over heating only on plane...

[1234dt]

Hi all, let me start by saying I have read don's sticky and I have read a few others posts. I have a 1979 350 with a 280 single prop raw water cooled.the boat will idle all day no problem 135 deg.but when I get up on plane it starts rising and will only drop when I get back off plane. So I think its a air leak at the water tube intake from out drive but idk... last year replaced raw water pump ,one manifold has been replaced 2 years ago other is 3 years old..salt water use boat.. where to start I'm sure someone has had same issue.. Thank you for your time to reply....

 

[Sparkinator]

Re: over heating only on plane...

My 95 HU Volvo started overheating at the beginning of last year, and I found the belt slipping ever so slightly. It would stay cool, but at the boat revved , the belt would slip, and engine start to overheat. After I tensioned the drive belt for the water pump, it quit overheating.

 

[vwbugman69]

Re: over heating only on plane...

You are correct. It is your water hose connection that needs to be replaced.

http://forums.iboats.com/volvo-penta-i-o-inboard-gas-engines-outdrives/volvo-280-raw-water-pickup-leaking-371622.html#post2483632

 

[1234dt]

Re: over heating only on plane...

So drive must come off? That would be bad as its in water on mooring and I have no trailer. I hire a guy to drop it spring an fall.. Is there a parts diagram to see what I'm up against?

 

[vwbugman69]

Re: over heating only on plane...

The easiest access is with the transmission (upper unit)/bellows removed. I've personally never just tried to replace the hose connection, so I don't know the bare minimum just to get that swapped.

There's usually a series of things I've done all at once "while I'm in there" so to speak. Bellows, Ujoints, drive oil, rubber intake hose (connected to hose connection), new seals on the fill/drain/inspection plugs on the drive, new o-rings between transmission and intermediate unit at a minimum.

 

[Walt T]

Re: over heating only on plane...

I've done those connections without removing the drive

View attachment INTERMEDIATE HOUSING DRIVE 280.pdf

 

[Maclin]

Re: over heating only on plane...

As mentioned, just need to remove upper unit, drive stays on, ends up being pretty simple. Once upper unit is off the raw water hose nipple (oops, we just lost Walt ) connection and hose are pretty easy to get at. On my drive the hose installs from the inside, that was the toughest part. And putting new bellows in at the same time is easy-peasy too.

 

[Maclin]

Re: over heating only on plane...

Ah, just noticed the mooring comment. Wouldn't do this on the water...

 

[Scott Danforth]

Re: over heating only on plane...

I would pull the boat and pull the drive. that way you can also do a u-joint inspection and bellows change.

my last water inlet housing lasted exactly 2 years and that is with flushing in between uses and it was a volvo unit (not a sierra). I epoxy coated this last one a few weeks ago.