That's crazy. Really opposite of what I've seen. On the 6.9 - EGT's are certainly directly correlated with my coolant temp. No sure why your rig is opposite of that. Kind of a head scratcher.
What are your coolant temps doing/running?
Heath
Gt3788 guys... a question
- Thread starter laserjock
- Start date
What are your coolant temps doing/running?
Heath
Ok, let’s take what causes the overheat out of the equation, and look at the differences in the trucks themselves.
1st. Heath has a 6.9, Mike and Elisha (sorry if I spelled your name wrong), have 7.3’s, not sure about @tjsea truck. But, the 6.9’s seem to run cooler when turned up, due to the open coolant passages.
All the trucks have an aluminum radiator, correct? If so, I would think that would be a “push”.....
All trucks are have a CAC, correct? But, they are executed differently. Elisha’s is not in the cooling stack, it how much of the radiator is the CAC covering on the other trucks? I know the hypermax style is low I. The front, and only covers part of the radiator. But a 6.0 style covers the entire radiator...... bigger CAC, less air flow, and more of the radiator is subjected to the CAC heat.......
Heaths’ truck is a Bull, but yours and Elisha’s are bricks. Again, not sure about @tjsea, but what about the grille or other differences in the front. Could a stock grille and bumper be blocking enough of the air flow that it could make a difference?
What about other little things? Things like the cowl seal, or under hood blanket, or body line gaps? Maybe these little, seemingly insignificant things can make one truck “leak” more air, allowing a bit of extra air flow?
Could even the trailer type come into play? Heath has a 5er... and you have a bumper pull, and Elisha was empty...... Airflow can do strange things?
Try and think of any other things that mignt not seem to matter..... I know this may seem odd, but I’ve figured many things out by analyzing it like this.....
Too bad we couldn’t get a 4 trucks in the same place, and do something like the comparison videos of moving the same load on the same course.....
1st. Heath has a 6.9, Mike and Elisha (sorry if I spelled your name wrong), have 7.3’s, not sure about @tjsea truck. But, the 6.9’s seem to run cooler when turned up, due to the open coolant passages.
All the trucks have an aluminum radiator, correct? If so, I would think that would be a “push”.....
All trucks are have a CAC, correct? But, they are executed differently. Elisha’s is not in the cooling stack, it how much of the radiator is the CAC covering on the other trucks? I know the hypermax style is low I. The front, and only covers part of the radiator. But a 6.0 style covers the entire radiator...... bigger CAC, less air flow, and more of the radiator is subjected to the CAC heat.......
Heaths’ truck is a Bull, but yours and Elisha’s are bricks. Again, not sure about @tjsea, but what about the grille or other differences in the front. Could a stock grille and bumper be blocking enough of the air flow that it could make a difference?
What about other little things? Things like the cowl seal, or under hood blanket, or body line gaps? Maybe these little, seemingly insignificant things can make one truck “leak” more air, allowing a bit of extra air flow?
Could even the trailer type come into play? Heath has a 5er... and you have a bumper pull, and Elisha was empty...... Airflow can do strange things?
Try and think of any other things that mignt not seem to matter..... I know this may seem odd, but I’ve figured many things out by analyzing it like this.....
Too bad we couldn’t get a 4 trucks in the same place, and do something like the comparison videos of moving the same load on the same course.....
hoodshauler
Full Access Member
I agree with this analysis. Air flow can make a big difference. Also the weight of what your towing plays a big factor
@lazerjock what are your temps when towing? I didn’t see it mentioned.
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Heath, according to my auto meter electric gauge, I’m pushing 240-245 and at that point I’m trying to back off which looses boost and up go egts.
I’m glad to hear you say that behavior is ass backwards. That confirms most of what I’ve read.
So I have a cx racing IC0022 with a new AC condenser behind it and a new 3 core champion rad behind it. I also have the psd OBS cutout in my bumper to help air flow.
I’m really torn on the fan clutch. I swear I’ve never “heard” it. Everyone swears you will. It’s a brand new motor craft clutch. Brand new motor craft thermostat.
Most of the time pushing the truck on flat and rolling hills with the camper (70-75 mph) I see 210-225. Outside temp and the AC make a big difference. In the spring going over I-68 it was way more manageable. I think I had the ac on but it was in the 70’s more than the 90’s.
The RPM piece has to be important. That’s what’s different about my truck from everyone else it seems. Maybe the WP is cavitating at RPM and it’s not flowing as well which would cause heating. It’s also a NOS motor craft water pump. Too much resistance to flow would mean that regardless of the rpm,it’s not flowing enough.
You know, setting here reading what I typed, it just about has to be a flow problem. Here’s the other bit. It cools very quickly once you let off meaning the radiator isn’t heat soaked. If the radiators not hot, the fan clutch won’t come on. It almost has to be a flow problem. Now the question, do I pull the thermostat or bypass part of the coolant around it...
I’m glad to hear you say that behavior is ass backwards. That confirms most of what I’ve read.
So I have a cx racing IC0022 with a new AC condenser behind it and a new 3 core champion rad behind it. I also have the psd OBS cutout in my bumper to help air flow.
I’m really torn on the fan clutch. I swear I’ve never “heard” it. Everyone swears you will. It’s a brand new motor craft clutch. Brand new motor craft thermostat.
Most of the time pushing the truck on flat and rolling hills with the camper (70-75 mph) I see 210-225. Outside temp and the AC make a big difference. In the spring going over I-68 it was way more manageable. I think I had the ac on but it was in the 70’s more than the 90’s.
The RPM piece has to be important. That’s what’s different about my truck from everyone else it seems. Maybe the WP is cavitating at RPM and it’s not flowing as well which would cause heating. It’s also a NOS motor craft water pump. Too much resistance to flow would mean that regardless of the rpm,it’s not flowing enough.
You know, setting here reading what I typed, it just about has to be a flow problem. Here’s the other bit. It cools very quickly once you let off meaning the radiator isn’t heat soaked. If the radiators not hot, the fan clutch won’t come on. It almost has to be a flow problem. Now the question, do I pull the thermostat or bypass part of the coolant around it...
The coolant plugs in the head and block are most likely the biggest restriction to flow in the cooling system, after removing them I can run the shop truck with no fan in 100 degree heat no problem as long as I’m empty, I’m working on an electric fan setup to go on but I’ve been really impressed by the difference the plugs make.
Now obviously no way of fixing that, so I wonder if pulling one of the rear cylinder head coolant plugs out of each head and running a crossover would help? I think I remember that’s a common mod on the psds, can’t remwber if it’s the 6.0 or 7.3
Now obviously no way of fixing that, so I wonder if pulling one of the rear cylinder head coolant plugs out of each head and running a crossover would help? I think I remember that’s a common mod on the psds, can’t remwber if it’s the 6.0 or 7.3
My 6.9 has a 7.3 PSD intercooler. It is in front of the A/C condenser, which is in front of the Rodney Red. So the order is IC, AC, radiator. I had to move the radiator and AC condenser back toward the engine 1.5 inches to have room for the IC. Don't know if that helps or not, but did not see a real change in coolant temps before/after the IC.
I did block all gaps that would allow air to bypass the cooling stack. That I think was a big help in keeping proper airflow through all the coolers.
The PSD intercooler covers the lower 2/3rds of the radiator (at least).
I see a typical max temp of 209-210 while hauling the camper. I did get a little bit higher while pulling over the mountains coming to PA in 2016. The fifth wheel is 32 foot and is about 9-10K ready to camp. The truck and camper on the scales was just under 17K.
I typically try and keep the RPM between 2200-3000 while hauling. ZF5 (460 version) and US gear underdrive to help split gears when needed. If I get below 2200 for long, the EGT's will climb.
Heath
I did block all gaps that would allow air to bypass the cooling stack. That I think was a big help in keeping proper airflow through all the coolers.
The PSD intercooler covers the lower 2/3rds of the radiator (at least).
I see a typical max temp of 209-210 while hauling the camper. I did get a little bit higher while pulling over the mountains coming to PA in 2016. The fifth wheel is 32 foot and is about 9-10K ready to camp. The truck and camper on the scales was just under 17K.
I typically try and keep the RPM between 2200-3000 while hauling. ZF5 (460 version) and US gear underdrive to help split gears when needed. If I get below 2200 for long, the EGT's will climb.
Heath
I think the key here is that the fan clutch isn’t coming on. I know I could have gotten a bad one out of the box but that doesn’t seem all that likely.
My rig is 12.5k ish loaded up all together. It’s really frustrating because I don’t feel like the truck is working that hard. If it were balls out screaming for mercy and the temps were up there I could understand. I think I’m going to look for a port to put in the top radiator hose and bypass part of the coolant. The way I’m plumbed, my turbo water comes from the driver head. The heater core from the Pass. It all comes together and runs back to the WP. I may plug that port in the WP and dump that water back to the top rad hose and give that a go. It will cause it to heat up slower, but I don’t drive it in the winter. I could even put a diverter valve on a temp switch as a permanent solution if this solves the problem.
My rig is 12.5k ish loaded up all together. It’s really frustrating because I don’t feel like the truck is working that hard. If it were balls out screaming for mercy and the temps were up there I could understand. I think I’m going to look for a port to put in the top radiator hose and bypass part of the coolant. The way I’m plumbed, my turbo water comes from the driver head. The heater core from the Pass. It all comes together and runs back to the WP. I may plug that port in the WP and dump that water back to the top rad hose and give that a go. It will cause it to heat up slower, but I don’t drive it in the winter. I could even put a diverter valve on a temp switch as a permanent solution if this solves the problem.
I have a motorcraft fan clutch that was on my 7.3 you can have. I thought it was bad after doing my water pump and bought a new one irritated after the truck overheated with the ac on idling [went up to 220/230] but was totally fine going down the road.
The next morning I realized while installing it that I didnt put the fan shroud back on. ******* moment. But the old clutch is probably fine, never overheated once before the water pump died etc. Just sitting in a box if you want to test it.
The next morning I realized while installing it that I didnt put the fan shroud back on. ******* moment. But the old clutch is probably fine, never overheated once before the water pump died etc. Just sitting in a box if you want to test it.
austin92
Full Access Member
Has anyone tired something’s like royal purple ice in the coolant? What about running coolant through the heater core first, then through an aux cooler, then into the turbo? You could even add a small fan to it if needed? I don’t have experience but these are things I’d try
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Dirtleg
Full Access Member
Mike I can't let go of the idea that perhaps your water pump impeller may not be in great shape and is incapable of pumping properly at higher rpms. Therr was mention of cavitation earlier in this thread and when you described what conditions it ran hot under that seemed like it could be your issue. A bad impeller can do that.
Whatever it is I hope you get it sorted soon.
Whatever it is I hope you get it sorted soon.
i would start with the fan clutch. it is a tough comparison. i have one less cooler in the stack and i did use 6.9 gaskets with the plug drilled out. i am also not towing a camper but do have some good weight on the truck and am working it harder then if it were empty.
The_Josh_Bear
Full Access Member
I agree on both the fan clutch and impeller as next steps to test.
Test the radiator "Delta T" first to check flow. Use a temp gun on upper and lower rad hoses after you drive somewhere(t stat needs to be open). The difference should be about 15*. If its 9* or 5* or whatever you have a significant flow problem, then can hunt down the cause. If'n it's fine, then:
Test the fan clutch: Take a piece of cardboard and block off the radiator but cut a hole where the fan clutch is and run it. If the fan doesn't come on you have at least one problem.
FWIW, dont think *any* turbo would add the kind of heat to your system you're worried about.
Test the radiator "Delta T" first to check flow. Use a temp gun on upper and lower rad hoses after you drive somewhere(t stat needs to be open). The difference should be about 15*. If its 9* or 5* or whatever you have a significant flow problem, then can hunt down the cause. If'n it's fine, then:
Test the fan clutch: Take a piece of cardboard and block off the radiator but cut a hole where the fan clutch is and run it. If the fan doesn't come on you have at least one problem.
FWIW, dont think *any* turbo would add the kind of heat to your system you're worried about.
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Perhaps it would be worthwhile creating a little schematic illustrating the flow path of your coolant to determine if there's an issue regarding how it's plumbed.
pafixitman
Registered User
Just pull out all of your gauges. Problem solved - Ignorance is bliss. 
You win Joe!!!Just pull out all of your gauges. Problem solved - Ignorance is bliss.
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