Well then why is he wanting to put in a 70 amp relay????

 

During startup the fan can draw up to 130 amps for a few milliseconds, so the 70 amp relay is better equipped to handle that surge. It's a bit of overkill as many people run them w/ lower amp relays, but better safe than sorry. I just used the 70 amp relay myself b/c it was what the wiring diagram and setup I followed called for.

 

well the problem is the truck/trailer are parked at nellis afb in las vegas while im visiting the folks in pittsburgh. when i get back to nellis on monday evening, i need to get the truck fixed and hit the road asap. the fan really should be on high anyway, so im gonna do both the re-wiring and the rad flush at the same time and hope that fixes it. if not, next overnight stop is salt lake city.

 

You always want to run wiring and a relay rated for 1.5 times the load rating.

Put a new radiator in the truck and be done with it. My Mustang ran hotter than I likes on the highway because the radiator was partially clogged. In town at lower rpm/lighter loads, cooled fine. I too have the taurus e-fan on low. now runs 180 degrees in 95* weather.
Also had the highway overheat problem in a friends 97 Ram 5.2L. He ended up cooking the engine twice. First time, I had to replace the head gaskets, second time it started knocking (and blown gaskets). I replaced it with a 5.9L, and it ran normal in town, as soon as you hit the highway, it just kept getting hotter and hotter. Replaced the radiator, never over 1/2 on the gauge again.
Replace radiator/save engine!!! E-fan will be fine. It won't even run going down the highway. Mine only come on when sitting or when driving under about 30mph.

 

but why spend a ton of money on a new rad when a simple flush should clear it?

 

Because most likely a flush won't clear it. I did two flushes on mine and just wasted money. I then got a radiator for $150 off radiatorbarn.com and never looked back.

 

i'd rather be sure and get the problem fixed instead of just trying different things and troubleshooting them, so i decided to just get a new radiator. i'll also be wiring up the fan on high. autozone and pepboys in vegas want $300 for a new radiator. carquest has it for $206 in stock so i ordered that one. I'll pick it up tuesday morning when i get back in to vegas.

 

Get a variable controller for that thing dude...that way you can have low and high speed. Having it on high all the time in town is going to get annoying.

 

good call on going with the new rad. I would NOT run that fan on high full time. no need, creates extra load, wear out the fan, load the alternator. and going highway speeds pushes more air in than the fan will pull anyway. Seriously, leave it on low. once that rad is fixed you'll be fine.

 

^ +1 Not needed. It has a high speed because the Taurus A/C condenser is in front of the radiator and needs high speed for the a/c.
It only runs low speed when it cycles on and off to keep the engine cool. High speed when the a/c is on. Since your condenser has it's own fan, no need for high.