Merc 400 - Lower Unit Help

[alanbcooper]

Hey guys I recently got a project boat for basically free and it came with a 45 HP Merc 400 motor. The good news is I was able to get the motor to fire up last night but I noticed no water was coming out of the nozzle so I shut the motor off. Correct me if I'm wrong but when I removed the lower unit, it appeared that entire water pump housing and impeller were completely missing.

The other main issue is I cannot get the gearbox to shift into forward. Only reverse and neutral are my options. I even tried shifting with the lower unit remover and turning the shift shaft

 

[racerone]

??-------No they are not missing.----They are under that plate with the 4 holes.----Might have a left hand thread.-----Remove it and install a new impeller.------Keep trying and you will find forward gear !!-----Nice running motor if you take your time to go over ALL of the systems.

 

[alanbcooper]

Thank you for the quick response! I cannot see any signs of a screw head or anything like that in those 4 holes. What should I be looking for? A screw head? It is either completely corroded or I'm looking in the wrong area

 

[alanbcooper]

Just found it! Thank you! The impeller was definitely the issue. Going to order a new one. Should it just slide off of the top of the prop shaft?

 

[alanbcooper]

Turns out the small gasket was blocking it from coming off. Good to go now. Just wish the gearbox would shift now

 

[racerone]

So the plate with the 4 holes did come out as clearly stated ?----How did you determine that there is no forward gear ?

 

[alanbcooper]

Yes I was able to remove the plate. As far as the gear issue I orginally tried shifting with the Lower Unit attached but was only able to shift into neutral and reverse.

Aftet removing the lower unit I was still unable to shift by rotating the shift shaft and pulling up. I am still waiting for my service manual to come in which will make things a lot more clearer.

 

[racerone]

Did you say you were pulling up on the shift shaft ?----Why ?----Very difficult to loose forward on these units.----Any oil in the lower unit ?----Any water in there ?

 

[alanbcooper]

Since this is new to me it was my understanding the shift shaft either rotates or moves up and down to push the dog clutch forward or backward. There was oil in the gearbox. On a Merc I'm assuming the shift shaft needs to rotate only to shift and engage the dog clutch into gear. I have tried roating past neutral and I am feeling quite a bit of resistance, like it is trying to sprig back for the last part of the turn if that makes sense?

 

[racerone]

Yes there is a strong spring in there.-----Are you 100% sure you do not have forward now ???-----In case you are wondering I do have more than one of those " cloud white " mercury motors.-----Turn the driveshaft the way the motor rotates.----Does the prop turn clockwise looking from the back ?

 

[racerone]

Yes there is a strong spring in there.-----Are you 100% sure you do not have forward now ???-----In case you are wondering I do have more than one of those " cloud white " mercury motors.-----Turn the driveshaft the way the motor rotates.----Does the prop turn clockwise looking from the back ?----Hard to believe you do not have forward gear.

 

[alanbcooper]

It will only turn counter-clockwise or spin freely which is neutral. Otherwise it will spin clockwise but it clicks telling me it is not actually in Forward gear.

 

[racerone]

Well you may be surprised by that clicking.-----Will it turn the other way.?-----If the answer is no then that is forward gear.------If it clicks turning clockwise and locks counterclockwise it is in forward gear !----And you need to turn the propshaft if you go through neutral to get reverse.-----Use a pair of pliers on the shift rod as the spring is quite strong.

 

[alanbcooper]

Well it turns out it has been fine this whole time! I just assumed in reverse in should click while spinning the opposite direction but that it is definitely not the case. Thank you for all the help.

I think I may have found the issue with the water pump. The impeller looks like it may not be spinning because when I turn the drive shaft it stays in place. Should this spin with the drive shaft? There appears to be a notch where the impeller meets the driveshaft but it is not grabbing at all.

 

[racerone]

Of course the impeller has to turn when the driveshaft turns.------------These motors are so simple !!!