A little info please.I need to replace the impellers on my 496ho's in my 2004 30'outlaw.It does not seem possible to do these without removing the back seat of the boat.removing that seat seems like quite a task.Also I've never done the pumps on a 496 and am hoping that it is similar to the pumps I had on my last 502.Any help I can get on doing these pumps I would really appreciate

Good luck with your question--I posted a similar question on the Baja thread the other day and got NO response. I will tell you that if you do a search for impeller replacement you will find a lot of information about doing the replacement however I didn't find any "tricks" to deal with the lack of space. I asked on the Baja thread hoping that some of the guys that use to work for baja might have a trick of the trade but I got no response. Do a search and you might learn something that will help. Sorry--I haven't tried to tackle mine yet--I have a mechanic that I will let fight with them.
Jay

I will tell you that you should look very close at the back cover and the inside of the body. If there are any deep grooves replace the whole pump. We have had alot of pumps still not cooling after new impellers, Because of the by passing on the ends of the impellers. These pumps are NOT CHEAP, But like you said it is very tight and you wouldn't want to do it twice!!!

I'll try and help. Do you have Gen two or three cool fuel on your motor? If your back cove is groved we have surfaced them on a large belt sander and worked fine. I will tell you the task at hand any way you put it is not easy.My shop # 281-326-4800.

You don't have to pull the seat. I do mine every year. I've typed up some pretty detailed descriptions over on TBM. Check it out...hope it helps.

http://www.teambajamarine.com/forum/...light=impeller

I copied some of the details from the link above.

Post #1
I've done 496 impellers several times and I can't remember dealing with any air lines. I just loosen the tensioner on the alternator and remove the serpentine belt. Next, there is a pulley assembly (#16 in the link below) that you have to remove, I believe there is one bolt and two nuts that hold this on and the nuts also help hold the seawater pump bracket in place. A mirror and good lighting are essential tools for getting that pulley assembly off! Once you get the pulley assembly off, you can see the seawater pump and the additional 10mm bolts that you'll have to remove along with the two hose clamps on the inlet and outlet of the pump. There is also an electrical plug going to the water pressure sensor that you'll need to unplug. I do remember removing the fuel/water seperator and the two nuts that hold the bracket that the fuel/water seperator screws on to (sorry I don't know the technical name for this). I think I removed this to get better access to the hose clamps. Once you get the seawater pump off, you can set it on the workbench and easily change the impeller.

http://www.mercruiserparts.com/Show...c=SEAWATER+PUMP

Post #2
I changed my impellers the other night and did see the air lines you were referring to. These just run near the seawater pump but you don't disconnect them or anything.

I made a mental note of the tools required:

10mm socket - to take alternator tensioner bracket assembly off and also to disassemble the seawater pump once you get it out of the boat
13mm socket - for top bolt that holds pulley assembly and also to remove the two lock nuts that hold fuel/water seperator and cool fuel assembly (you can just drop this down without removing)
15mm deep socket - for the two locknuts that hold the pulley assembly
17mm socket /15mm wrench - to tighten alternator tensioner when you're finished
5/16" socket / flathead screwdriver - for hose clamps
Small Mirror - so see where the nuts and bolt are for the pulley assembly
Locktite (blue) - to reassemble seawater pump

In summary, bring a ratchet; a couple of different length extensions; sockets in 5/16", 10mm, 13mm, 15mm (deep style), 17mm; 15mm open end wrench; flat head screwdrivers, a small mirror; blue loctite, and lots of patience! As mentioned above, an extending magnet and some bandaids are helpful too.

I believe that's about it. If you're going to change the impellers now is a good time to change the fuel/water seperators and clean the small fuel filter canisters (these look like standard GM fuel filters but they're not). I just backflush the little canisters in the parts washer and blow them out. These things are about $50 each and have a thread pattern that I could never find at the auto store. I cut one open a long time ago and there is just stainless steel screen in there which I suppose is just to block larger particles. Also, you can get the Fuel/Water seperators from any auto store that sells Wix filters. Wix has a direct cross-reference number for the mercury part number. Sorry, I don't have the Wix number handy right now.

Chris,
Thanks for taking the time to post the detailed description of this "fun" job. I think this will make it much eaiser for those of us that haven't tackled the job yet.
Jay

Busta has a very good disc.
What year is your boat. My 03 29OL with 496 was just like Busta's disc. My 2006 HO's dont have the water pressure sender on teh pump and I have a auto belt tensioner. More like a car.
I also have the air lines. Just be careful removing them. Its a push in clip and remove the hose.
The hardest part to me on both engines was removing the freakin water hoses. they are a Bit@H!

Also since you are doing the hoses. Its best to remove the inlet on the oil cooler side and flush some water through. My oil coolers were plugged pretty good. As the water was running I was swabbing my finger inside the cooler and getting out all kind of gunk. (seeweed, etc...)

Dont worry every time I do the job I get very frusterated and almost say boating is not worth it.....Well those words may come out a few times but when the job is done. I calm back down

Chris,thanks for your time posting that very detailed repair.You make it sound so fun I think i'll leave it until the spring.If you did'nt say it could be done I would have bet my life that the back seat had to come out.I tried to get a look at the starboard side pump and I could'nt even fit my head in there to get a look.I can tell there is going to be alot of cursing going on when I do this job.thanks Charlie

The starboard side is a bit more difficult to get to. I would start with the port side just so you can get the procedure down and the tackle the starboard side. After you've done one, it's not that bad. The hoses that go to the waterpump are a pain to get off. When you put the hoses back on, spray a little WD-40 inside each of them and this will make you life a little easier!

Now that I've done it a few times, I can change both impellers in about 3 hours.