'94 Buick 3100 to '98 Lumina w/ bad 3100

[bigj-dog]

Hi, this is probably a no brainer for you guys, but I've got a '98 lumina with a 3100 that snapped the camshaft. I just happen to have a '94 Century (M code) with a 3100 that has pretty low mileage and I was wondering if it's worth swapping in, or should I just get a junkyard engine instead. I bought the Century for $350 and it'd cost anywhere from 400-600 to buy a used correct year 3100. Thanks for reading. bigj-dog - the newbie

[bszopi]

With the exception of maybe a few sensors (which could be swapped from the old motor), it should be a direct swap. You might have to use the plenum and definately the TB from the Lumina, due to the Century being a "unique" 3100, as it didn't have a MAP and the MAF was built into the TB. But other than just a little parts swapping, you should be good to go.

[bigj-dog]

That's what I was hoping to hear. I was planning on changing both upper and lower intake manifolds to update the gaskets anyway. I did notice a couple of little things. The '94's timing cover has an extra bolt hole in front of the a/c compressor, and the rear head also has an extra sensor, what should I do with that? I was planning on switching the balancer from the '98 to the '94 (because the '94's is all rusty) and all the sensors (except the cps from the timing cover). I appreciate the quick response. I have been posting in automotiveforums.com for years and just happened on to your site this morning. Too bad, since almost all my work in on 3.1Ls.

[bszopi]

When I swapped in a 3400 into my 94, I had to change the timing cover due to the different mounting bosses. If the extra hole isn't needed and everything else clears (there was a boss that stuck out further and interferred with something... it's been too long to remember what now), I'd just use the 94 cover. But its fairly simple to swap front covers, so it wouldn't be a waste to put the 98 on.

The extra sensor in the rear head is taken care of via a 3-wire sensor in the lower intake manifold. It is the temp sensor for the gauges, but was incorporated into the temp sensor for the PCM (hence the 3 wires) in 96 IIRC. Just leave the sensor in there to keep the hole plugged up (or find an insert to plug it), then use the 3-wire sensor from the 98 and you're good to go.

[1bad93z24]

THE 98 has roller rockers but just a few horse power no difference your are gona see i cant rember any more its been awle

[bigj-dog]

The swap is almost complete, I'm left with just one problem. In my haste, I didn't notice that the oil pan from the '98 had a low oil sensor in it, and the '94 doesn't. I haven't looked at it too hard, but does anyone know if you can knock out the boss and install the sensor, or do I have to switch pans? FYI, you are correct about the roller rockers, the heads are a little different because of them, but the lower intakes are the same for both engines. I ended up just swapping the timing covers, too bad I was too fish-eyed to notice the oil pan difference before I put the engine back in the car. Thank you guys a ton for your help.

[1bad93z24]

ya that happens to the best of us . you should be able to swap tthe oil pan in the car ive done them b4 i dont know about knocking the boss out that is a stamped oil pan and it may crack

[bigj-dog]

That's what I'll do then. I'm gonna start it and test drive it first though, to make sure there's no other problems. It should run w/out that sensor, right?

[bszopi]

Swapping the oil pan of a 3.1 in the car is alot easier than a 3100, since the 3100 has the side pan bolts. The 2 on the back side are almost impossible to get to because there is minimal clearance between the pan and the tranny. It can be done, but it is far from easy.

Interesting on the oil sensor... never heard of an older 3100 not having the sensor, although I know the newer engines (03+ maybe?) don't.

[1bad93z24]

if you dont want to swap the oil pan you could use a jumper wire to turn the light off it will not affect the car in any way saw it done many time my 98 regal was like that from a previous engine instal

[bigj-dog]

So, I looked up the oil pan change on chilton's online site, that's a disappointing turn of events. Anyone object to me not having a low oil sensor? That's the way I'm leaning, of course I may be leaning because of the fact that I've been kicking my own a** for the last 20 minutes for not noticeing that sensor.

[ragtop69gs]

Bigjdog,

I'll be doing pretty much the same swap on my '98 Grand Am GT. the engine threw a rod. Only difference is I picked up a 3100 from a 95 Olds Cutlass.

Did you swap upper plenums & TB ? What about the EGR? I'm not sure if the 98 3100 in the GA has the low oil sensor or not but I'll keep that in mind when I do the swap this week.

Any tips or tricks you can pass on to make the job easier?


Jay

[bigj-dog]

I actually swapped timing covers, upper and lower plenums and exhaust manifolds. You may not have to switch the timing covers, but mine had 2 different ac compressors and engine side mounts (dog bones), so I had to switch all that stuff anyway. You don't have to change lower plenums, but I had mine off of the '98 already cleaned up and I wanted to put intake gaskets either way. I bought the felpro metal gaskets, not cheap, and they are made to work with either old style (non-roller rockers) or new style (roller types). When I got the beast started it chattered for awhile (oil seeping out of lifters, I'm guessing), but this engine runs better than the old one did, and it's quieter in the morning (less rocker slap) than the old one too. The low oil plugin is just hanging there now, when it's cold, the light comes on, but goes off in a couple of minutes. No big deal. When I swap these engines, I usually leave the upper plenum off to put them back in, easier to access wires and cat. pipe on back of engine, no real tricks otherwise.

[ragtop69gs]

Thanks for the reply. My biggest concern was the TB & EGR swap but I guess that is no big deal either did you use the 98 or 94 exhaust manifolds? if I can use the 98's can I just unbolt them from the engine and pull it, leaving the exh. manifolds on the pipes (Clearance) ?

[bigj-dog]

I used the '98, the front was the same, but the rear had a different angle going to the cat and a different gasket also. I don't know about the grand am body engine compartment, but it's a pain to get the rear exhaust manifold off the head in the car on the lumina/monte carlo/grand prix cars. Just get under there with a long extension and a universal adapter and take out the two bolts/nuts that connect the rear exhaust manifold to the down pipe. You'll also have to remove the crossover pipe to get at the top bellhousing bolts. If you keep your old ex. manifold ('9 and intake, it'll have both egr parts. It's easier to leave the manifolds on, there isn't a clearance problem front to back, just pull it to the passenger side to clear the flexplate from the bellhousing and go straight up.