3.9 V8 ran hot yesterday....what now?

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Originally Posted by Rick1970

Two switches yes, wire fans through relays so they run in series for low speed, and parallel for high speed.
Keep an eye on the temps in the really hard going stuff, sand, long hills, towing etc......that’s where the extra air shifted by the original fan can become noticeable

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Well I'm hoping after i fold up a shroud the airflow will increase dramatically. They seem to have heaps of power behind them the only thing letting it down is the shroud. I was thinking of wiring one to come on at 75 and the other to come on at 80 if possible. I'll have to work out how I'm going to power it all withought making a mess of my engine bay. I still like the commo fuse box but it's not really a sealed unit. Gonna have to suss out a different sub board maybe.

I once saw a test where the tester dynod a Land Rover with viscous fan and estimated that the fan drew 6BHP when locked.
6BHP equates to about 200AMPs.

Now how many amps do your electric fans draw?

Much to it would seem your surprise this conversion has been done many many times over the years and in many cases resulted in the modifier changing back after an initial drive on sand or up steep hills on a hot day.

What is happening with your aircon fans also. Do you still have them in place? Lots of people manually switch the fans to assist the viscous.

Regards Philip A

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Originally Posted by PhilipA

I once saw a test where the tester dynod a Land Rover with viscous fan and estimated that the fan drew 6BHP when locked.
6BHP equates to about 200AMPs.

Now how many amps do your electric fans draw?

Much to it would seem your surprise this conversion has been done many many times over the years and in many cases resulted in the modifier changing back after an initial drive on sand or up steep hills on a hot day.

What is happening with your aircon fans also. Do you still have them in place? Lots of people manually switch the fans to assist the viscous.

Regards Philip A

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Well going by the fuses its a max of 40amps, I have 2 20amp fuses. I notice them come on at idle but my base idle is too low. I havnt got a switch for the condenser fans yet but if the viscous is as good as everyone says it is then why would it need the extra help lol but I will no doubt put a switch on. I left the condensor fans I'm my racecar and put a switch in, it seemed to help not that it needed it.
Look maybe I will go back to the viscous one day I'm just experimenting. If I do it's no loss the thermos just go into another project and I get a new viscous coupling easy done. Like I said before plenty of pros and cons to both.

Cheers Jim

75 is a bit cool, your running temp should be in the high 80’s at least or you may run into overfueling problems. Maybe low 90’s and high 90’s would be better.

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Originally Posted by Rick1970

75 is a bit cool, your running temp should be in the high 80’s at least or you may run into overfueling problems. Maybe low 90’s and high 90’s would be better.

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No worries thanks I thought the 90s were getting in the warmer zone. I'll turn the thermo controller up some more. I was wondering why it was smelling a bit more fuely. Cheers

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Originally Posted by LRJim

Well going by the fuses its a max of 40amps, I have 2 20amp fuses. I notice them come on at idle but my base idle is too low. I havnt got a switch for the condenser fans yet but if the viscous is as good as everyone says it is then why would it need the extra help lol but I will no doubt put a switch on. I left the condensor fans I'm my racecar and put a switch in, it seemed to help not that it needed it.
Look maybe I will go back to the viscous one day I'm just experimenting. If I do it's no loss the thermos just go into another project and I get a new viscous coupling easy done. Like I said before plenty of pros and cons to both.

Cheers Jim

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Most likely the fans are 12 amp each as this is the most common draw.
Just be careful with switching in the aircon fans , as they are about 12 amp and that all adds up to 48amps which is a lot. Actually electric fans do fail and mostly at the most inconvenient time. I had both my aircon fans on my 91 RRC fail at Kununurra and the starter wouldn't turn the engine with aircon on due to the head pressure.! I had to drive home to Avoca only using aircon while moving .
You should also check whether yours actually work.I fitted a Mercedes 16 inch fan (must have been 20 amps or so) to an 81RRC I had in Saudi. It helped a bit but the car still got hot in tail wind at 50C.
I toyed with the idea of Falcon fans but always backed off as I wanted reliability in the boondocks.
Regards Philip A

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Originally Posted by PhilipA

Most likely the fans are 12 amp each as this is the most common draw.
Just be careful with switching in the aircon fans , as they are about 12 amp and that all adds up to 48amps which is a lot. Actually electric fans do fail and mostly at the most inconvenient time. I had both my aircon fans on my 91 RRC fail at Kununurra and the starter wouldn't turn the engine with aircon on due to the head pressure.! I had to drive home to Avoca only using aircon while moving .
You should also check whether yours actually work.I fitted a Mercedes 16 inch fan (must have been 20 amps or so) to an 81RRC I had in Saudi. It helped a bit but the car still got hot in tail wind at 50C.
I toyed with the idea of Falcon fans but always backed off as I wanted reliability in the boondocks.
Regards Philip A

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Yes no doubt it will fail at the worst time just like the viscous did halfway through a rough uphill climb. Hopfully if the thermo gos only one dies and I'll have the backup....high hopes. I'm pretty sure the A.c fans work I'll double check now that you said that. I'm gonna do some more experimenting with them. I'm gonna put some cardboard in front of the grille and see if they can keep it cool still. I was even thinking about moving the fans in front of the radiator to see what sort of airflow I get but I don't think it's worth the effort. I will defiantly keep an eye on the draw I'll put in a voltmeter and get all the accessories running and see how the alternator is handling it all. I may try and find a spot to stash the viscous even cable tie it under the car in case I get left out out the middle of nowere with no fans it's an easy reinstall.
Cheers Jim

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Originally Posted by PhilipA

Much to it would seem your surprise this conversion has been done many many times over the years and in many cases resulted in the modifier changing back after an initial drive on sand or up steep hills on a hot day.

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Yep. I changed mine back after experiencing Melbourne peak hour traffic on a warm day. The electric fans are now collecting dust in the garage.

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Yes no doubt it will fail at the worst time just like the viscous did halfway through a rough uphill climb.

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I must say in my pretty long experience VCs don't just "fail". They degrade over a long period.
I have learned that I can generally tell if the VC is dying by looking at it.
If there is black **** all over the back of it then the seal has failed and the silicone fluid has leaked out. Of course if you are clean freak and hose any evidence off you will not know.
AFAIK you cannot rebuild them as the thing that lets the fluid out is the failed seal. You could I suppose refill it by drilling a hole and adding some Toyota fluid which I understand is sold by dealers.
If the spring on the front is broken then it is US as the spring lengthens with heat and closes a valve which stiffens it up.
I just thought that one way to test would be to blow a hair dryer or heat gun on the spring and see if the VC becomes stiffer as they usually lock up at about 94or so C.
Of course if the radiator is partially blocked in front of the VC it will not lock up as that part will be cooler.
Regards Philip A

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Originally Posted by PhilipA

I must say in my pretty long experience VCs don't just "fail". They degrade over a long period.
I have learned that I can generally tell if the VC is dying by looking at it.
If there is black **** all over the back of it then the seal has failed and the silicone fluid has leaked out. Of course if you are clean freak and hose any evidence off you will not know.
AFAIK you cannot rebuild them as the thing that lets the fluid out is the failed seal. You could I suppose refill it by drilling a hole and adding some Toyota fluid which I understand is sold by dealers.
If the spring on the front is broken then it is US as the spring lengthens with heat and closes a valve which stiffens it up.
I just thought that one way to test would be to blow a hair dryer or heat gun on the spring and see if the VC becomes stiffer as they usually lock up at about 94or so C.
Of course if the radiator is partially blocked in front of the VC it will not lock up as that part will be cooler.
Regards Philip A

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I've never really looked for the evidence before they go, I've normally noticed that they have died when it's too late. It could have leaked out since I really needed it last. To be honest I havnt even looked at it since pulling it out I was in a hurry. I just noticed it hadn't engaged when I was already hot.
Maybe it's worth attempting to refill it, it's rubbish anyway. There's a good picture of it in RAVE you could work out a good spot. The only other thing is plugging the hole maybe a piece of wire with arldyte or similar same size as the hole. If I can be bothered getting some fluid I'll have a crack. But there's all the other possible issues like the coil and seal as you said.
My old rodeo v6 viscous failed I think I pulled the coil out and it stayed on full time, worked well for a few thousand ks till the head finally blew out at 480ish. Went a long time on 5 cyl before she finally gave in.
Cheers Jim