110 2.5td converted to 3.9v8 overheating problem.

Hi

I have converted my 110 hicap from the old 19j engine to a 3.9 V8 serpentine belt with efi but after six months or so having problems with overheating.

I have the original 2.5td radiator which i believe should provide the best cooling characteristics of all 90/110/defender radiators.

The water pump was new when i fitted the engine and so was the thermostat.

The viscous coupling is also new but doesn't seem to function as it should. I don't currently have a cooling fan cowl and wonder if this would cause the viscous fan not to lock?

Any other ideas?

Thanks in advance

Phil

Given that after a quick peek, the V8 radiator is double the price of the td one, I would guess they are very different. Probably for a reason. Car manufacturers do not like having to duplicate parts that perform the same function unless there is a necessity. You may believe the original radiator is best, I suspect in their wisdom LandRover actually tested which radiator was best for the body/engine combination, hence there being a range of different radiators, dependent on engine fitted.

A cowl hinders airflow normally, but with the fan running will increase airflow, and lessen hot-spots, thus increasing cooling efficiency. The presence of a cowl or not should have little impact on whether the viscous coupling for the fan works.

Personally my plan would be 1) make fan is working correctly immediately. 2) fit correct rad, ASAP 3) fit cowling, in that order. The 3.9 really does not like being overheated.

Seffy said:

Given that after a quick peek, the V8 radiator is double the price of the td one, I would guess they are very different. Probably for a reason. Car manufacturers do not like having to duplicate parts that perform the same function unless there is a necessity. You may believe the original radiator is best, I suspect in their wisdom LandRover actually tested which radiator was best for the body/engine combination, hence there being a range of different radiators, dependent on engine fitted.

A cowl hinders airflow normally, but with the fan running will increase airflow, and lessen hot-spots, thus increasing cooling efficiency. The presence of a cowl or not should have little impact on whether the viscous coupling for the fan works.

Personally my plan would be 1) make fan is working correctly immediately. 2) fit correct rad, ASAP 3) fit cowling, in that order. The 3.9 really does not like being overheated.

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The fan is not working correctly even though the viscous coupling is new. on start up from cold the viscous coupling is slightly stiff until warm but once the temp is up it is not locking. I don't get this because its brand new coupling fitted only a few days ago.

I think that the rad price being much higher is not because it is a much better efficiency but due to it being a much rarer item only available in a few models like the 50th anniversary v8? correct me if i'm wrong.

I am not sure of the correct cowling to fit, can find NTC5685 or ESR3226/ERR7307 but they are mega bucks.

If the V8 efi did not need a different rad, LR would not fit it with one, its a money thing. LR would certainly not have a new rad for a low volume production run unless they had good reason. Doubly so if they had a few thousand 2.5td rads with high production volumes and lower costs available that were already efficient enough. LR did not believe your current rad could cool a V8 effectively (or unlikely, over cooled it), I would tend to take their engineering and desire to avoid irate owners of cooked motors over personal belief. Doubly so as you are suffering overheating

I got my prices for rads from rimmer brothers. http://www.rimmerbros.co.uk/Item--i-GRID010421. with around 8 different variants for non efi rads.and one for EFIs. The most expensive rad on the page, is for a carb V8 as a LR original part. almost all rads available with 2-3 day turn around. I suspect that even a carb V8 rad would be a better option. Rads with oil coolers can have a significant effect on engine temperature too, especially as oil is in contact with moving parts, and up at the very top of the engine in the rockers where water does not normally circulate.

I wouldn't be driving more than a few yards as is, a cooked 3.9 is a scrap 3.9.

As for correct cowling, that is a far lower priority than a working fan and the correct radiator. Carts and horses should be in the correct order.

The fan won't work correctly, in terms of airflow, without a cowl. It won't efficiently pull air through the rad but rather just stir it up in the engine bay.

How have you established its over heating? Are you going by the dash gauge or do you have an aftermarket gauge fitted or have you measures with an IR temp gun?

Is what I mean is it deffo overheating or could it be a duff gauge?

I thought visco fans worked like this:
1. Initially stiff on start up but loosen as they warm
2. Remains loose while engine is correct temp and therefore not providing any drive to the fan
3. Stiffen up again as the temp rises thereby locking and then providing drive to the fan for extra cooling?

flat said:

The fan won't work correctly, in terms of airflow, without a cowl. It won't efficiently pull air through the rad but rather just stir it up in the engine bay.

How have you established its over heating? Are you going by the dash gauge or do you have an aftermarket gauge fitted or have you measures with an IR temp gun?

Is what I mean is it deffo overheating or could it be a duff gauge?

I thought visco fans worked like this:
1. Initially stiff on start up but loosen as they warm
2. Remains loose while engine is correct temp and therefore not providing any drive to the fan
3. Stiffen up again as the temp rises thereby locking and then providing drive to the fan for extra cooling?

Click to expand...

After doing the conversion the original 3.9 coolant sender and 110 gauge didn't match so I have fitted a vdo gauge and sender matching set. I also have an ecumate which shows coolant temp from Ecu which reads about 5 degrees cooler.

That is also my understanding of the visco but mine isn't getting to the point of locking even though I regard the engine as being hot enough to 98- 105 degrees, maybe I'm being overcautious and that isn't that hot but when I first don't the conversion it always say about the 92 degrees once warm with no fluctuations.

Is an air lock possible?
Is the rad in good condition and no cold spots?
Remove thermostat, check it is 82deg check operation in a tub of hot water.
The viscous fan should be locked up when overheating so it shouldn't spin when you cut engine. It shouldn't be needed unless you are working hard or in traffic.
If the cowl is big money, an electric fan up front maybe a better bet.
Flat has suggested a good course of action with the ir gun.

My only experance is for the 3.9 disco which I own, so the radiator is more expensive because it includes an engine oil cooler, the viscous fan will only move one blade width when cold, but will soon loosen up as soon as the locked fan spins therefore circulating the fluid into the various parts ot the coupling so initially nothing to do with temperature.

When the fan is locked it has a loud turbine sound that's quite distintive, so for me that's for the first 50 yards down the road from a cold start, then things go quite, and again sometimes returns in traffic on a hot day with the AC on as the engine bay then is at its hottest.
The thermostat is 88c which is correct, for 3.5s its 82c

So bottom line is fit the correct rad with its cowl plus the 11 blade fan as your starter.

have you got an oil cooler in your set up? or just the old td water rad?

discool said:

The thermostat is 88c which is correct, for 3.5s its 82c

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he'll be better off with 82deg all things considered. Hotwire works fine with 82

Old school rule of thumb................ when you think you're overheating is your heater blowing hot? If so you're not overheating [yet] good luck
- by the way, my original [carb] V8 rad looked fine but ran hot - even after flushing etc. I managed to get a tatty 2nd hand one and it's way better. Maybe just invest in a 2nd hand V8 rad and see - if improvement then there's your answer

highlanderv8 said:

Hi

I have converted my 110 hicap from the old 19j engine to a 3.9 V8 serpentine belt with efi but after six months or so having problems with overheating.

I have the original 2.5td radiator which i believe should provide the best cooling characteristics of all 90/110/defender radiators.

The water pump was new when i fitted the engine and so was the thermostat.

The viscous coupling is also new but doesn't seem to function as it should. I don't currently have a cooling fan cowl and wonder if this would cause the viscous fan not to lock?

Any other ideas?

Thanks in advance

Phil

Click to expand...

As suggested above, I would get a v8 rad, and a cowl, see if it goes away.

My old 3.5 RR always ran at the same temp year in year out but it took 3 miles to reach it... even then heater temp was still pathectic even after putting cardboard in front of the rad in winter.
Maybe down to the low opening temp of thermostat, ten winters I had to put up with it and some of them were very cold back then.
But no probs with a 3.5 TVR before the RR... strange

My 3.9 only takes a mile and the gauge is on its way moving up from the stop and the heater is already blowing warm air, another couple of miles and I'd be turning down the heat, but then the disco does have a different heater system.

Apologies i have not replied back to peoples posts, Ive been working away this week.

So this morning i replaced the 88 degree thermostat with an 82 degree one and its running fine now.

Thanks everyone for the advice.