Pulling the crankshaft '71 Merc 800

[Moody Blue]

Part of my winter maintenance this year is to replace the crankshaft seals and both upper and lower crank bearings.

Wondering if it's possible to remove the crankshaft while leaving the pistons/rods in the cylinders. Can I raise the crank and pistons enough to remove the rod caps and pull the crank by itself?

Just wondering.

 

[daveswaves]

Re: Pulling the crankshaft '71 Merc 800

Part of my winter maintenance this year is to replace the crankshaft seals and both upper and lower crank bearings.

Wondering if it's possible to remove the crankshaft while leaving the pistons/rods in the cylinders. Can I raise the crank and pistons enough to remove the rod caps and pull the crank by itself?

Just wondering.

MB, yes you can, just support the crank on either end while you futz with the rod nuts. You can also re assemble the same way. Use a really stiff assembly lube to hold the needles when you put them back in.

 

[Faztbullet]

Re: Pulling the crankshaft '71 Merc 800

Hello Dave!! How did the project turn out????

 

[Moody Blue]

Re: Pulling the crankshaft '71 Merc 800

I was hoping that was the case. Will the nuts be accessible enough to get a torque wrench in there to re-install the rod bolt nuts?

The heads of the rod bolts are exposed while the nuts are facing the pistons.

 

[daveswaves]

Re: Pulling the crankshaft '71 Merc 800

I was hoping that was the case. Will the nuts be accessible enough to get a torque wrench in there to re-install the rod bolt nuts?

The heads of the rod bolts are exposed while the nuts are facing the pistons.[/QUOTe

It is tight in there so what I did was use a box end wrench that I thinned the end on. I hook a digital pull scale (fish scale) in the other end of the box and pull the appropriate pull for the length of the wrench. You will have to anchor the block to the bench or have a buddy hold it down while you torque.

 

[daveswaves]

Re: Pulling the crankshaft '71 Merc 800

Hello Dave!! How did the project turn out????

The project is currently suffering from lack of motivation on my part and a desire to fish instead. I have a new computer system on it from PRS and need to do the fuel map. The problem is the 1500 that I built to put it on runs so damn good with the carbs I have no reason to pull the front cover and swap in the FI front so I can play with it. I
need to pick up another 1500 block or late model 115 inline 6 block to play off line.

 

[Maxz695]

Re: Pulling the crankshaft '71 Merc 800

On one manual the tightening specs for the 70 HP said to tourque to 30 PSI then tun the nut another 90 degrees. so if the tightness is close it should be ok. I have done two engine with a grinded down 7/16th wrench and snugged them tight with a bit more of a pull on them and never had one let go. You can buy what they call a crows foot that extends a bit from the wrench and grind it to form to the nut and counterweights. A few tips count the pins and make sure there all there after removing them if they fall into the motor thay can get lodged in the exhaust port or transfer port. Never use a magnet to get them out of the block as the needles will become magnatised and attract metal and mees up the rod crank etc. Tip the engine over several times to get the neeldle out. when reinstalling 2 stroke oil is suggested to keep the bearings in place leave a bit of room between the Crank and the rod holding it snug to the bearings as you turn it into the upper rod section not giving it room for the pins to fall out or you have to start over. I used engine assembly greese (White) I got it at Nappa. Removing the wear sleeve is a bit of a job I started on the outer rim where the crankshaft goes in and split the sleeve and worked my way to the end of the seal area peling it off. Putting the new sleeve on must be carefullydone . Locktite is recommended and the sleeve must be knocked on using a piece of wood keeping it centered as you go. I just replaced mine and reassembled gonna take it out this afternoon for a run. While your there check the center mains by rocking the reedblocks and see if there is more than a little if any play. Inspect the reeds to see that there a tight fit to the blocks.

 

[Chris1956]

Re: Pulling the crankshaft '71 Merc 800

Moody, If you want to replace the crankshaft seals and upper and lower main bearings, you normally do not need to remove the crankshaft from the block. Simply remove the crankcase cover, pull the endcaps and then the bearings. You may need to use a puller to get the bearings off. Tap the new ones on using a drift to place them.

 

[Moody Blue]

Re: Pulling the crankshaft '71 Merc 800

Thanks to everyone for the valuable info and tips. I'll decide how far I go once I remove the crankcase cover. If I have clear access to the bearings (only inner race left of lower bearing) and everything else looks good, I won't go deeper.

 

[buzzm19]

Re: Pulling the crankshaft '71 Merc 800

Moody, I knew Chris would chime in on this one, he told me the same thing and it worked, but in my case I did have to remove the crank to get the bearings off (1972 140p l6). I was able to remove the crank without taking the pistons/rods out, after taking the rod caps off I just pushed the rods down and did not have to move the crank up at all (just be careful when you rotate the crank not to hit the rod bolts). On assembly I watched a girl on youtube use vaseline and it worked great. If you take it apart make sure you check the bearing cages especially along the sides for cracks(I found two on mine). If you have to replace the bearings, I read here that if you heat the new bearings in an oven to 350 degrees they will slip on easly and yes it worked for me. When I re- torqued the bolts I welded a 1/4 in socket to the 7/16 wrench about two inches back did the math and used a $19.00 1/4 in torque wrench from harbor freight and that worked great. Buz