Dumb mistake dry running

[efdog]

I was winterizing my 97 90HP Merc 2 Stroke, and totally forgot to put the muffs on. It ran for about 30 seconds or so before I noticed and killed the engine. I immediately put put the muffs on and ran it for another 6-8 minutes. It still had a strong stream coming from the telltale. How difficult is it for me to inspect the impeller? Should I be worried? Thanks to anyone with some advise for me.

 

[1fishbone]

Re: Dumb mistake dry running

I'll guess you used it all year?

I would like to have piece of mind!
Replacing it isn't hard, or expensive.

 

[Moody Blue]

Re: Dumb mistake dry running

I've seen photos of impellers after running dry for only 30 seconds. Not pretty. I'd replace it.

To inspect the impeller, you need to remove the lower unit and take off the upper waterpump housing. No special tools required and can be completed in about 1hour your first time and will cost between $15 and $50 depending on what needs to be replaced. As a general rule of thumb, it it advisable to replace it every second season.

 

[redjmp]

Re: Dumb mistake dry running

If it is still pissing well at idle it is fine but they should get changed every 2 at most 3 years so if it hasn't been changed recently its time to change it anyways.
At higher speeds the ends of the vanes don't even make contact with the housing wall so it does not matter if the ends are a little scuffed as long as it still has a strong telltale at idle.

The biggest problem with them is the rubber deteriorates and cracks with age and can separate from the hub.

 

[CharlieB]

Re: Dumb mistake dry running

ERROR

Hose pressure while using the muffs can comepletely push enough water that a fried impeller isn't noticable, till you launch the boat next year only to find out you have a weak stream, or worse, no stream.

Even at a moderate high idle speed, an impeller will melt in as little as 30 seconds, or LESS.

Pull it apart for close inspection. Check the flat stainless surfaces for a line worn into them from the impeller hub, check the plastic housing for any signs of deformation from heating. If you find either signs then replace with a complete rebuild kit.

Seriously, you would much rather take care of it now than leave it and waste your trip or weekend next spring.

 

[efdog]

Re: Dumb mistake dry running

I don't think I'll take my chances. I'll replace it just to be safe. It hasn't been changed in a couple years anyway. Cheers!

 

[efdog]

Re: Dumb mistake dry running

My serial is 06528043. I can't seem to reference this anywhere? It's a 1997 90HP 2 Stroke ELPTO. I want the OEM impeller, and need the part # for the kit. Any advise on where I can find this? The reference through this site has no mention of my serial, and only sells aftermarket . Thanks

 

[Moody Blue]

Re: Dumb mistake dry running

I think your S/N might be 0G528043.

 

[efdog]

Re: Dumb mistake dry running

You were correct. Got the correct serial # and found the part (47-43026T 2). Thanks as always!

 

[efdog]

Re: Dumb mistake dry running

So after a ton of searching and finally calling Mercury directly, it seems as though they no longer produce my OEM impeller as a kit to include the rings, and gaskets etc.. So my options are either to replace only the impeller with OEM, or go with a Sierra kit. Anyone have any opinions or experience with the aftermarket impellers?

 

[jbjennings]

Re: Dumb mistake dry running

I'd replace it with an oem impeller, not buy the kit, and go fishing. The dry run likely didn't harm the other parts. I've had good luck with sierra impellers although I don't run motors as large as yours. You'll know if you need the other parts to the kit when you get the housing lid off.
JMO,
JBJ

 

[will941s]

Re: Dumb mistake dry running

Sierra is fine. I use their carb and waterpump kits and have never had a problem with them. And thy are cheaper too.

 

[Moody Blue]

Re: Dumb mistake dry running

If you don't know the last time the impeller was changed, I would replace at least the impeller, upper housing, wear plate and gaskets (upper waterpump kit). Even the slightest scoring/grooves will affect pump performance.

To be thorough, the lower pump housing should be changed as well because it contains the driveshaft seals into the lower unit. Once you get things apart, you will be able to see the condition of the existing parts.

As for the OEM vs Sierra question, I would not hesitate to use Sierra parts. Never had a problem with their stuff. Because they are generic, many times you will find "extra" parts in the kits because it is applicable to several different motors/models. Just use the parts you need and toss the rest.

 

[efdog]

Re: Dumb mistake dry running

I've gone ahead and ordered an OE impeller. I think I will aslo grab a sierra kit specifically for the gaskets, plate etc, and to give myself a spare on hand. I've yet to hear anything negative about sierra parts. Oh yeah, I forgot to mention, someone I spoke with today from Mercury marine outboards division told me I should be replacing the entire water pump, housing and all. Any truth to this? To me it seems like a waste of money. How could I damage the actual housing?
Thanks everyone!

 

[Moody Blue]

Re: Dumb mistake dry running

Oh yeah, I forgot to mention, someone I spoke with today from Mercury marine outboards division told me I should be replacing the entire water pump, housing and all. Any truth to this? To me it seems like a waste of money. How could I damage the actual housing?
Thanks everyone!

See my previous post. The pump housing is molded plastic and could be damaged/distorted by the heat generated by running the pump dry. Because there was no water in the system, the heat from the exhaust as well as the friction of the impeller, has the potential to melt the housing completely. Only a visual inspection will tell the extent of damage.