[tylerwerrin]

Hi guys,

I was wondering if anyone out there has added a fan timer relay to their LT1's so that the fans run for a couple minutes after driving around in the heat. My honda has one, as did my old Saab. Since my engine is in an XJ6, i've heard that the engine bays can trap heat, and having a fan to cool the engine after shut off would be good insurance to prevent another head gasket from blowing (like what happened to me last year).

Can anyone out there chime in?

thanks!

 

[cocobolo95]

Instead of a timer, have you considered reprogramming the fan turn on temps to a lower setting?

If you want a little extra cooling, the manual fan switch, as diagramed on shoebox's site would help. This is because, as wired, when fan switch is off, pcm can still command fans on and they will run. When fan switch is on, what your doing is suppling the same ground to fan relay that pcm would provide if it commanded relay on.

 

[shoebox]

I can see it possibly cooling the engine bay a little, but not sure what real benefit this is. The engine, itself, is not going to benefit much when there is no coolant circulation. As long as you are running normal temps, I don't see it as much of a concern.

 

[tylerwerrin]

I already have set the fans to come on lower, per Shbox's suggested temps -- i'm also running a 160 degree t-stat, for added insurance.

My car is a conversion, so I am running a coolant header tank, instead of using the radiator to fill. The tank is from a 99 Malibu, and has a PSI rating of 15psi. I believe this is the same as a 1995 Camaro, although now it looks like 16psi is the new standard. I could ditch the header tank system and go back to a stock one but that'd mean buying a new radiator and new fan shroud.

 

[Roger Mabry]

No problem with LT1 in Jag with stock dual fans

I used the stock Camaro dual fans with louvers, stock radiator and AC condenser that all slip together easily with built in "hooks". I use the stock high GM temps
and let the PCM control things. Never had any problems in heavy stop and go So Cal traffic with the AC. Have used it in 112F degree weather. Id o have an
electric water pump to cut down on the HP needed and to move more water through the system...

I do have the sides and top of the radiator sealed off to make all the air go through the radiator instead of escaping around the sides and top.

See no reason to change a setup that worked in more cars than Jaguar has ever built!

 

[lt1-xjs]

I have the fill cap spliced into the pump discharge, driver top hose which is the highest point in the system. Once filled there is no bleeding, it is full. I run an unpressurized overflow tank with a partial fill for makeup. It runs in the 160/170* range. I use a CSR pump and a large Griffin race radiator.
A 12 year old conversion.

 

[tylerwerrin]

in retrospect i should have stuck with the stock setup, but I liked Bob Loftus' set up so much that I went with that -- plus that way i didn't have to cut into the radiator cross member.

It should function operationally stock -- however, that plastic tank blew last summer while driving out in Redlands (it was around 105 outside). I've been looking for a welded replacement so I can up the PSI to 18, but haven't had any luck yet.

It's either that or buy a new radiator & shroud.

 

[bobdec]

Would a thermal controlled switch on the radiator (220*F on /180*F off) do the job. W/O water pump running you will only be cooling the radiator, plus blowing some air into the engine compartment. It would keep radiator stuff below boiling after a stop. You would need a $10-20.00 switch to pick a relay that will feed +12 to 1 or 2 fans. It should probably run a short time till radiator is cooled down. Would run independently of PCM control. No DTC's as +12 is not monitored by PCM and when running normally I doubt the radiator coolant will ever hit 220, it's usually cooler than the head temp except for an overheating situation.
Other solution would need to design a circuit that monitors for +12v ignition going to 0V, then kicks off a timer that picks the same relay as discussed above. But that would be a PITA w/o intelligent circuitry to prevent activation on a cold engine and you don't want fans running every time key is flicked on to off.

 

[bym]

dont find a benefit at all more than sucking up you amps... still it wont flow through the engine wont prevent a blown head gasket...
what I usually do is if my fans are running when im parking, I let the car idle for a while till the fans shut off. then turn the ignition off. this means the car is at its lower working temperatures...
but if your freaked out about this then go ahead and install a timer...

 

[Roger Mabry]

Would help if he had an electric water pump

Could change the water pump to electric and run the water pump after shutting down and the fans together.

But, it would draw a lot of amps....still do not know why you think you need to do this???

 

[tylerwerrin]

I just want to make sure i'm not gonna have to re-do another head gasket job -- it's a real pain in the butt!

The thermostatic switch idea is good, and I could splice it easily enough. I'm looking for billet tanks right now to prevent my overflow from bursting in the future.

 

[bym]

I just want to make sure i'm not gonna have to re-do another head gasket job -- it's a real pain in the butt!

The thermostatic switch idea is good, and I could splice it easily enough. I'm looking for billet tanks right now to prevent my overflow from bursting in the future.

well if you dont want to blow a head gasket, you shouldnt really care about cooling the car while its NOT running.
you should be focusing on:
having a good water pump working as it should
having no water leaks
having your water system clean "no deposits or corrosion etc"
having a radiator and hoses in good shape.
getting a lower temperature thermostat.
having your fans working properly and having them tuned to a lower starting point.
having your system bleed properly "air free"
using the right coolant or either water wetter

an over heated engine does not only occur by fan failure, it can also be caused by poor lubrication, excessive rpm range for a long time, water sistem clogged, corrosion in water paths inside your engine, drain plugs destroyed from the inside....

takes a lot more than just a simple switch to turn on the fans while your car is not running.

think about this:
if you are using your car, it gets to working temperatures, the fans kick on, they eventually should stop once the desired low engine temperature is reached, so it start climbing up again and fans kick in again.
if you park your car and your fans are not working it means that the car is still in a minimum operating temperature... why in the world would you want to lower this temperatures while the engine is not WORKING?

you are basically chugging tylenol and you dont even have a headache, just to prevent one.. which is not good for your liver "in this case your battery"

I do know that engine temperature rises a little once you turn off the car, but dont think this temperature reaches 230°F.... it does rises in the first 5 min a couple of degrees 3 to 8 degrees at the most!!!!, but nothing to blow a head gasket..

go ahead and do your mod, im not telling dont do it, but it just seems that your heading out in a wrong path to prevent a blown head gasket....

commonly head gaskets blow in operating engine conditions, not while its off, the do blow sometimes if you are quite dumb to get cold fresh water into your engine while its not and you have your engine off.

but what the hell, go for it!

by the way, overflow tanks are designed to overflow and release pressure so hoses dont blow up..... read a little more before http://www.custompistols.com/cars/articles/overflow.htm

 

[tylerwerrin]

i was just thinking more for added security -- i didn't think the fans running for a few minutes after shutting off the car would stress my battery that badly.

all the other stuff i have is new -- new waterpump, newish radiator, new gaskets, coolant, 160 deg thermostat, lowered temps for the radiator fans to kick on, etc.

This looks like it would do the trick:

http://i483.photobucket.com/albums/rr194/turbvert04/nos371.jpg

This also might do:

Canton Racing Products 80-201 2 Quart Aluminum Recovery Tank : Amazon.com : Automotive

A new radiator is 80, and a new shroud is another 50 or so. As issue i've run into is the stock Camaro radiators have an extra outlet on the bottom, which fed the old "oil warmer", which I've removed.

also, XJSLT1, when you say you added the inline filler, isn't the heater core higher than the highest radiator hose?

 

[bym]

i was just thinking more for added security -- i didn't think the fans running for a few minutes after shutting off the car would stress my battery that badly.

all the other stuff i have is new -- new waterpump, newish radiator, new gaskets, coolant, 160 deg thermostat, lowered temps for the radiator fans to kick on, etc.

This looks like it would do the trick:

http://i483.photobucket.com/albums/rr194/turbvert04/nos371.jpg

This also might do:

Canton Racing Products 80-201 2 Quart Aluminum Recovery Tank : Amazon.com : Automotive

A new radiator is 80, and a new shroud is another 50 or so. As issue i've run into is the stock Camaro radiators have an extra outlet on the bottom, which fed the old "oil warmer", which I've removed.

also, XJSLT1, when you say you added the inline filler, isn't the heater core higher than the highest radiator hose?

yup obd1 camaros had that oil "cooler" for the engine which was eliminated in obd2 engines..