1980 2.5L Mercruiser shifting problem.

[wvmedic]

I had to replace my impeller on my 1980 2.5L, I didn't have the water pump kit for the R drive but I did have one for my MR drive. I put the water pump kit in the 1985 MR drive and put it on the boat, I adjusted the shift cable per the manual.

Now the boat (drive) will not go into drive without raising the RPM and it slams into forward, I only did this once. It goes into reverse fine, and when I shift it into forward out of the water the prop will not rotate counterclockwise it will rotate clockwise. When shifted into reverse it will ratchet counterclockwise and will not rotate clock wise.

Any thoughts as to the problem?

I have read that these two lower units should interchange, the R has a preload pin in top of the shaft and the MR doesn't. Are they in fact interchangeable?

Jeff

 

[Bondo]

Re: 1980 2.5L Mercruiser shifting problem.

and when I shift it into forward out of the water the prop will not rotate counterclockwise it will rotate clockwise. When shifted into reverse it will ratchet counterclockwise and will not rotate clock wise.

Ayuh,... If it's not racketin' in forward, the cable is not Right....

Yes, the lowers are interchangable...

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Bond-o, I adjusted the shift cable to the required 6" from the center of the brass barrel to the center of the hole on the cable. I just did this to double check, I did have to adjust about an 1/16" to an 1/8 ". The prop dose free spin clockwise when in F. I don't see how changing the lower unit would require an adjustment, because the shift cable runs from the shoe up to the shift plate. I did notice while the lower unit was off, I could turn the shift rod and it wouldn't stay in place. If I put it in neutral it would turn it's self to F or R.

And just to note the drive worked flawlessly while on the boat I striped the 1985 running gear from, I took motor, transom plate and drive of of the 85.
Jeff

 

[Bondo]

Re: 1980 2.5L Mercruiser shifting problem.

I could turn the shift rod and it wouldn't stay in place. If I put it in neutral it would turn it's self to F or R.

Ayuh,... Ya need a bungee strap around the propshaft, to the cavplate to HOLD it in Forward....
If the cable wasn't just replaced, No, it shouldn't need Adjustin'....
I'd guess you're off by a spline on the Lower...

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Ok, I will try that.

But why would it go into forward at a high RPM, I dunked the boat while on the trailer, shifted into F no go shift to R it went in fine. Shift back to N and then shifted into F, advanced the throttle a little and she slammed into forward. I stopped there, other than shifting back t R and N both of which worked ok.

Jeff

 

[Bondo]

Re: 1980 2.5L Mercruiser shifting problem.

But why would it go into forward at a high RPM,

Ayuh,... Ya messed with the cable adjustments, Who Knows...

Advancing the throttle must tension the shift cable slightly more, probably in the control, and it Jumps inta gear...
What's the History of the lower cable,..??

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Bond-o, I adjusted the cable after I first put the LU back on and no forward. I took the LU off for the second time, to double check it. Went to the water and still no forward, came home and adjusted the shift cable per Mercruiser specs, it is now at the required 6 inch length, I only had to adjust it a 1/16 to an 1/8 of an inch.

As to the history of the lower cable, I'm not sure when it was changed. It did however work fine prior to the LU switch.

From what I can tell the lower cable on the 1980 comes off of the shift plate and runs to the port side and thru the transom plate. The 1985 attached to the port side of the motor and ran back thru the transom plate.

Jeff

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Here is a pic of the shift mechanism. The black cable is the shift cable.

Jeff

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

~^~

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Bond-o, my memory evades me sometimes. While getting ready for work this morning I happened to remember that there was a shifting issue with the 1985 last year, I thought the problem was in the control box. I guess that is what I get for thinking.

While running the Sea Ray last year to check the motor, the boat was difficult shifting to neutral when say pulling up to the doc. Also while going from neutral to forward while docking. It was a little hard going into forward and would shift into forward a little hard, not slamming into forward like is dose now but still a real solid shift.

So I now think the issue is the LU, but what would cause this? The reason I'm asking about the cause is to determine if I will try to repair or replace when the time comes.

I am going to switch back to my R drive for now.

Jeff

 

[fishrdan]

Re: 1980 2.5L Mercruiser shifting problem.

I noticed you said the 6" lower shift cable adjustment was made, but were the F&R cable adjustments made also?

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

fishrdan, no the shift cable is moving it's full range of motion from F to R.


Jeff

 

[fishrdan]

Re: 1980 2.5L Mercruiser shifting problem.

So you made the anchor point cable adjustments for forward and reverse, just not the 6" lower shift cable adjustment? I've had my drive shifting like you mention when the cables were out of adjustment.

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

No the anchor point you are referring to is the lower cable adjustment. Mercruiser manual #4, section 4 page 4-10.

Jeff

 

[fishrdan]

Re: 1980 2.5L Mercruiser shifting problem.

Yup, Merc Manual #4, did you complete the entire shift cable adjustment procedure in Sec 4, page 10-11, lower shift cable at 6", adjust remote control's shift cable barrel and movable stud.

Maybe I missed something, but was the entire shift cable(s) adjustment procedure completed, both pages?

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

fishrdan, no Sir I have not. Sorry I didn't understand, I will check it though.

Thank you for sticking with me.

Jeff

 

[backyard mechanic]

Re: 1980 2.5L Mercruiser shifting problem.

My bet is the (outer) shift cable is broken at the outdrive and needing replacement. When measurements are right but nothing else matches up what else can it be? All Mercruisers require the shifter to be in fwd coming off and going back on. It simply won't come off or go back on unless the shifter is aligned and he wouldn't need to take the SS out for R&R of a WP impeller.

I guess the control box could be screwed but that is not going to happen just because they dropped the lower end.

Yeahhhhh I'm betting on the cable being shot. 1980 model? Yup, it's over due.

(Just my 2cents worth...)

 

[bigskiohio]

Re: 1980 2.5L Mercruiser shifting problem.

The prop dose free spin clockwise when in F.

It should not spin free in forward. It should lock and ratchet.

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

backyard mechanic, no it is not broke. I can see the foot and can work it via the control box.

Like I said above I really believe now that it is an issue with this LU, so I'm going to replace the water pump on the old one and use it since I know there is no issue with it. I had forgot about the shift issue with the MR from last year, I had only ran that boat twice before taking the running gear out to transplant in my Starcraft. I made an assumption ( you know what that means) that the shift problem on that boat was an out of adjustment issue or a bad control box. Though with the problem I'm having now I think it is an issue with this LU.


Jeff

 

[wvmedic]

Re: 1980 2.5L Mercruiser shifting problem.

Well I put the R LU back on, everything feels right. I think the clutch dogs are worn out on the MR.

I am leaving now for a test run on the river, and hopefully some fishing if all is well.

I will report back to update if in fact it's fixed, or not but I am optimistic.

Jeff