1988 F350 - 7.3 Navistar vs. 6.9 Navistar?

[sunstardude]

I'm looking at buying a 1988 Ford F350 4x4 crew cab with a 7.3 diesel for $3000. Would this most likely be a Navistar IDI engine? Is this a good engine? Is it as good as the old 6.9 Navistar IDI engine? How does the 7.3 compare to the 6.9? Any major reasons to stay away from this 7.3?

Thanks!

[bockhold]

it is a navistar engine and is better than the 6.9. 7.3 has more power.

[coletrain777]

It does have a little more power than the 6.9 due to the larger displacement, but the larger displacement comes at a cost. The 7.3 has more displacement due to a larger cylinder bore, this means thinner cylinder walls. Diesel engines can can suffer from something called "cavitation" if not treated with SCA's (coolant additive) that helps prevent this. Cavitation is a kind of "eating away" of the cylinder walls, so the 7.3 can be more prone to cavitation problems if not treated with SCA's due to their thinner cylinder walls. All this said, they are great engines! Get one in good shape, treat it right, and it will treat you right.

[mankypro]

As mentioned earlier they're the same block, there were supposedly some changes in the oil galleries and coolant gallery castings as well.

In most circles you'll hear that the 6.9 is more of a workhorse because it's simply heavier and able to withstand more heat/pressure. Well cared for either engine should be a tremendous asset.

I'd at minimum have it compression tested. If not that at least look for leaks and check for blowby on a hot engine.