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From mechanical to electric fan for more engine temp?
Looking at converting my ‘85 T/A non cc LG4 from mechanical fan to dual electric for improved temperature control.
Have done full exhaust and headers (lost heat riser pipe and EFE valve), car struggles to get up to temp unless I flog it or get it out on the highway (rare). Canadian, so it doesn’t see high ambient temps. Oem Dual fans as that’s available locally for a clean appearance/bolt on.
Re: From mechanical to electric fan for more engine temp?
Only one: you may need to beef up your charging system and the wiring between alt & fan. Or, wire your fan power source as close to the batt as reliably practical, such as, at the big post on the starter. Which is usually the easiest point to pick off full batt power without burning up any intervening wiring. The charging system (alternator) needs to be able to deliver the current the fan(s) draw, plus the AC, headlights, etc., INDEFINITELY, with some room to spare. Not a place to cut corners.
Re: From mechanical to electric fan for more engine temp?
Nope,..... adding an electric fan ( or 2 ! ) means the fans will never kick on until (whatever) sensor you use tells it too. Wire it just like stock; power to a relay and a ON/OFF sensor mounted in the head. ( Using quality wiring & Alternator as SOFA suggested ! ) I suggest a head mounted fan temp sensor over a radiator "probe" type or any sensor mounted in the intake.
However: the first thing I'd do is to MAKE SURE the T-Stat was a stock 195 degree. ( quick,CHEAP, and easy ) If it's a 180 or lower temp T-Stat than it's going to open and start cooling the engine way sooner than you really want it to (being in a cold temp environment.) Start the car and let it idle while holding the upper hose. When the thermostat opens the hose will get hot,... let go of the hose and read the gauge to see what temp it reads when the thermostat opens. If you don't notice a pretty "quick" change in the temperature of the upper hose ( hose just gradually gets hotter and hotter from a cold start ) then the thermostat might be stuck open at all times.
Re: From mechanical to electric fan for more engine temp?
I wouldn't go through all the trouble adding electric fans, making things more complicated vs. a fan that will never break down or quit working. There should be no issue of that engine warming up if it has the stock 195 thermostat and a functioning stock thermostatic clutch fan(turns less when cold and faster when warm). Im in ND and drove mine when it was -10 below zero and when I had the stock 305 it had no issues warming up and actually blew too hot and had to turn it down after driving for a while. If everything else checks out ok might be a partially plugged heater core if the coolant hasn't been maintained over the years or someone added stop leak at some point, I had lincoln towncar from the 80s that would never blow hot air and it was the heater core from unmaintained antifreeze.
Re: From mechanical to electric fan for more engine temp?
Originally Posted by sofakingdom
Only one: you may need to beef up your charging system and the wiring between alt & fan. Or, wire your fan power source as close to the batt as reliably practical, such as, at the big post on the starter. Which is usually the easiest point to pick off full batt power without burning up any intervening wiring. The charging system (alternator) needs to be able to deliver the current the fan(s) draw, plus the AC, headlights, etc., INDEFINITELY, with some room to spare. Not a place to cut corners.
As far as cooling though, no negatives at all.
thanks Sofa, I’d thought of this - been through it after adding an electric water pump / fans to a buddies mustang. You may recall I have plans for a mild cam and intake as well - I’m considering blocking off the exhaust crossover which will leave coolant as the only means to warm the carb/intake, my wife wants to drive the car too which means it has to have decent manners (possibly sniper in the future).
Re: From mechanical to electric fan for more engine temp?
Originally Posted by John in RI
Nope,..... adding an electric fan ( or 2 ! ) means the fans will never kick on until (whatever) sensor you use tells it too. Wire it just like stock; power to a relay and a ON/OFF sensor mounted in the head. ( Using quality wiring & Alternator as SOFA suggested ! ) I suggest a head mounted fan temp sensor over a radiator "probe" type or any sensor mounted in the intake.
However: the first thing I'd do is to MAKE SURE the T-Stat was a stock 195 degree. ( quick,CHEAP, and easy ) If it's a 180 or lower temp T-Stat than it's going to open and start cooling the engine way sooner than you really want it to (being in a cold temp environment.) Start the car and let it idle while holding the upper hose. When the thermostat opens the hose will get hot,... let go of the hose and read the gauge to see what temp it reads when the thermostat opens. If you don't notice a pretty "quick" change in the temperature of the upper hose ( hose just gradually gets hotter and hotter from a cold start ) then the thermostat might be stuck open at all times.
thanks John, I’m picking up what you’re throwing down. I’m almost certain the existing thermostat is stuck open or not closing properly at least - but I have a new 195 on the shelf to install with the new intake. I want the engine running as close to 195 as I can keep it.
I’ll be running the fans off a 30A relay, switched using factory parts. I will be making use of the now unused empty ports in the thermostat neck (lg4, thermal switches for distributor vacuum and egr) for temp monitoring and fan control, That’ll help keep the wiring tidy too.
Last edited by theraymondguy; 12-10-2020 at 04:50 PM.
Re: From mechanical to electric fan for more engine temp?
Originally Posted by 2knight
I wouldn't go through all the trouble adding electric fans, making things more complicated vs. a fan that will never break down or quit working. There should be no issue of that engine warming up if it has the stock 195 thermostat and a functioning stock thermostatic clutch fan(turns less when cold and faster when warm). Im in ND and drove mine when it was -10 below zero and when I had the stock 305 it had no issues warming up and actually blew too hot and had to turn it down after driving for a while. If everything else checks out ok might be a partially plugged heater core if the coolant hasn't been maintained over the years or someone added stop leak at some point, I had lincoln towncar from the 80s that would never blow hot air and it was the heater core
from unmaintained antifreeze.
as a stock car the mechanical fan worked well. As a now (lightly) modded car having lost the EFE and manifold heat riser, plus plans for cam, intake and blocking the exhaust crossover I need the cooling system kept toasty and more finite control. I don’t have my heater core even connected, t top summer car, it gets hot enough!
Last edited by theraymondguy; 12-10-2020 at 04:50 PM.
Re: From mechanical to electric fan for more engine temp?
Biggest advantage of an electric fan over the typical mechanical one IMO, is the power is DOESN'T consume.
While I don't have hard data, I've "heard" "them" say that a typical mech fan eats about 12 - 15 HP. Anecdotally, I can tell you that when I swapped my truck (04 Avalanche) from the clutch fan to a 06 or so electric, the gas mileage improved several tenths (i.e. nearly doubled ) and the truck felt noticeably snappier at higher engine RPMs.
I don't find electric to be any more "complicated", "unreliable", or any other such thing, compared to mech.
I would recommend using the port in the pass head for fan control rather than the water outlet. The temp there is MUCH more stable.
Re: From mechanical to electric fan for more engine temp?
Originally Posted by T.L.
This is the first time I ever heard of anyone wanting their thirdgen to run hotter...
Originally Posted by deadbird
Try a new thermostat....
Originally Posted by sofakingdom
Biggest advantage of an electric fan over the typical mechanical one IMO, is the power is DOESN'T consume.
While I don't have hard data, I've "heard" "them" say that a typical mech fan eats about 12 - 15 HP. Anecdotally, I can tell you that when I swapped my truck (04 Avalanche) from the clutch fan to a 06 or so electric, the gas mileage improved several tenths (i.e. nearly doubled ) and the truck felt noticeably snappier at higher engine RPMs.
I don't find electric to be any more "complicated", "unreliable", or any other such thing, compared to mech.
I would recommend using the port in the pass head for fan control rather than the water outlet. The temp there is MUCH more stable.
Bingo. The LG4 is stingy on power, 14-15 Hp is 10% of rated if I found the correct data. I do plan on adding a cam, and if a guy was to show up on test/tune night it’d be great to have a means to cool the engine “on demand”.
I bought 2 sets to find enough bits to cobble a complete dual cooling fan setup together - couldn’t find one single fan setup, but double fan setups line the ditches locally (Canadians are big on A/C). Or at least I think, I know I’m missing one rubber isolator, and I’m hoping the mechanical fan uses the same.
What went in the center location? There is an m6 folded nut, but nothing in place?
Last edited by theraymondguy; 01-05-2021 at 07:28 PM.
Re: From mechanical to electric fan for more engine temp?
Originally Posted by 8t2 z-chev
those stock dual fans pull 7.5 amps each once up to speed-startup surge might be 15-18 amps each.
I was thinking of having 1 relay each, mounted on the firewall to make for a clean install. I cannot stand to see a spiders web of cable coming off of battery terminals, especially side posts.
Easy access to B+, B-ve at the alternator, clean access to the switch once mounted in the head. Leaving just the fan power to route, I’d probably follow the harness coming off the passenger head then come down the frame rail to the radiator support.
Last edited by theraymondguy; 01-10-2021 at 07:48 AM.
Re: From mechanical to electric fan for more engine temp?
I thought I’d follow up on this thread. I’ve completed the fan install and relay wiring. As noted, b+ve off of the alternator stud, switched ignition off of the choke wire.
Currently I have one fan operating (drivers side, a little air flow over the mechanical fuel pump can’t hurt). The fans switch on at an indicated 220F, half of the gauge - and cycles off at indicated 203F. I checked it with an inexpensive infrared thermometer and at the cooling fan switch it cycles on at 195F, of at 185. In my experience as a mechanic, it’s my opinion that the engine is decidedly not at 220F when the cooling fan is engaged.
I have no real faith in either the infrared thermometer or the coolant gauge. However, the car comes up to temp nicely, doesn’t have the constant drag from the mechanical fan, runs a few degrees warmer on the gauge and cools well with the fan: everything I wanted.
I will be adding in the second fan but I’ve just discovered a very minor weep at the radiator and recognized that the cooling system needs a flush, and if I’m going to get into that I may as well go for the cam and intake install at the same time for the sake of the coolant...
Re: From mechanical to electric fan for more engine temp?
Well, that didn’t last long.
First trip over 50 mph resulted in the car running at about 3/4 of the gauge (with the mechanical fan it would run at half of the gauge). The coolant wasn’t boiling in the surge tank, so not an overheating situation.
I’m missing the air dam from the bottom of the bumper: the mount still appears to be in place?
Re: From mechanical to electric fan for more engine temp?
done a few dual fan swaps myself. only thing i might add is to ensure that neither fan circuit shares a common failure point with the other as much as possible. I run separate controllers, fan power feeds and acc power feeds to each.
i've always used factory relays, usually from the later models with the better connectors.
Re: From mechanical to electric fan for more engine temp?
Originally Posted by naf
done a few dual fan swaps myself. only thing i might add is to ensure that neither fan circuit shares a common failure point with the other as much as possible. I run separate controllers, fan power feeds and acc power feeds to each.
i've always used factory relays, usually from the later models with the better connectors.
aside from the choke wire, are there other switched ignition sources under the hood? I’d like to avoid the distributor.
Re: From mechanical to electric fan for more engine temp?
Well that escalated quickly.
New CU951 radiator, system flush + overflow bottle cleaning. Two new cooling fan motors plus a warranty fan motor.
I completely pulled everything I had done for wiring and reworked the install - moving the relays to the chassis rail near the coolant bottle. This allows nice short 12 gauge runs to the fans and makes it all easily accessible. I’ve powered the coil on the second relay from the output of the first, so as not to overwhelm the choke circuit.
The star washer on the battery -ve is critical. I had misplaced it, found the alternator was overcharging, acting like the regulator had failed, (voltage oscillating). My battery has both top and side posts, I’ll probably end up making new cables for the top posts, increase the ground and positive cable sizes as I’ve got plans to add a couple of amps to the stereo in the future.
Edelbrock performer intake has a port in the cooling on the drivers side, I’ll probably use that for the second fan switch, for now all of that waits while finish up some foundation work.
12-09-2020, 07:47 PM
) and the truck felt noticeably snappier at higher engine RPMs.
