# 7.3 Overheating



## DGODGR (Nov 30, 2008)

I have done some searching here and there is a lot of threads on this. I am posting because I think my situation is a bit different from those I have read about. For the first time this year my 2000 F350 has over heated. It happened three times in 2 days. I mounted the plow (Western 8' straight) last year before plowing season. I had no problems with over heating last year. I would drive with the plow up and it didn't seem to matter if it was straight or angled. This year has been different (see above). Each time I had to put 2.5 to 4 gallons of coolant back in to top it off. The first time it boiled I was pulling my skid steer and the plow was mounted on the front. The load on the trailer was about 10k# and I was driving at 60 MPH. The road to town is up hill but not very steep. I would guess about 2-3%. I was watching the temp gauge for a lot of the way. It was probably 1-2 minutes from the last time I looked at the gauge and I saw steam coming out from under the hood. The temp gauge was pegged!. After cool down and refill of coolant I continued on my way. I did some plowing (using both truck and skid) and then loaded up to go to the next site. A steep, slow climb and it boiled again. At this point I'm thinking it's too much load for the truck if it has the plow up front. The next morning I had a job to clean up and drove into town (same drive as the first boil over). This time I had just the truck, with plow, but no trailer. As I said before it has never boiled like this before. This time it over heated but it did not boil. When I saw the gauge I slowed, dropped the plow as close as I could to the ground, and it did not cool down. Once it cooled I was able to drive, without incident, but I had the plow close to the ground while transporting. This all sounds like most stuff I read, and all pointed to the plow as the source of the trouble. I am still left to wonder why my truck never had this problem until now. Any ideas?
Let me give some background on the vehicle in question:
2000 F350, 7.3 PSD, auto trans, SRW, no snow plow pkg.
Bought new, now has 250,000 miles.
Recently replaced the thermostat, water pump, coolant, fan clutch, upper hose, and belt.
Replaced about a month ago and was due to coolant coming from the WP weep hole.
Parts were obtained from NAPA.


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## Rick547 (Oct 9, 2009)

Put the old thermostat back in and see if you still have the problem.


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## Milwaukee (Dec 28, 2007)

Time to pull radiator and clean them REALLY GOOD.










On thermostat IT IMPORTANT TO USE MOTORCRAFT. I don't care if you claim new thermostat. Aftermarktet thermostat had proof it fail many times I had.

On other subject do you hear fan running? When you are close to overheat. Pop hood and look at fan does it spin HARD sound like airplane at idle? Could be bad fan clutch not lock.


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## DGODGR (Nov 30, 2008)

Rick547;1420113 said:


> Put the old thermostat back in and see if you still have the problem.


I have a new t-stat that I intend to put in tomorrow.



Milwaukee;142021 said:


> Time to pull radiator and clean them REALLY GOOD.
> 
> 
> 
> ...


I will look at the radiator tomorrow. Which side is exposed in your photo? Is that between the radiator and intercooler? Maybe I will buy a Motorcraft t-stat. I have been suspicious of NAPA parts for a while.


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## Milwaukee (Dec 28, 2007)

That picture come from google search.

It coolant radiator for 7.3L. Pull that out and power wash them plus put water hose in radiator to flush any dirt out it. It got me about 30 mins of rinse/flush in radiator. Tons of brown crap come out. It feel like sand something.

It best to use ELC Red coolant. They supposed to be cooler and protect cavitation on diesel.


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## DGODGR (Nov 30, 2008)

Milwaukee;1420221 said:


> On other subject do you hear fan running? When you are close to overheat. Pop hood and look at fan does it spin HARD sound like airplane at idle? Could be bad fan clutch not lock.


Per my first post I just replaced it too (the fan clutch). I have heard it running but not each time it overheated. At first I suspected the fan clutch because of this. I have since heard it come on so I now think that the blocked air flow prevented the fan clutch from functioning correctly. IMO the heated air (air is heated after going through the radiator) is getting blocked enough that it can not get the fan clutch hot enough to engage.


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## DGODGR (Nov 30, 2008)

Milwaukee;1420324 said:


> That picture come from google search.
> 
> It coolant radiator for 7.3L. Pull that out and power wash them plus put water hose in radiator to flush any dirt out it. It got me about 30 mins of rinse/flush in radiator. Tons of brown crap come out. It feel like sand something.
> 
> It best to use ELC Red coolant. They supposed to be cooler and protect cavitation on diesel.


I may go to the ELC since I have it in all my Cat equipment. When I replaced the pump, etc, the coolant was still nice and green. No corrosion was evident either.


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## kimber750 (Sep 19, 2011)

Check your tranny fluid, see if it has a burnt smell to it. This could be the early sign of an upcoming failure.


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## Milwaukee (Dec 28, 2007)

That not matter. Coolant come out were GREEN.

Put water hose in radiator and shake radiator and brown crap will coming out.

Mine had 220K miles.


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## broncscott (Dec 9, 2007)

Make sure the thermostat is not in backwards


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## DGODGR (Nov 30, 2008)

broncscott;1420590 said:


> Make sure the thermostat is not in backwards


Umm, OK.....Which way is forward? When I put it in last time I placed it in the housing with the spring down. I suppose could put it in with the spring to the top but that would make it so it was protruding into the steel bend/tube and not in the housing. I guess this could be correct but it would be the first time I have ever seen one placed with the spring up.


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## dieselss (Jan 3, 2008)

ok,,you def. have a cooling problem...i have a 03 7.3 and never had this thing overheat!!!!! last years blizzard we had,,,the entire front of my condersor was full,,,truck ran at 190. now,,,when was the last time you FLUSHED your cooling system. i mean pulled all the hoses,,garden hose through them all??? i was surprised at the crap that came outta mine this year,,brown nasty stuff... 
the other question that im thinking is....did all this happen since you did all the cooling stuff???


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## clydebusa (Jul 10, 2010)

All could be true but pulling 10k with plow on the front running 60 imo is too much even if it doesn't get hot.


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## oldmankent (Mar 2, 2001)

I don't know about the Super Duty's for sure. But, with my old OBS truck there were two thermostats that would fit in the truck. But one was either too long or too short. Can't remember which. I would definitely only use a Motorcraft thermostat and make sure you have the correct one. Wouldn't hurt to clean the radiator like suggested. Especially with that many mile. My truck never ever overheated once the 12 years I owned it.


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## dieselss (Jan 3, 2008)

should go to dieselsite.com and get the one there.


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## tjctransport (Nov 22, 2008)

get a thermostat from ford or international and your problems will go away. there is something about parts store thermostats and navastar diesel engines that don't go together. 
i have seen stant t-stats put in navastar diesels that overheat instantly, pull it out and put a ford or international stat in it and it works perfectly

as for installing it, the stub goes into the engine, the flat side goes to the radiator.


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## DGODGR (Nov 30, 2008)

dieselss;1421258 said:


> ok,,you def. have a cooling problem...i have a 03 7.3 and never had this thing overheat!!!!! last years blizzard we had,,,the entire front of my condersor was full,,,truck ran at 190. now,,,when was the last time you FLUSHED your cooling system. i mean pulled all the hoses,,garden hose through them all??? i was surprised at the crap that came outta mine this year,,brown nasty stuff...
> the other question that im thinking is....did all this happen since you did all the cooling stuff???


Yes. My problems have all surfaced after I replaced all those components.


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## dieselss (Jan 3, 2008)

Ah ha!!!! I'll bet dollars to deniro that you had an air pocket in the system that never got out. --short story. I had a 01 at the dealer that took 2 days to bleed.... Refill system run truck with cap off,,,,turn heat on.....might take 15 mins to and hour to get all air outta system. If you want you can get whats called a spill free funnel to help with this. I would also think about a different t-stat as well. As was stated before,,2 different ones,,long and short. You need the short 203 one.


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## DGODGR (Nov 30, 2008)

The truck has had several hundred miles, probably over a thousand, between the components R&R and the heating issues. The coolant level in the resevoir never went down. I would think that the engine running that much would have forced any air from the system. I also suspect that any air pocket would cause problems even without the plow being mounted.


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## dieselss (Jan 3, 2008)

Proballly correct....only thing I'm thinking is clogged tad, internally and ext. Or t-stat went south


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## DGODGR (Nov 30, 2008)

OK. I replaced the t-stat today. I went to Ford and got a Motorcraft unit. I am also suspecting the flush is wrranted too. I will see how it does with the new t-sat first but I have found evidence that maybe the brown stuff you guys are mentionig is present too. Does that stuff smear, kinda like grease, when you touch it?


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## dieselss (Jan 3, 2008)

the junk in the bottom of the rad???
when i did my "flush" i got alot outta the lower rad hoses.
do you best and flush out the degas bottle too. lotta junk get collected in there as well.


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## DGODGR (Nov 30, 2008)

The Degas bottle is mostly clean. It had a few spots near the cap (about 1 MM dia) which is partly why I'm a bit suspicious that the radiator might have crud in it..


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## dieselss (Jan 3, 2008)

if you didnt flush it,,i think that would help,,,and flust the heater core as well.
was the new t-stat a long one of short??? just wondering


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## DGODGR (Nov 30, 2008)

I don't know which one it is. The box is labeled:
RT-1201
F6TZ-8575-EA
On the t-stat it says Whaler (the MFR?) and 89 deg. celsius.
It seemed to be the same size as the one I removed, and that one seemed identical to the original one I removed at that time.


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## dieselss (Jan 3, 2008)

Ok there are 2 for the 7.3 a long and short. The long one blocks the heater core intake at the t-stat housing. If you ck out dieselsite.com it explains all about them.


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## damian (Jan 29, 2009)

stop,dont do any more swapping. is your back pressure device stuck partially closed, when the truck is at 195-200 is the full radiator warm,upper and lower hoses close in temp showing flow,one cool,one hot no flow.do you hear the fan clutch engaged fan working making noise at rpm.an infra red heat gun is handy for this type of troubleshooting.i agree the radiator should be checked for external blockage,leaves wood chips etc. aftermarket t-stats and fan clutches are often suspect.


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## DGODGR (Nov 30, 2008)

I noticed that the condensor has many bent "fins". Enough of them that I think the air is some what restricted. At this time I do not want to bare the expense of a new condensor, so it will have to do for now. Today I pulled the radiator and checked to see how much crud may be blocking it. I did not see much on the front. It was not nearly as bad as the picture posted earlier in this thread. Once I removed the radiator I could see lots of crud stuck inside. There was a lot of weed seeds, grass, bugs, feathers and what seemed like hair. It took me a couple hours, of water and compressed air, to get it mostly clean. I still can see some crud in there but it is much cleaner than before. I got enough crud removed that I think the radiator will cool much more effectively.


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## Milwaukee (Dec 28, 2007)

Hope that fix issues.

That why I did mine because I suspect fan stay SPIN you could hear airplane at idle.

Got me about 1 hour of power washer and rinse those fin.


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