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newbie also with compression loss

Michael Alapaki

New member
Yesterday, my 1986 Alpha One 205 (4.3L) suddenly reduced RPM with the throttle at max. While cruising with the throttle maxed, the RPM rolled back from 3000 to 1000 and so I started to nurse it home to the dock. The last ten minutes sounded rough with an occasional sound like one of the cylinders making a whacking noise when it came its turn to fire. Finally, 20 feet from the dock, the motor quit completely and we rowed to shore.

I'm guessing that old age blew the head gasket, no? Is this something a newbie can repair if I bought the manual?

Appreciate any feedback. Please use little words.
 
Yesterday, my 1986 Alpha One 205 (4.3L) suddenly reduced RPM with the throttle at max. While cruising with the throttle maxed, the RPM rolled back from 3000 to 1000 and so I started to nurse it home to the dock. The last ten minutes sounded rough with an occasional sound like one of the cylinders making a whacking noise when it came its turn to fire. Finally, 20 feet from the dock, the motor quit completely and we rowed to shore.

I'm guessing that old age blew the head gasket, no? Is this something a newbie can repair if I bought the manual?

Appreciate any feedback. Please use little words.

Ayuh,.... If Wot was 3000 rpms, That's a Problem,... over-propped, or under-fueled,..??

To continue to push it, My guess is ya Burnt the motor up,...

I'd think a blown head gasket is the least of yer issues,...

How long has 3000 rpms been it's Wot,..??
 
Ayuh,.... If Wot was 3000 rpms, That's a Problem,... over-propped, or under-fueled,..??

To continue to push it, My guess is ya Burnt the motor up,...

I'd think a blown head gasket is the least of yer issues,...

How long has 3000 rpms been it's Wot,..??

I'll check the prop. Fuel is street 87 octane with stabilizer.
Since I bought the boat, I've had 3 weekends of fun with her. Is there a duty cycle or some other limit on WOT?

I forgot to mention, white smoke came out of the engine compartment when it malfunctioned. Then it seemed to use up oil and gas very quickly.

Any and all comments appreciated.
 
........... Is there a duty cycle or some other limit on WOT?

I forgot to mention, white smoke came out of the engine compartment when it malfunctioned. Then it seemed to use up oil and gas very quickly.

Any and all comments appreciated.
WOT RPM = wide open throttle revolutions per minute.

WOT RPM is to be reserved for testing prop pitch, prop diameter, and correct over-all gear reduction.

WOT RPM is NOT intended to be sustained for any duration. Testing ONLY.


The white smoke is generally caused from cooling water being consumed within a cylinder or two.
The oil consumption may be due to a piston or pistons (plural) issue.
 
The size of the propeller enables the "load" (made up mostly b the hull) to be matched to the engine's power curve and is determined by the WOT RPM the engine achieves....like Bondo said, if WOT = 3000 RPM, the engine has been working its tail off....

Some OEM's will provide you a max continuous RPM and some won't....either way, you won't find a detailed "duty factor" like you will in a diesel owner's manual...like rick suggests, for a production gasoline engine, continuous WOT will shorten the life big time!!
 
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