4.6 engine questions

[blitz]

Does anyone know what the optimum operating temperature of the 4.6 is?

Also what is the thread size of the temp light sender attached to the thermostat housing on the 3.9 manifold?

As the viscous clutch is seized on my disco I am going to fit the ford AU II electric fan assembly to it to see what difference it makes. If I dont like it I will simply buy another clutch and put it back to standard.

Fitting the fan assembly is easy, what I intend to do is remove the warning light sender unit fit a tee in refit the warning light sensor and then fit the right heat range electric thermostat in the other side of the tee. use that to power a relay and Bobs your mothers brother.

It should be pretty easy to make it look like that is how it comes from the factory. I will take photos and put it up as a project here

[tempestv8]

4.6 with Thor inlet or the common plenum chamber (trumpets)?

The Discovery II has a 4.0 with coolant operating temperature at around 97-98 Deg C, and presumably the 4.6 version found in the P38A will be running at the same temp.

[Hardchina]

I would be running the 4.6 as cool as possible, 75 degree? If you can figure out a way to trick the ecu into thinking this temp is 20 degrees higher - you'll be sweet.

High temps and alloy motors aren't a good thing.

[bee utey]

Make a small hose tee (threaded 1/8 NPT with 5/16 nipples) to install into the bleeder line to the top tank of the radiator. Place it near the thermostat and you will read engine temp no probs. I would suggest an 80C thermostat is a good compromise between engine reliability and economy. 88 to 90C is best for economy, 75C is for brute force. My experiments indicate about 10% economy increase with every 10C rise in engine temp.

[RoverP6B]

blitz wrote,...
Does anyone know what the optimum operating temperature of the 4.6 is?

Yes it very much depends on whether your engine is running carburettors or fuel injection.

I run twin SU carburettors on mine with a 74 degree thermostat.

Ron.

[blitz]

It's got the normal 3.9 inlet manifold on it and it is injected.

I dont want to use an adjustable thermostat I would rather get one from a car that has electric fans and adapt it to fit. There are hundreds of them I just need the right thread size and I will go fromt here.

[Hardchina]

It's got the normal 3.9 inlet manifold on it and it is injected.

I dont want to use an adjustable thermostat I would rather get one from a car that has electric fans and adapt it to fit. There are hundreds of them I just need the right thread size and I will go fro mt here.

A fan temp switch wont control the engine temperature (well not directly or properly).

To find the correct temp for a fan controller setting - i'd find out the temp of the return water in the lower rad hose during a 40+kph cruise then add a few degrees. This way the fans wont turn on during normal driving, just as needed. I'm guessing 50 degree ish??

[blitz]

A fan temp switch wont control the engine temperature (well not directly or properly).

To find the correct temp for a fan controller setting - i'd find out the temp of the return water in the lower rad hose during a 40+kph cruise then add a few degrees. This way the fans wont turn on during normal driving, just as needed. I'm guessing 50 degree ish??

I'm just going to fit a set fan temperature sensor switch in the same place as fords do, as I am using a ford electric fan assembly, i figure if ford are happy doing it that way who am I to argue - I just wanted the optimum running temp

[RoverP6B]

Being fuel injected, is not 88 degrees C the typical operating temperature for such engines?

4.6 or 3.9, running the latter manifold and electronics would requre that the engine run at the temperature commensurate with that system,..would it not?

So that would be the minimum temp to run the engine for the system to function correctly, so running within a window of say 88 to 92 degrees at all times for fuel economy and engine longevity.

No point in going hotter than you need to.

Ron.

[blitz]

Cool Ron that was what I was after. as the factory thermostat switches have set ranges I just need to fit the correct one at the engine thermostat adn it's all done - also I can make it look like a factory fit doing that way.

[bee utey]

I think people weren't sure what exactly you were asking. The engine fan thermo switch should be rated above the engine thermostat temp rating. So your fans don't come on until there is water going to the rad! Try an 88C engine thermostat and a fan thermostat switch around 92C. Many front wheel drive cars should run at about this temp so you should have no probs sourcing one. Just remember modern cars run the fan from the ECU so you would be looking around the late 80's when ECU's were primitive.

[blitz]

I think people weren't sure what exactly you were asking. The engine fan thermo switch should be rated above the engine thermostat temp rating. So your fans don't come on until there is water going to the rad! Try an 88C engine thermostat and a fan thermostat switch around 92C. Many front wheel drive cars should run at about this temp so you should have no probs sourcing one. Just remember modern cars run the fan from the ECU so you would be looking around the late 80's when ECU's were primitive.

Sage words Jilden, it helps to be very clear when asking a question - I have obviously not been as clear as I could have been

What I aim to do is as you have said. use an electric thermostat fitted piggy back to where the engine thermostat mounts so I have an accurate reference point at which to measure the water temperature temperature at a known figure. from this I can then control the fans at say 3 degrees higher so as you said the engine thermostat will be open when the fans come on.

As the AU ford has 2 fans I am not sure if I will use a 2 stage thermostat so I can sequence the fans cycle or for simplicities sake a single stage unit.

[400HPONGAS]

Blitz, the MONDEO thermo fans will fit your Radiator assembly better than Au , even the EF version is closer than the AU .They all will need some degree of Modification to fit , the Mondeo's will be the easiest . they are all cheap as on Fleabay and all do the same thing anyway.

[Hardchina]

Sage words Jilden, it helps to be very clear when asking a question - I have obviously not been as clear as I could have been

What I aim to do is as you have said. use an electric thermostat fitted piggy back to where the engine thermostat mounts so I have an accurate reference point at which to measure the water temperature temperature at a known figure. from this I can then control the fans at say 3 degrees higher so as you said the engine thermostat will be open when the fans come on.

As the AU ford has 2 fans I am not sure if I will use a 2 stage thermostat so I can sequence the fans cycle or for simplicities sake a single stage unit.

I still reckon there is little point in controlling the fans from the engine outlet, your motor will be overheating by the time they switch on. Fans should come on when the radiator needs them: ie you're stopped for a length of time or you're going too slow to enable enough natural airflow through the rad.

[350RRC]

Cool Ron that was what I was after. as the factory thermostat switches have set ranges I just need to fit the correct one at the engine thermostat adn it's all done - also I can make it look like a factory fit doing that way.

Hi Blitz,

The info you seek is here, you may have to join:

Outer Limits 4x4 Board • Login (http://www.outerlimits4x4.com/viewtopic.php?f=28&t=147839)

You can control each fan separately, which is what I do with a 350. One is on all the time, the other with an adjustable temp switch. Will be going to two temp switches in top rad hose when I get time.

Anyone know where I can get the metal tube with two threaded temp sender holes for stock upper RRC rad hose dia? X-Eng have them in the UK, but I'm sure I've seen similar in one of the Autobarn catalogues or similar.

cheers, DL

[blitz]

I still reckon there is little point in controlling the fans from the engine outlet, your motor will be overheating by the time they switch on. Fans should come on when the radiator needs them: ie you're stopped for a length of time or you're going too slow to enable enough natural airflow through the rad.

I take your thoughts onboard Hard China, I will do some research and make sure that it will be done correctly. it wont be hard to chase up - thanks for the input as I really cant afford to stuff this engine up as the conversion cost the better part of 10k with the brake up grade as well

[400HPONGAS]

350RRC , all that stuff comes from Tebfa , with adapters for all hose sizes and fitting the temp probes in any position as well as Craig davies temp controller stuff .No drag racer runs without a Tebfa walter filter system and usually twin tERMOS DEPENDING ON THE CLASS ., best radiator protector money can by and is only $50 .Would never build and engine with out one being installed . cLASS 101 IN COOLING BASICS !!!

[blitz]

350RRC , all that stuff comes from Tebfa , with adapters for all hose sizes and fitting the temp probes in any position as well as Craig davies temp controller stuff .No drag racer runs without a Tebfa walter filter system and usually twin tERMOS DEPENDING ON THE CLASS ., best radiator protector money can by and is only $50 .Would never build and engine with out one being installed . cLASS 101 IN COOLING BASICS !!!

Hey big fella have you got any info on this or contact details so I can chase it up please?