Oppo help! 

"4muddyfeet - bare knuckle with an EZ30" (4muddyfeet) 01/15/2016 at 13:19 • Filed to: None

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Yesterday the water temp gauge on the Defender steadily rose into the red after about about 2 minutes of driving. Normally it sits bang in the middle even when towing, so this was a little odd. I stopped before it got it went fully into the red and checked the coolant in the expansion tank which let of a little bit of pressure and a few steamy wisps and that was all. After leaving it a while I drove slowly to my yard with no mad temp climb. Come to today, and after replacing the thermostat and squeezing all the pipes for blockages (it seems to run freely), I started the engine and the temperature gauge went of on it’s merry way up to the red after about 10mins of idling and some revs. Yes the vehicle was stationary, but considering it’s 1°C and Defenders are built to run at revs while at a standstill, this shouldn’t be happening.

There is no oil in the water, or vice-versa, so I very much doubt hgf. I’ve even had the valve cover off just to make sure, using the opportunity to replace the gasket and do a full oil change because Land Rover. Also the radiator is luke warm to the touch, and the silicone hose coming away from the pump and supplying the bottom of the rad is hot. The expansion tank is the same as when it first happened- hot, but not excessively.

So what are my next steps? I will assume some kind of system flush or hosepipe jobby to make sure it’s clear? Or am I looking at the water pump here?

20 year old unknown service history Land Rover valve train for your time.

And Land Rover wee.

Berang > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:25

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If you leave the radiator cap off and let it run and heat up, you will know for sure if the pump and thermostat are working when it starts to puke coolant. If nothing happens though, you have a problem.

davedave1111 > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:26

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Since it’s an old Landy, have you checked if the temperature gauge is working properly?

4muddyfeet - bare knuckle with an EZ30 > davedave1111 01/15/2016 at 13:30

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The gauge is slow to get going (normal) and on after it hits midway does it start to steadily climb. Not sure if that's indicative of a faulty gauge(?). How would I test?

4muddyfeet - bare knuckle with an EZ30 > Berang 01/15/2016 at 13:30

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I’ll give it a shot. Should it be on a level? Because the front is ramped atm.

RamblinRover Luxury-Yacht > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:33

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Sounds fairly similar to the time my Series water pump went, as it had a plastic impeller that only half sheared from the shaft. Sometimes it spun, sometimes it didn’t, mostly didn’t. I shouldn’t hesitate to add that since that diesel you’ve got, IIRC, is a long separated family member of the 2.25 Series diesel and petrol, there are good odds on a similarly crummy pump.

Berang > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:34

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I don’t know that it should make much of a difference if everything is working properly. But it would probably be easier to watch if the car is on the ground.

RWS Motorsport > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:43

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My first thought was an airlock, but I have no idea if Land Rover cooling systems need bleeding if its had anything done to it? I made that mistake on a friends Punto by swapping the radiator, but then didnt open the bleed valves when I refilled the system. Promptly overheated once it got towards operating temperature.

'Wägen, EPA LOL > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:44

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Just to verify, the fan is turning on and running to draw air through the radiator, correct?

davedave1111 > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:46

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There’s presumably a sender somewhere and the gauge. Typically they work by putting 12v through a temperature variable resistor, and the gauge is just a simple ammeter. First thing is to check the connections, earth connections, etc. Put in a temporary wire to check, maybe. Put 12v (or whatever it uses) through the gauge itself to make sure that’s all working fine, then use a multimeter to test the sender unit.

If I understood correctly, and the problem went away for a bit before coming back, my first guess would be your earth connection. Every weird problem that even tangentially involves electrics seems to turn out to be a dodgy earth.

4muddyfeet - bare knuckle with an EZ30 > Berang 01/15/2016 at 13:50

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This is it while in the red. A small spill but that was judder during deceleration I think. Pump?

4muddyfeet - bare knuckle with an EZ30 > 'Wägen, EPA LOL 01/15/2016 at 13:51

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Yarp

4muddyfeet - bare knuckle with an EZ30 > RamblinRover Luxury-Yacht 01/15/2016 at 13:52

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Certainly looks like it. If only the weather was a bit warmer and parts stores had stuff in for same day collection :(

4muddyfeet - bare knuckle with an EZ30 > RWS Motorsport 01/15/2016 at 13:54

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They can get airlock, but I bled it when I did the thermostat. Pump has gone tits up according to the Oppo brain trust.

Berang > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:55

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Is the coolant visible flowing in the radiator? It should be moving pretty good if everything is right. If not, I would say the pump is not working.

RamblinRover Luxury-Yacht > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 13:57

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A Series petrol cools so very well on thermosiphon that it took me ages to diagnose, too. “No, it can’t possibly be the water pump - it’s not doing it every time, and it’s not getting hot that quickly!” More fool me.

RamblinRover Luxury-Yacht > davedave1111 01/15/2016 at 13:59

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I suspect his Defender has a capillary gauge as all the Series did. Not 100% sure on this, however. His as a diesel has a somewhat-modernized version of the old 2.25. The capillaries are very bad for getting pinched and giving up working, but at least it’s not a hit and miss bad ground, I guess.

4muddyfeet - bare knuckle with an EZ30 > Berang 01/15/2016 at 14:00

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Doesn’t look like any movement at all. Thanks, pump hunting now.

'Wägen, EPA LOL > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 14:02

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Next step water pump, imo...

RallyWrench > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 14:05

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Sounds like you haven’t got any circulation across the radiator, perhaps the core is blocked somehow or the water pump isn’t one anymore. Convection can only do so much. Thermostats are designed to fail open to prevent overheating so that’s unlikely, and because the lower hose is hot it sounds like it’s open but the coolant has nowhere to go once it passes out of the block.

davedave1111 > RamblinRover Luxury-Yacht 01/15/2016 at 14:08

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Oh, wow. I never even knew that was a thing before now.

RamblinRover Luxury-Yacht > davedave1111 01/15/2016 at 14:14

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They’re a real pestilence on the Series II Landies as the original dual gauge by Smiths with oil on top and temp on the bottom isn’t made exactly like original anymore and at this point any on a Series II/IIa are 40+ years old and pretty knackered. It *is* possible to get a new probe and capillary, refill the ether with a syringe, and plug the hole in the probe, but it’s a huge pain.

HammerheadFistpunch > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 15:34

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My overheating issue was 100% super old and clogged radiator. Sorry its no help and that I have no diagnosis for it. With Toyota if you mix coolants you get a kind of sludge in the system that makes a huge mess of the whole system, which is what the PO had done. New rad and its been fine since.

4muddyfeet - bare knuckle with an EZ30 > RallyWrench 01/15/2016 at 16:26

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I've managed to source a pump for £17, and if that doesn't work then it has to be a full system flush, and I literally will rip everything out and run the pressure washer through it. I need my work vehicle back ASAP.

4muddyfeet - bare knuckle with an EZ30 > HammerheadFistpunch 01/15/2016 at 16:30

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I thought I’d done this actually, I only topped the coolant up a month ago with some new stuff and I never thought to check what kind of gloop it was. Turns out it was the right stuff, but I was still cursing my stupidity yesterday.

4muddyfeet - bare knuckle with an EZ30 > RamblinRover Luxury-Yacht 01/15/2016 at 16:35

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I could’ve sworn the 300tdi pump is alloy, but then that may just be the aftermarket units, probably to avoid this issue. And being ex-military it’ll be a genuine Land Rover pump whether previously replaced or not, four times the price and half the quality, all the best for our troops.

RamblinRover Luxury-Yacht > 4muddyfeet - bare knuckle with an EZ30 01/15/2016 at 16:54

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Your other option, of course is that you had alloy blades and the blades became porous over time and crumbled/eroded away from that fairly suddenly. Very possible, too.

4muddyfeet - bare knuckle with an EZ30 > RamblinRover Luxury-Yacht 01/15/2016 at 16:58

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There’s only one way to find out

4muddyfeet - bare knuckle with an EZ30 > davedave1111 01/16/2016 at 14:17

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You may end up being correct. You are mistaken in the fact that the problem disappeared and came back, the drive up to my yard is less than a mile and I started from cold and took it real easy. I’m not sure it even had the chance to hit normal temp, never mind hitting the red. Otherwise, your idea of the gauge or sender being bad is quite literally my only option left. So far it’s had a system flush, water pump replacement, thermostat replacement, and a complete disassembly and second flush of the cooling system to further check for blockages. Once I've rebuilt the front of the engine bay tomorrow I'll be sure to test it all and give you the h/t you deserve if it turns out to be electrical!

davedave1111 > 4muddyfeet - bare knuckle with an EZ30 01/16/2016 at 14:42

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It’s not really deserved. I always say ‘check the earth connection’ when I have no idea. The only surprising bit is that I’m averaging something like 80% with that diagnosis on here :)

brianbrannon > 4muddyfeet - bare knuckle with an EZ30 01/17/2016 at 21:20

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Check for bubbles in the coolant. Blown head gasket