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Fit a Water Temperature Gauge

Firstly apologies for the rather haphazard way of adding the images, one even being upside down even, but at my great age, these things don't come easy (or so the song says).

So why add a water temperature gauge? Well I feared that the engine was getting too hot and I doubted the efficiency of the fan sensor and the cylinder head temperature sensor.

So before I began with the gauge, I fitted a new radiator as the bottom of the old one was pretty rotten.

Then I fitted a new fan sensor. Still after allowing the engine to tick over for twenty minutes, the fan refused to come on. Out with my tester and I found that one of the feed wires for the fan sensor was rigid. When I stripped back the insulation, I found the copper wire was jet black, so I replaced this 18" length of wire with new and got the fan to come on. But I still had my doubts as the fan still proved temperamental and sometimes failed to come on every time.

The cylinder head temperature sensor. Renown for being 'iffy', the red light sometimes came on especially after a trip on the motorway at 70mph followed by stop-start traffic. Also the red warning light flickered rather than staying lit. I cleaned it up but that made no difference.

I should say at this point that the radiator fan should come on at 85c, followed by the red warning light at 115c, after which serious problems might/will occur - failed cylinder head gasket warped cylinder head, failed cylinder liner seals.

Time to fit a water temperature gauge so I could actually SEE what the hell was happening.

Image 4. Water Temperature Gauge from eBay = about £7. This came with a temperature sensor. Now where to fit it?

Image 2. The is an existing plug (at least on my R4GTL) on the water pump. Undo this using a 10mm Allen key. The threaded female hole has an M18x1.5 thread and for the sensor to fit, I bought a brass water temp gauge adaptor from eBay (£6.99) - M18x1.5 to 1/8NPT. Don't forget to use a decent copper crush washer twixt adaptor and water pump.

Image 3. I gave some thought as to where to mount the gauge as I wanted it to be in my eye line but neither stuck up on top of the dash nor pinching too much of storage shelving. So I chose to place it alongside the instrument binnacle. I drilled a couple of holes at the side and fitted a pair of M5 rivnuts. These are threaded 'rivets' and expand in the holes. I had to fit a small block of wood with a pair of M5x50 screws, to bring the gauge out to the right so it wasn't obscured by the steering wheels. Ikea meets Renault.

Image 1. There were three terminals on the back of the gauge - S = signal wire (to sender), + = ignition switch, - = earth. The two thin wires, black and red, are for the internal lights which I have chosen not to connect as the internal light is apparently much too bright.

All wiring was in 5amp wire with 5amp heat shrink crimped connector, wonderful things unlike their non-heat shrink counterparts. For the ignition switch, I undid the plastic steering column surround and found a connecting block close to the ignition switch. Rather than splice into one of the wires (the cream coloured one) I found a 5amp bullet connector made a nice push fit into the block.

So all wired up, ignition on, and the needle of the temperature gauge gave a nice twitch. Off on a test drive to see a friend four miles away, and I watched the needle climb, and climb and climb. 85c reached and no apparent sound of the fan coming on, 100c reached (a bead of sweat runs down my forehead) then 110c, before I arrive home. The system was properly bled yesterday with the expansion tank raised to it's highest point, the heater was in the 'On' position, the radiator topped up and the top hose 'massaged' to eliminate any trapped bubbles. No unwanted bubbles or smells coming from the expansion tank.

A puzzle, and I'm running out of ideas.
 
I am sorry to hear about your engine troubles but i do love this and am thankful for hte detail you provide.

Plan to install two gauges where the ashtray should be on my GTL when he is finished
 
Yes, another option and although I'm a non-smoker so it wouldn't be a loss, it mean't too much of an alteration for my taste. I've seen some images of this mod on the Italian R4 website. No kidding but half of the problem for a non-electrician is gathering the information about sizes of wires, crimped connectors, and so on, and Jonathan of this parish has been most helpful with regards to this. Now why is the engine getting SO hot???
 
Eoynteenie said:
I am sorry to hear about your engine troubles but i do love this and am thankful for hte detail you provide.

Plan to install two gauges where the ashtray should be on my GTL when he is finished
Click to expand...
Same here, Temp and rev counter
 
Paul,

I'm putting my thinking cap on in an effort to sort this one.... Ignoring the gauge you've just fitted for the moment, which the engine on tick-over and at normal operating temperature the fan should come on & go off as the engine temperature goes up & down. The easiest way to check this is to warm the motor with a short drive, leaving the engine running, park up & put the heater controls to "off' (cold). After a short period of time the temperature of the coolant will rise enough to make the sensor switch the fan on. The fan will then turn itself OFF as the temperature of the coolant drops. This cycle should allow the engine to perform quite happily on tick-over. I'm sorry if this is "teaching one's grandmother to suck eggs" but you need to check this is O.K. first. If this part of the cooling system is working properly that's half the battle. If it's NOT doing this you need to find out why. Bleeding Renault 4 engines is a pain in the rectal zone, but with patience, effort and perseverance it can be done!

Report back and I'll think some more......
 
hi Paul - great write-up! Certainly food for thought.

My R4 cooling system cycles as it is supposed to with the fan (on & off at tickover etc), though the original wiring had a bullet (?) connector to the fan near the alternator that VERY easily pulled out (usually when trouble-shooting something else!), rendering the fan inpoperable, and the header tank pretty soon boiling. Please check that joint if not done so already! As I recall the +12v feed goes through the above bullet connector to the radiator sensor then onto the radiator fan. Perhaps check that +12v is getting to the fan sensor ? Should be +12v all the time on one side of the sensor with the engine running.
 
Paul well done with the fitting of the gauge. I'd love a link to the adaptor you got from eBay. Though mine works great just pushed into a hole on the pump.

I'm thinking that the temperature sensor switch could still be the culprit as it's surely the main item that's capable of limiting temperature. Maybe worthwhile checking that wiring again and the earth coupling close by
 
When you remove the plug from the water pump is this wet? Eg coolant pours out?
 
Well I've had the water temperature gauge fitted a few weeks now and how are things working out?

1. Andrew - yes the radiator fan SHOULD kick in as the coolant reaches 85C but mine doesn't hence the decision to fit a rocker switch.

2. Referring to the gauge, when it reaches 85C I switch on the radiator fan.

3. No, I can't hear it come on. It's a noisy little car so I leave off my hearing aids. But it does come on as I've stopped the car to check this is happening.

4. Even with the fan on, the temperature according to the gauge continues to rise and will soon reach 100C - 105C. Yes, this is high isn't it?

5. Bleeding the system. I have now bypassed the heater matrix but get the engine nice and hot, whilst kneeding the coolant hoses.

6. So is the engine ACTUALLY overheating as I've given up taking notice of the cylinder head temp sensor/warning light. I'm told that undoing the cap to the expansion tank might reveal tell tale bubbles and 'a certain smell'. Nothing of the sort found on mine. So after a run, I lift the bonnet as 'admire' the engine and wonder if it's overheating or not. It doesn't APPEAR overly hot and certainly no signs of steam pouring from every orifice. Timing retarded has been mentioned but I adjusted the timing a week or two ago and it's spot on.

7. In 2006 whilst undergoing a 17,000 mile solo motorcycle ride around the US, I was staying with a friend in Tucson AZ, during a 100F heatwave. He complained that his Chevrolet got very hot and I discovered that his radiator fan had been wired up wrongly. The fan was trying to push the hot engine bay air FORWARDS into the radiator! Ten seconds after swopping two wires over the engine got back to its proper temp. So when looking from the engine forwards at the fan, which direction should it spin? Anti-clockwise or clockwise. Mine spins anti-clockwise.
 
Should be easy to check airflow - switch your radiator fan on & hold a piece of paper in front or behind the fan. If it blows front-to-back you're ok!
 
I'm thinking for ease and just for now, is there any reason I can't connect this to the block sensor, the water pump screw is really tight and i don't want to tackle this until later on when I remove the gear box, so thought I could temporarily connect it to the block sensor, piggy back style
 
Don't forget that the existing block/head sensor is either a low-power on/off switch (a negative wire to feed the warning light) or a temperature-dependent resistor (to feed a gauge).
 
Tight? A short length of scaffold pole on the 10mm Allen key and it should budge. These modern Gaz blowtorches with the needle flame are great for releasing reluctant bolts/nuts. The existing heat sensor can be quite variable in its efficiency. As you know mine lit up the red warning light at 85c. I wouldn't trust it hence the Water Temperature Gauge.
 
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