Help! My mom has a 3.8 V-6 1995 Bonneville with a blown motor. I am trying to figure out how far back I can go to find a swap.

I found a 1986 Buick 3.8 liter for approx 50.00. Are the intake bolt patterns the same? Can all the parts swap over? Anyone know if the Bonneville is based off Chevy? How about a 4.3 liter...I found a good price on one of those too. It came out of a 85 Chevy. Are the 4.3 and the 3.8 interchangable?

Without confusing the situation anymore...is the Series II 3.8 based on the old Chevy 3.8 or the buick 3.8?

What do I need to look for?

 

I think as long as the 86 Buick is a FWD motor, It would work. The 3.8 series II motors are Buick based so a 4.3 would be a major pain to fit in there (plus the 4.3 is chevy based).

There is a website about these 3.8 series II motors in Bonnevilles. I think the problem is in the cylinder heads with cooling.

My neighbor has a 95 bonneville and the motor locked up on him. One of these days we're going to strip the motor down to see if it's the heads that are causing the lockup.

Check with the junkyards and dealers in your area to be sure if the Series II motors interchange with the earlier motors.

 

When you said "blown motor" I thought you meant it had a blower hooked up hehe

My mom has a 93 Bonnie, which I am inheriting for Christmas (yessss!!) with the 3.8, and so far there have been absolutely no engine problems, only alternator and water pump, over the last 8 years she's had it.

I would say any front wheel drive 3.8 made for about 200 hp would work.

 

93 was still the series one motor. I think 1995 was the first year for the Series II. On that 93, make sure you are prepared to rebuild the tranny. The trans in my wife's 93 Lesabre crapped out at 105,000. There is a reverse drum in the tranny that goes bad. the new piece is made of a hardened material. Just an FYI...

 

I don't think you'd be able to put the '86 motor in it....but you wouldn't want that '86 motor anyway. The early FWD FI 3.8's didn't have balance shafts and they vibrate alot. Even when they were new.

 

tranny overhaul in the 93 Bonnie I had: $1800.
reason: plastic radiator. ws cracked, & would seep coolant into tranny fluid when heated up. on regular pressure check would pass, needed the heat.

I would do some serious research before getting the 86 motor. even if you just look in the haynes book for the bonnevilles, you cn see the different layouts & ecms for the motors. in 86, it was called a 3.8 motor. I believe the 3800 came out in 91-92. WHen the revision came out, the 3800 became the 3800 Series I, & the new motor 3800 Series II.

main differences were the heads & intake. N/A Series II motors are just as powerful as Supercharged Series I motors. something to think about.