L322 Viscous Fan Speed

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Grrrrrr said:
Usually the fan fails by failing to lock up. I've never heard of one exploding on a P38A, although that doesn't mean it isn't possible. It certainly can be damaged by wading although so far I have been lucky and it just chucked water all over the engine. I think @Salisbury Nick was not so lucky? @Graculus might know more about the L322 fan.
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The Fan exploded on my brothers P38 and we've bought a second one in the meantime that has the same marks in the bonnet of the fan exploding.

But in the L322 workshop manual its specifically mentioned that a car with a siezed viscous must not be driven because of the exploding fan.
 
From memory, the L322 (and L319/L320) fan spins at 1:1 when fully locked, the control strategy is part of the ECM and goes something like:-
The fan is fully locked within the first 30 second of the engine running, this is to check the speed sensor signal is valid, after that, it is released to a 10% duty, increasing to 25% duty once the engine coolant goes over 89 degrees - or - the aircon load is such that the control valve current is >400mA.
Duty is increased to 50% if the engine coolant goes above 92 degrees, aircon control valve current is >480mA or the transmission temperature is >95Degrees
Beyond that, it's pretty hazy, I have never heard the myth of exploding fans nor seen any evidence, the viscous coupling is designed to cope with the fan being immersed with no effect on the engine speed and is certainly rated beyond 'maximum engine speed' for TDV6 & TDV8's used in L319,320 & 322's.
 
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Graculus said:
From memory, the L322 (and L319/L320) fan spins at 1:1 when fully locked, the control strategy is part of the ECM and goes something like:-
The fan is fully locked within the first 30 second of the engine running, this is to check the speed sensor signal is valid, after that, it is released to a 10% duty, increasing to 25% duty once the engine coolant goes over 89 degrees - or - the aircon load is such that the control valve current is >400mA.
Duty is increased to 50% if the engine coolant goes above 92 degrees, aircon control valve current is >480mA or the transmission temperature is >95Degrees
Beyond that, it's pretty hazy, I have never heard the myth of exploding fans nor seen any evidence, the viscous coupling is designed to cope with the fan being immersed with no effect on the engine speed and is certainly rated beyond 'maximum engine speed' for TDV6 & TDV8's used in L319,320 & 322's.
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So the L322 fan is currently on my P38 and i have a little control board with a PID algorithm and i can request a fan speed and then the board engages the solenoid to hold the fan at the requested speed. Ive only been brave enough to take the fan upto 2500RPM and it gets ****ing loud and i get nervous
So my suspicion is that in the ecu theres some bit of code that says if engine speed goes above lets say 3000RPM fully disengage the viscous fan. So im trying to hear if there is something like that and at what point that happens.
 
I was intrigued about the 'exploding fan' so I did a quick search of the L322 workshop manual using the keyword 'viscous', no warnings of exploding components were found, I did however, find this:-
Regulation of the coolant temperature is achieved via engagement of the electro-viscous fan assembly. This is
controlled by a Pulse Width Modulated (PWM) signal with a duty cycle of between 0 and 100%, provided by the
ECM and derived from inputs based on:

Coolant temperature

Ambient air temperature

Engine inlet air temperature

Air Conditioning (AC) system pressure

AC switch operation

Transmission oil temperature

Fan speed control is variable; however, because the fan is driven directly from the engine, the maximum fan
speed available is tied to engine speed. At high engine speeds the fan is progressively disengaged to protect
the clutch unit. This system provides very high levels of fan power, up to 5 kilo Watts (kW), with enhanced
noise and fuel economy benefits compared to mechanically controlled viscous fans.
For additional information, refer to: Electronic Engine Controls (303-14C Electronic Engine Controls - TDV8
3.6L Diesel, Description and Operation).

The speed of the cooling fan is also influenced by vehicle road speed. The ECM adjusts the speed of the cooling
fans, to compensate for the ram effect of vehicle speed, using the Controller Area Network (CAN) road speed
signal received from the Anti-lock Braking System (ABS) module.
Click to expand...

Which makes me think your desire to replicate the functionality of the L322's fan control strategy in a P38 will be problematic.
 
Grrrrrr said:
Usually the fan fails by failing to lock up. I've never heard of one exploding on a P38A, although that doesn't mean it isn't possible. It certainly can be damaged by wading although so far I have been lucky and it just chucked water all over the engine. I think @Salisbury Nick was not so lucky? @Graculus might know more about the L322 fan.
Click to expand...
There have been reports of the P38 viscous shedding blades when the coupling has locked up.
 
Love it, replace a known to be unreliable viscous fan with a complex potentially more unreliable viscous fan.
Many large modern cars rely on electric cooling fans without problems.
 
So controlling the fan wont be a problem, im going to be getting all the info like coolant temp and engine RPM and road speed from the OBD 2 port and feeding that to my "fan control board".

I cant seem to find where i read that about the L322 fans.
The P38s though i personally know of 2 cars that its happened to and a bunch of them on forums.
With my borthers car i was in the car when it happened. It was quite a hot day sitting in stop go traffic with the aircon on and engine quite hot. He pulled away under full power trying to merge with traffic and id guess at about 5000RPM the fan exploded. So i think what happens is the the fan gets old and then if you have a really hot day with hot radiator the fan goes to fully engaged and if you then redline the engine the fan doesnt have time to fully disengage and it spins at engine RPM resulting in an explosion
 
Datatek said:
Love it, replace a known to be unreliable viscous fan with a complex potentially more unreliable viscous fan.
Many large modern cars rely on electric cooling fans without problems.
Click to expand...
Im not sure why you are calling the viscous fans unreliable.
All the P38 fans that ive read of not working where all just 20 years old and failing. Thats to be expected, you just replace them with the actual borg warner and they last another 20 years.

All the L322 fans where also either just getting old and the guy replaces the viscous unit and all is fine again or some guy rebuilt his engine and swapped 2 connectors and the ecu gets a wrong coolant temp value and then the fan freaks out. Ive found about 3 threads where guys switched the coolant temp connector with another connector close by.
 
FEI said:
Im not sure why you are calling the viscous fans unreliable.
All the P38 fans that ive read of not working where all just 20 years old and failing. Thats to be expected, you just replace them with the actual borg warner and they last another 20 years.

All the L322 fans where also either just getting old and the guy replaces the viscous unit and all is fine again or some guy rebuilt his engine and swapped 2 connectors and the ecu gets a wrong coolant temp value and then the fan freaks out. Ive found about 3 threads where guys switched the coolant temp connector with another connector close by.
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Funny that viscous fans on other vehicles such as my Transit seem to go on for ever.
 
Datatek said:
Love it, replace a known to be unreliable viscous fan with a complex potentially more unreliable viscous fan.
Many large modern cars rely on electric cooling fans without problems.
Click to expand...
Yes and all of them that use electric fans have oversized radiators as a result.
biketeacherdave said:
If you won't listen to datatek regarding this matter on his simple mod .......I'm out.
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Its not about whether im listening to him or not, im just saying i dont agree with him, i dont think its going to work for my situation and im providing facts as to why i dont think its going to work.
 
FEI said:
Yes and all of them that use electric fans have oversized radiators as a result.

Its not about whether im listening to him or not, im just saying i dont agree with him, i dont think its going to work for my situation and im providing facts as to why i dont think its going to work.
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Not seen any facts but not interested, your complicated set up is IMO a failure waiting to happen. KISS technology is my preference, you are welcome to disagree.
 
FEI said:
@Datatek ive read about your mod. Ive decided against it and rather for the electro viscous fan.
Reasoning I dont want that extra load on the alternator. Im guessing those AC fans are around 30amp draw and then the largest SPAL i can fit is another 40 amp. So extra 70 amp almost constant draw in hot weather. So that is roughly a 0.9KW of cooling fans.
That will just cause preamature alternator failure.
I live in South Africa, so those fans are going to be on almost permanently.

So looking at some stuff i can find online:
Horton makes electro viscous fans. One of their smaller units takes a 500mm-700mm diameter fan and can provide upto 60nm of torque through to the fan from the engine. The P38 fan has a 460mm diameter fan and the L322 has a 500mm diameter fan. So at 2000RPM fan speed that relates to 12.57KW. So lets be really conservative and say that the P38 viscous fan uses max 5KW.
How does the AC fans and a huge SPAL fan of 0.9KW comare to 5KW of cooling. Then the next question, if all of that 5KW of cooling wasnt necessary why would landrover put it there?

Then another thing is effiency again. There is energy loss converting the rotational energy to electrical, a really good alternator will probably have a 75% effiency. Then later you want to convert the electrical energy back to rotational in the fan, roughly another 70% efficient.
So in order for your alternator to produce 0.9KW you are going to draw +- 1.2KW of energy from the engine and then at the spinning electrical fan you only going to get out 0.63KW of rotational energy.
So with a viscous fan you have none of those losses. The only loss that a viscous fan will have more than a electrical fan is the extra weight of the viscous clutch itsself.
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@Datatek did you bother to read this?
 
FEI said:
So controlling the fan wont be a problem, im going to be getting all the info like coolant temp and engine RPM and road speed from the OBD 2 port and feeding that to my "fan control board".

I cant seem to find where i read that about the L322 fans.
The P38s though i personally know of 2 cars that its happened to and a bunch of them on forums.
With my borthers car i was in the car when it happened. It was quite a hot day sitting in stop go traffic with the aircon on and engine quite hot. He pulled away under full power trying to merge with traffic and id guess at about 5000RPM the fan exploded. So i think what happens is the the fan gets old and then if you have a really hot day with hot radiator the fan goes to fully engaged and if you then redline the engine the fan doesnt have time to fully disengage and it spins at engine RPM resulting in an explosion
Click to expand...
Different technology - I'd be interested to see how you get on with this mod (I'm probably one of the few on here that embrace progress and change) especially how you work out the percentage of lock with rate of rise once the thermostat is fully opened and how you slow it down again with as the thermostat closes. Road speed will obviously give a ram-air cooling effect and engine speed clearly needs a progressive disengage to allow for timely acceleration, regardless of road speed or coolant temperature.
Good luck!
 
Graculus said:
Different technology - I'd be interested to see how you get on with this mod (I'm probably one of the few on here that embrace progress and change) especially how you work out the percentage of lock with rate of rise once the thermostat is fully opened and how you slow it down again with as the thermostat closes. Road speed will obviously give a ram-air cooling effect and engine speed clearly needs a progressive disengage to allow for timely acceleration, regardless of road speed or coolant temperature.
Good luck!
Click to expand...
Yeah looking at @Datatek attitude i can see that.

How im planning on having the basics work is a PID algorithm that recieves coolant temp input and outputs a target fan speed in order to mantain the target coolant temp of lets say 95 deg. Then a second PID that receives actual fan speed and target fan speed from the first PID and then tries to maintain the target fan speed.
So ill first just sort that part out and get it running and then start looking at integrating inputs like AC state, road speed and stuff like that.
 
Graculus said:
Different technology - I'd be interested to see how you get on with this mod (I'm probably one of the few on here that embrace progress and change) especially how you work out the percentage of lock with rate of rise once the thermostat is fully opened and how you slow it down again with as the thermostat closes. Road speed will obviously give a ram-air cooling effect and engine speed clearly needs a progressive disengage to allow for timely acceleration, regardless of road speed or coolant temperature.
Good luck!
Click to expand...
Nothing wrong with progress, I used to design, manufacture and maintain computer hardware and micro controllers. Excessive complication to do what is basically a simple job is not IMO progress. There is an obsession in certain age groups with tech.
 
I'd consider a drop-off in lockup percentage from 2400 to 2800 with 2400 being 100% of requested to 2800 being 10% of requested. Also bear in mind that even at 0%, there is still some 'drag' from the viscous coupling.

You may want to consider the 'ignore' function, I find it cuts out a lot of white noise...
 
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