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3,9 V8 overheats when idling


stobbie

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Given all of the above, if replacing the water pump didn't work, then I reckon on the rad. New doesn't guarantee "good", and you could have a lot of blockages in there from poor construction.

The biggest problem I had was a brand-new G&M radiator. It didn't have enough rows - counted from top to bottom - and replacing it with a good used radiator solved it. I got another new one in the end, but putting the used rad in was the evidence I needed of how bad that G&M rad was.

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That bottom hose is too hot - the rad isn't cooling the water properly.

This

You can get an all copper rad, I think mine is allmakes, with an oil cooler on the side for about £300(it might have been a little less than that) and at 50mph+ my temp gauge doesn't creep up much past 1/3 and gets just over 2/3 when my fans kick in to bring it down in traffic. I am not running a stat though

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Well...

we have compared the new pattern waterpump to an original used one, and it is EXACTLY the same, so we have fitted the pattern one again.

We have fitted the new radiator instead of the slightly bent one, and nog temps seem to have gone done a few degrees.

I can leave it idling now and it stays at around 93 degrees, but it is not as hot outside as a few days ago and I'm not sure how much the weather influences the water temp. I don't think a 5 degrees fall of the outside temp would cause a 5 degrees lower water temp as well?

I would like to see it a bit lower, but if it stays like this it should be OK. Tomorrow I'm going to simulate some slow traffic with a lot of stopping and accelerating, and hope it will be OK with that as well.

I don't think the twin China fans are up to the job, if I take out the fuse ofcourese the temp rises to the red mark, and when I connect them again temps don't come down again. Heater on and aircon fan on will get them to 93 again. And at that temp the twin fans are able to keep it there..

What is a good pulling fan from a breaker that has high capacity and fits a TD radiator nicely?

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The twin electric fans are only for AC vehicles you don't need both.

Use a bit of science on it rather than throwing money at it.

Changing the rad was a good shout based in the temperatures on inlet and outlet,did you check the pump impeller was firmly attached?

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The electric on my D2td5 starts up when the engine gets hot.

First time I noticed when I had non working thermostat, and I had put some cardboard in between the radiator and the oil cooler for the automatic, and drove on the highway. This was during winter, and normally it would not be a problem.

Second time was after I removed the viscous fan before towing my bobtail Pickup down to Poland, and I forgot to switch on the electric replacement fan when towing through a german city (I think it was).

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Pump impeller was fine.

There is so much heat under the bonnet, the bonnet is around 80 degrees on the outside, almost too hot for the paintwork. The wings as well. The wings had closed wing tops, I have replaced them for mesh versions, there's a lot of heat coming out of there now. Every little bit helps I hope...

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My RRC and my current td5, the electric fans only cut in when the temperature rises. The point is that they have both electric and viscous fans when fitted with air conditioning. This conversion has air conditioning and a gearbox oil cooler in front of the rad so I would say needs both.

Toby

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What rad panel does it have? The standard flat nose, or the protruding aircon equipped protruding nose? You need more airflow like Nuts said. I hadn't noticed the earlier mentions of aircon - between that and the other coolers, you have far too much in there for those meagre electric fans to deal with. You need the viscous fan and electric booster fans on the front like LR did, and if you have the flat nose, getting the protruding nose is how to fit it.

Using a 200Tdi left outer wing would allow you more ventilation, and removing the bonnet rear seal from the bulkhead may make a small difference. Wrapping the manifolds in exhaust wrap may bring under bonnet temperatures down a tad and help the block shed a bit of heat. You could try running with the bonnet removed (or just open) to see if it helps with temperatures, and that'd give an indication of whether putting vents into the bonnet may help, but it's going to start looking ugly. However, I think it's more a problem of a lack of air through the heat exchangers than exhausting the engine bay.

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Looking more closely at the photo, I see you have the long nose. But I also see that you sited the transmission cooler in front of the aircon condenser. I'd fit a steering guard and mount the transmission cooler as high up under the cross member as possible to move the rad and condenser forwards to their proper positions so you can fit the proper fans and shroud from a V8 Defender.

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I have a SVX nose, so even more space than with an aircon nose, but there still isn't much space left.

I have used an aftermarket TD5 condensor with a TD5 aircon fan. I could remove the single TD5 fan and maybe fit two push fans behind the grille.

The radiator is in the standard position. Is there a fan shroud availabe for a 3,9 V8 serpentine engine? A 3.5 carb shroud doesn't fit at all..

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I can probably use the 50th anniversery fan shroud.. but it is expensive. How can I be sure that that will help?

That's what I has in mind. Why not make up a cardboard shroud to try it out, and if it works, then either make up a proper one, adapt a cheap shroud or splash out on the 50th ANN part.

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Out of curiosity, what is the temperature sender in your top hose? Rad fan triggers go in the bottom hose or the fans will run all the time instead of only when the rad can't cope without fan assistance. Not an issue until you can get enough cooling anyway, but just wondering if that is what the sensor is.

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I would say Td5 fans as a minimum, if you can fit better do so! As for the viscous fan make sure you have the right fan for your engine as I think serpentine water pumps turn backwards compared to the earlier types and that will just screw everything up!! Do one thing at a time, so you know what works. I would say this will work as it is then roughly as built by Land Rover and that worked.

I didn't have any cooling issues on my 4.2 V8, but I did not have air con or gearbox oil coolers to contend with and that was with a standard V8 radiator. I did have the big EFI type fan from an RRC and I used a RRC fan cowl butchered on the ends to fit in the 90 engine bay.

Toby

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  • 2 weeks later...

Something's odd and I think bodges like adding holes in the bonnet, bolting oil coolers on etc. are going to mask the true cause not help.

That engine in that vehicle should have no problem with cooling with a standard rad and whatever flavour of fan.

The only unusual factor about the install compared to hundreds of others out there is the fact it's got aircon in the way. It sounds like there's some standard aircon helper fans you can fit, so I'd fit those to operate in the standard way (I assume RAVE manual will tell you how they are controlled). Your top hose outlet has the factory aircon fan switch on it, can't see if it's wired up or not but that might be an easy win.

After that, be it electric or viscous fan, wherever you stick your temperature switch/sensor etc. that vehicle should not overheat.

I have a 4.6 in a 109 with a small-ish rad, and another 4.6 in a 127 on the factory V8 defender rad, neither have oil coolers and neither ever break a sweat. Both have twin electric fans (one Saab pair, one freelander 1 pair) under ECU (MS) control. Both have standard 88deg thermostats in the inlet manifold (not the P38 pig's heart style). I have never had the fans come on full-speed including towing, driving mountain passes, etc.

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That's right, and I know because I think I've tried it all by now! As long as everything else is working correctly, (proper-sized fans working, engine ok, etc.), then as far as I'm concerned the fault is in the radiator. Airflow in and out of Landie and Rangie engine bays is horrible, but won't be a problem on your end of the globe, just here when conditions become extreme, which is why I've added a few extra vents. 

I just put aircon in my Range Rover and it is now a bit too warm at idle with the aircon running, but is otherwise fine at 37c ambient. This is with a viscous fan and the condensor fans wired to come on and help a bit, (they don't make much difference, though.) I think the radiator isn't rejecting enough heat with a hot condensor in front of it, so an aluminium rad is in the post and we'll see how it goes. 

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