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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red
300tdi Overheating

I've done a fair bit of reading on this today, so apologies if I'm repeating old discussions, but thought I'd check a few things Smile

After many months of trouble free running, I've now had my first 'almost' breakdown. On a drive this morning, I noticed the air from the heater getting quite warm. I then saw the temperature gauge right at the top, so quickly pulled over and checked everything. Couldn't see anything obviously wrong with the coolant system, and was only 30 seconds away from the journey end, so slowly made it there.

I've now left it parked up, and begun some testing:

- Checked the coolant level, that was still at the correct level
- Checked the oil filler cap, no white mayo showing
- Removed the thermostat and tested in some hot water, it opened as the water got up to temperature (no thermometer so don't know the exact figure, but it operated as expected when the water began showing bubbles)

My next idea is to check the water pump, and hose Y connector for blockages. I wanted to see if anyone had any other thoughts as well?

The Defender isn't in an ideal place for emptying the coolant system either, so do you think it would be OK doing a short drive in it (sub-40mph, about 10 miles)?

Thanks

Post #602442 16th Feb 2017 11:01pm
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ickle



Member Since: 22 Jul 2010
Location: BROADWAY
Posts: 1016

United Kingdom 2008 Defender 110 Puma 2.4 CSW Alpine White

Try carefully removing the threaded plug on top of the thermostat with the engine running - when its cool obviously - and check the pump is actually pumping.

Then I suppose start with basics and make sure radiator is clean and in blocked inside and out, that he fan is working, not that it will do much in this weather -

Best of luck

Keith

Post #602446 16th Feb 2017 11:15pm
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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red

Thanks for the suggestion. When checking the pump, what should I expect to see? Will a bit of coolant be flowing through the thermostat housing, or will it start pumping out the hole?

Post #602453 16th Feb 2017 11:26pm
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L110CDL



Member Since: 31 Oct 2015
Location: Devon
Posts: 3825

England 

Hi, the only time my landy temperature gauge went up to the red was when the viscous fan stopped working, so it was time for a new one, cured the problem for me, hope this helps you Thumbs Up 1996 Golf Blue 300Tdi 110 Pick up. Keeper.
1988 Land Rover 90 Blue (project )
McCormick International B414 Tractor.

Clayton.

Post #602460 16th Feb 2017 11:43pm
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StephenO



Member Since: 03 Dec 2010
Location: Glasgow
Posts: 175

Scotland 

A blockage in the Y is quite common, had issues with that before 1995 Defender 90 Coniston Green
2005 Discovery 3 Zambezi Silver

Post #602465 16th Feb 2017 11:59pm
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Conan



Member Since: 05 Sep 2016
Location: the danger zone
Posts: 27

Belgium 1996 Defender 90 300 Tdi HT Coniston Green

Check if all your grounds are good also. It happened to me when I removed my safari door to repair it. I installed a used one in place of mine, and didn't bother fixing the ground wire on the door. Took the Defender for a ride and the temperature gauge went in the red. Had to stop but everything seemed normal. I fixed it back and the problem was solved! One of those little things...

Post #602547 17th Feb 2017 11:48am
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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red

Interesting point about the grounds, I've been re-doing the rear lamp and tow electrics wiring recently as it was all a mess. I think this is the first proper trip I've done since then...

Are you suggesting it's just the temp sender that is reading wrong then, and the actual coolant temp is fine? Or could the electrics affect some part of the coolant system?

Post #602568 17th Feb 2017 1:03pm
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LandRoverAnorak



Member Since: 17 Jul 2011
Location: Surrey
Posts: 4399

United Kingdom 1992 Defender 90 200 Tdi SW Arles Blue

Given you noticed the air temperature first, it seems more likely to be a mechanical fault Confused 
Click image to enlarge

MY BUILD THREAD

Post #602576 17th Feb 2017 1:55pm
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Conan



Member Since: 05 Sep 2016
Location: the danger zone
Posts: 27

Belgium 1996 Defender 90 300 Tdi HT Coniston Green

jr1104 wrote:
Interesting point about the grounds, I've been re-doing the rear lamp and tow electrics wiring recently as it was all a mess. I think this is the first proper trip I've done since then...

Are you suggesting it's just the temp sender that is reading wrong then, and the actual coolant temp is fine? Or could the electrics affect some part of the coolant system?


I think that it's an electrical problem. The coolant temp is (should be) fine. In my case it was fine. I had enough coolant and all the hoses were at a reasonable temperature.

I found about the bad ground on another forum. I did a quick search on google as soon as I got home, and I read that it is a common problem on Defenders. If I'm not mistaken, there are not too many grounds on a Defender and if one is not good, it can mess things up pretty quickly.

It did the trick for me, I just reattached the ground to the door, and the gauge went back to normal.

If I were you I'd check the ground wires, specially since you've worked on some electrical components, it could save you a lot of unnecessary work around the rest of the cooling system. If they are fine, then keep digging. but It could be a quick fix. hope this helps.

Post #602582 17th Feb 2017 2:26pm
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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red

Thanks, I'll definitely give that a try next.

I had a quick look at the car this afternoon, and the water pump is working (found out by starting it up and watching it rapidly start flowing out the thermostat bleed plug hole, which I quickly re-fitted :/)

I then gave it a fast idle for 10 mins then a short drive around. Once warmed up, the temp gauge was bang in the middle for the whole time, and all the right pipes were hot once the thermostat had opened.

My only other thoughts left (apart from electrical issue) are an air block that just happened to be in the wrong place (will be flushing and re-filling/bleeding anyway after having the thermostat out).

Also, as an aside, should the 300tdi have a viscous or electric fan? I thought it was viscous, but mine has an electric one...

Post #602667 17th Feb 2017 7:40pm
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Ramsay



Member Since: 30 Sep 2015
Location: Burnham, Bucks
Posts: 310

United Kingdom 1995 Defender 110 300 Tdi CSW Auto Keswick Green

Viscous fan as standard. Lots retro fitted with electric fans.
Have you seen the electric fan operating ? 1995 Defender 110 CSW
1971 SIIA Lightweight

Post #602674 17th Feb 2017 8:05pm
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Scotm



Member Since: 28 Feb 2014
Location: Aberdeenshire
Posts: 244

Scotland 2012 Defender 110 Puma 2.2 SW Orkney Grey

What condition is the radiator in? Fins could be blocked up or corroded away?

Post #602745 18th Feb 2017 8:41am
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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red

I will be checking the flow through the radiator when I drain it and flush the system. It seems in good condition externally though, vains haven't rusted or crumbled away and both top and bottom pipes were warm when the engine was running at temperature.

I'll check the electric fan, as that may be a culprit, but given it was overheating when I'd only been driving for 10 mins at about 7am it seems unlikely it would really be needed?

P.s. Thanks for everyone's help with this, it makes this forum a great place to be Smile

Post #602764 18th Feb 2017 10:25am
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Balvaig



Member Since: 19 Feb 2016
Location: Fife
Posts: 187

Scotland 2015 Defender 90 Puma 2.2 Landmark LE Corris Grey

There is an article in LRO magazine, March 2017 page 87 which describes your symptoms and identifies the main earth strap as the problem. May be worth checking out, as iit is a simple fix.

Post #602766 18th Feb 2017 10:46am
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jr1104



Member Since: 05 May 2016
Location: England
Posts: 70

United Kingdom 1998 Defender 90 300 Tdi CSW Rioja Red

An update for everyone, think I've found the problem...

Took it for another drive on Sunday afternoon, and after about 7-8 miles the temperature started rising over half-way again. I pulled over and opened the bonnet whilst it was still running, and spotted that the electric fan hadn't come on. I had a good look around the wiring and relay for it, but couldn't see anything untoward.

Figuring I'd just let it cool down then do the last couple of miles home, and check it properly with a multimeter there, I closed the bonnet and got back inside. It then occurred to me that there was a mystery switch on the dashboard that I'd never been able to trace. Gave it a click, and the fan came on!

Looks like whoever retrofitted the electric fan also put in an override switch. So I drove the rest of the way home with the fan on 100%, and the temp was fine.

So, long story short, it looks like the thermistor that controls the aftermarket fan is not activating (checked the voltage across its terminals when the engine was hot, and got nothing through. Flick the switch and those terminals jump to 12v).

Has anyone used the X-Eng thermostatic fan switch? Is it worth the money, and will it just be plug and play with the control system for the Kenlowe electric fan on mine?

Thanks again for everyone's help

Post #603827 22nd Feb 2017 7:30am
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