Hey guys, I'm new here from Ala-freakin-bama. I've never had a small trk with a diesel, always big trucks. So, I'm lost and wondering aimlessly in the dark about a truck I found. I'm hoping that you guys can steer me in the right direction here. Ok, I've found a 1989 Ford F350 4x4 with the 7.3 IDI motor in it. As if now it runs like a watch. I have read to where these motors are prone to "cavitation " which I'm not 100% sure of what this does to the motor. However, the truck only has 48k ORIGINAL miles on it. So, I don't know if the motor would be ok or not due to the age or if the "cavitation" will have ALREADY done the damage. Need help guys, thanks in advance.

Howdy and welcome. I'm out in NM, but really enjoyed my adventures in LA. ( I trust you'll get that)

Has the truck been maintained? If so, I wouldn't be afraid of it. I haven't seen an IDI have that particular problem, but I have seen cracked cylinder walls on those blocks. The one I have records on did it around 200k, some did it new, some never did. I think the cavitation thing was more of a Powerstroke thing. But, anything is possible, and that's just my experience.

Honest opinion, I'd jump on a low mileage 7.3 IDI, especially if it's turboed. Provided the truck is not a pile of rust draped over two frame rails.

Here's a picture of cavitation on a Cummins cylinder liner, an IDI is not a linered engine, but it's easier to photograph since it's out. To prevent this, if you get the truck, change the coolant, proper mix of green low silicate and distilled water, and use an additive, I prefer NAPACOOL. ( Available at Napa)

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cavitation is when the cylinder wall develop pinholes at the coolant passages. if it had it, you would know because it would not start due to the cylinder being full of coolant. and cavitation is more of a myth than a fact.
in 36 years, i have seen 2 cases.

as for the truck only having 48,000 miles on it, you can not believe it unless you are buying it from the original owner and you trust him.

the odometer on these trucks rolls back to zero at 99,999 miles.
my 88 only shows a little over 95,000 miles on the clock, but it has rolled back 4 times so it actually has a little over 495,000 miles on it.

In all my IDI's only trouble with the coolant system I have ever had was 1 head gasket. I Like the fat guy said, the speedo could have turned over, I have one here that shows 22,000 for the 5th time.

If it runs and starts good , I would buy it. If it only has 48 k on it the rest of the truck will reflect those kind of miles. I would believe 148k before 48k unless the owner can prove it. Hope it works out for you.

I have had a IDI cavitate. Sometimes they have wear behind the front cover and lose coolant.
As @Blue-Truck-Nut97 stated, flush the old coolant out, replace with Fleet Charge. It is pink and has the SCA's that you need. I buy and dilute 50/50 myself with distilled water. Gonna need about 4 gallons IIRC.


If you have coolant in oil, then also look to pull oil cooler and clean or replace as well as the o-rings on each end.

Hey guys, thanks for the input. I, however, made a slight misquote. Instead of it having 48k miles, it is 43k miles. Lol. The miles are correct. This truck was the "Brush truck" for the local , small town volunteer fire dept. It has a steel flatbed on it but the tank was removed. The owner is a firefighter at a paid station in the neighboring town and is a volunteer in the town where the truck was used. So, it actually did a lot of sitting. For the age, the he body is in real good condition, no rust, just a cpl dings here a nd there. The A/C wrks but leaks dwn and it is non turbo. The turbo would only add another 5 hp from what I've read. What are your thoughts, is it worth taking a chance on Or pass it by??

a fire truck. that makes a big difference.
what trans is in it, and what is he asking for it?

Not saying this one is , but a lot of truck like that are like the good old low miles farm trucks that people like to buy at auctions. In real life they lots of times they have been rode hard and put away wet. Meaning lots of pedal to the metal getting to the fire, out across the field low gears across ditches and such. Not trying to scare yo off, but a lot of these low miles trucks used like that are not that great. Just check it out .

Turbo wakes it right up. It will act like a totally different truck

I would buy the truck, and expect to put some money into soft parts. rubber lines, etc.