99 Malibu 3.1 and 95 Buick Centruy 3.1 engine exchange

[Johnny R]

Are the 99 Malibu 3.1 engines interchangeable with the 95 Buick Century 3.1 engines? Reason I ask is that my Malibu engine has a piston slap for the first 5 minutes after starting. My Buick Century has a trouble free engine, with about the same mileage, and is ready to trade in. I'd sure like to lwitch them around. Thanks in advance.

[gapboi210]

I had piston slap in my Malbu when the engine hit 39,000 miles. They said it was a poor design in all the 3.1s but it was nothing to be concerned about (according to GM). well. I was concerned and the replaced the pistons with Polymer coated ones that are good so far.

[mattjordan]

IMO piston slap isn't really a big problem... it's just excess clearances until the piston warms up and expands to fill the cylinder...

I've had the "slap" on my grand prix for many years now...

[quaddriver]

Actually its not slap. there was a spate of wrist pins that were on the low end of acceptable mated with pistons drilled for wrist pins on the high end of acceptable.

fill with 5-30 synthetic oil and drive in health.

[gapboi210]

Isn't that grade oil too thin for Texas weather? And in my case it was piston slap.

[quaddriver]

Originally Posted by gapboi210

Isn't that grade oil too thin for Texas weather? And in my case it was piston slap.

nah, 3.1s want 5-30 anywhere. remember, at high temps, 5-30 behaves (with respect to viscosity index) like 30, which is what would be specced if this was some older engine or industrial engine.

only if a 3.1 had real bad bearings would I recommend going to 10-30