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Joined: Apr 23 2019
Posts: 190

As I look back I had two near misses this summer, both on hot days, after 15-20 minutes of slow traffic ie just the fan running at barely above idle, and no air ram effect on the rad... I pulled over quickly each time, let the engine cool, and then as soon as the traffic cleared, hit the open road and no problem, back in the centre of the dial. OK, so I did subsequently have one HG go, which I'm sure wasn't helped by the first over-heating episode, but a HG change was in the tea leaves anyway.
So my question is, should I expect (and so try to avoid) these kind of heavy traffic/ hot weather over-heating scenarios, or does it sound like my waterways might be bunged up (ooerr). All the hoses are changed out since I bought it, but I haven't touched the water pump (yet) or the rad. The system did have some rad weld in it for a few weeks last year, but I have done a couple of changes of the coolant since then. I was wondering if the radiator was free flowing...if I stuck a hose in the top of the rad and blasted it through would it make any difference, or should I consider a new rad - I couldn't swear to it being the original one, but it's certainly the normal abs/ aluminium build and so possibly due a new one anyway

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Joined: Aug 19 2019
Posts: 21

As far as I'm concerned, you shouldn't overheat in slow traffic in hot weather. I don't have years of experience on LR V8's, but I don't think it should happen on any good vehicle. We have reasonably hot summer's here, high 30's C and my 4.6 hasn't overheated in my 2 summer's with it.

Member
Joined: Feb 11 2018
Posts: 151

I would suspect the fan viscous coupling. If it doesn't quieten down from a cold start it probably fooled. It'll sound like a plane taking off then go quiet. It should get louder as engine starts to get a little too warm.

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Joined: Dec 30 2015
Posts: 3695

Water pump with corroded impeller so less flow, partially clogged radiator and knackered viscous are the usual causes. If the rad is clogged a good test is to poke the Prog button on the HEVAC, if the temperature starts to come down, it's the rad. I've got an Airtex water pump, a fairly new OEM viscous and a Direnza high capacity alloy rad on mine and I sat in heavy traffic for over 30 minutes coming through Lyon a few weeks ago. This was after cruising at 65-70 mph for 250 miles, with a trailer on the back loaded with a '69 Ford Mustang and an ambient temperature of 39 degrees C. Gauge didn't move from the centre. So, if the cooling system is in good shape, there's no need to avoid traffic in hot weather but it will certainly show up any weaknesses if there are any. I only fitted the Direnza rad as it wasn't that much more expensive than a standard one and there's no telling what the quality will be like on a standard one these days.

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Joined: Sep 14 2016
Posts: 402

Mine has been rock steady Eddie in the middle of the gauge when sat in the mid afternoon 8 mile queue for the Dartford crossing for an hour / hour and a half at a time this summer. The gas had gotten low in the air con system last Monday causing it to down tools about 15 minutes in so no help from the electric fans for about an hour of crawling but the gauge still stayed steady.

Recent Airtex water pump but still same radiator as when I bought the car. Factory type but if original or a replacement I know not.

Clive

Member
Joined: Apr 23 2019
Posts: 190

Thanks for the feedback. I had my eye on the Direnza rad already :o)
I think the viscous fan's fine, although I'm not sure I've ever seen it disengaged/ heard it changing pitch tbh, it always seems to be running.

How/why does the Prog test work Richard ? Because the heater matrix is being used ? I put the HEVAC on Hi to cool things down anyway (and opened the windows), but as soon as I was on the open road I was back on the a/c.

Anyway, it sounds like current performance is abnormal, so I see a new shiny rad in my future. I did try and stick an endoscope in the water pump housing situ when i did the HG rebuild, but I couldn't get it to work, shame, I was feeling really clever having thought of it.

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Joined: Dec 30 2015
Posts: 3695

Prog puts the blend motors to full heat, the diverter up to the screen and the fans on flat out. Does the same as putting the heater on Hi but with one single button push rather than poking the two temp buttons lots of times and hoping that the outside temperature is low enough for the fans to go on full.

In warm weather the viscous is locked up as soon as you start the engine so you'll hear the rushing noise over the normal engine noises, once moving for a short time it goes quiet so you can listen to the V8 rumble instead.

Member
Joined: Apr 23 2019
Posts: 190

Just drained my coolant, and flushed it through several times, there isn't/ wasn't much crud in there, so perhaps the rad is not the issue. I'll give the viscous fan coupling a go next, i think