Thread: Water gauge

Originally Posted by Homestar

Sticking your finger out the window is more accurate that the factory gauge.

Nothing wrong with the D2 gauge. As long as the actual temp doesn't go above about 85° it's spot on, and when the needle suddenly goes all the way up it's HOT.....

Originally Posted by chev_1973

v8 , I just want a simple gauge that is more accurate than the factory one.

So, you want a temperature gauge.

Originally Posted by chev_1973

v8 , I just want a simple gauge that is more accurate than the factory one.

Quickest simplest and still accurate way on a V8 is via a bluetooth OBD dongle, and a program like Torque.
I dunno if Torque is available for iOS, but works good on Android, and you can also set up gauges for some other variables too.

I've used that kind of setup in my V8, as well as nanocom, and they show same values.
Handy thing about having a OBD gauge, as opposed to just using the dash gauge is that the OBD gauge shows you the actual temps as they rise in an overheat situation.

I can't remember exact numbers, but goes something like this on the std gauge. From about 40-something it begins to indicate on the temp gauge, obviously down really low. From about 65/70-ish deg to 110°C shows the normal range on the dash gauge.
From what I've read, 110 is ok for a while on a V8, just don't want it there for too long(eg. towing up a steep incline for a short period, but then backing off a few mins later ... coolant temp should settle back down to high 80s to low 90s again.

The critical area is the 110-115(ish) temp range where the needle does rise a very small amount, but if you're overheating and it hits roughly 117, in a blink of the eye, it's in the red zone.

I watched all this play out on my V8 a while ago before I then killed the engine(which was a gonner way before I got the car anyhow).

OBD doesn't work only on the TD5 in the D2 era, but works fine on the V8s.

I have a few OBD devices I can use, everything from a thousand dollar setup to the cheapest $10 ELM27(which now cost as low as $5 ish on ebay) ... they all work fine.

TD5 OBD works on Nanocom, so I'd say it was your OBD device that couldn't read the temperature, Arthur.

Originally Posted by V8Ian

TD5 OBD works on Nanocom, so I'd say it was your OBD device that couldn't read the temperature, Arthur.

Whilst the port on a TD5 is physically compatible with OBD2 the TD5 ECU is not.

The nanocom doesn't use OBD2 to communicate with that ECU.

The TCU on a Discovery 2 has *some* OBD2 support, but the nanocom doesn't use it to communicate


The V8 motronic however has reasonably good OBD2 support.

Originally Posted by V8Ian

TD5 OBD works on Nanocom, so I'd say it was your OBD device that couldn't read the temperature, Arthur.

I think U miss understand Ian.

TD5 isn't OBD, just that the comms port is an OBD type, same as the V8. So TD5 can't use the ODB protocols, and hence the diagnostics other than nanocom/Haweye/LRs own, don't work.

But V8 is different, in that just about any OBD scan tool works on the OBD system(due to US requirements).

So where TD5 works only with nanocom(or LRs or Hawkeye) ... V8 works with cheapo $5 bluetooth dongle and diagnostic software to suit too.
The free version of Torque(phone app) also was able to read and clear codes, except one issue with ABS.

Of course nanocom recognises all functions on the D2 like operate electrics and set air suspensions and stuff like that, at the time I didn't have any ODB tools with that high level diagnostics.
I now have a U-beaut high end diagnostic tool, but I haven't tried to connect to the V8 D2 ... the V8 is a future project that I don't have time for just yet.

Once it was established that the OP has a V8 D2, then my comments were that the quickest simplest way to see coolant temps, is via a cheapie bluetooth dongle, a ODB diag app on a smart phone(like Torque) and a few minutes of set up time to set Torque with a dash set up.

Someone mentioned the bleed plugs as a easy way to hook a temp probe to the coolant circuit, but I personally would be weary of that, as both the V8 and the TD5s bleed plugs are quite fragile if pushed a bit. V8 better than TD5(as standard setups) .. but on the bros TD5 we changed to all silicon hoses for coolant, and went with the 'separated' top hose where instead of the bleed plug being embedded in the top hose, it uses a T piece(aluminium) with a nice sturdy bleed bolt(metal too), and would easily hold a temp probe up there(other than bonnet clearance issues).

IMO for engine temp monitoring the best is a standalone gauge with it's own sensor, the OBD device(i mean any compatible diagnostic tool regardless of engine type) shows the reading calculated by the ECU based on the ECT sensor's input which in some cases is not very accurate. There are gauges with bolt on sensors easy to install under any bolt on the head or block which will show the real temperature at that point. Not cheap but that's the real thing IMO, i like this one ENGINE GUARD Single bolt-on temperature sensor alarm there are cheaper options too for example Cylinder Head Temperature Gauge and Sensor Kit, CHT. 18mm – Mainline Sensors

Originally Posted by sierrafery

IMO for engine temp monitoring the best is a standalone gauge with it's own sensor, ....

Fair call, and I kind of partially agree, but not fully.
I have both. TDi D1 doesn't do OBD so only way to get one going is the 'standalone' method, which I've done.

I have experience with both types of setups and the difference is too minor to concern with.
Whats important is the ability to recognise if the motor is actually overheating, or is it just a case of a stressed situation, which of course, will increase coolant temp for the time that there is more stress on the motor.

eg. lets say the motor generally runs its coolant at 85°C consistently in mild weather, and on a hot day it may sit at closer to 88°C. Turn on AC and suddenly coolant shows 95°C on this hot day. Is it overheating or not?
Ive watched this scenario on the TD5 for nigh on 2 or more years now .. this is normal. Turning on AC doesn't cause 'overheating'. The point being that does it really matter what 'actual' temp the coolant is? My concern is only in the change in temps and under what situations it happens.
So in my example above, does it really matter that it's 95°C or is it critical if it's' really 100°C, or again it makes no difference if the actual temps is really 90°C. To me, whats more important is, is it going any higher than this on a low stress drive.
Now hit the sandy track on this hot day, lower tyre pressures, and what temp will it get too now? 110°C? I'd expect that on a hot day with AC on, reduced tyre pressures and on a sandy track .. if it didn't get up into the low 100s I'd be more worried that something doesn't seem right.

I doubt very much that just by deciding that you want to use a standalone setup that it's going to be actually more accurate. With the amount of variables present in the system, I believe this to be less of a reality and more of a philosophical ideology.

Again, my reason for writing this is my Tdi. I used a fairly reliable system, using quite high quality parts(eg, VDO sensors and suchlike). As these sensors all work on the idea of resistance to send the signal to the gauge, just the type/quality/location of the wiring could easily affect the accuracy of the reading, which I've watched many times over in the Tdi. The VDO sensor I got uses a spade terminal(male) on it's end. Originally I used a std spade connector(female) and it worked a treat. Over time, I used to get non standard readings. ie, looked like overheating. Of course being worried about it, I'd pull up and check coolant, feel hoses, etc ... not issues that can be noticed. But then one day I did notice that the stupid spade connector I used was half off the sensor terminal ... doh!Easy fix, get a 'proper' spade terminal sensor connector for it. Quality item from a reputable source. Cost far too much for a simple connector, but worth the effort. But again, over time this type also failed to provide a secure connection and again I'd get too hot reading for no reason.
In the end, I just soldered a cable to the sensor and fitted a much more positive connection type.
This is just my specific situation, and set up .. ie. vibration of tdi can cause weird issues such as this, and the point being that trying to get 'accurate' info in such circumstances can be a foolish endeavour.