Funny how you make fun of the 3.0 but not only did it replace the poor 2.9 but it has more hp and torque, on paper and on the road. There's a reason why they stopped making the 2.9's obviously and that's why they used the 3.0 for how many years now? Oh from 1991-2008.. The 2.9 1986-1992... 17 years for the 3.0 and only 6 years for the 2.9. I can keep going if you want. There's plenty more stats comparing the two.
You said it yourself, "the 3.0 was used in a lot of stuff" where as the 2.9 was only used in the ranger.... Seems like they were scared to use it in anything else. Untapped potential doesn't matter, you can put a turbo on anything if you really wanted to. Once I get my truck fixed I will be ready to spank any 2.9 out there (if there is one running around here) haha.
So...
Cologne V4/V6 was NEVER intended, designed, or meant for RBVs, with the exception of the 4.0 and SOHC.
When Ford originally designed the Cologne V4, they essentially had no idea what to do with it. A few attempts were made to use it with industrial and agricultural equipment. Eventually the Cologne family was given to Ford Europe to figure out if it was applicable to vehicles.
First use was the Ford Taunus in 1964, and Saab Sonnet to replace Taunus's sidevalve I4 and Saab's 2 stroke nightmare.
The colognes had a TON of different forms and iterations. 1.8, 2.0, 2.3, 2.4, 2.6, 2.8, 2.9, and 4.0 were just the V6 engines. There was an entire series of V4 as well. Additionally, even though the Cologne engines went by the wayside with the advent of GDI, a lot of design characteristics unique to Colognes lives on in other engines, and the new Aston Martin Valkyrie V12 (1000hp engine coupled with 1000+hp electric drive) is essentially two modernized Cologne 2.9s with a common head.
For an engine Ford didn't know what to do with, they were overwhelmingly successful. At one point, the Cologne famiky turned into a contender for Group A and Group B rally. The 2.9 12v (German built Ranger engine) and the 2.9 cosworth were run up against the 2.3 Cosworth, and missed selection only by a narrow margin.
The reason I spew a bit of hate for the 4.0 is that they're a bastardization of the engine group. Colognes are a bit of a different animal; wide bore, short stroke, and TINY footprint, but with a decent punch. The 4.0 was taking a euro performance engine and turning it into a small truck motor - the 2.9 was the last of the sports / touring car engines.
Oh, and btw, as far as vehicles the 2.9 was used in, this is the list of vehicles for both forms (12v and 24v):
TVR S2/S3(C)/S4C
Ford Bronco II
Ford Ranger
Ford Sierra XR 4X4
Ford Granada
Ford Scorpio
Ford Transit
Merkur Scorpio
Panther Kallista
The reason most of the RBV 2.9s suffered head issues were the exhaust manifolds and poor maintainence by American owners. The RBV engines received a unique egr equipped version of the standard center-port exhaust manifolds. They hold extra heat, and combined with a coolant leak will warp the heads and in some cases, warp the block.
These are euro sports sedan engines, not truck motors. Keep them well lubricated with a high ZDDP oil, clean as f*ck, and toss the sh*tty exhaust manifolds on the scrap pile, and they'll live forever.
Didnt you use to drive a ford escort?
Aka Ford Sierra ?
Hmmmm those are the same reasons they stopped selling the 3.0 after the 2.3 duratec came out.
Because the 3.0 was the American attempt of "refining" the 2.9 into a bloated, cast iron paperweight that's even fussier on maintainence due to a sh*tty head design.