Electric Fan: Time Delay Relay Shutoff

[Char-Broil]

So I searched, but I'm lazy and of course everything that came up had to do with headlights. I don't see it as being much different though, so this may be a question I already know the answer to, just want to know if there is a better/easier or cleaner way to do this. I just got a Derale performance thermal controller for my taurus fan. Works great. It has a wire that the instructions say to run to ignition switched power, so the fan will only run when the key is on. It also as an override wire. Right now I have the ignition wire run to constant power and the fan runs for about 2 min after shutting the engine down on a mild day. Of course it kicks back on and off a few times as the coolant heats back up again. What I would like is for the fan to run the 2 min or so while the engine is still the most hot after shut-down, and then not be able to come back on. I figure a time-delay relay is the only/best way to do this, my question is, anyone done it and have a p/n of a good relay to use? How does the jeep headlight timer delay system work and can I re-purpose one of those for my fan? :dunno:

 

[jeeperjohn]

I would think you could use a time delay unit for headlights, I would use it to control a relay to the fan control unit. You might try a google search for " 12 volt time delay unit"

 

[ehall]

I can't find the timer module in the parts catalog I have. I'd probably just pull one at a junkyard that already had the lower dash ripped out (which is basically all of them) and then go from there. Either that or find a car that had a temperature-driven electric fan controller and grab the assembly for adaptation.

 

[lazyxj]

I figure a time-delay relay is the only/best way to do this, my question is, anyone done it and have a p/n of a good relay to use? How does the jeep headlight timer delay system work and can I re-purpose one of those for my fan?

I have used a delay relay for over a year now for hot day to combat the hot soak problem that 2001 XJs suffer.
http://www.flickr.com/photos/lwade/sets/72157617434915718/
Check the photos for details.
I only need to use it hot days when stopping for a short time after a long drive.
I'm now thinking about pulling the exhaust manifold and then wrapping the first 2-3" of each runner with header heat wrap. The exhaust dumps too much heat into the intake manifold. It may work great in Alaska but not so well in our desert climate. Older models of the 4.0 can use a heat shield between the intake and exhaust manifolds but the 2001's dual mini-cat headers fit too close to the intake to allow this.

 

[Char-Broil]

Thanks for the replies, next time I'm at the bone yard I will pull a time delay control. I already have a temperature controller with a relay, and I will hook the time controller up to the "ignition switch" wire of the fan controller I already have, this way it will already be using my existing relay, and after the jeep shuts off, it will continue to have power to the fan until the timer runs up. Lazyxj - what kind of time delay control is that? I like how you have it set to run from a push button switch, I will probably just have it set to run all the time, then if the thermostat kills the fan before the timer does (on a cold day) at least it won't come back on if the coolant heats back up a little. Do you have a p/n for that, and a price if you don't mind. I like that it is adjustable.

 

[lazyxj]

I like how you have it set to run from a push button switch, I will probably just have it set to run all the time, then if the thermostat kills the fan before the timer does (on a cold day) at least it won't come back on if the coolant heats back up a little. Do you have a p/n for that, and a price if you don't mind. I like that it is adjustable.

This is what I used. It is adjusted to run about three minutes, when activated.
http://www.at-fairfax.com/search-results.php?keywords=Elk-960&submit=Go

 

[Char-Broil]

cool, did you just put it in a little project enclosure then?

 

[lazyxj]

cool, did you just put it in a little project enclosure then?

Actually, I used the plastic box the timer came in.
It's mounted in a protected area and all the box does is to keeps dirt and dust out.

 

[badron]

Here I go off in a different tangent.
Vent the hood and watch a host of problems go away. Not as cool as time delay fans but it works.

 

[xcm]

hood vents are a bandaid, and he obviously wants to go another direction.

i'd be GREAT if someone hacked into the existing wiring, and used the headlight delay...
basically adding another circuit to power for that 2 minutes or whatever...

i'd love to see someone do it, if for no other reason then copying it to power my stereo during the same time...

cool thread.

 

[5-90]

Interesting idea. Ideally, it would be coupled with an electric impeller pump to continue circulating coolant with the engine off (you'll get a little bit from convection once you get a temperature differential, but not much.)

Running the fan over the radiator without water circulation would have a limited positive effect - but having water circulation as well would be more beneficial. Using an impeller pump would all the electric pump to be 'along for the ride' with the engine running (the OEM water pump is also an impeller type - which can be "flowed past" if necessary,) vice a "positive displacement" pump - which has to be running if there is to be any flow through it (an impeller may spin freely if not powered, and presents only a little restriction to fluid flow. Centrifugal superchargers and turbochargers are also impeller-type pumps, just with different impellers and running at much higher spees.)

 

[fuzzydog]

Interesting idea. Ideally, it would be coupled with an electric impeller pump to continue circulating coolant with the engine off (you'll get a little bit from convection once you get a temperature differential, but not much.)

Running the fan over the radiator without water circulation would have a limited positive effect - but having water circulation as well would be more beneficial. Using an impeller pump would all the electric pump to be 'along for the ride' with the engine running (the OEM water pump is also an impeller type - which can be "flowed past" if necessary,) vice a "positive displacement" pump - which has to be running if there is to be any flow through it (an impeller may spin freely if not powered, and presents only a little restriction to fluid flow. Centrifugal superchargers and turbochargers are also impeller-type pumps, just with different impellers and running at much higher spees.)

I was thinking the same thing. One of my previous vehicular afflictions was late 80's Audi turbos. They have a kick ass after run system. There is an electric auxiliary water pump plumbed into the cooling system. When the car is running the coolant is pumped by the mechanical pump and the electric is totally bypassed. Upon shutdown, a thermoswitch will trigger the electric fan and the electric pump which pumps coolant in a reverse direction to what the mechanical pump does. This cooled the rad, engine and most importantly the turbo. The upper rad hose was molded to have a smaller line coming out of it, going to the aux pump. Might be modifiable to fit the 4l...
I was going to install an afterrun system on the jeep but, since I just fixed my cooling system (new rad, pump, hoses, taurus fan (single for now, but twins ready to go in)) and installed lebaron vents, I no longer have any heat issues.

 

[5-90]

I was thinking the same thing. One of my previous vehicular afflictions was late 80's Audi turbos. They have a kick ass after run system. There is an electric auxiliary water pump plumbed into the cooling system. When the car is running the coolant is pumped by the mechanical pump and the electric is totally bypassed. Upon shutdown, a thermoswitch will trigger the electric fan and the electric pump which pumps coolant in a reverse direction to what the mechanical pump does. This cooled the rad, engine and most importantly the turbo. The upper rad hose was molded to have a smaller line coming out of it, going to the aux pump. Might be modifiable to fit the 4l...
I was going to install an afterrun system on the jeep but, since I just fixed my cooling system (new rad, pump, hoses, taurus fan (single for now, but twins ready to go in)) and installed lebaron vents, I no longer have any heat issues.

Water-cooled turbocharger? That had to be fun to design!

I'd done some afterrun systems for turbocharger oiling on some custom builds - but I used a pressurised reservoir and a metering orifice. Worked rather well - and was dirt simple!

 

[fuzzydog]

Water-cooled turbocharger? That had to be fun to design!

I'd done some afterrun systems for turbocharger oiling on some custom builds - but I used a pressurised reservoir and a metering orifice. Worked rather well - and was dirt simple!

the Audi engineers did the designing for me - KKK K26 turbo(IIRC). It was a nice system except for that one tiny little piece of hose that was such a pita to replace because of limited access. IMHO it should have been a hardline but I suppose the engineers had their reasons. I think I still have one of those turbos sitting on a shelf somewhere.

I see one of these cars now and again at the PNP. It would probably have everything you need - the pump, upper hose, timer relays, etc. The ones I am familiar with are the 86-88 5000 Turbo Quattros. Others of that vintage, including some VWs (were there any turbo gas VWs back then?), would be similar

 

[lazyxj]

i'd be GREAT if someone hacked into the existing wiring, and used the headlight delay...
basically adding another circuit to power for that 2 minutes or whatever...
i'd love to see someone do it, if for no other reason then copying it to power my stereo during the same time... cool thread.

The headlight timer on my 2001 XJ times out after only 45 seconds, not long enough for the fan to be effective. Three minutes seems to work well.
It does not appear that the headlight timer interval is adjustable.
Looking at the Factory wiring diagram show that the timer is a stand-alone unit and could be replaced with an adjustable timer, like what I used.
I prefer to leave the stock wiring as unmolested as much as possible so added a new timer instead. I already had an electric fan bypass relay and switch so adding the timer was not that big a project.
A fan timer should not be needed in most XJs. The California 2001 XJs have an exhaust header with two small, built-in catalytic converters. A few months ago I sent 5-90 detailed photos of what one looks like out of the car for his collection.

The mini-cats dump a lot of heat right under the intake manifold. The new exhaust manifold is shaped a little differently than the old and there is no room to slide a heat shield between the intake and exhaust manifolds.
I have tried insulating and making small heat shields for the injectors without success. I have tested the injection system for leaks using a pressure gauge to look for leak-down and that's OK. I have no overheating problems when the engine is running.

I get the vapor lock problem only in certain conditions and I know when to activate the fan. It happens often, when off-roading, after a long, hard climb. Shut the engine off for more than five minutes and it will stumble and barely run on restart. After 20-30 seconds, it clears up but it usually will turn on the CEL and sets a code.
The $30 timer has cured the problem for a year now. I could wire it into an adjustable temperature switch but why? Just something else to go bad.

If someone has a better solution or cure, I'm open to suggestions.
The less parts the better.

 

[87baseomatic]

My vr6 vw has a fan control module and an electric after-run coolant pump. When you the car is shut down the pump runs for 10 minutes to keep things flowing so you don't get hot spots in the head. The fans can run for a while to depending on the coolant temp when the car is shut off. Its a good system but alot of people eliminate the pump when it goes bad, and it will go bad. They all do.

Actually all vw's except the 98-05 passats had fans that ran when the motor was off. I like the system personally. Ive had a few occasions where I would restart the xj after it was shut off hot and it would be stumpling and the temps would be way up there.I wish the fan on the xj would run for a few minutes when the car is off. I always though about putting it on a timer.

 

[Char-Broil]

Thanks again for all the input guys, I love where this has gone. I had thought of putting a coolant afterrun system on it but really didn't have a good idea of where to start. I will look into the audi/vw systems and get to a PNP to look for one soon. When I do, I promise I will keep this thread going with pictures and a writeup. Since I have a 2000 now, with a freshly installed 80k mi motor, I would really rather not have the head go south for a while, and don't wanna deal with vapor lock problems and such.

fuzzydog - dual taurus fans? Why? I guess maybe I don't get the same cooling issues with a manual trans but dual taurus fans seems like massive overkill and a PITA to boot. Just currious if you think you need it or just want it. My 94 was always fine with the stock e fan and 1 taurus fan. I never even hooked up high speed on the taurus fan and rarely ran the stock e fan because I never needed it. The only time I really ran the stock e fan was before i had the thermo fan controller and I forgot to turn on the taurus fan and was approaching meltdown temps and needed to drop the temp asap.

 

[muduck18]

Coolant after run system? Your talking electric Coolant pumps to cool the motor.. .
Just look at summit/jegs.
http://www.jegs.com/i/Proform/778/66225RK/10002/-1

basically all Drag cars run coolant after run kits.
Little electric water pumps that run the coolant and leave the fan on.

 

[Char-Broil]

well yeah but I don't think it necessary to run the water pump all the time--doesn't need that kind of flow and it doesn't need to be that expensive! Like 5-90 said, the stock mech. pump is an impeller type so coolant can flow thru it even when it is not pumping. All you want is a little circulation.

 

[fuzzydog]

fuzzydog - dual taurus fans? Why? I guess maybe I don't get the same cooling issues with a manual trans but dual taurus fans seems like massive overkill and a PITA to boot. Just currious if you think you need it or just want it. My 94 was always fine with the stock e fan and 1 taurus fan. I never even hooked up high speed on the taurus fan and rarely ran the stock e fan because I never needed it. The only time I really ran the stock e fan was before i had the thermo fan controller and I forgot to turn on the taurus fan and was approaching meltdown temps and needed to drop the temp asap.

I just like the idea of having 2 fans instead of just one. Most of my wheeling is a long way from civilization and cell service so if my efan craps out it's going to be a looooong drive home, waiting for it to cool all the time.