I have a 1983 F350 6.9l 4speed in need of a new motor and would like to get another 6.9l. I found a truck for sale on craigslist, 1986 with what the guy says is a 6.9l in it but I am not sure. I am wondering if there is anything visually I can use to tell the difference between the two engines when I go to see this new vehicle. From the pictures I can tell that the engine oil fill is different from the one on my 6.9 which comes off the fuel pump housing straight up. The one on this new engine comes off the fuel pump housing at a slant like alot of the 7.3 I have seen but I dont know if that means its has to be a 7.3. Why I am worried about this is that the tranny is out in the truck I am wanting to buy and the current owner says that the motor is a rebuilt one and I am afraid he put a 7.3 in there instead of the 6.9 it was supposed to have and it wont work with the 4speed

 

All of the transmissions from any IDI will bolt up to any other IDI so that's not an issue.

You could look at the label on the valve cover and hope the valve cover wasn't switched out some time in the past. Possible, but not likely.

 

I'm not sure, but I think the block is the same, so the 7.3 will work with the four speed. Some 6.9's had the new style filler neck pump gear covers so that is not a tell tale sign. The best way I know to be sure is the casting number. There is a thread on here that tells you how to interpret it. One thing for sure, is that all 6.9's have 7/16ths head bolts and all 7.3's have 1/2" head bolts, so I would think that if you took a socket that fit your head bolts. (some are outside the valve covers, so no need to remove anything) if it didn't fit the head bolts on the other motor then it is a 7.3. I am assuming, of course, that the bolt head would be bigger on the bigger bolt, but I am not certain.

Let us know,

Mac.

 

the engine displacment is stamped on the block on the drivers side of the injection pump housing foreward of the valley pan

 

Well I'll be dipped! There ya go! Learned sumptin new today!

 

Awesome, thanks everyone

 

You can bring 2, 12 point sockets and try 'em on a head bolt. That's the only sure tell way of telling 'em apart.

6.9 is 7/16 and 7.3 is 1/2.


83-86 6.9 had the old screw in head glow plug controller at the back of the drivers side head, and the old straight up oil filler.

87 6.9 looked exactly like a 7.3. Same oil fill, and same updated glow plug system.

 

Me too, and he's right. Just checked mine and under all the gunk and grime was 6.9D then a long series of numbers.

Good info to know!