I have a 1972 Merc 850 Inline 4. Serial# 3146873. It appears the idle is pretty high. The idle stops are resting on the seats, so I can't turn the idle down any further. The low speed jets are about 1 1/4 out. <br /><br />The compression is 160PSI on all but one cylinder. The other has about 159psi. What am I missing here? It appears to idle and run great, but the high idle is bothering me, as if you listen closely you can hear that this isn't good for the lower unit, because it makes a little rattle when it goes into gear. It isn't drastically high, but I would like it to turn the idle down further. <br /><br />One other problem. I received this boat with the lower unit spanner nut which backed out, and the bearing carrier was out as well. The whole assembly just pulled right out. I looked, and it all looked clean, so I replaced the spanner nut as the old nut seemed a little loose when I attempted to spin it back in. I also had to purchase a bearing assembly key, because that was lost when it came out. I also replaced the two propshaft seals, and assembled it back together with a different spanner nut, which fit much tighter. I kept and used the original spacers for the bearing carrier. I am assuming those are the things they use to adjust the backlash? <br /><br />I then ran it on some muffs, and it shifted fine, from forward to neutral and then to reverse. But I saw that it was leaking gear lube, out of the water pick up vents on the side of the lower unit. I removed the lower unit, and the driveshaft, would lift up enough to make the driveshaft wobble. If I pushed the driveshaft down in the lower unit, it tightened up and would spin true. I removed the water pump housing, and then the water pump base, and saw that it was leaking from there. The bearing and seat looks good. Is there some spacers or washers, between the pinion gear and housing, that would keep the driveshaft from lifting, and keep it tight to the bearing, so it doesn't lift and wobble? <br /><br />I have seen several other mercs of this vintage, spit the spanner nut and bearing carrier as well. What causes this? and what can one do to prevent this from happening in the future? I wouldn't care If I had to spot weld the spanner nut in place, to get a few more miles out of it. But, I have to take care of this lifting, and wobbling driveshaft. Everything looks good, as far as clean bearings and gears. It has a tight true propshaft, that spins freely. The spots on the driveshaft and propshaft where the seals ride looks smooth with no grooves. <br /><br />Could the driveshaft condition have caused the excessive force that blew out the bearing carrier? <br /><br />I just ordered a bearing carrier puller. Any other tool I might need that would come in handy to do this job right? Can't have enough tools you know. Besides I have another merc with lower unit problems, so it looks like I am going to need them anyways.<br /> <br />As usual, any and all help would be greatly appreciated. Thanks Mike
