7.3 idi F350 overheats while pulling

[crr31c]

Ok so this is my first diesel. 1988 F350 dually 7.3 idi C6 2WD 3.55 rear. Bought as a project. Built gassers and hot rods all my life so was wanted to try something new and needed a tow vehicle for my 32' double slide TT. about 8500 lb.

So here's the rub. Got about 500 miles on rebuilt engine and tranny. Reman IP and injectors. She'll run all day no problems can get up to 70 mph temp never gets above 165. Hook my trailer up, and i can do 55 no problem on the back roads, but too many hills or too much highway and she starts running hot. At 55 no EGT to speak of. I can get to 60 on the hwy temp gets to around 195-210. Exhaust temp 700. Anything above 60 and temp starts rising. On hills the egt's run up to about 1290-1325. If i push too long or hill is too long/steep temp starts climbing. Oh an fyi oil temp stays around 180-188 while pulling. Rotella T5 15w40 syn. Blend. New aluminum 4 core radiator. Please help. I have completely restored this truck but starting to wonder if it's going to meet my needs. Would hate to sell it. There is definitely an emotional attachment. But still need a tow vehicle. Any input welcome.

 

[The_Josh_Bear]

1150 is considered the safe high-side in the EGT range for towing/hills etc. One reason you have high coolant temps is because you're passing that threshold quite a bit.

Did you turn up the fuel on the IP? What's your timing at? Sounds like no turbo?
What kind of smoke do you have at those EGTs? High altitue?

There are many reasons any IDI might struggle with that load, and trying to push past 60 on a hill is one.

 

[crr31c]

She runs about 700 exhaust temp at 60 mph on flat interstate. Can't even get close to 60 on an incline. No turbo. Idk what the timing is. But is set to the mark at 2000 rpm by ferret meter as procedure states. No real smoke to speak of cruising on flat land at 60. Accelerating while pulling trailer is black at high egt's on hills black when i ease of on hills and lose speed-no smoke

 

[Kizer]

Do you hear/feel the fan clutch engage, or otherwise prove that it's working?

 

[YJMike92]

The first questions I have based upon your post.
Is the thermostat a Motorcraft unit? Is the fan shroud intact? What kind of shape is the fan clutch in?

 

[crr31c]

Motorcraft oe thermostat brand new. Fan clutch brand new. Fan shroud intact. Fan like a wind tunnel when the clutch engaged. So yes it's working. I guess my concern is that this is annoy all the old girl can do with out adding a GV overdrive and a turbo. Like i stated in my first post i can run 55 all day long. No problem and as long as i don't push to ******* hills I'm ok. But she does no better on hills than my 5.3 gasser suburban.

 

[YJMike92]

It sounds like you have all the bases covered, but something is not right. Since the engine is a fresh rebuild It's safe to assume the water pump is new.

 

[crr31c]

Yep new pump.

 

[YJMike92]

When she is starting to run warm that fan clutch is kicking in and doing the wind tunnel thing you described?

 

[YJMike92]

I'm no IDI expert but I don't think it should run hot under that kind of load. Maybe slow but not hot. Maybe some of the other guys will chime in.

 

[Oledirtypearl86]

I know you got a new water pump but to me sounds like a low circulation problem how does the inside of the radiator look

 

[Clb]

Explain the timing by ferrett!
Sounds like you used a standard non setback light???

 

[chillman88]

But she does no better on hills than my 5.3 gasser suburban.

Well regardless of the heating situation I have to point out that N/A she won't. Even the early 5.3 was rated at 270hp and 315lbs/ft whereas the early 7.3 was rated at 185hp and 338lbs/ft.

It will however get better mileage pulling that load. If you want it to pull better than that 5.3 you're going to need a turbo. That won't help your cooling issue though.

A couple things need to be asked here.

1. WHO rebuilt the injection pump, and was it built to specs for a Turbo 7.3? It could possibly be pushing too much fuel.

2. Where is your EGT probe located?

3. As CLB said, explain more on how the timing was set because if you don't know what it's set to how can we know it's correct?

Not out to give you a hard time, just need to cover all the bases.

 

[Black dawg]

Honestly sounds like the fuel is turned up, and engine is being worked too hard.

Can you hear the fan when it engages, I know you said it is moving air, but can you hear it in the cab when it engages?

Our 32 ft tt is right at 12k on the scales. Are you sure of the weight of yours?

 

[crr31c]

K. I am aware of the HP difference. I'm not looking for it to be the fastest truck up the hill. Just don't wanna be at 30 mph to keep the EGT's under 1200, and overheating. So my question-is this possible without a turbo and a GV overdrive. I'm about 7K deep into putting this truck back together. I love the truck, but just can't see putting another 6K into a turbo and a GV. Also runs about 2800 rpm on flat ground around 60mph pulling With the c6 that seems about right to me

Chillman88 as for your questions

A local diesel shop highly recommended by a few of my friends in the diesel community rebuilt the IP. I trust that.

EGT probe just past the #8 cylinder at the downturn on the exhaust manifold

I know what the timing was. Just couldn't remember the spec last night. It is set to 9.5 btdc at 2000 rpm with an advance light set to 2000