Stuck in first gear Mercury Thunderbolt 85 Hp

I had to take off the lower unit and replace the impellar. I put the unit back on and now the engine is stuck in first gear! Aligned the gear shaft right. And checked the control box for problems!

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

I almost guarantee when you put the motor back up, the shift lever was in neutral, and the gear box was in forward. We see it all the time with the Mercs because you can literally have the splines be lined up improperly and still get the L/U back up.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

Also, lower units on these motors tend to spring into forward.Pull the Lower unit back off. Put the control stick into forward, along with the shiftshaft in the lower unit, and put her back up. Now BEFORE you tighten her down, check that the gears work WITH MOTOR OFF. In neutral the prop will spin both ways.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

It is very easy to misalign the upper and lower shift shafts, if both are in forward or reverse. Alternatively, set both the control and the gearcase to neutral and it is easy to align them properly.

If the gearcase is in forward, use a cresent wrench to turn it CCW until it clicks and stays in neutral. Now set the throttle handle to neutral and install the gearcase.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

Chris1956 said:

It is very easy to misalign the upper and lower shift shafts, if both are in forward or reverse. Alternatively, set both the control and the gearcase to neutral and it is easy to align them properly.

If the gearcase is in forward, use a cresent wrench to turn it CCW until it clicks and stays in neutral. Now set the throttle handle to neutral and install the gearcase.

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My gearcases tends to spring into forward, so I just leave them both in forward during install.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

Off in neutral,on in neutral....easy and confusion free.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

Hey thanks guys it worked perfectly!!!

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

first gear..lol, I been waiting for my motor to hit 2nd gear for years...

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

SparkieBoat said:

first gear..lol, I been waiting for my motor to hit 2nd gear for years...

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Hahaha, yeah I was wondering when someone was going to say something. But for real, Im glad you got it figured out Rich.

Re: Stuck in first gear Mercury Thunderbolt 85 Hp

Thank you SOOO much for this thread! We 'inherited' a 16' Fiberform boat with a '68 Merc 500 50hp on it. Knowing a little about them - friends had one growing up - I immediately replaced the impeller. However, the motor had been abused and this led to a nosebleed of fixes.

However, upon completing them, I put it all back together and headed out for a nice Sunday morning cruise of Puget Sound. Rats! It's stuck in forward. Back home, do some research. Tah dah! This thread! I immediately took the lower end off, turned the shift linkage CCW (instead of CW, which is what I read I was supposed to do on another BBS) until the prop spun freely. Since the remote is already in neutral, it appears ready to put back together ....correctly!

If it isn't, I may impart a tad more wisdom from you. I'm just so glad there are people who know and understand 45 year old engines.

On another note, when I just took the lower unit off, sea water poured out. Is this normal? The exhaust lip was sealed with silicon, but the tube up into the engine wasn't, and the seam between the units isn't exactly flat. Also, when I took the trim zinc off, a little water poured out of it too. Is this a problem, or is this how they were built?

Is there a way to drain/flush this area after each use, or is it fine leaving it alone to flush it now and then, like once a month?