"T" engine to"M" swap

[shmoo]

My question is about the difficulty in replacing a 3.1 "M" in a 94 Century with a 3.1 "T" out of a 94 Lumina. My in-law's Buick has alot of water in the crankcase and have been told the motor's shot. I have access to a newly rebuilt T code motor out of a Lumina at a good price. Is this a fairly easy swap, or am I going to run into problems? All of the bolt-on parts on the Buick (intake, electrical etc.) are in fine shape.

[Zboy]

I'm not sure what vin code means what. Is the engine in the Century a 3100? If this is the case, I think a whole topend swap including heads will required. the mounts should be the same. The 3.1 has a problem withhead gaskets, and since a 3100 to 3.1 requires head gaskets, be sure the engine is indeed junk.

[GPXSS]

The 3.1 has a problem withhead gaskets...

Since when? I never once had a head gasket problem on my Vin T 3.1, and i've never heard that to be a problem.

The M engine is a 3100, T engine is a 3.1MPFI

This backwards swap will be kinda difficult because the ECM needs more sensors than the 3.1 has on it.. the fuel tables are also setup way different (intake manifolds are night and day between the 2 flow wise).

Now.. you can swap the 3100's plenum, heads(required), intake and such over to the 3.1 bottom end and have a hybrid (lots of people have had good results with this).. youll just need to keep the 3.1 oil pan and get a 3.1 Wbody front mount. You will also need to put the 3100's front cover and crank pulley on for the 24x sensor. What you will lose is the 2x or whatever Cam trigger, but it is not required to actually "run" the vehicle.

Overall its kindof a difficult swap but it is doable. Its certainly not something that will happen quickly, you will need to take your time and figure some stuff out since you will be the first person to effectively run a 3.1 on a 3100 ECM.

[Zboy]

[quote="GPX$$"]

The 3.1 has a problem withhead gaskets...

Since when?

Since they were built! 3.1s have a tendency to blow head gaskets around 80,000-100,000 miles. Now I'm not saying every single engine has this problem, but last spring I helped out at a friends shop and we ended up doing head gaskets on 6 3.1 GM cars. I'm not saying head gaskets are a huge problem with a 3.1, but the head gaskets are known to fail on these engines.

[RidgeRunner]

Well, head gaskets are known to fail on pretty much any engine.

[GPXSS]

Well, head gaskets are known to fail on pretty much any engine.

especially after 100,000 miles!

plus when you think of just how many 2.8's 3.1's and 3x00's were produced by GM and are on the road (2nd in production ONLY to the 5.7 family) you're gonna have a few of them go bad and show up in a garage somewhere.

I just dont think thats a fair statement about the 3.1.

a more appropriate one would be "3x00's have a problem with intake gaskets leaking coolant"

[Rhedalert]

Myself I've had 4 60 degree V6's and 3 more between my immediate family, 4 of 7 are over 130k never had a gasket fail. Now if you mention "you have 2 3100's in service" I start getting a little nervous ala intake gaskets

[Erich]

The Century engine has a weird setup only used in the A bodies. It is a MAF style 3100 similar to a 3300/3800.

[RebelGT]

the early 660's according to the v6 performance book had a problem with the head sealing because of the minimal amount of meat to the block and heads, this is because they were both designed to be as light as possible, this being the case they had a tendency to warp under high temps and cause leaks.