Hi all,
I recently purchased a 1993 Seaswirl Spyder 208 with OMC Cobra 5.8L EFI. Yep, shoulda done more research and gotten something with a Mercruiser (dumb mistake #1). Oh well, it's what I've got, so I want to make sure it's as reliable as I can make it.
Currently, it idles great, about 800 rpms. When increasing throttle, there is a hesitation as it goes through about 3000 rpm. If I set the rpm at 2800-3000, it seems to hunt between those 2. That is, it will rev to 3000 for a bit (maybe 5-15 seconds), then drop to 2800 for a bit, etc. Below or above that range, it hums right along wherever I set it.
Any ideas what causes this?
Some background:
Before purchasing I insisted on a pre-purchase inspection and test-ride. The inspection revealed it needed a new impeller and housing (dumb mistake #2). The seller paid to fix those, and the inspection continued, to include compression testing. The shop said it was good to go, so I took it for a quick test ride. It started, idled, and drove nice for the 5-10 minutes we had it out so we completed the deal (dumbest mistake!).
The first time I took it out, it ran great for 15-20 minutes while we were cruising at 2600 rpm/25 mph. Slowed in a no-wake zone for 5-10 minutes, then when accelerating out, the boat started a rapid stutter at about 2800 rpm. If I pulled back to 2200 or so, it would get on plane and I could then increase rpms to whatever I wanted and it would run well. Every time we'd idle for any length of time, the same thing would happen. Started watching the temps, thinking maybe the shop screwed up the impeller replacement. At speed, temp would be 140-160*. At idle, it would creep up to 200*. Finished the day with no other issues.
Took it out again a couple of days later, and it was doing the same thing. Then at the far end of the lake (of course!) and accelerating out of a no-wake zone, it wouldn't go above 2000 rpms. Shut it down and inspected the prop, no issues. Tried re-starting, and it was hard starting and would die almost immediately. Finally got it started and moving, and once moving it ran normally. Stopped at a marina for lunch, hoping it would cool off and "reset." Got back out, and - nothing! Hydro-locked. Called the shop, told them the story, they told me to bring it in.
They inspected it (apparently more closely) and found evidence of it having overheated in the past. Said I would probably need a new head gasket. Started tearing it down, found missing exhaust flappers, were going to just replace those and see if that fixed it. I told them to also check the riser gaskets and replace them (thanks to reading here!!). They replaced the gaskets and flappers, took it for a much longer and more thorough test-ride, and the problem seemed to be solved. Temps are rock-solid at 140*, no matter if I'm idling or WOT.
Of course now I've got this other issue - related? Thanks for any help and input!
I recently purchased a 1993 Seaswirl Spyder 208 with OMC Cobra 5.8L EFI. Yep, shoulda done more research and gotten something with a Mercruiser (dumb mistake #1). Oh well, it's what I've got, so I want to make sure it's as reliable as I can make it.
Currently, it idles great, about 800 rpms. When increasing throttle, there is a hesitation as it goes through about 3000 rpm. If I set the rpm at 2800-3000, it seems to hunt between those 2. That is, it will rev to 3000 for a bit (maybe 5-15 seconds), then drop to 2800 for a bit, etc. Below or above that range, it hums right along wherever I set it.
Any ideas what causes this?
Some background:
Before purchasing I insisted on a pre-purchase inspection and test-ride. The inspection revealed it needed a new impeller and housing (dumb mistake #2). The seller paid to fix those, and the inspection continued, to include compression testing. The shop said it was good to go, so I took it for a quick test ride. It started, idled, and drove nice for the 5-10 minutes we had it out so we completed the deal (dumbest mistake!).
The first time I took it out, it ran great for 15-20 minutes while we were cruising at 2600 rpm/25 mph. Slowed in a no-wake zone for 5-10 minutes, then when accelerating out, the boat started a rapid stutter at about 2800 rpm. If I pulled back to 2200 or so, it would get on plane and I could then increase rpms to whatever I wanted and it would run well. Every time we'd idle for any length of time, the same thing would happen. Started watching the temps, thinking maybe the shop screwed up the impeller replacement. At speed, temp would be 140-160*. At idle, it would creep up to 200*. Finished the day with no other issues.
Took it out again a couple of days later, and it was doing the same thing. Then at the far end of the lake (of course!) and accelerating out of a no-wake zone, it wouldn't go above 2000 rpms. Shut it down and inspected the prop, no issues. Tried re-starting, and it was hard starting and would die almost immediately. Finally got it started and moving, and once moving it ran normally. Stopped at a marina for lunch, hoping it would cool off and "reset." Got back out, and - nothing! Hydro-locked. Called the shop, told them the story, they told me to bring it in.
They inspected it (apparently more closely) and found evidence of it having overheated in the past. Said I would probably need a new head gasket. Started tearing it down, found missing exhaust flappers, were going to just replace those and see if that fixed it. I told them to also check the riser gaskets and replace them (thanks to reading here!!). They replaced the gaskets and flappers, took it for a much longer and more thorough test-ride, and the problem seemed to be solved. Temps are rock-solid at 140*, no matter if I'm idling or WOT.
Of course now I've got this other issue - related? Thanks for any help and input!
