitor, and oil temp takes too long to go up and down. Still have an oil temp guage though.
VDO make a sensor that sits around the spark plug.
We use N.o 3 cylinder on the beetle, since it is the one that always runs hotter, since it gets less air than the others.
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Reply By: desert - Tuesday, Feb 21, 2006 at 08:24

Tuesday, Feb 21, 2006 at 08:24
Electric gauges are more convienient to fit because you can run the wiring un-obtrusively just about anywhere you like. The mechanic gauge is limited in it's neatness due to the restrictions caused by the bawden tube that it attached to the sender unit. This also means you have to drill a fairly large hole through the firewall to be able to pass this sender through to the engine compartment. The sender does not have to go into the thermo housing. You could use any blank plug that enters a water jacket anywhere on the cylinder head, or even the top tank of the radiator or have a ferrel soldered in just for that purpose. The rear of the cylinder head is usually a few degree's hotter than the front, so this might influence your placement too.
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Reply By: Willem - Tuesday, Feb 21, 2006 at 09:18

Tuesday, Feb 21, 2006 at 09:18
After many emails and discussions with Roachie about what to do about my GQ's water temp gauge I ended up with a VDO which is married up to a Nissan sender. Whether it is accurate or not is another thing. I sometimes think it reads too hot.

I soon found out that Mechanical and/or VDO gauges are basically made for ordinary cars and trucks as nothing seems to fit my plurry Nissan.

Your best bet is to do as Roachie suggests and fit the sender unit in to the top radiator hose.

Have fun!!!
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Follow Up By: Truckster (Vic) - Tuesday, Feb 21, 2006 at 14:47

Tuesday, Feb 21, 2006 at 14:47
>>> Whether it is accurate or not is another thing. I sometimes think it reads too hot.

its not, you have to get the VDO Sender. Gotta get one myself one day, back to the dash gauge working currently
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Follow Up By: Willem - Tuesday, Feb 21, 2006 at 19:40

Tuesday, Feb 21, 2006 at 19:40
Yes but the VDO sender does not fit and I was not able to find a combination of connectors which would make it fit. The only other option was to fit a pipe inside the top radiator hose and then make a fitting for the VDO sender to fit into. Had everything bought and then it seemed too hard so I gave the bits to Roachie to play with. My gauge seldom gets up to 115 but has been up to 120 although I reckon that that is inaccurate as the radiator is only hot and but not boiling at that stage.
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Follow Up By: Truckster (Vic) - Wednesday, Feb 22, 2006 at 00:32

Wednesday, Feb 22, 2006 at 00:32
I was told VDO one didnt fit too.. but Rochie has one that fitted
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Reply By: Member - Reiner G (QLD) 4124 - Tuesday, Feb 21, 2006 at 09:43

Tuesday, Feb 21, 2006 at 09:43
fitting a temp feeler in the top of the radiator tank is not the way to go in MHO.... when you loose water the gauge will show you a much cooler temperature while not sitting in water.
The gauge needs to be at the bootom of the radiator or be a oil temp gauge.
My 2 cents worth anyway....

Reiner
AnswerID: 156205

Reply By: Mike DiD - Tuesday, Feb 21, 2006 at 12:02

Tuesday, Feb 21, 2006 at 12:02
No wonder so many people cook their engines with the Temperature sensor being in the water flow.

If you run low on water (cracked radiator, stone in radiator etc etc) there is no longer any water to heat the sensor !

In this case the part of the engine that will heat up fastest will be the source of heat - the cylinder head. That's where I'll be putting an overtemperature switch that will sound an audible alarm - well before cooking the engine. I suspect around 110 degrees would prevent false alarms form heatsoak after the engine has shut down.

I'll have to do some temperature measurements to see what is normal.

Mike
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 12:11

Tuesday, Feb 21, 2006 at 12:11
Yeah I'd been thinking about an audiable alarm too, should be easy to fit a stock temp switch, you can buy them 110c. Maybe the audiable alarm coupled with a temp guage in the top hose (for ease of installation). Thanks Roachie, I was looking at the top radiator hose and wondering how i could put it in there, the joiner is a bomber idea. Thanks everyone!
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Follow Up By: Eddy - Tuesday, Feb 21, 2006 at 14:39

Tuesday, Feb 21, 2006 at 14:39
Hi Mike DiD.

I would be very carefull about putting a heat sensor on the cylinder head as they heat up from the inside to outside.
They always crack internally after an overheat.
Not a lot of margin for error there unfortunately.

What you said about the water flow is true though, you need something to tell you when the water is gone.
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Follow Up By: Member - Roachie (SA) - Tuesday, Feb 21, 2006 at 14:49

Tuesday, Feb 21, 2006 at 14:49
Quote: "What you said about the water flow is true though, you need something to tell you when the water is gone."

Spot on Eddy, That's why I mentioned (and have fitted myself as well), a product called "ENGINE SAVER Low Water Alarms". This gives you an immediate warning of lack of water in the top radiator hose, via an audible alarm as well as a large red LED. I have one of these fitted to the GU as well as the previously mentioned VDO gauge in the top hose and a oil temp sender in the sump, and a EGT gauge with thermocouples in both manifold and dump pipe. You cannot have too much info as far as I'm concerned.

For info about the Engine Saver Low Water Alarm, contact David Jones (owner). see www.enginesaver.com.au or email sales@enginesaver.com.au

I have no financial or other interest in this business, other than being a satisfied customer.

Cheers

Roachie
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Follow Up By: Mike DiD - Tuesday, Feb 21, 2006 at 15:05

Tuesday, Feb 21, 2006 at 15:05
So can you suggest a place for the sensor that will give a QUICKER indication that the engine is overheating ???

Since you can't put a sensor on the inside of the cylinder head, the next best place is as close as possible to it.

Measuring the oil temperature will give you a delayed response - the hot oil leaving the head area will be cooled down by the rest of teh Block and the other oil in the sump.

Mike
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 15:34

Tuesday, Feb 21, 2006 at 15:34
Ummm, yeah I kinda agree, and ok so if the inside of the head is hotter (which I don't think anyone is disputing) then just use a cooler temp sensor, but I would have thought the head could have gone to 110c+ with no problems as my turbo timer switch is 70c and that barley needs the car warmed up to activate.

Hee hee, reminds me of my mates ol Kinga, had no shroud on the radiator so when we used to sit in the drive through waiting for our tucker the third party temp guage (origional didn't work) used to climb and climb and climb, and go past 120c and climb... you'd say "hey benny man, your temp guage is going off the end of the scale" and the Kinga would start to smell like hot metal and FINALLY they'd give you your chicken and chips and he'd calmly cough and splutter off down the driveway, 30 seconds after you'd start moving the temp would be back down to below 100 and the old girl would be sweet as again! LOL Well apart from the fact you could see the road through the floor and roof was held on by bog, but it was a beast. He went more 4x4 in that thing that most people do in their 4x4's!!
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Follow Up By: Member - Roachie (SA) - Tuesday, Feb 21, 2006 at 16:11

Tuesday, Feb 21, 2006 at 16:11
With all these sensors I have, by far the easiest and quickest one to monitor head temp would have to be the EGT in the mainfold. It reacts EXTREMELY quickly to any slight change in road slope etc. The manifold is measuring exhast gas temp within a millisecond of it exiting the head, so you'd have to say this would be the best place to get up-to-date temp readings (even on a non-turbo engine).

As for the notion that head temp of 70oC is achievable, I'm sorry but this is total fantasy. My digital EGT gauge reaches 70oC from a dead cold start, within about 30 seconds. At idle, after a completely warm run, the EGT is around 170oC if you let it idle for several minutes.

Cheers

Roachie
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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 16:15

Tuesday, Feb 21, 2006 at 16:15
"As for the notion that head temp of 70oC is achievable, I'm sorry but this is total fantasy. My digital EGT gauge reaches 70oC from a dead cold start"

I'm not sure what your saying here roachie? I think I was agreeing with that statement?
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Follow Up By: Member - Roachie (SA) - Tuesday, Feb 21, 2006 at 18:12

Tuesday, Feb 21, 2006 at 18:12
Sorry Jeff, I totally misunderstood what you meant....I'll take a Bex and have a little lie down.hahaha ;-)))

Cheers mate

Roachie
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Follow Up By: Mike DiD - Wednesday, Feb 22, 2006 at 07:27

Wednesday, Feb 22, 2006 at 07:27
I thought the whole focus of this thread was about getting the earliest indication possible if something goes wrong with the cooling system.

EGT doesn't help you for that.

Mike
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Follow Up By: Member - Roachie (SA) - Wednesday, Feb 22, 2006 at 09:23

Wednesday, Feb 22, 2006 at 09:23
Mike, of course you are correct. The discussion seems to have de-railed somewhere. I perpetuated that by mentioning EGTs, but I was "guided" that way when people started talking about cylinder head temps etc.
Sorry for misguiding info.
Cheers
Roachie
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Follow Up By: Member - Jeff M (WA) - Wednesday, Feb 22, 2006 at 12:43

Wednesday, Feb 22, 2006 at 12:43
Actually guys, I think the purpose of this thread (seeings as I wrote it) LOL, was about weather to go a mechanical or electric type guage and where the EASIEST place was to install the sender, not the fasted to respond or the best if you blow a hose or what my head tempeture is or weather the moon is made of cheese or not... Mind you I have found the discussion interesting and that's what's great about these forums, especially this one, a simple question can start a HUGE debate that may not be exactly on topic but is based on experience, technical know how and is still full of interesting information that the 1000's of readers of this site can take away with them.

But I think I'm going to go with Roachies idea of putting it in the top hose with Exploders help.
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Follow Up By: Member - Jeff M (WA) - Wednesday, Feb 22, 2006 at 12:50

Wednesday, Feb 22, 2006 at 12:50
I'll also add this for all the parinoid out there! ;-)

Ok, I might put a water sensor in later, but there are a couple of things to note about blowing a hose. 1. I change them reguarly and use the old one as a spare, so the chances are slim anyway.
2. The surf runs so bloody hot when I'm working it (when the chance of a hose blowing is at it's maxium) that's I'd be AMAZED if I didn't notice the temp guage dropping as the coolant flow slowed and would think, hmmm, what's going on there.... It should be hot as a BBQ plate at christmas...
3. If you've seen under my bonnet there is'nt barley enough room for me to get my hand into the radiator shroud, there's CRAP EVERYWHERE and because of this there is not much airflow under there, I'm pretty sure that if a main hose was to go (which is what would have to happen in order for it to be as quick as these people are talking, a heater hose would happen slow enough for me to pick it up on the guage, had it happen in several vehicles before). Then I'm pretty sure I notice the oooodles of steam wafting out from under the bonnet... Had that happen in my Maxima when Nissan didn't do the hose clamp up on the top radiator hose and it blew off going over a speed bump, you can't exactly miss the steam bleep out from every avalible crack in the bonnet...
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Follow Up By: Mike DiD - Wednesday, Feb 22, 2006 at 13:44

Wednesday, Feb 22, 2006 at 13:44
Well, Jeff, I think we've all learnt a lesson - when you start a topic, write it out completely, so there is NO chance of anyone misunderstanding it, and it no-one will take as a personal criticism and start flaming ;-)

Mike
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Follow Up By: Member - Jeff M (WA) - Wednesday, Feb 22, 2006 at 13:47

Wednesday, Feb 22, 2006 at 13:47
"My question is:
1. is it better to go electric or mechanical or does it make no difference.
2. Is there any other way to fit a second temp guage without drilling and tapping into the thermostat housing? I really don't want to do that if I can help it, because it looks like a mongral to get off, might have to remove the power steering resivour to get to the bottom bolt, and just thought there might be an easier way."

I thought I did?? LOL.
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Reply By: muzzimbidgie - Tuesday, Feb 21, 2006 at 16:48

Tuesday, Feb 21, 2006 at 16:48
Jeff, my Brother cooked his 250Cortina from a burst hose cos the temp sender unit is in the top of the thermostat housing and once it is out of the water it's like peter brock in a volvo (no good to anyone) hahahahahaha

Since then I've had the same fears and have had a mechanical temp guage in every car I've had and it saved me twice.

In every car I put the sender in the drain plug at the back of the engine block (usually under the exhaust manifold) and yes it is interesting to see how it moves differently to the OE guage)

As long as you put the guage in a prominent position in the cab, and make a habit of checking it whenever you check the speedo, you should be right.

If you do burst a hose the temp will go up straight away (no longer under pressure) and coolant should remain in the block longer than the top radiator hose which I imagine would empty fairly quickly.

Cheers,

Muzz

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Follow Up By: Member - Jeff M (WA) - Tuesday, Feb 21, 2006 at 16:55

Tuesday, Feb 21, 2006 at 16:55
Awsome Muzz, sounds like another ripper idea, I'll have to get under and have a look when Truckster get's the guage to me! ;-)
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Follow Up By: Eddy - Tuesday, Feb 21, 2006 at 18:44

Tuesday, Feb 21, 2006 at 18:44
Hi Muzz,
Hope your right.

I reckon if you burst a hose ar 2500rpm, the water pump will empty the block quicker than you can say "toyota spare parts!"
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Follow Up By: muzzimbidgie - Tuesday, Feb 21, 2006 at 19:30

Tuesday, Feb 21, 2006 at 19:30
Yes you are right Eddy.

In the only time I have had an absolute catastrofic hose malfunction I WAS NOT quick enough to shut it down before there was a loud knock which later turned out to be a cracked head, but I WAS quick enough to avoid further serious damage!!

The temp guage in the dash only moved a little and had I been relying on this alone, it would have all ended in tears.
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