How to Change Your Impeller (Mercury Engine)

[lesaew]

Thank you for the write-up. I just had my 2001 21VLimited overheat on me and it appears to be the impeller.

How often should this be changed? Is it a preventative maintenance I should have the dealer do annually or just carry a spare for when I get the high-temp warning?

Thanks!
>jason

[chpthril]

Thank you for the write-up. I just had my 2001 21VLimited overheat on me and it appears to be the impeller.

How often should this be changed? Is it a preventative maintenance I should have the dealer do annually or just carry a spare for when I get the high-temp warning?

Thanks!
>jason

Once a year is the best and change it at the begining of the season so it is fresh v's sitting all winter in storage.

[sooner25]

Thank you for the write-up. I just had my 2001 21VLimited overheat on me and it appears to be the impeller.

How often should this be changed? Is it a preventative maintenance I should have the dealer do annually or just carry a spare for when I get the high-temp warning?

Thanks!
>jason

have you changed yours yet? I have the exact same boat and am wondering what its going to take. also, do you know the part number of the impeller? my serial number has rubbed off, so i can't get an exact part number.

[dogbert]

How often should this be changed? Is it a preventative maintenance I should have the dealer do annually or just carry a spare for when I get the high-temp warning?

I know they recommend once a year, but down here we do it every 2 years whether it needs it or not.
I've never had an issue, except for the first time when I forgot to do it after 2 years

[lesaew]

I have not replaced it since I've owned it (2 years) and I doubt the original owner replaced it in the 23 hrs he put on the boat.

Following the excellent instructions, I removed the pump in about 20 minutes. I have not opened the pump but ordered the impeller from the Overton's link on the thread. It appears to be a fairly generic part fitting all Mercs.

I will post after I attempt the replacement this weekend.

[lesaew]

OK! Excellent tutorial! I pulled the pump apart and found a smooth round cylinder which look like it may have had approximately 10 spines on it at one point, although I could only find enough pieces in the housing for about 8.

Anyway, it took about 20 minutes to pull everything apart, inspect, replace the impeller and put the pump back together and another 20 mins or so to put the pump back on the motor.

It smoked a little until the pump filled with water, but my temp steadied out at about 170.

Thanks again for the tech write-up. You all saved me a boat-load of repair costs and down time.

>j

[R&T Babich]

Our boat sat unused for 2 years before we bought it last October with 41 hours on it. The first thing I did was change the impeller. It looked like it was the original impeller (6 years) that had never been changed as the bolts still had paint on them. All the blades looked brand new, except for two of them. Two of the blades had cracks halfway thru the bases and would not have lasted long. The pump when sitting will have two blades bent over sharply. I suspect that when our boats sit for long periods of time without turning over the engine the impeller blades get stressed being bent over so much.

[rob_and_trish]

Just an fyi - for my '03 22v - the mercruiser 350 MAG MPI motor, the impeller part number is MER47-862232A2 not the -0001 overtons part number thats in the how to guide.

Just wanted to help anyone out that ran into the same problem.

_Rob

[noworries]

I replaced the impeller on my '02 Merc 350 MPI last night. I just bought the boat and it was the first time it'd been replaced. (The boat only has 25 hours on it). The vanes were just starting to crack at the ends so it was definitely time.

1. My 20V V-drive configuration has the fuel filter housing jammed tight against the rear battery panel cover so I didn't bother removing the filter assy as suggested in the FAQ. The seawater pump and bracket could be fished up between the engine and the hull after removal from the block. My pump is a heavy all-brass beast that looks like it'll last a lifetime.
2. The bolt holding the pump bracket to the engine had bottomed in the block and bunged up the bolt threads at the end of the bolt, so I chased the bolt threads with a 3/8-16 die and added a couple of washers to space it out some. Maybe the hole wasn't tapped all the way in by chevy or Merc left off a needed washer.
3. The removal and reattachment of the pump assembly to the block is a completely blind operation and is probably not a job for people who've not done a fair bit of wrenching. The use of an air ratchet made the job so much easier. There just isn't much room to swing a ratchet wrench back there and the nylock nut holding the bracket to the stud has to be wrenched a long way off and on. The bunged up threads on the bolt would have required ratcheting it all the way out as well. Not a fun job, but I now feel much better about heading out to the lake for a long weekend.

[Weil Thing]

Replacing impeller

I've got a question for you guys (V drive owners) who have replaced their impeller before...did you find it easier to access the impeller by going over the top of the engine, or getting down into one of the side compartments to get at it? I removed the screws from the cover to drain it last week, and did that by going over the top, but I have the closed cooling system installed, and it severely limits one's ability to access from the top.

[chpthril]

I've got a question for you guys (V drive owners) who have replaced their impeller before...did you find it easier to access the impeller by going over the top of the engine, or getting down into one of the side compartments to get at it? I removed the screws from the cover to drain it last week, and did that by going over the top, but I have the closed cooling system installed, and it severely limits one's ability to access from the top.

I'ld say go through the starboard storage area to change (not 100% with out seeing the closed cooling on but 1 tige)


Again, with out seeing the MP closed cooling setup, Couldn't you just pull the raw water hose off the pump to drain........would this be esier to do then pulling the cover?

[Weil Thing]

Thanks chp. I probably could have just loosened one of the hoses, but I also wanted to see what I would be getting into if I tried to do the impeller myself. The heat exchanger is amidships, and on the top aft end of the engine, making it tough to get an arm (or anything else!) down that way. Is a puller of some sort necessary to get the impeller out?

[lesaew]

I accessed mine through the port side compartment but there was still no direct access. I lost a little knuckle juice but it wasn't too bad.

I did not need a puller for the impeller, but a boxed end ratchet wrench came in handy for pulling off the pump.

[dogbert]

It probably depends on the engine, I've got a Merc so it's closer to the port side like lesaew said.

[jmstige]

Kudos Matt for the site....Kudos to RZMike for the article...

I have a 2001 V2300 and this article was a great help. I have the old impellor out, but I have a quck question on the comment about checking for scoring in the housing...

The bottom of the housing is scored, but no scoring on the sides.

I'm missing 1 tine and one is ripped 50%, do I really need to replace the housing?