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Discussion Starter #1
I just installed full gauges for assorted things, temp, tranny temp volts and oil pressure.
Gauge.jpg
On a long highway trip while towing a 5000# trailer my temp climbed into the 230s. I feel that is too hot and my factory gauge agreed it was not pegged but was close. Stopping and idling brought the temp back down pretty quickly, E-fan=good. I want to know where should I start to worry for engine temp and for tranny temp?
 

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If your regular temp gauge was close to pegged I'd say that's too hot..might be time for a radiator and water pump upgrade for more cooling capacity. 210 on the engine temps is ok for a period of time, I'll see that every now and then in the summer, but I'd be more concerned about the tranny temps..If I recall you don't really want to go over the 180 degree range..where did you plumb the temp for the tranny?
 

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Discussion Starter #3
The tranny temp is on the port right on the side of the tranny. I do have a cooler set up I have not got the fan wired back up after getting all of the other wiring in place. I was kind of hoping that the flex-a-lite would pull enough air to also help the tranny cooler. I will get that wired back up. It seemed to top out in the mid 190s but stayed better than that most of the time. I have the "super cooling" radiator. I need to get out on the road without the trailer and make sure that it cools normally then try and fix for the trailer.
 

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That's where I have my tranny temp plumbed as well..my understanding is the fluid is the hottest at that point where it's leaving the tranny to the cooler, so if you're topping out at the mid 190's I think you're okay.
 

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ate lug
88 + 96 broncos, 96 F250
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Trans temps, try to keep it under 200º.

I read from the test port on both of my E4OD equipped trucks as well.

My bronco runs around 140º while cruising, my diesel runs more like 165º when cruising, and doesnt get much warmer when towing the big bronco (which is 8-9k with the trailer). I never see 190º on either of them. Both have big Ford trans coolers i got out of a junkyard. Neither have a stand-alone fan. Neither have remote filters because thats kind of a waste on an E4OD.
 

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84 Bronco, 351w, c6, custom doubler, np208, 5.13’s, TTB44, 9”, locked f/r
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In my opinion, 230 on the engine is okay for pulling a steep hill or something as long as it drops back down once on level ground. You should have a 195 thermostat unless you swapped it to a non-factory one.
On the trans, your hottest point is in the torque converter, but the hottest measurable point is the line going out to the cooler. Under 200 is good. So you have an external trans cooler, or the one built into the radiator, or both? I usually run through the factory radiator cooler, then to an external, then back to the trans
 

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84 Bronco, 351w, c6, custom doubler, np208, 5.13’s, TTB44, 9”, locked f/r
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Has it been a while since the cooling system got a good flush?
 

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Discussion Starter #10
Actually i did a flush just before leaving. I did have a burping problem that appeared after just a few miles. Also a bad cap that allowed a bunch of fluid loss. Got both of those taken care of and stopped loosing coolant. I think I lost enough to call it a second flush:cry:
 

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95 Bronco, 351W, E4OD, 4.56 gears, 35x12.50x15 Patagonia MTs.
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How old is your thermostat? My caprice would get warm because the thermostat wasnt consistently opening fully. I'd verify flow to start. Could also be deposits if you haven't been using distilled water in the coolant, most people make the mistake of using tap water. The last option is a worn/eroded impeller on the water pump. My friends miata water pump had no fins left, and he only noticed it getting slightly warm when stopped in traffic.

For me? At 230 I shut off the AC and divert all life support to the engine. That's about my cutoff, any higher and with gauge inaccuracy you may actually boil. My pro comp gauge is about 10* warmer than what my infrared thermometer indicates, that's not uncommon at all in either direction of innaccuracy.
 

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This comes from a Ford transmission engineer regarding transmission temps:

230* all day long is ok.
At 250* the fluid starts breaking down. After about 30 minutes, all the fluid is broken down and you will start to damage your transmission.

He also related this story when he was working for a Baja race team. This was with a 4R100 (updated E4OD) transmission.

The coolers for the trans were in the bed of the truck with a couple of big fans. We couldn't put the coolers out front because they would get destroyed out there. In one race the fans failed. We couldn't get new fans installed, so the decision was made to keep going as long as possible since we were in the lead when it failed. The temp gauge was pegged at 320°F for several hours while they not only completed the race, they won!

After each race we'd get the trans back for teardown and inspection. This one definitely showed signs of heat. But nothing failed. The trans worked flawlessly. The only thing we found really wrong in that transmission is that the solder had melted and fell out of each solenoid. Solder melts at 450°F. Let that sink in for a while.


In other words, when properly built, these transmissions are robust and reliable.

For coolant temps, a 50/50 mix of coolant and water will boil at roughly 223*. That's why you put on a pressurized cap. It will increase the boiling point 3 degrees for every 1 psi of pressure. So a 15 degree cap will add 45* to the boiling point. So, with a properly working cap and a good mix of coolant and water, you theoretically shouldn't start boiling your fluid until 268*. To add a safety margin, I wouldn't want to go over 250*. 230* is warm, but to me it isn't in the danger zone. I would still verify that all parts of the cooling system are working properly.
 

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Addicted to Junk
85 Bronco, 309ci I6 w/4bbl, np435, 4" lift, 37" Irok NDs, 4.56 w/ Detroit Locker and tru trac
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Dave, I hit 240 water temp for a while out on Hells Revenge. Reading from the block, farthest from the WP. Caused all sorts of drivability issues since the carb was boiling fuel. But never had an issue on the 900 mile drive home to eastern KS. Ive done all sorts of things to mitigate the heat, but have yet to test my mods.
 

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Man of endless projects
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theres a several of these but most say the same thing. in short cooler trans fluid last longer. but you do want it to get up to operating tempature. i use my OBD-II reader to get trans temp right from the PCM. i dont like my trans over 200* but when offroading it will occasioanlly climb much higher than i like over 240*. i really like seeing it in the 160-180 range



if my engine temp is over 20* more than the t-stat it puts me on edge that something is wrong. and generally the temp will slowly creep higher and higher till it becomes an issue. and if your trans cools from radiator it will also warm it up also. my F250 has been running hot for last few months and i would slowly see the engine temp raise up to 220ish, then the trans temp would raise up to 200* as a result, then the engine would continue to raise. thats happened alot a couple weeks ago at an offroad event i was at. engine and trans would slowly creep up while i sat idling
 
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