OMC sterndrive not moving in gear.

[Scott Danforth]

The 400 is 4 cylinders only. You have to identify the upper. However I suspect someone swapped the whole drive

 

[Serf27]

How do I identify what the upper drive is?

 

[racerone]

The 400 uses gears similar to the 4 cylinder 115 HP outboards.-----The 800 uses bigger gears / housing similar to V-6 outboards.------Check gear ratio of upper gear box.

 

[Serf27]

The 400 is 4 cylinders only. You have to identify the upper. However I suspect someone swapped the whole drive

Is it possible to fit a 4cyl/400 drive onto the v6 engine?

Now I’m really worried about that unit I ordered. I had sent all these exact pictures to the seller and was told it was a direct fit and would work with no issues.

 

[Serf27]

The 400 uses gears similar to the 4 cylinder 115 HP outboards.-----The 800 uses bigger gears / housing similar to V-6 outboards.------Check gear ratio of upper gear box.

How would I know the gear ratio without taking it apart?
I don’t have the sticker on top of the drive that I see others have with information.
I will look for casting numbers and/or part numbers.

 

[racerone]

You turn one ( input ) shaft a full 10 turns.-----And you count how many turns the output shaft turns.----Simple enough in my opinion !!

 

[Serf27]

Well damn.
I found the serial number on the upper drive.
Model no: 983486
Serial no: J334779

A quick google search revealed a sold 400 unit on eBay.
It even brought me back to this forum where South Kings says

“983486 is the part number on the upper gear case for a Stringer 400. It's not your outdrive's model number. I think - but don't know - the other part number is a hydromechanical lower gear case; which is a different drive than you have”

I don’t see how I could turn any shafts while the upper gear case is still attached to the boat and intermediate housing.

I searched a couple years, over various models in the parts catalog and cannot find this exact serial number.
The closest I found was 982486 on 4 cyl models.
The upper drive HOUSING and upper drive shaft appears to be the same across all models.

The lower gear case housing and lower drive shafts are different part numbers.
3.8l/5.0l+ lower drive shaft: 982424
2.5l/3.0l lower drive shaft: 982423

3.8l/5.0l+ Lower gear case housing: 983506.
2.5l/3.0l lower gear case housing: 983505.

Those 2 pieces are off by the last number.
Can this still be corrected with propeller pitch changes?

Thanks.

 

[Redrig]

I don’t see how I could turn any shafts while the upper gear case is still attached to the boat and intermediate housing.

Sounds like you took the hard path of removing the lower unit with everything still on the boat.

The whole outdrive comes off quite easily , remove the entire drive , then split the upper and lower , then your upper is off and you can count the rotations.

(you can have the upper removed in probably 10 minutes max....break out your manual)

But at this point you know that your entire outdrive is for a 4banger.

if it were me , and I planned on keeping the boat long term I wouldn't try to combining that 400 upper and 800 lower and hope that prop changes can fix it. Get an 800 upper/lower with the correct prop as it was intended.

 

[racerone]

Post #16 says that you hope to use it next weekend.----Think you can meet your deadline by June 11 ??

 

[Serf27]

Sounds like you took the hard path of removing the lower unit with everything still on the boat.

The whole outdrive comes off quite easily , remove the entire drive , then split the upper and lower , then your upper is off and you can count the rotations.

(you can have the upper removed in probably 10 minutes max....break out your manual)

But at this point you know that your entire outdrive is for a 4banger.

if it were me , and I planned on keeping the boat long term I wouldn't try to combining that 400 upper and 800 lower and hope that prop changes can fix it. Get an 800 upper/lower with the correct prop as it was intended.

I’ve removed the upper drive once, I can’t remember why, but yea it was not difficult from what I remember.

4 years of fixing and replacing things and jt sitting in the yard. At this point I’m either too far invested to stop or can let it go. I do want to get some use out of it this summer.
My mistake was not taking it on the water right away because the engine and drive both worked on land.

This is an 800 lower unit and it looks exactly like mine. Color, letters and black pin stripes, I haven’t seen the pin stripes on any other drive.

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[Serf27]

Post #16 says that you hope to use it next weekend.----Think you can meet your deadline by June 11 ??

If the drive getting here on Wednesday physically fits and my prop slides onto the prop shaft then maybe I can.

 

[racerone]

Stop, stop-----The 400 and 800 drives appear the same in pictures !!---The 800 is bigger.------Can you not see the different thread for the prop nut on these ??----The 400 uses a coarse thread and the 800 uses a fine thread.------The 800 has 15 tooth spline.----The 400 has 13 tooth spline.

 

[Buzzsaw420]

I agree they look the same as my 1979 400 has 800 lower with 15 spline shaft. When looking up parts found many are used on both drives.

 

[Serf27]

I’ve just slapped the 800 lower case onto the 400 upper. They fit.
What propeller pitch are you using Buzzsaw?

 

[Buzzsaw420]

It came with a 15x17 Michigan 11007 that works fine. My spare is a 141/4x21 that I haven’t tried yet. My boat is 16’ with a 120 OMC.

 

[Serf27]

It came with a 15x17 Michigan 11007 that works fine. My spare is a 141/4x21 that I haven’t tried yet. My boat is 16’ with a 120 OMC.

I ordered a 15 spline and 15x17 pitch propeller too.
Is yours a 4 cylinder?
I wonder how my v6 and different gear ratio will perform.
Not looking to race it. Just want to be out there driving around.

 

[Buzzsaw420]

Yes 4 cylinder

 

[Redrig]

There is a formula you can use that will give you the overall ratio ( compound gears calculation iirc or something like that )

Post the ratio numbers of your upper and lower and the overall ratio , then prop guys on here can at least give you recommendations for prop numbers rather than just guessing.