Shamrock 22' I/O 5.7 GM

[Auxlarry]

Hi,

A friend of mine has a very nice 22' Shamrock CC with a GM 5.7L engine. The boat has 235 hours on it and when we had it out yesterday I noticed it powers up great, pulls up on plane but when the engine hits around 4,200 RPM it appeared the engine started revving yet no noticeable increase in speed. It sounds like a clutch slipping on a car. Does this sound plausible? I didn't have a lot of time to look things over but it appeared to have a Power Pump bolted up to the rear of the engine and the shaft came out of the rear of that.
She just had new cables (throttle and shift) and starter installed. Is there a relationship between the shift cable and this possible slipping if the cable is not adjusted properly or what else could be an issue.

Much appreciated!

Larry

 

[Bondo]

Re: Shamrock 22' I/O 5.7 GM

Hi,

A friend of mine has a very nice 22' Shamrock CC with a GM 5.7L engine. The boat has 235 hours on it and when we had it out yesterday I noticed it powers up great, pulls up on plane but when the engine hits around 4,200 RPM it appeared the engine started revving yet no noticeable increase in speed. It sounds like a clutch slipping on a car. Does this sound plausible? I didn't have a lot of time to look things over but it appeared to have a Power Pump bolted up to the rear of the engine and the shaft came out of the rear of that.
She just had new cables (throttle and shift) and starter installed. Is there a relationship between the shift cable and this possible slipping if the cable is not adjusted properly or what else could be an issue.

Much appreciated!

Larry

Ayuh,.... Without knowin' What I/O is bolted to the back of the boat, yer question is Unanswerable...

When ya say it Rev'ed,..?? What'd the Tach jump too,..??

'n What's this "Power Pump" yer talkin' 'bout,..??

 

[Auxlarry]

Re: Shamrock 22' I/O 5.7 GM

My mistake...this is an inboard!
Using a flashlight last night I couldn't read much of what was on the transmission. Could this be an automatic transmission? I did notice a dip stick on it.

The engine acted like an o/b does when you spin the prop except this is good on the power end. Good pulling power and planes good. It's after it's on plane about 3,200rpm you throttle up and after 4,000-4,200 rpm it acts like a transmission slip!

Larry

 

[Bondo]

Re: Shamrock 22' I/O 5.7 GM

My mistake...this is an inboard!

Ayuh,... Then you've gotta ID the Transmission in it....

 

[Don S]

Re: Shamrock 22' I/O 5.7 GM

Probably a Borg-Warner Velvet dive. A common transmission on small inboards, and about all inboard ski-boats. They do have clutch packs in them like an automatic transmission, and an oil pump. Is the fluid red like ATF, or does it look and smell kind of burned?

 

[muc]

Re: Shamrock 22' I/O 5.7 GM

Most common cause of your symptom is a damaged or fouled prop.
Next most common cause is too much fluid in the transmission.