Ford diesel mechanics ???

[Harter66]

I have an 89' F350 bone stock 196k . Rolling along hit a long pull it got hot but cooled out . Next pull it got really hot and wouldn't cool out , got stopped let it cool filled it back up with water , no leaks , no bad stuff . Take off again and running flat ground it's ok but it heats on the slightest hill .........
So in the last 150 miles I've changed the thermostat , lower hose , water pump and lost about 6 gallons of water coolant . With the new water pump it looks like 45 mph and no hills might be a thing ........ I've got 900 miles to go 825 on I40 to get where I'm going .

Is a radiator going to fix it . Could a radiator go from a note temp rise to full blown heat at moderate load in 1000 miles ? Gas typically won't but will a diesel ?

[Handloader109]

HMMM. Do you see any water in your oil? There was an issue with the Powerstrokes and thin wall between water channel and oil. I thought it was in the '95-96+ age range, but might be mistaken.
You say you are losing water, where is it going? just boilover? maybe radiator is stopped up, hard to tell. When hot, put your hand on the radiator. Are there cold spots? or hot all over the face of the radiator?
If some spots way cooler, then probably stopped up.

[Houndog]

Sounds like a blown head gasket or a cracked head to me. Some of the 6+ liter engines are real bad for that. I hope not for your sake! BIG $$$$ if you have to buy heads!

[Hannibal]

Is it this a 7.3 or a 6.9? As I recall, some of those had 2 thermostats, but maybe I've slept too many times since I last owned one . . . .

[Brassduck]

check the fan, should turn easy when cold and hard when hot? may need a new fan drive. good luck

[Harter66]

All the water and oil are separated correctly . No bubbles or glups in the radiator . Just a straight up failure to cool .
Not a power stroke.
7.3 commercial 12,000 mgvw . 5 row , 4 gallon radiator .

Hot on the inlet side about 4-6" wide luke warm about 8×16 of the 23" radiator on the outlet side while the cap is venting .

The truck ran 5 k new to me then this just bang out of the blue .

[Hannibal]

Ok, I'm *not certain about your particular model*, but some had an upper and a lower thermostat. The purpose of the lower thermostat was to allow some of the coolant to bypass the radiator, thus allowing for a faster warm-up.

I don't want to send you 'off in the tall grass', but you might want to check into it and find out if your truck is so equipped. It would certainly explain what you are seeing.

[Dieselhorses]

This reminds me when I owned my 87 F250 which already had 450K miles on it (6.9 Navistar). Someone musta been taking care of it! I could literally pull a small house with it! Anyway, about 10 years ago (and another 100k miles-550K total) when I was between wives, I was driving to gf's house about 80 miles away when temp needle soared to the max and I had to pull over on an exit in front of Waffle house. Smoke was pouring out so heck I called the fire dept. thinking that something was burning. They took a reading with one of them fancy digital thermometer guns and it read 648 degrees! Had it towed to the house. Next morning, it cranked right up, didn't miss, didn't smoke, oil and water level was fine, no water in oil and vice versa. Don't understand, I checked everything. I ended up selling it for what I paid used for it. I like diesel anything and I loved that Ford for that year but you couldn't give me another Ford these days.

[Tatume]

My 1999 7.3L Turbodiesel F250 requires a periodic additive to the coolant. The coolant prevents a bubble forming on top of the cylinder head and causing a hot spot.

[jimlj]

I'm no diesel mechanic, but I have worked on quite a few company and personal diesels. On the Cat and Cummins engines I have worked on I was told to use only Cat or Cummins thermostats. A 3208 Cat engine in a bucket truck I had was heating up and I thought I'd use a couple parts store thermostats. It was worse after the Napa thermostats than before. I ordered genuine Caterpillar thermostats for about 5 times the price and never had any more trouble. Is the thermostat you used Motorcraft or Navistar (International) brand? In my experience any extra cost over a parts store thermostat for the engine manufacturer thermostat is money well spent.

[NyFirefighter357]

https://www.thedieselstop.com/forums/f30/urgent-7-3l-idi-overheating-421610/

I say check the fan clutch and hose off the the radiator. The aluminum radiators clog easily too. I only see one thermostat but I see several aftermarket thermostatic fan control switches which come with a preset or an adjustable setting, this could be the problem as it seems to get a lot of aftermarket attention.

[sigep1764]

Might have to check the water pump, make sure the impeller is still turning. Ive had impellers spin off or shear blades before.

[rancher1913]

if it only does it on hill climbs, I would look at a bad tranny cooler being the problem.

[jj850]

I had a similar problem with a newer F750 and a cummins engine. Every things fine until you had to pull a hill. In my case it was the fan clutch.

[Harter66]

Appearently it was the radiator . Million miles in mostly 10+ yo trucks an cars . Never had a radiator go from warm on a hill cool out on the crest to full boil out in 16 miles from a cold start in 300 miles an 72 hr .

[Hannibal]

Well, glad to hear you're back on the road. Always worry about problems on long trips myself. I drive older stuff, too. I'm sure it's not a matter of if, just when.

[Harter66]

I'm getting pretty fast with getting the accessories off an on .....