I have been fighting temps creeping up on the highway (in the warmer months) for a couple years now. When i say creep i mean i will get on the higheay at 195-200, and in 5 miles i will be up about 5-7*. After about 15 min of driving temps will be pushing the 220-225. The only way to keep it there is run the heater pn high.

As I said its only in the warmer months. I have a 351 with mustang EFI and the Explorer serp set up.

Here is what I have done to combat the heat issues:

I have installed an aluminum radiator- Champions large version
Drilled the lower intake to have flow thru the additional port
I have dropped base timing 2* to 10
I have had the motor tuned and it's running 12.7 A/F ratios thru the entire power band (before the tune it was running 14.6)
Water wetter- no change from this

I have also tried BOTH the Taurus electric fan and the Explorer mechanical fan. I have been running the Taurus fan for years now. I just swapped to the explorer fan this weekend. I have to say to everyone that says a mech fan works better than electric.... I am proof other wise. The mech fan lets temps rise faster than the taurus fan on high. The bummer is after all the work of finding a shroud, building the shroud extension, moving wiring ect, and getting everything to fit, its worse off. I didn't remove any of the wiring for the elec fan so I can go back to it, but I like the simplicity of not having to mess with the elec fan.

If anyone has any ideas... Please let me know!!!
Thanks!
Ryan

how much total ignition advance do you have?

10*. I don't know what is built into the tune. It's a basic custom tune.

Would the tuner be manually locked into "open loop" make a difference? The tuning shop did this because there was a question if the new o2 sensors were bad.

I'm subscribing, because I know this is a common problem with 351W swaps, and I'm planning one. I just spoke to our local machine shop about getting the block ready, and he asked "How you going to cool it?".

The only advice I can lend, I don't think my clutch fan cools as well as my old fixed blade fan. Its hard to tell, I went EFI, clutch fan (not Explorer), and a hotter tstat at the same time. The clutch fan I'm using is this one:

http://classicbroncos.com/forums/showthread.php?t=81601

I don't know if its better or worse than the Explorer fan, its a standard rotation, and fit my vbelt front accessories. My truck has had only easy running highway use since the EFI swap. With my fixed fan my temps would stay right at my tstat (I ran a 180*) temp on the highway. My clutch fan, on hot days, runs 200-210, 10*+ over my tstat temp (195*). It doesn't bother me now, but I wonder what will happen with summer heat/serious off roading/and 351 in a year or so, give or take.

"open loop" is like it's limp home mode, isn't it? I'm not very EFI savvy...
but i would think that if that's the case, then yes it may play a role in running too hot.
on my 351, I had more problems with running hot, when the ignition was too retarded...once I got the timing curve dialed in, it doesn't run as hot. it still hates sitting in traffic, but on the highway the temp stays right around 200*

RTreads,
I'm sorry to hear you worked so hard, just to have it run hotter than before. I say...
consider replacing the fluid with 100% water. If you're having cooling problems in the hot months, maybe water will keep you 10* cooler. You could run some high quality H2O in the hot 7 months, and switch to 50/50 when the temps drop.

Another thought... (because my $.02 is always free)
Maybe now that you've engineered a new shroud, extention and plumbing, you could be just around the corner from the answer. Try swapping back in the electric fan with the new airflow and hopefully your time and efforts will be worth it.

Oil Cooler? Maybe just throw more money at it.

Moneypit is running a cooling fluid that isn't antifreeze based and runs at a different pressure than stock. PM him and post up what it is, I believe he's running a 351.

I think this is it- http://www.evanscooling.com/products/coolants/

Boogers 351 doesn't run hot. Max at 195 and that's with 3/4 the radiator blocked by the 8274. Some tricks are not using the radiator for the transmission cooler. Run a desperate cooler for that. Next a big one is a way to force all air possible through the radiator. A nice fix blade fan and shroud.

do you have the shut off for heater heat in line under the hood still if so that might not be full open i had that once and had same trouble .i could wheel all day in moab , run fine , 10 mins on hiway and temp would climp fast ..good luck

I fought through some heating problems until I separated the auto trans to a separate cooler and then closed off the top of the grille to rad support. I went so far as to increase the t-stat to 195 after reading some info on allowing more time for the coolant to transfer the heat by raising the t-stat temp. It seems that going higher may cause the t-stat to close occasionally allowing more time for the coolant to transfer the heat in the radiator. Another thing is that aluminum is a poorer heat conductor than copper (pound for pound). Sure most heat sinks are aluminum but that's because copper ones would weigh so much more so given the size of radiators mostly the only advantage of going aluminum is weight savings. The reason the OEM's went to aluminum is because they can save weight with aluminum not because it's any better. Strength advantage also goes to copper.

Another thing- I didn't see mention of the water pump. Have you tried a different one?