WaterPump 200 Merc

[TN444PSD]

Can a water pump impeller be installed wrong/upside down? I have a 99 model 200 merc and it just doesnt seem to have the pressure I would like.

 

[tyler ware]

Not on my boat, don't think so. Did you just install it yourself, or did you have someone install a new one for you? If you don't get everything lined up in there it can cause this problem I believe.

 

[wrechin2]

Can go on either way. Does not matter. A omc can go on only 1 way, but the way it is made will not let it go on if not right. What pressure are you running? 15-18 at WOT with lower buried is normal and no less than 12 if running a jack plate, can be too high and pulling air. I have filled up many holes on lowers to allow higher water pressure. On Ditchdocs,I filled up 5 holes on each side. Before we did that at wot it was around 13-14 PSI, now runs 18-19 PSI. Low water pressure can come from several places, poppet, is what contros water pressue, blown gasket under pump sucking air after on plane, ect. Need to know what PSI you are running. If you want to run it by one day, I can test the gauge for accuracy. May be a gauge issue, pinched hose, ect. Hope this helps.</p>

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[wrechin2]

Tyler,
Man i may have found some info. I may be able to cut the booster port in your 115 and turn it into a 150. You would need to find some specific # of carbs to utilize the added power. I am trying to get the location I would need to mill them in. Looks like would take just a few minutes. Will just have to get the loccation and angle they need to be cut. Just a thought.

 

[TN444PSD]

Wrechin2,
Heres the set up,
20' bullet, 12" JP
center of hub is 1.5" or 1.75" below pad, cant remember, need to check
Top 3 holes in lower unit plugged both sides
26P trophy plus prop or 25p trophy (cracked at the moment)

At idle around 2-3 psi and sputing waterer out the piss hole
At wot depending on trim it could be 7-8 psi or as high as 16-17

After startup, takes quite a few seconds for water to pee
bring the RPMs up to about 1800 and it helps to get it going

Coming on plane, if I dont keep her wot and start trimming her flat the pressure is 7-8
Hit the magic spot on plane and it comes up slowly to 15 or so
Slightest turn and it drops to 10 +/- 2 psi

I am thinking of putting a water temp gauge in like my last boat just so I can see how the wp affects the temp.

I put a housing and impeller in last summer after I bought the boat and it wasnt any better then what it was.

Some people tell me these numbers are ok but I just would like to see the 30 psi my buddie gets with his evinrude... its the warm and fuzzy feeling of not cooking the motor im looking for.

I would love to bring it by some time and have you give it a look.

 

[wrechin2]

APPLES TO APPLES. IF you see 30 PSI on your merc, you have a PROBLEM!!!!OMC have a lot LARGER pump and have 2 housings 1with bleed hole and 1 without. Your WOT numbers at 7-8 are NOT good. Mercury wants at least 12PSI. The reason it takes a few minutes to pee is that on a merc it is on the expelled water side. The engine has to reach 143 at IDLE to pump out the pee tube or the poppet has to open. OMC Pee tube is on the inlet side of the system. If you feel the pee on a OMC it is warm to cold, a merc is HOT. The delay in pee'n is normal. The 2-3 PSI at idle is normal.The jackplate being that high is starting to suck air or aerated water dropping the PSI. Take a pic of your water intake on you lower and post it. I ususally just leave 3 open on each side. That is more that the tube can handle. My low water pick up has 5 holes total and some of the HP CLE's only had 2 holes. </p>

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The problem with water temp is that you have 2 thermostats and you can overheat the port side and not set the alarm off or you install a temp gauge and it only shows you the port heat. Can set the alarm off and show 160* as temp and the starboard head be at 260 degrees. I install 2 overheat temp switches to ensure that this doesnt happen like a OMC. </p>

 

[TN444PSD]

Wrechin2, You think the motor is to high at 1.5-1.75 BELOW pad? For some reason I think my lwr unit has 7 or 8 holes leaving 4-5 open now with the top 3 plugged. I feel a bit better with what you stated about the delay on the pee and the idle psi, as for the WOT, as long as I trim it I get the 15-18 psi but I cant just cruise around 40mph , I have to have her skinned back to keep the pressure. I dropped the motor once last week and kept better water pressure but the boat would not handle worth a dam. Ill re-measure my below pad number tonight and also take a pic of the holes for ya and post them tonight. I think im just gonna have to break down and buy a low water pick up unit or system.

 

[wrechin2]

Now pressure at say 3500 RPM will be about 8-10. The faster the pump turns the more pressure it will make. I fill in all but 3 on each side. They will carry more water than the supply tube can handle. On taylor's we went to 18-19 psi at wot from 13-14. Keep inmind LWP will sometimes slow a boat down by about 4 MPH due to the increase in drag from more lower, unless you can fully utilize it. It also makes them safer at 84+ from not blowing out and making you go swimming. The reason the boat handle like crap was the additional drag from the lower unit and the boat was reacting by chine walking more, usually what it does.

 

[TN444PSD]

Thanks for your input, i will look this evening after a bussiness dinner and let you know what I find.

 

[wrechin2]

No problem, post a pic if you will. Later.

 

[Skeeter]

Not trying to highjack your thread but Wrechin said something that caught my attention. James you said that on a Merc. 30PSI is not good. That it was diffrent on a OMC. I have a 200 Johnson that stays at 30 (regular) and about 40 at WOT. Is that ok on a OMC?

Thanks,

 

[wrechin2]

On a omc with no bleeder hole in the housing it wil probably reach that. You may have a bias gauge. Does your gauge show 0 when off or like 7-8 PSi? Sounds like you are not picking up any aerated water and getting good pressue. The engines have poppets that control water pressure. If a passage gets stopped up it will cause the water pressure to increase due to no way to "relieve" pressue. This will cause high water pressure and a overheat issue due to no flow. Should see some of the looks I get when I tell someone that!!!

 

[Skeeter]

The gauge is reading good. ("0" when off.) The reason I asked is my 98 Venom 200 would push about 15-20 wot and this 94 is twice that.

 

[wrechin2]

V-6's to 92 have a "weep" hole (LEAK) in the water pump housing and V-6's 93-up do not have a "weep" hole thus able to make more pressure. The "weep" hole is a actual 1/4 hole in the water pump housing. It bleeds off some pressure. So both yours should not have had no weep hole. Are these power head swaps or engine changes? It could be possible that they had mismatched lowers or water pump housings. What is the full story. Didn't you just have a powerhead change? It could be as simple as you had a late model engine that someone had put the early model pump housing on (low pressure) and then it got swapped out to the correct housing( higher pressure). ALOT of parts will interchange and things like that happen.

 

[Skeeter]

It was a complete swap. The 98 blew and could not be rebuilt (within reason) so I found a 94 on a boat and just swapped complete motors.

 

[wrechin2]

Thing is would have been a easy mistake for one to have had the incorrect housing, as they look the sames except the hole.

 

[TN444PSD]

Ok, I have not been able to post the pic of the lower unit but I have 8 holes either side with the top 3 on both sides plugged, should I plug another 2 on each side? Do you think this will help with the pressure?

 

[wrechin2]

I run those cases with 5 on each side filled. It will help if the water line is right at those other 2 holes.