VP SX Cobra lower unit cracked

[Tsteverson]

I have a 96 sunbird with a 4.3 and a 1.66 ratio Volvo Penta SX Cobra outdrive that is cracked from water getting in and freezing. I was stupid and left it stored covered with the foot raised this winter.
My question is will the lower unit swap with a OMC Cobra if they are the same ratio, or must it be the VP unit?

 

[Don S]

Re: VP SX Cobra lower unit cracked

My question is will the lower unit swap with a OMC Cobra

It will with an OMC SX Cobra, but not with the older dog clutch style Cobra from 93 and earlier.

 

[Tsteverson]

Re: VP SX Cobra lower unit cracked

Does swapping out the lower unit require any of the special tools or is it pretty straightforward? Have turned wrenches for years on gas, diesel, and small engines, but never an outdrive.
Just curious if swapping the lower unit is best left to someone more experienced.

 

[Don S]

Re: VP SX Cobra lower unit cracked

Did you understand what I said in my previous post. It won't work if you are talking about a dog clutch cobra.

 

[Tsteverson]

Re: VP SX Cobra lower unit cracked

Honestly, no. Just figured I'd do best to go with the Volvo Penta if there was any doubt. Haven't gotten a service manual as of yet to do any reading other than here on the website

 

[Tsteverson]

Re: VP SX Cobra lower unit cracked

Have seen at least two different service manuals for the outdrive. Is one "preferred" over the other?
I have to replace the exhaust bellows as well as the lower unit as it has ruptured. Other than the upper bellows as well, what other parts should I expect to change or are recommended to chanhe while its apart?

 

[Augoose]

Re: VP SX Cobra lower unit cracked

Where is the crack exactly on the outdrive? In the upper gear unit or lower gear unit? I'm dealing with the same issue in a spare SX outdrive I have but the crack is repairable. See this thread....
In answer to your question, you need to inspect the ujoints, the two orings on the shaft, an grease the splines at the very least. Your outdrive will have a seal I believe as well.

 

[Tsteverson]

Re: VP SX Cobra lower unit cracked

Is the lower unit. Is from being stored with the foot raised and freezing.
I left the boat at my ex's for a couple years when I got divorced and just went and got it. Trying to get it fixed up again.

 

[RaiderGrad78]

Re: VP SX Cobra lower unit cracked

I can't add anything on the technical side, but I will say that I went through this exact same issue and it was a pain in my arse. I spent a year trying to just find an empty gear case to swap my guts into and it was impossible to find one (at least in Texas). Here is one for sale: Volvo Penta OMC Lower Unit Housing 3857061 3854729 3855428 3854385 | eBay

The route I went was to just buy a whole rebuilt drive ready to bolt on from these guys linked below. I sent my drive to them first and they credited my purchase by several hundred dollars so I think it only ended up costing me about 1500. By the time I would have found a housing, paid someone to put everything in and get it shimmed properly, I probably saved money by just swapping the whole drive. Plus, it came with a warranty.
Volvo Penta SX OMC Cobra SX Outdrive Lower Unit | eBay