Merc V6 135 1986 Prop Shaft and Drive Shaft removal - Request for Help

[UKMike]

Hi all,

I have an issue that I guess all you seasoned Merc guys must have seen before. I am doing a total engine overhaul and part of that is to change all the bearings and seals in the lower section "Gearbox" or Foot as some call it and I have run into some issues. I have the original service manual and have followed it step by step but for some reason the section for the gearbox is very limited when it comes to describing how to take it apart. Now this engine is a 1986 and it has been run in salt water all that time so I had real issues getting the gear housing retainer screw off and ended up having to drill it out, then I had to drill out the Carrier too, photo's attached but when the carrier came out it should have bought the bearing, thrust washer and Front drive gear out with it but they stayed put, it looks like the thrust washer has also corroded against the outer casing wall? Now I have tried soaking it in vinegar to losing the Calcium but hasn't worked and until I can get this out I can't undo the nut on the driveshaft gear, and that means I can't get the drive shaft out so can't change the bearing on the D/shaft which is one of bearings in the worst condition.

I was told that I could force the driveshaft up using a puller and that would strip out the oil lubrication sleeve on its way up but they are no NLA so I am stuck.

Please could someone help me? Your advice is always welcomed.

UKMike

 

[jimmbo]

Well you are looking at the bearing pressed on the reverse gear. Have you removed the shift shaft? Once that is done the propshaft and the reverse gear should pull out

 

[UKMike]

Thanks Jimmbo,

No not yet, I am waiting for the tool to arrive, but what about the driveshaft? That's still in, I was trying to get the bearing and reverse gear out so that I could undo the driveshaft gear nut so I could remove the driveshaft.

 

[jimmbo]

The driveshaft is the long one sticking out of the top of the gear case. The shaft showing the bearing is the propshaft. Once the shift shaft is removed, the propshaft, the reverse gear and bearing, and the clutch dog should all pull out together. Once they are out, then you can put a wrench on the nut securing the pinion gear to the driveshaft

 

[UKMike]

Thanks Jimmbo,

How does the propshaft and other stuff come out past the pinion gear? It sits between the firward and reverse gears and I cant pull the driveshaft up because the pinion is attached to the bottom of it?

 

[UKMike]

serial is 0a961186

 

[UKMike]

Hi Jimmbo,

Could you let me know how removing the shift shaft helps? What about the Driveshaft Pinion?

 

[jimmbo]

Removal of the shift shaft will allow the prop shaft and reverse gear to be removed. The pinion and its retaining nut are then accessible. Once the pinion is out the forward gear can be removed

 

[UKMike]

Thanks Jimmbo,

I'm down at my Merc dealer in 12 Hrs, he has the shift shaft removal tool and will unlock the shaft, then I can get on with the rest
Thanks for your help man, it's really appreciated

Best regards
UKMike

 

[UKMike]

Just rebuilt the mid section with all new kit..

 

[UKMike]

Not bad for a 1986 Merc!

 

[UKMike]

Hi Jimmbo,

Got the prop out so thanks for the advice, I needed to heat the outer casing as the thrust washer had corroded against the outer casing, do you have any tricks on how to get the driveshaft nut of the bottom of the drive shaft, just below the gear? Is it a normal anti clockwise to undo?.

 

[UKMike]

No Title

 

[Faztbullet]

You do know that if you change any bearings and races the unit will need to be reshimmed?????? To remove nut use a 7/8 shallow socket on 3/8 rachet and pipe wrench counterclockwise

 

[UKMike]

Hi Faztbullet,

Thanks, got it off and swapped out the driveshaft bearing, put original shim back in and looks the same alignment and height, maybe 1 TH higher on the pinion gear. The reverse bearing is staying as is, I'm only replacing the main Forward Bearing and the carrier, which I believe comes with the remaining bearing and seals.

Would you mind advising if this needs any further shimming?

Isn't it normally possible to feel if things are aligned with only those changes? What would happen if it's not 100% accurate on the shimming?

P.S. there was only 1 shim below the Driveshaft bearing and from what I can see the only other shim is in front of the reverse bearing, I haven't changed this bearing, it's stayed put.

Thanks again for your advice!