1978 Volvo 280 Slipping Under Load

[Flamingoguy]

Hoping someone can offer some help quickly as I have someone interested in buying my boat and trying to fix what I thought was a simple slipping prop problem but marked the nose cone and prop hub today and no change after taking it for a run. Am I right in assuming the nose cone is splined onto the prop shaft and shouldn't also slip if the prop was actually slipping on it's rubber hub?
The nose cone also has the center bolt attaching it to the end of the prop shaft.
Is there some other simple trouble shooting things I should check first that might be out of adjustment that would cause the slightly higher revs when under load. Occassionally it will sound like it just slipped completely out of gear when at top speed and I'll throttle back and throttle back up and it will revert to it's normal slightly higher revving routine while getting up to plane. No other strange noises coming from the out drive that would indicate problems and boat and motor well maintained with lot's of like left in the AQ140. Cruise around at slower speeds for hours and no problems what so ever.
Could a gear system be slightly slipping somehow and then occasionally totally slip? If it sounds like a overhaul of the leg I was contemplating just buying a used 280 for $700.00 and throwing it on just to get the boat gone now and then haul apart the old 280 over the winter and sell it come Spring. Thoughts anyone?
Thanks.
Glen

 

[Don S]

Re: 1978 Volvo 280 Slipping Under Load

First a note on props slipping. When they do that, they go real bad, real fast. If it slips once, the rubber hub has let go of the prop. From there, anything over idle is impossible. After 1 slip.

On the Volvo drives, usually slipping starts because of water getting into the drive. Usually from the bellows being bad and water getting into the drive.
Drain the oil and see if it is milky.

You can also pull that back cover and make sure the when you shift, the shift arm (similar to one in pic below) is going all the way into forward, and reverse, and centered when in neutral.

If you do go the used drive approch. Make sure you have the right gear ratio.

 

[obwhan]

Re: 1978 Volvo 280 Slipping Under Load

I also have a like problem The boat goes the same speed at 2000 rpm as it does at 4800 rpm. The bow (front)of the boat comes way up like it's going to take off but doesn't go any faster. At the higher RPM the bow stays up high. Is there anything in the stern drive that would slip. Not totally sure but I think the propeller and hub is okay, not sure I am new to this forum and just bought the boat. A 78 Bayliner with a 4 cyc Volvo eng. Can I put it in gear shut off the engine and try to turn the prop. to check it out.

 

[oneathefaintest]

Re: 1978 Volvo 280 Slipping Under Load

I have the same problem, I have a feeling there's about a million different reasons for this. Guess we'll have to just take it in and pay the man $200 an hour.