repair or replace '95 3.1L?

[johnlivingston]

I bought my daughter a 95 Century with a non-running 3.1L. Had loads of water in the engine. Ran a compression test, which looked good. Replaced the intake gaskets. Ran it a few weeks, then started getting a head gasket leak. She's been adding water and driving it gingerly, waiting for me to spend my summer break putting in the new head gasket. The engine currently has about 130K on it.

Went to put oil in it last night (it was about a quart low) and found water evidence inside the filler cap and valve cover. There is none showing on the dipstick. The engine is suddenly idling rougher, too, which could just be the head gasket getting worse and letting water in the cylinder when it sits. The oil pressure light does come on at idle, when warm, so the main bearings are probably in need of replacement, too.

Should I go ahead and try the head and intake gasket replacement (I've already bought the parts), find a used engine, or what? A local guy is selling a 2000 Century with a factory-rebuilt engine (his son totaled the car days after the engine went in), but I'm assuming there are too many differences between the 2000 and 1995 3.1 to make that work.

Thanks.

John

[johnlivingston]

This is to add to my initial post.

Just pulled the plugs and #3 had obvious water on it. Ran a compression test and here's what I got: #1 - 205, #2 - 180, #3 - 190, #4 - 195, #5 - 200, #6 - 195.

Doesn't 190 seem high for a cylinder with a head gasket leak? This is the middle cylinder at the rear (toward the firewall). I had trouble reinserting the longer pushrod on that cylinder when I did the intake gasket. It required my loosening the rocker more than the others, and ended up being noisy. My mechanic said I had a stuck lifter.

Anyhow, any thoughts on whether I should go ahead, tear this thing down, and do the head gaskets, etc.? It seems used engines are a bit tough to find.

It's also got a bad oil leak in the front of the engine, but that may just be a poor seal on the oil filter.

[GTP Dad]

Based on your description I would go ahead and replace the current engine. If you can get a good deal on the second car then it would be worth purchasing it to replace the original engine. Although the compression is good it may not last much longer due to all the issues you have.

130K is not high mileage but given the issues you have a good used engine may avert issues and more repair time later.

[johnlivingston]

Thanks. I'm keeping my eyes open for a used engine. It seems like I'm stuck with the 94/95 "M" VIN engines, which rules out the one in the 2000. If anyone knows different, please let me know.

John

[noimaD]

Quite possibly the motor mounts or the wireing harness, but the actual 3.1 engines are the same .
My 98 Lumina and 95 Monte and 98 Buick all have swappable 3.1 's

[pizon6979]

If you look up the gm 3.1L at the Wikipedia web site it gives you all the info on the motors. it says roughly the 3.1's from '94-'99 are the same and 2000 and up are different, But not why. Check it out.

[bozr]

A quick check on part numbers on RockAuto shows a different piston and cylinder head between the two year/motors.
More importantly though the crankshafts (flange) are the same part number.
Different motor mounts but that may be a sub-frame change.
Worth investigating if the price is right.

Edit; Motor mount. There's only one lower mount that bolts to the engine, the other is located at the transaxle.