VP Overheating

[Viking...]

When my VP 125B w/270 Outdrive started heating up, I hopped on the forums here to review the previous threads with the same issue.

Replaced the Impeller, disassembled and cleaned the heat exchanger, ordered a new thermostat and checked all hoses, fittings and clamps.

There was definitely some worry when I couldn't find anything wrong. Impeller looked new, pump looked good, heat exchange element was clean as a whistle.
No leaks or kinks anywhere, and nothing appeared to be blocking the inlet stream.

A recent post from another boater indicated that his impeller pump had somehow turned inside, and the inlet/outlet ports were no longer lined up, so I pulled mine off and checked to see if mine had the same issue. Nope.

While I had it off, I noticed a rubber coupling called a "Crosspiece" that drives the impeller. Looks like it's pretty chewed up.
I'll be ordering a new one on Monday. It looks as though it might still sort of work, which might explain why my boat was overheating at higher loads (say, above 40% throttle).

Just thought I'd throw this out there, for anyone else having overheating issues...something else to check out when trouble-shooting.

Cheers.

 

[Don S]

Re: VP Overheating

While that cross piece does need to be replaced, it's not your problem.

It looks as though it might still sort of work, which might explain why my boat was overheating at higher loads (say, above 40% throttle).

I would bet money that the hose connection on the outdrive has corroded away. When you start to get on plane, it comes out of the water and the pump sucks air, not water. AKA Overheat.

Grab and move the water intake hose where it connects to the outdrive. It will probably fall off the drive. Very common problem on those drives.

 

[Viking...]

Re: VP Overheating

Thanks Don, I'll give that a try when the rain stops.

 

[Viking...]

Re: VP Overheating

All appears solid in that regard.

I taped up the inlets (sides and bottom hole) and connected the garden hose from the engine side.
Backpressure wasn't too high with that arrangement, but enough that it should have shown any leaks in the outdrive connections.
Physically the connections are solid as well, no movement when you give them a bit of a pry or wiggle.

The boat appears to have been well taken care of, with regular maintenance and cleaning (it's new to me a few weeks ago).
It's never seen salt water, having spent it's life at Big Rideau Lake (fresh-water inland).

Is it possible the cross-piece is the culprit, allowing the impeller to slip at higher rpm's?
I realize the riser could be restricting flow, it being over 20 years old now.
That is likely my next target for investigation if this repair doesn't yield good results.

Unless of course, you think another issue should be checked first.
Thanks Don.
Cheers

 

[Robj]

Re: VP Overheating

As Don stated the crosspiece is NOT causing your problem. While it is chewed up, it is a mechanical coupling that will not slip, unless it is broken. Double check the water intake like Don suggested, but this time remove the hose and see what it looks like.

Have a great day

Rob.