Ok, I have my 1989 RS 305 L03 (tbi). I recently changed the outside rad, as it was cracked and leaking. I tested system, found cooling fans to kick in at right time, all was good.. until yesterday.

Ran car, left for a little to talk to my dad, heard bubbling, so I ran back to find steam and a puddle in my passenger foot well (fans didnt kick in)

I can fix my blowen heatercore no problems, but can I hook up an OLDER engine driven fan on my L03?

 

not a good Idea, Just fix the fan. If you want the fan to run the whole time the car is running all you have to do is find the relay for the fan. splice into the green wire and ground it to the body. This will make the fan run without stopping.

 

Will that not make the fan run with out the key on also?

 

i had this problem(well close) for a couple years id drive the car idle and the temp would rise above half( which isnt right for my car cause i was running a 180 fan switch,, id go pop the hood and wiggle around the fan relay and shed come on,, after 3 relays and alot of tinkering i relized it had to be the relay assembley itself, bieng 20 year old car i couldnt find it anywhere,SO i wired both fans to a toggle switch inside my car when I FEEL they need to come on i flic the switch and when its cool enough i flic it off,, ive never had any problems besides forgetting to turn it OFF and draining my battery(im also runnin power pulleys possibly why) just pay attention and it should be fine, i mounted mine on the passanger side tranny hump,( when chicks are in the car warn them your turning your fans on not grabbin there leg lol) or gte smacked like me lol

 

No, the fan will only run with the key in the run position. Thats how my fans are and my temp never gets over 180* on the hottest days.

 

I went out and tested it after I posted and you are right the 12v to the relay
coil is hot only when the key is on . Thats a good ideal, I will wire mine like that tonight. Thanks