Changed water pump for my 1st time, no water flow. Most likely thing I got wrong?

[Bumblebeeman]

I installed a water pump kit for my first time on a 1996 Merc 200 EFI. Before installing the kit, for the past 14 months since I bought the boat water flowed just fine. I'm mechanically inclined, but obviously got something wrong. I ran the engine on water muffs, which I have done many times before. I was waiting for the peeing to start and it seemed like it was taking a long time. Then the overheat alarm went off so I shut it down. I know the alarm was not a lack of oil because this engine was converted to pre-mix with the block off kit long before I bought it.

What is the most likely thing or things I could have gotten wrong that it will not flow water? Knowing that in advance may help me in taking the water pump assembly apart to diagnose it. I was certain I got the key in the right place. I rotated the drive shaft clockwise as I slowly pushed the pump housing on to the impeller. I followed the steps in my shop manual verbatim.

Thank you

[mrichartz]

If no water.. are you sure you got water tube slid into the housing when sliding lower up?

[Bumblebeeman]

If no water.. are you sure you got water tube slid into the housing when sliding lower up?

No I'm not entirely sure. The water tube came off still stuck to the pump housing, not attached to the top of the housing. Do you think it is more likely not attached at the top or not attached at the bottom?

[mrichartz]

The water tube(tube the goes up mid section) came off
When you dropped lower... ?

[berdes]

Happened to me too. Need to reinstall it in the mid, then install the lower. You'll never get it in trying to do it with the lower.

The water tube(tube the goes up mid section) came off
When you dropped lower... ?

[mrichartz]

It's not connected at the top...
Yes if that's what happened whole tube came out...
Like berdes said you will need to drop the lower and reinstall the tube first..then install lower unit
There's no way you will be able to line it up in the top
With it on the lower unit.

[Bumblebeeman]

Yes the water tube came off its upper attachment when I lowered the gear case and came off attached to the water pump housing. At reassembly I removed it from the water pump housing and with a flash light tried to put it in its attachment at the top of the mid section. I thought I got it in there but it is tough to see. I then guided it in to the white guide tube when I attached the lower unit.

[rochelle howell]

Drop lower, pull water tube, check to make sure it was not bent from previous install, insert water tube into mid, reinstall lower.
Make sure there is a bushing or grommet in good shape up in the water tube mounting area before installing water tube, if it calls for one.
A little lube on pump housing grommet or bushing where water tube slides in is a good idea to possibly keep this from happening next time.
Might help to trim engine up for a better view if yours is not. Perhaps have a buddy hold a flashlight on pump housing and water tube junction area, and help "coach" you when reassembling.
That's where I would start.

[tunnelmike]

Are you sure you got the little key in the impeller ? Mike

[Bumblebeeman]

I'm absolutely sure I got the key on the flat spot of the drive shaft and the key ridge into the slot on the impeller. The previous consensus was that I probably didn't get the water tube lined up properly. I dropped the lower unit and completely disassembled the water pump assembly. The impeller vanes were splayed out in the proper direction so the key had to be properly turning the impeller as I lowered the pump housing during the initial installation. When you lower the impeller in the housing a 2nd time you don't have to turn the drive shaft. You can concentrate on making sure the key stays in its place on the flat of the drive shaft. I watched the impeller slide properly onto the key.

With a very strong flashlight I verified the upper part of the water tube was properly seated into its receptacle. I made extra sure the bottom of the water tube went in to the guide tube properly. The water tube looked good and was not bent. I blasted compressed air into the water intake holes covering the other side to make sure there was no blockage before putting the lower unit back on.

I thought maybe the new thermostats might be defective so I took them out for a test run. Hooked up the water muffs and no water flow whatsoever after 30 seconds. I thought could something be wrong with the water muffs or the flow rate of my hose? So I jacked the trailer up and then down with the lower unit and midsection going into a huge trash can I have submerging to just above the cav plate. Still no water flow after 40 seconds of idling. Shut it down without the overheat alarm going on.

I just have no idea what could be wrong. I drop the boat off Wednesday at Mullis Marine in Cocoa FL. I'm sure Dana there can figure it out. He's worked on Merc outboards for decades.

Thanks for your thought Mike. I will update this post with what I find out.

[mrichartz]

Forgot to ask did you actually take the boat down to the water and put it in I know there's some that have a problem with on the muffs not enough pressure or whatever but as soon as you put it in the all the way in water it's fine..
I know mine with the low water pickups are a pain till I made one that works .. instead of wasting the $55 dollars

[1954bmw]

Did the same thing on the same motor on my son's bassn boat towed to Palatka from Cincy and no water, found a local mechanic and went to dinner, before we were done eating, got a call, boats fixed, get back to the boat and mechanic asked if I had ever seen the rubber gromet that goes in the water pump housing outlet, said yep and he said you need to remove old one before installing new one, with two installed, the water tube collapses the gromet on top and blocks the water flow, check that, good luck.

[mrichartz]

Just hate to see you bring it in and it's something small just over looked..

[Bumblebeeman]

Thanks for all the recent comments. I ran the engine with the lower unit submerged in a large trash can with water up a little above the cav plate, so not sure taking it to the lake would be any improvement.

I was really intrigued with 1954bmw's comment about accidentally getting 2 rubber grommets in the water pump housing until I went over the assembly instructions again. The kit I bought came with a brand new water pump housing with that rubber grommet already installed. I did not try to install a new one. Unless there is something here I don't understand, this is not my issue. Although the kit did come with a confusing array of other o-rings, grommets and plastic washers the Merc shop manual does not call for. Maybe they want to be able to sell the same kit to be used on different motors. And of course the kit came with no instructions whatsoever.

Thank you though.

[Merc 2.5]

It shouldn't b attached ,, u have to pull the top grommet to get housing off and after u put it back the grommet goes over shaft down to pump