Any differences in the Mercury 3.0L Powerheads?

**speedthriller** · 10-14-2016, 02:16 AM

I'm finding parts to rebuild my 2003 Mercury 250 efi. Are the internals for all year 250 the same? Is there any difference on the Powerheads between the years. For example I found a good crankshaft that I can use since I don't think I'll be able to reuse mine but it's for a 1998 3.0L 250. Thanks for any help just asking to gain knowledge

**baja200merk** · 10-14-2016, 05:41 AM

The crank splines and exhaust port changed a few times over the years. Make sure the splines match your driveshaft.

**XstreamVking** · 10-14-2016, 05:59 AM

Def check splines on that. I think.... the 98 has the coarser spline and the 2003 will be the fine spline.

**Todd D** · 10-14-2016, 10:11 AM

1998 should be 13 spline like the 2003. It was pre 96 or 97 that had 8 splines in the bottom of the crank. The 98 will fit the 2003 but has 2 rows of loose roller bearings where the newer motors have a single caged bearing on the crank.

**JUPITER PULSARE** · 10-14-2016, 02:16 PM

1995 3.0L Merc also had 13 spline drive shafts. I just took two apart...

**baja200merk** · 10-14-2016, 07:13 PM

Originally Posted by Todd D

1998 should be 13 spline like the 2003. It was pre 96 or 97 that had 8 splines in the bottom of the crank. The 98 will fit the 2003 but has 2 rows of loose roller bearings where the newer motors have a single caged bearing on the crank.

Omc bearing>Merc bearing