7.3 running hot

[Black dawg]

When I was towing with mine all the time in the heat (heat being 90 here) I found that removing the t stat and blocking the bypass was pretty effective. Couldnt get temp over 230 ish wide open over big passes. Temp would run 180-190 running down the highway with 900-1000 degree egt.
Going to a manual made a pretty big difference also.
Do you know any history on your a/c stuff. even a slight overcharge can cause crazy high condensor temps.....especially at 100 degrees.

 

[franklin2]

I will tell you one thing I found out pulling heavy loads in the heat. I was having heating problems also, changed everything, and it turned out to be the fan clutch. I mechanically locked the clutch with some little brackets I made. Problem gone for the most part. But pulling a heavy load up the mountain on a hot day, I can still get it hot. These engines have a lot of pull down in the low rpms, so I have a tendency to let it work down there in the lower rpms. I found out that is the wrong thing to do. Even with everything new and the locked fan, I can overheat it if I don't keep the rpms up. Once the gauge starts climbing, all I have to do is downshift and it stops climbing. My head of steam up the mountain is reduced some, but the overheating stops.

I would not let that computer on your E4OD do all the thinking. I would pull it down a gear or two manually and see if that helps it.

 

[IDIBRONCO]

Two weeks before my accident, I ordered a frozen boost air/water intercooler and its still sitting in the box in my shed. I've kicked the idea around of fabbing up a setup for this truck but just havent.

Doing that may not help with this issue, but it sure won't hurt. I think that you should go ahead and get it working.

Not gonna lie. The company I bought this trailer from, said its towable with a 1/2 ton truck and I was considering buying one to eliminate all this overheating headache but from what I've read lately, most say its too sketchy to use that size truck for such a big trailer.

Did they say that it's towable with a half ton or say that it's safe to tow with a half ton? Is that at highway speeds or around town? I've seen (and heard) a lot of crazy things about towing, but I still believe that the bigger the load, the bigger the truck. Sure, half tons are rated at much higher towing capacity now then they were back in the IDI days. One thing that always gets me, though, is when somebody tows a big/heavy load with a light weight truck like a half ton. I feel that you need enough tow vehicle to at least have a chance of keeping everything under control if things go bad. My opinion is that a longer, heavier truck will keep the load under control better than a shorter, lighter one will. To me, towing is more than pulling and stopping the load.

 

[vegas39]

Don't get me wrong, not suggesting you drive around with A/C off in 115 degree heat. Just suggesting you check your A/C pump to insure it is free to spin as needed.(Its not like alternator, it will have some resistance, but it should move with medium effort.) Then test and monitor to see if the A/C is putting you over the top. (Putting more strain on the engine creating more coolant heat. Then taking 115 degree air to say 135 degree air behind the condensor and sending that at your radiator.) If a/c is putting you over the top can you turn off on the hills for 3-5 minutes till you crest and come down the otherside.

That does not take into consideration your air cooled tranny cooler and what that is doing to your air headed to the radiator. So a thought is at somepoint look at if your tranny cooler is heating the air to the air conditioner condensor, that is then sending super heated air at your radiator. (Causing a fail.) If you deem so perhaps you can arrange in a better way so it is not double heating the air. Or doing so in a more ideal part of the radiator.

Lastly if you find it is brief times your getting hot (2-3 minutes up a incline) I have found like the misters in the restuarants, doing so for your radiator works really well. Could be simple like a 2 gallon bug sprayer on the front seat and a hose to the nozzle in front of the radiator. It could be a junk yard window wiper system. (Just get one with more than a quart capacity.) It could be more heavy duty like a tank, pump, hose, sprayer, and switch on the dash. You do not want to spray a stream of cool/cold water at hot components. Rather a nice wide mist. It robs the heat off the metal very fast and I have found it seems to also cool the engine compartment. (But does not soak your components with water, think more like humidity.) We did this years ago on a trip, my buddies truck kept getting hot on the grades, we routed his window wiper wash hose with a drip line mister head, it allowed us to keep the truck cool towards the top of the grades and not have to pull over and wait or try to put cold wanter on the radiator and hope we did not create a bigger issue. We did so on a different trip pulling a friends boat trailer but used a bug sprayer from Home Depot. Both cases it was just to make the hills/inclines but would not be effective if your truck over heats on the flats too.

Very good info, thank you.
I've often thought about the misting system. I could throw a tank in the bed and use and rv pump for water supply. Be nice if it was wired with some components to be temp controlled.

 

[vegas39]

When I was towing with mine all the time in the heat (heat being 90 here) I found that removing the t stat and blocking the bypass was pretty effective. Couldnt get temp over 230 ish wide open over big passes. Temp would run 180-190 running down the highway with 900-1000 degree egt.
Going to a manual made a pretty big difference also.
Do you know any history on your a/c stuff. even a slight overcharge can cause crazy high condensor temps.....especially at 100 degrees.

Interesting. I know we all fight for bigger radiators and roaring big fans but what about water flow? I mean, we can have all the size and air we want but if were not moving enough liquid through it, its pointless.
I've thought about removing the stat and trying it, or at least modifying one to move more coolant, even if it required ruining the t stat just for experimenting

 

[vegas39]

Doing that may not help with this issue, but it sure won't hurt. I think that you should go ahead and get it working.

Did they say that it's towable with a half ton or say that it's safe to tow with a half ton? Is that at highway speeds or around town? I've seen (and heard) a lot of crazy things about towing, but I still believe that the bigger the load, the bigger the truck. Sure, half tons are rated at much higher towing capacity now then they were back in the IDI days. One thing that always gets me, though, is when somebody tows a big/heavy load with a light weight truck like a half ton. I feel that you need enough tow vehicle to at least have a chance of keeping everything under control if things go bad. My opinion is that a longer, heavier truck will keep the load under control better than a shorter, lighter one will. To me, towing is more than pulling and stopping the load.

Might fool with the kit again but I'll have to find an intake hat. Seems like I saw a company on the net selling them, similar to the one that Russ makes and sells on here.

The dealer I bought the trailer from said the trailer was rated for 1/2 ton truck but now that I've watched a few youtube vids, there are guys saying that its not safe in certain conditions. I dont wanna be on the edge of danger the whole time I'm driving.

 

[vegas39]

I will tell you one thing I found out pulling heavy loads in the heat. I was having heating problems also, changed everything, and it turned out to be the fan clutch. I mechanically locked the clutch with some little brackets I made. Problem gone for the most part. But pulling a heavy load up the mountain on a hot day, I can still get it hot. These engines have a lot of pull down in the low rpms, so I have a tendency to let it work down there in the lower rpms. I found out that is the wrong thing to do. Even with everything new and the locked fan, I can overheat it if I don't keep the rpms up. Once the gauge starts climbing, all I have to do is downshift and it stops climbing. My head of steam up the mountain is reduced some, but the overheating stops.

I would not let that computer on your E4OD do all the thinking. I would pull it down a gear or two manually and see if that helps it.

I can reach in and pop the spring out of its slot on the front of the fan clutch. It screams pretty loud going down the road, so I know its locked in good.
I tow with the o/d shut off and if I do hit a really steep hill, I'll pull the lever down and keep the rpm's up

 

[IDIBRONCO]

I've thought about removing the stat and trying it, or at least modifying one to move more coolant, even if it required ruining the t stat just for experimenting

That's not a good idea. From what I've seen others say on here, they have overheating issues after removing the thermostat. The coolant goes through the radiator too fast to completely remove enough heat.

 

[Black dawg]

That's not a good idea. From what I've seen others say on here, they have overheating issues after removing the thermostat. The coolant goes through the radiator too fast to completely remove enough heat.

So then, how would my truck run 230 deg sustained heavy load 1200 deg egt with no stat and by pass mostly blocked, vs 270+ with several different motorcraft/robertshaw t stats.

 

[IDIBRONCO]

I have no idea.

 

[Big Bart]

So many have replaced their radiator, so a big part of the equation is what radiator is being used? Two different radiators could have very different outcomes. Stick vs auto will also change the outcome. Then air temp and grade degree. Turbo vs non-turbo adds to the issue. So hard to compare apples with apples. So good for one truck and perhaps bad for another.

 

[Booyah45828]

Pulling the thermostat might work, so long as the bypass below it is sealed off with a freeze plug or something else. Another thing I haven't seen mentioned is shutting off coolant flow to the heater. That can also allow coolant to bypass the radiator.

 

[Black dawg]

Interesting. I know we all fight for bigger radiators and roaring big fans but what about water flow? I mean, we can have all the size and air we want but if were not moving enough liquid through it, its pointless.
I've thought about removing the stat and trying it, or at least modifying one to move more coolant, even if it required ruining the t stat just for experimenting

When running hot, stop and measure temp top tank vs bottom tank on radiator. When I first did this, with coolant temp above 260, lower tank temp was low 100 degrees, And this was in low 90 degree temps.

With no stat, temp drop through the radiator was still only 50 degrees (so at 220 coolant temp, lower tank temp would be 170.) . A local here, was having the typical 7.3 idi heating issues, and since he had the ability to build a pulley, I talked him into speeding up the fan/water pump (as an experiment). I never got to see it personally, but he said this cured his heating issues 100%.

The hotter you can get the radiator the better it will work.

 

[Black dawg]

Pulling the thermostat might work, so long as the bypass below it is sealed off with a freeze plug or something else. Another thing I haven't seen mentioned is shutting off coolant flow to the heater. That can also allow coolant to bypass the radiator.

Blocking coolant to the heater core helped mine too. I dont like having the bypass blocked completely though...especially with the heater hose shut off.

 

[Booyah45828]

You for sure don't want to block the heater hose and the thermostat bypass. That dead heads the system giving you no coolant circulation during warm up.

Have one or the other blocked, but not both. IMO I'd put a ball valve on the heater line, to block the heater flow and then leave the thermostat/bypass port normal. That would be the easiest solution. They make cable and vacuum operated valves as well, if you're concerned with needing to turn on the heat while driving.

If you've got an oe thermostat, it's a high flow model by design. As long as it's functioning correctly, pulling it and plugging the bypass will only gain you a little flow IMO.