1984 7.5 hp Merc shifting issue

[beamin1]

Ok, still working on my waterpump but when I put the lower unit back together, it's not shifting right, reverse is neutral and nut and fwd both go fwd... I've read around on here that rotating the shifter is bad but on this one, the control rod on the lower unit doesn't rotate, it just moves about 3/4 turn back and forth, and the splines are flat spotted on one side so it only goes in one way and I had to move it a little(1/8th turn or so) to get it to go in smoothly.

What could I have done to screw this up??

 

[Laddies]

Re: 1984 7.5 hp Merc shifting issue

The shift shaft is not lined up, you have let it turn by the fwd position. Get a pair of pliers and the shaft will turn, there is a spring in the the lower unit that shifts the unit in fwd gear for default in case the linkage breaks so it's jumped by the normal fwd position use the pliers to find neutral or rev in the unit (I use Rev for best results) then shift the upper linkage into the same gear and reinstall the unit.

 

[beamin1]

Re: 1984 7.5 hp Merc shifting issue

Ok dropped it down just enough to disengage the shift shaft, found neutral on the LU and shifted the lever to neutral but can't get the LU to go back up unless I move the shifter towards fwd..With the unit out, there's a flat spot\missing spline whatever which keeps it from going in...so it does the same thing.. am I missing something?? not sure how to get around the flat spot in the shift rod?

Edit: Also just realised that I can't get the motor to tilt up without pulling out the tilt pin..something that hasn't been an issue in the past(though it has always had to be in fwd to tilt up) is it possible these 2 are part of the same problem? While titled up the other day I nearly lost my hand when it came off the tilt catch and slammed down locked....related???

 

[Laddies]

Re: 1984 7.5 hp Merc shifting issue

You may have bent the locking dogs or damage the cam the ingages them

 

[Laddies]

Re: 1984 7.5 hp Merc shifting issue

I am not sure of you serial number but here's a link to the rev lock linkagr the cam that joins the upper and lower shift rod may be damaged take a look at it, item # 23 http://www.mercruiserparts.com/Show...7&bnbr=130&bdesc=DRIVE+SHAFT+HOUSING+ASSEMBLY

 

[beamin1]

Re: 1984 7.5 hp Merc shifting issue

That #23 looks like the piece I can see looking up from the bottom when shifting, it moves and stops in 3 positions...other than that can't tell much. Also, when I dropped it(LU) enough to see the shaft it would move\stop in three positions...So I'm guessing I need to drop it again and look for pieces broken in the LU?

With the LU off, I think it was doing the same thing but not sure...This is something new just since replacing the water pump impeller and or when it slammed down the other day....

 

[beamin1]

Re: 1984 7.5 hp Merc shifting issue

You may have bent the locking dogs or damage the cam the ingages them

Locking dogs were slightly bent after fixing this and dropping the LU again we're shifting well enough from what I can tell outta the water!

Thanks Laddie

Now if I can just figure out the problem with the pump I'd be done for a few days maybe lol...still getting low pressure from the pump or having an issue getting it from the pump through the motor.

I can blow air and pump water up thru the copper tube with no problem and with the drill running the shaft at 850 rpms the pump shoots about a 5-6" stream out of the copper tube with the LU sitting in a bucket of water...The copper tube appears to be sealing off well enough top and bottom so I'm wondering if the pump housing is worn down inside and letting water blow by?

When I put the impeller in I noticed some of the edges of the top half of the housing were worn or had been heated at some point, possibly not sealing the inner passages well maybe?

Thanks again for the help Laddie Much appreciated.'

 

[Laddies]

Re: 1984 7.5 hp Merc shifting issue

If the impeller was missing blades and you did not recover them they may be blocking the sysem of if the engine got hot the upper water grommit bushing may have melted and be obstruting the flow. Blowing air won't tell much as you can now see. Let us know and we can be more help with this issue.

 

[beamin1]

Re: 1984 7.5 hp Merc shifting issue

Ok, here's what I did, with the copper tube connected to the upper grommet as normal I pulled off the top hose that goes to the pee hole so there's just the fitting there...

I have a small piece of 1/2id clear tubing that's a bit bigger than the copper tube, one ends attached to my waterhose the other end, I stretched a piece of electrical tape over it and poked a hole in it so it would slip over the copper pipe and slide up a couple of inches.

Running the hose results in a fairly decent flow of water coming out of the top end at the fitting at pretty low(input) pressure, not enough to blow the clear tube off of the copper one...

I've gone ahead and pulled the entire pump and don't see any cracks or breaks in it anywhere, and no sign of water in the gearbox underneath so should I put it all back together and try it again or ????

Edit: Is it possible that backpressure is getting into the system anywhere to prevent water getting thru with the motor running somehow?..This one has no thermostat(or anywhere to put one) on it FYI. The only access to the water system I can see on the top end is the exit tube to the pee hole.

 

[Laddies]

Re: 1984 7.5 hp Merc shifting issue

After you reinstall the unit if it still don't cool, here's the fix. Your going to hate it but there is no short cut. Remove the power head and inspect or replace the plastic grommet that melts. Item 10 and the gasket #14 http://www.mercruiserparts.com/Show...&bnbr=110&bdesc=BOTTOM+COWL+AND+SHIFT+LINKAGE
Next remove the exhaust covers and check for debrie behind the plates use new gaskets on the plates - #26+28 http://www.mercruiserparts.com/Show...97&bnbr=80&bdesc=CYLINDER+BLOCK+AND+CRANKCASE
The last place that plugs it the areas that the water travels from the exhaust to the block and requires that you remove the water jacket cover #22 to inspect it and replace the gasket #24. It's a pain but the only way to clear the system. Use care as the bolts can snap easily as most are 1/4 ".