225 promax rods?????

[Mercmonster86]

Rebuilding a 1997 efi promax 225. Got crankcase together and rolled it over several times while laying on its back and the stood it up on the bench to install electricals decided to spin a few more times and after about 3 revolutions the motor binds up. Look through the intake and found that the connecting rods are falling down to the bottom of the crank journal. Is this normal on a top guided rod or does this mean i have too much slack elsewhere??????

[MTOLLEY]

Did you put the washers on either side of the rod when u pushed the wrist pin in? It's normal for the big end to"float" some but not to an extreme. Can't say I've ever had one bind from the small amount of movement at that point. Are you sure it's not a crank sealing ring. Are they matching block and front half and are the pins in? Id be taking back apart and double checking everything!

[Mercmonster86]

I did put all the washers on the pistons. As far as the block halves , they are both stamped with the same number , guessing thats all i can do to check. I will end up splitting it back open. To make a long story short, this crank is used. The old one was damaged on number 2 journal. This crank comes out of a 2.5 200 efi with o- ring heads which i was told doesnt matter. All new bearings. Old crank journals seam to all have signs of heating. Manuals do not give anything specs on wear limits for crankshafts as far as i know

[TEXAS20225]

does the crank have the little bitty shoulders on the rod journal throws is so double check your caps you may be just fuzz mismatched on one of them my pmax had the wide shoulders like a bottom guided crank

[tony1204au]

Do you have the lower end cap on... I once put one together and had yet to put that cap on and she was binding in much the same way..

[Mercmonster86]

Yes i sure do i have upper and lower caps installed. Once the motor starts to feel like its tightening up i can reach through the intake with a flat screw driver and lift up on the rods to center up on the journals and it will free up for a few more rounds.

[Jay Smith]

Side to side rod movement is not only normal but a MUST on top guided Pro max style rods... Your binding can be from a miss alignment on the crack capped fit of the rod cap. Anytime the rotating assembly does not turn free STOP. Something is wrong.

Also if your've torqued the rod and cap to specs in a mis alignment posistion that rod can be damaged beyond use....

I have a TEE bar that incerts into the crank spline and I check free rotation and movement EVERY rod that is installed....

Rod alignment and conditioning is my "thing" if one is not right it can take out your whole investment...

Jay

[Mercmonster86]

Gonna be pulling it back down saturday to inspect everything. Hopefully find something obvious. Just seems funny that if i spin it clockwise it gradually tightens up in about 4 revolutions. Turn it counter clockwise and it doesnt do it everytime. Im definately sending the rods to jay to get them checked out/lightened. Keep yall posted. :o

[rev.ronnie]

If something is skewed up on a rod cap it will drive the roller bearings down to one side or the other and lock up like a roller clutch or sprag so to speak. Harley cranks do it when a bearing goes bad. They will roll over and eventually lock up. I have a twin cam engine in right now that will lock up spinning forward, but not backwards. It is just a crank in a case, no parts.

I agree with Jay, if a rod cap is not seated right, you now need a new rod.

[Mercmonster86]

I hope its a rod lol. I dont mind buying a rod when a crank is about 10 times more expensive. Appreciate the help

[Dave S]

HeeHee Rod Droop.....Top rods with too much piston slop. In the old daze I usta run 66 cid mercs. L6 motors. Though I was smart. They are top rod motors. Made a plastic washer to let in oil and make the small end lighter. Ate up 2 crans and THEN figgered out the rod has to be held 90 dregrees to the crank. Early V6 cranks keep the rod rite. Late pistons keep the rod rite. If ya got slop on top ya got bind.... run it and ya got parts. Been learning for years......

[Mercmonster86]

Ok guys its past 12 oclock and ive come to the conclusion that i have too much play on the top end weather it be pistons, washers, sloppy bore, or rods. Sending rods to jay, replacing washers, and sending block and pistons to get checked. Hopfully we find something obvious.