2.4 crank in a 2.5?

[Smalltownbassin]

T-REX

04-11-2005, 08:22 AM

I have put several early 2.0 and 2.4 fish'in motor cranks in 2.5 blocks, with NO cumbacks wit crank problems...all are still work'in!!...My modified 2.5 had a early 2.0 crank wit no oiler in it...it turned over 9k quite offen...It broke a piston and ruined the block and crank, or I would have kep use'in it!!!...It's newer cranks in OLDER blocks that gives ya problems...I wuzn't aware ov any differnce when I put a newer 2.0 crank in a 2.4...It ran, and ran good, for a lil while...then it locked up...thought it wuz a piston, but found the center bearings gaulded, and the crank BLUE and screwed up!!...then I found out about the shoulders and personally found out what crank works where...U kan shop for special bearings to use the 2.5 crank in a 2.4, but it ain't worth tha trouble...simple lil rule to live by: 2.4 crank will work in 2.5, but not visa versa!!!......(sum 2.4's have differnt top bearins too, so keep on ya toes!!, and remember, Mercury Luvz ya!!)


Can anyone verify this? Ive been looking for a good 2.5L crank for a while now with poor results. Just had someone donate a running 2.4L rotator that i plan to use the crank out of if this old post from T-REX is accurate. If it's a bad idea...anyone looking to trade?

[tlwjkw]

tha only 2.4 crank that will work ina 2.5 is tha High 2.4 Performance crank.................. one exception, '91 XR4

[Smalltownbassin]

tha only 2.4 crank that will work ina 2.5 is tha High 2.4 Performance crank.................. one exception, '91 XR4

How can i ID it? Who knows whats actually in this block.

[ChrisCarsonMarine]

tha only 2.4 crank that will work ina 2.5 is tha High 2.4 Performance crank..................

Respectfully disagree...If the crank has flanged center mains it can run in a 2.5.Many early non oiler cranks,most 2.4s and all 2.o 9 ringers will work,and are great cranks...the 2.0 and some 2.4 cranks have 1.5 top mains,instead of 1.375 used in 2.5s...you can modify a 2.4 top main cap to mount the stator,and install a 1.5 bearing from the 2.0...the 1.5 bearing wont fit in a 2.5 top cap,Chris

[tlwjkw]

excuse me... not thinking 'bout '80, '81, '82 pre oiler's.................

[nelson edens]

Chris, I think that if you would post a pic of "flanged center main", it would clear up a lot of confusion.

Nelson

[Smalltownbassin]

Respectfully disagree...If the crank has flanged center mains it can run in a 2.5.Many early non oiler cranks,most 2.4s and all 2.o 9 ringers will work,and are great cranks...the 2.0 and some 2.4 cranks have 1.5 top mains,instead of 1.375 used in 2.5s...you can modify a 2.4 top main cap to mount the stator,and install a 1.5 bearing from the 2.0...the 1.5 bearing wont fit in a 2.5 top cap,Chris

Good info. Ill know more when i get it torn down then. Thanks Chris!

[Smalltownbassin]

Chris, I think that if you would post a pic of "flanged center main", it would clear up a lot of confusion.

Nelson

Similar to the shoulders for top guided rods right? But found in the center main journals?

[ChrisCarsonMarine]

Not up on pics,but heres the difference.The non-flanged center main has a small radiused area between the main journal and counterweight,and is used with a center main bearing that has a flange on the bearing shells facing the crank,to hold the ends of the needles captive...no contact with the counterweight.The flanged center crank has a small thrust surface(not really a thrust surface,more of a guide)and is used with a bearing with a plastic cage and open-ended bearing shells,the plastic cage riding on the smooth flange.2.4 oiler cranks are the radiused type and although the main journal is the same diameter,the open ended 2.5 bearing(larger outside shell diameter to fit the larger 2.5 main ways)the plastic cage will ride on the counter weight and wear due to the rough casting instead of smooth flange,causing the end of the plastic cage to fail and ruin the needle alighnment,and the crank/bearing...hope this helps,Chris

[tlwjkw]

if you go to this add you can move your cursor over tha pics and see tha "shoulder" in question on tha center mains.... you gotta have that ta run ina 2.5 (any fat block)

MERCURY MARINER OUTBOARD 2.5 L V6 XRi XR6 150/175/200 CRANK CRANKSHAFT CORE | eBay

[Smalltownbassin]

That's axactly how I imagined it. Thanks.

[ChrisCarsonMarine]

Ok,because it has flanged center mains,it will work in just about anything with the correct rods and bearings.1976-1991 are bottom guided,92 and newer are top guided.You can run top guided rods on a bottom guided flanged centers crank,but not bottom guided rods on a top guided crank.A bottom guide rod only has a few thousandths up/down clearance on the crank,and plenty on the wrist,a top guide is tight clearanced on the wrist,and plenty clearance up/down on the crank end.Your crank is probably top guided,but it could be the somewhat rare 1991 2.5 bottom guide,either way it can run top guide rods.There ya go,Chris

[David - WI]

if you go to this add you can move your cursor over tha pics and see tha "shoulder" in question on tha center mains.... you gotta have that ta run ina 2.5 (any fat block)

MERCURY MARINER OUTBOARD 2.5 L V6 XRi XR6 150/175/200 CRANK CRANKSHAFT CORE | eBay

[tlwjkw]

[25two.stroke]

Just for the record I took two pics here. I did not understand the shouldered/non-shouldered crank for the longest time. I hope these pics will help everyone in the future identify what they have. As mentioned above, shouldered are needed for any of the "fat blocks" 2.5 and 2.0.

SHOULDERED:

NON SHOULDERED: