OB will not engage forward it only revs. Reverse works Fine

Motor specs:

HP 85
Make Mercury
Serial Number 4294947
Thunderbolt ignition

Today I took the pontoon out on the lake and after cruising for about 20 minutes I turned the motor off to relax. After about an hour I started the boat and it would not go forward. No weird sounds or clunks, it just revs. Reverse is good as long as you don't give it full throttle (reverse has been this way since I bought the motor.) I pulled the prop to check for a spun prop but could not see any obvious damage. I took cover and cowling off to view the different actions (to forward and Reverse from neutral) and everything looked to move as it should. I was in 50ft of water when it happened so I'm certain I did not hit anything. I do not have a manual and would prefer to fix myself unless this is a quick fix for marine mechanic. !!!PLEASE HELP!!!

Re: OB will not engage forward it only revs. Reverse works Fine

hi.check for gears with shift cable disconnected and motor OFF.move slider by hand and spin prop/shaft.in neutral shaft should spin freelly.in forward should click one way and in reverse should be 'locked'.. check if retaining nut that holds the bearring carrier is tight.to that proppeller has to be off.

Re: OB will not engage forward it only revs. Reverse works Fine

With the toon on a trailor or backed in shallow water check all the linkage in the upper motor cowling for movement. The shift rod to the LU has to turn at every location. You will need someone to help by running the control, when doing this. If everything is good there, the trouble could be just a stuck cam follower in the prop shaft. Without the proper tools and knowledge to take the LU apart , it would be best to take it to a good repair shop that works on them. Without a manual and proper tools your SOL when it comes to going inside of the LU. The best case would be if the shifting bar is broke or cracked or the arm on the shift rod were broke or bent all located in the motor cowling. JMO.
Oldman570

Re: OB will not engage forward it only revs. Reverse works Fine

First, Thank you both for the reply's. The prop locks as it should in reverse, moves freely in neutral and clicks in forward. I've tested the controls with a second person and everything seems to be moving as it. Retainer nut it tight, I checked after pulling the prop to test for spun prop. I'm pretty good with mechanics, I've rebuilt a lower unit on an evinrude 35hp, Is it similar? How do I go about checking for a stuck cam follower or shift bar if everything looks good under the cowling? and would that allow reverse to work and not forward?

Thanks again,

Re: OB will not engage forward it only revs. Reverse works Fine

Interesting problem. I think I would first drain the LU oil and inspect it. Then refill with fresh and new gaskets on the fill/drain screws. If the fluid is blue/black with minimal finite metal particles, assuming you used Quicksilver oil and not Pennzoil which is honey colored, not chocolate colored, but honey colored and clear you are good to go. If that (not chocolate/coffee with milk colored) were the case I would not suspect the cam follower or shift linkage in the LU, nor the shift dog, nor any other components in the LU.

If you had a spun prop and you could move in reverse you could still move in F gear, just would tend to overrev as you increased the throttle. You would get some movement of the boat at idle.

The next step is linkage and play in it starting at the engine with the remote cables removed. With 2 people and obviously the engine off, slide the shifter linkage (using the pin that the remotes connect to) through the gears and mark where the different gears first engage. Remember that reverse is slotted, not ratcheted like forward gear, so you must have the helper rotating the prop every time you shift into R without the engine running. If you don't move the slot/lobes to line up before you complete the shift you can damage your shifting linkage.

While doing that do it several times and ensure that the break/connect points are repeatable. If so, great move on. While still in the engine, look at where the cables deadman. Right after they enter the engine cowling the cable has a brass barrel on it which locks into a slot (one for each cable) with a plastic retainer that keeps the barrels in the slots. This anchors the outer shield of the cable. It should hold the barrels snug.

If ok move on to the cables and with someone moving the shifter lever on the remote control, hold onto the barrel and the center wire adapter and have the other person move the shift lever while you hold onto the end attempting to prevent movement in both directions. You should have positive response and no slop as the lever is moved and you resist. Any slop and you have your problem. Additionally look at the barrel and the adapter that fits the engine and check for soundness and lack of wear in the hole of the adapter.

I'm out of ideas.

HTH,
Mark

Re: OB will not engage forward it only revs. Reverse works Fine

I'll be trying each of these steps today. I will get back to you guys on the progress.

Thanks again,

Re: OB will not engage forward it only revs. Reverse works Fine

You say that you checked the prop for a spun hub but did you actually put a witness mark across it and rev the engine in fwd to see if the mark stays aligned or moves? If your prop is engaging correctly as you said in your previous post, throughout the gears, I would definitely check that prop again.

Gerry

Re: OB will not engage forward it only revs. Reverse works Fine

Prior to posting I searched for an answer and a few posting stated "You will be able to see OBVIOUS damage to the rubber hub if the prop is spun" Honestly, I checked for damaged rubber and did not see it. I will place witness marks today and give it a go. Having said that. How would reverse work if the prop has spun and no movement in forward gear?

Thanks,

Re: OB will not engage forward it only revs. Reverse works Fine

did you tried to adjust shift cable????im thinking that somwhere on the way gear slips.it is possible that you will be able to shift gears with out load and then will "come"out of gear.you said reverse gear is dissconecting also?

Re: OB will not engage forward it only revs. Reverse works Fine

Yes, I tried adjusting. I'm going to try shifting with the cable disconnected but the weird thing is that the prop locks as it should when in each gear. Reverse gear is working. It just moves slow but it is on a 22 ft pontoon and it is reverse. I'll post back on progress.

Thanks again,

Any update?

From 9 yrs ago?

No replies tick me off. Happens on other forums too. I keep a list of these people and don't reply.