Difficulty installing lower unit - 12 hp Chrysler

chrysler_12hp

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After purchasing a non-running 79 Chrysler Outboard, among a variety of noted problems, we saw lower unit oil leaking from weep holes in the gear case. We removed the lower unit, replaced the impeller seal, impeller, and cleaned/lubricated the drive shaft splines. During the re-assembly, I carefully lined up the drive shaft to coupler and water tube. As expected the drive shaft did not align, so I rotated the prop clock-wise to mesh the drive shaft with crankshaft coupler. They meshed and I can turn the prop and see the flywheel rotate, but I am still 3/4" - 1" short of closing the gap on the leg with the lower unit housing. There is no interference between the upper and lower shift rod and I see no other obstructions. What is the problem? Any insight is appreciated.
 

Frank Acampora

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If your upper and lower shift rods are screwed together, and if the lower unit is in forward gear while the engine linkage is in reverse, then that will give about 3/4 clearance between the lower unit and midleg. If this is the case, simply put the engine in forward while pushing up on the lower unit.
 

chrysler_12hp

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No, I removed the lower unit completely and separated the upper and lower shift rod by removing the allen screw. I'm really stumped as to why the gap remains yet the drive shaft is properly synced with the coupler.
 

Frank Acampora

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Did you remove the drive shaft from the lower unit? If so, the lower splines may not have entered the pinion. The pinion gear may have cocked in the gear case just enough to prevent entry. However, if that were the case, you would not be able to use the drive pin for the impeller because the hole on the shaft would be too high.
 
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Frank Acampora

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Last night It occurred to me: You cleaned and lubricated the drive shaft splines. How much grease or anti-seize did you use? Too much grease and you will cause the drive shaft to hydraulic lock inside the crankshaft, thus not be able to push it all the way in.
 

chrysler_12hp

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No, I did not remove the drive shaft from the lower unit. Also, the drive shaft spins free when you rotate the prop. I cleaned the drive shaft splines with a rag and toothbrush to clean the grooves and put a very small amount of Mercury 2-4-C lubricant on the splines, Certainly, not a gob or anywhere near enough to produce the condition you describe. When I try to bridge the gap it is a clear metal on metal sound. This lower unit did not just fall off after I removed the machine screws and separated the shift rods. I did have to put a block of wood on the gear case and remove it with some force, but I did not find that unusual either. It was a couple of well placed hits straight down on the gear case. I have seen this before on other older motors that have not had the lower unit removed in many years.

However, Is there a bushing on the crankshaft end or could the coupler somehow be riding lower on the crankshaft now? I shine an LED light into the coupler looking up the mid-leg from the bottom and it looks good.
 

Nordin

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Have you rotate or moved the shiftrod lower? Check that the shiftrod lower is right adjusted to the shiftcam.

The center of the hole in the shiftrod lower should be 3/16 plus/minus 3/64 in from the motor leg-to-gearcase surface when the gearcase is in neutral.

Have you connect the shiftrod lower correct to the shiftrod uper? The shiftrods has a flat surface and they should line up straight when they are connected.
The shiftrod should be straight all the way from shiftrod lower to the shiftrod uper.
Hope you understand what I mean.
 
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chrysler_12hp

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No, I have not connected the shiftrod lower to upper yet. The mating surfaces and alignment planes between upper and lower look good and have not changed since I dropped the lower unit. Right now, the gap between the lower unit and mid leg is too great to mate the shift rods or lower unit to mid leg.
 

chrysler_12hp

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Well, I hate to admit it but I had the opportunity to look at this motor last weekend and discovered the water tube was a little out of line with the drive shaft. On earlier attempts it appeared to align with the upper tube, but obviously that was not the case. Once I plumbed the water tube with the drive shaft, ensured it aligned with the upper tube, and rotated the propeller with the gear case in forward it fell together. We started and ran the motor after 10 years in a guy's barn and except for a carb issue, broken rewind spring, and broken shift handle pin, the motor did not run half bad. There was no oil running out of the weep holes of the lower unit to boot!

Thanks to all who responded.
 
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