OMC Cobra bellows are aged rubber on a discontinued drive, and cracked ones let water into the boat and onto the gimbal bearing just like any other sterndrive. The difference is that most shops will not source Cobra parts. Brad does. He replaces the Cobra bellows set, checks the gimbal bearing behind the driveshaft boot, and gets the drive sealed back up. If your Cobra is soaking the bilge, it does not mean the boat is done. Mail it in or drop it off.
OMC Cobra bellows symptoms
- Bilge water that appears with the drive in gear or underway
- Hardened, cracked rubber typical of an old Cobra drive
- Gimbal bearing growl from water past a split boot
- A collapsed or brittle exhaust bellows
- Water pushing in through the drive on a hose test
- Bellows that are simply original and decades old
What Brad checks on a Cobra re-bellows
- Inspect all Cobra bellows for cracks and hardening
- Check the gimbal bearing behind the driveshaft bellows
- Look at the u-joints and driveshaft condition
- Verify the Cobra shift cable and boot
- Assess the gimbal housing for corrosion
- Source the correct OMC Cobra bellows and clamps
The fix and what to expect
Brad sources correct OMC Cobra bellows, replaces the set with new clamps, and inspects and services the gimbal bearing while the drive is off, then water tests it. Because the parts take sourcing, a Cobra re-bellows can take a little longer than a current MerCruiser, and he tells you that up front. For an owner keeping a good Cobra boat, this is a fraction of the cost of converting to a modern drive and transom. Price and timeline are set before the work starts.
Cobra bellows and the corrosion underneath
With an OMC Cobra the bellows job is also a chance to catch the corrosion these old drives hide. Cobra transom and gimbal housings have often sat wet for decades, so when the drive comes off for bellows, Brad looks hard at the housing, the bearing carrier and the exhaust tube for the rot that ages these units. Sometimes a Cobra needs bellows and nothing else, and sometimes the re-bellows reveals a housing that has to be addressed. Either way you find out with the drive off, before it becomes a surprise on the water.