mercruiser 454 impeller problems

[navybrat]

We put our 32' boat in the water yesterday. It has twin Mercruiser 454's w/bravo 2 outdrives. It was retrofitted with FWC. Starboard engine ran fine, Port side however overheated immediately. It went up to almost 250, but didn't pop the cap. Let it cool down and took apart the belts and pump, and found the impeller was shot. One side of the impeller looked intact, however, turned it around and all the pieces were missing. It did not appear to have dry rot, it was still very pliable. Also, there was antifreeze in the hose where there should only be sea water.

What would cause only one side to break apart like that? I haven't found any of the pieces, any ideas where they could have gone? Any ideas about why or how the antifreeze got in the hose?

We will be putting in a new impeller today. I could only get an impeller and not the whole kit, but the o rings and plate look ok. Not knowing where the other pieces are, would this be a problem?

Thanks for any help or info.

Also, both engines have always been run together, and serviced alike.

 

[Bondo]

Re: mercruiser 454 impeller problems

I haven't found any of the pieces, any ideas where they could have gone?

Ayuh,....

Somewhere Downstream,+ Yes, You Absolutely Need to find ALL of the pieces...

Any ideas about why or how the antifreeze got in the hose?

Left over from Winterization,..??..??

 

[HT32BSX115]

Re: mercruiser 454 impeller problems

If you have an oil cooler/power steering cooler downstream of the raw water pump AND prior to the heat exchanger, that's where they'll be. The oil cooler has holes that are much too small for impeller blade fragments to pass.

That's where I found the remnants of my last impeller failure.


Regards,


Rick

 

[hard-3]

Re: mercruiser 454 impeller problems

when you take off the hoses from the raw water pump , try and catch the water coming from the discharge. take the hose loose from the inlet of the thermostat housing and back flush with a garden hose to wash all of the debris from the oil coolers. when you back flush you should see the debris coming back out of the discharge hose. any small pieces can get through the cooler and become lodged in the thermostat housing or in the cylinder head water passages. best thing to do is take hoses loose every where and flush out with water from garden hose as best that you can then replace impellar and run on muffs while monitoring temps not hard to do just a pain to get at all of the hose connections

 

[navybrat]

Re: mercruiser 454 impeller problems

Thanks Everyone for the help. I found most of them in the oil cooler. You're right, it is a pain getting at all those hoses. I'm hoping the rest got chewed up enough and were flushed out. We'll see. I've heard this happens because it was run dry, but I'm sure we never did that. Always used muffs in the yard, and watched for exhaust back out. Also, temp never went above 180 before.
However, the impellers in both engines are, were 6 years old. Seems like I had to learn the hard way, that the saying "If it ain't broke, don't fix it." does not always apply.

 

[Bondo]

Re: mercruiser 454 impeller problems

However, the impellers in both engines are, were 6 years old. Seems like I had to learn the hard way, that the saying "If it ain't broke, don't fix it." does not always apply.

Ayuh,.... I change mine every Year or 2....