Volvo impeller housing got really hot - why?

[security6]

I was winterizing my boat on Saturday, and the first step is to warm up the engine. I put it on muffs and started it up. I had it running at about 1000 rpms, and verified that water was coming out near the transom shield. It ran for about 10 minutes, everything seemed fine. All of the sudden I noticed that my temperature guage was up to 180 (normal is 172) so I shut it down. Yes the hose was still on and water was flowing to the muffs. I opened up the engine housing and noticed that a rubber piece on the impeller housing had melted some and was smoking. Obviously the impeller housing got really hot. What happened?

After things cooled down, I pulled the impeller and it looked ok. One of the vanes was slightly torn and mashed, but the other vanes looked fine. Of course, I will replace it with a new impeller. I still can't figure out why the housing got so hot.

Details:
1999 Volvo 5.7 PEFS
Impeller was replaced (by me) last June with a genuiene Volvo replacement
I have run the engine with the same muffs and hose many times without issue
Boat has been running fine

Thanks!

 

[erie_guy]

Re: Volvo impeller housing got really hot - why?

Sounds to me like it ran dry for some unexplained reason. Perhaps the external hose connection between the transom shield and the lower leg has a kink or a collapsed portion and I would also look at the inside tubing that leads up to the raw water pump - as it also could be damaged.

The pump impeller should last at least a couple years so overheat is certainly plausable. Another thought : Did you have excess water flow to the muffs so the pump did not have suction difficulties ?

Will be pulling my VP powered boat in a few weeks but I always winterize by draining and sucking the water (wet vac) from the engine's block and hoses.

May the winter be short and warm.

erie_guy
Port Clinton, OH

 

[security6]

Re: Volvo impeller housing got really hot - why?

I figured it ran dry, but I wasn't sure why. Is it common to get kinks in the boat hoses? Perhaps I had a kink in the external hose, but I think I would have noticed it when I took the muffs off.

I was warming up engine for the oil change, so I'd have to do it whether I drained the block/manifolds or used a vacuum as you do (sounds a little scary to be honest).

I had the hose hooked up and the faucet all the way open. We're on city water, so sufficient pressure has never been a problem.

 

[erie_guy]

Re: Volvo impeller housing got really hot - why?

Common, no I only had that problem once with the short external hose from the stern drive to the transom shield - so it is not common. I would put my bet on the garden hose stopping flow because of a kink. That happens to me often when watering the lawn and pulling on it a bit.

Using a wetvac to get the water out of the engine, manifolds, and risers is for me the easiest way to assure no water is going to cause problems. I also use this technique on my boat's water system, hot water tank, fresh water tank, an A/C heat exhangers. I tried the pink antifreeze in the fresh water system, but I could taste it all the following year.

Warming the engine for an oil change is good policy, but I do my oil change before pulling the boat for winter storage. On a trailer problems can develop with the cooling system.

erie_guy

 

[Lou C]

Re: Volvo impeller housing got really hot - why?

I dont' use garden hose to run the engine for that reason, I use Goodyear 5/8 in heater hose with a good set of dual feed muffs, the heater hose does not kink like garden hoses can....

 

[BILL INGRAHAM]

Re: Volvo impeller housing got really hot - why?

on my 2001 5.0 gxi mufflers did not work. i reasoned because of high hour seawater pump[had internal wear but impeller was fine] would not pick up water but worked fine with boat in the water. i now feed disconnected hose at power steering cooler with elevated 5 gallon bucket and feed the bucket with water[draws it down fast]. for winterization-i ad red rv solution to bucket and run until bucket almost empty.takes care of seawater side components.my engine is protected any way as it has enclosed cooling.