Backwards sea pump
 

Just wondering if anyone has ever tried mounting a merc sea pump backwards...

When you look on the back of them they say the can pump water in either direction.so it should work fine.

Yeah I know. I'm just wondering if anyone has done it. Im doing it regardless so I can put a decent oil pan on the motor. And gonna mount my oil cooler/ p/s cooler off the front bulkhead so I think it will make rigging a little easier.

I don't believe there is a backward to that style of pump. Kinda like a PD pump.

You have to change the inlet and outlet on the pump if you spin it in the opposit direction. They don't pump if you have them backwards. The KPM pumps will move enough water at idle if you plumb them backwards but will heat up with any kind of throttle the merc pump will suck the water out of the motor and pressurize the drive if they are backwards.

I am lost here as are you asking about the water sea pump impeller and housing or the water circ pump on the front of the motor ?

The water circ pump for whomever fYI - They are bi directional as the water circ pump the brass or bronze impeller can pump in either direction but the reason for that is whatever rotation the engine is itself. Lefthand common or some of the inboards are righthand rotation engines.

If you turned the actually water circ pump 180 almost 100 % sure the bolt holes will not line up and or not fit up and under for the GM apps on the front of the motor. Matter of fact I know for sure that on some GM / Marine apps that you could not mount them turned 180 degrees.

The real reason I am lost about what exactly you are asking if in fact - you are talking about sea water pump / impeller housing turning that around completely backwards, what about the pulley and belt, how are you going to install that ? I guess I am totally missing the question sorry.

Sea pump. I don't run circ pump.

I had to change my wording up so it reads a little different from my 1st post. I know what you are talking after I had to think especially now I see about the oil pan post as if you are installing an oil pan with kick outs.

If you have enough front clearance not to put fold over bends in your water hoses input and output hoses from the impeller housing body and if you can line up the pulley and belt perfectly straight, it can be done, but there is a but.

These stock Mercruiser pumps are one way inlet and one way outlet specific. The complete pump turned backwards now runs in the opposite direction so the outlet becomes the inlet and the inlet becomes outlet water directions, I know that's how it would work for the inlets & outlets but would test it 100 % beforehand and I am 99 % sure about it. its always that 1 % u have to worry about. Just saying

These stock merc waterpumps are inlet and outlet specific as I do know that for a fact. Important never change rotation direction of a used impeller and housings - you will have to start with completely brand new parts here.

IMO I would test it first before any lake runs on the water with the new positioned outlet hose in a bucket to see the volume of water flow or not.

I don't really see an issue on the inlet side guys run 90 degree fittings on them all the time. I was gonna use a 180 degree fitting on the inlet. My only concern was the mounting. I don't have a block in front of me. I was gonna use two head studs with aluminum spacer tubes to mount the pump just wasn't sure if the belt will hit the spacers. I don't think it will. That's why I was asking if anyone has done it.

You can run the pump backwards. Same housing and impeller used on reverse rotation inboards, just switch the hose routing. Never seen it done but can't see why it wouldn't work.

It works don't try to re-invent the wheel

you talk to much

You should listen more!

Your grammar sucks.

so its going to be mounted 180 out from its original stance correct, if its mounted solid to your custom bracket, and the lines are plumbed correctly for the direction of water flow and the transfer mechanics line up/ belt pulleys etc.--your good to go. pump does not care it just pumps as fitted. what pan you using on the 632?

Going to run a Stef's pan. Told them not to worry about a notch for the sea pump so it can have a decent kickout. I just know from drag race stuff the more you kick the pan out the more power they will make. I was looking at Lightning Peformance groups website. Looks like they have a couple motors with twin (not dual stage) pumps and one is turned around backwards. I know it will work that not my concern. I think the belt will just clear the bracket setup I'm thinking about which would work great I can fab everything up in an hour or so.

I actually did this on my first sea pump changes on my 25ol. I pulled it off, installed a new housing kit and greased it up.

Started it up and less than a minute, no water! uh oh.. So I I was baffled, then I pulled the hose going into the t stat and cranked it up again and it was "sucking"!!!!

whew, ok so I swapped hoses and cranked her up again and voila she was blowing, turned off, turned on hose and there came the water!!! My issue was that I searched for a diagram online and the diagram confused me with top and bottom hoses instead looking at where the hoses were coming from. Also, inlet hose has the wire in it to prevent suction from collapsing it. duh!

Why not use a crank driven pump?

"you talk to much" Thanks Pinball wizard, I am a thinker and do this for a living so its a habit especially when you have to explain details to your customers. try it sometime, it will get you moved up the ladder. Anyways sorry I take up to much space up here and your time as you can always skip over my novels. .

I would like to see pics of the your 24 Carrera if that you would make you feel better. Is it for sale ? Not messin around about this.

Randy, that's a good idea: Jabsco, Sherwood and others. easy to service. ski boats run em. that might work for him. If he was doing a super charged engine, pulley depth could be an issue, but he's going N/A I believe.

Dry sump mandrel will not allow. Can't use cam driven cause I have a front mount distributor.

Which merc sea pump do you want to run backwards .The older plastic housing pump ..or newer bronze housing. The plastic housing pumps are made to run either direction ,just swapping the inlet and outlet hose depending on rotation .

Seeing as I already have a plastic merc, brass merc and a dual stage KPM pump. I think I'm gonna go with a single stage Keith Eickert stainless pump...

Most crank mounted sea water pumps are RPM limited before they start to cavitate. Volvo Penta has forever used crank mounted sea water pumps until their LS 6.0 engine - they spin that motor at 6000 rpms and had to change their crank mounted pump to a big pulley and belt driven pump located on the front port side of the engine.

Do you have a picture of your setup Black Baja? Just wondering if you could space the pump away from the engine enough to clear your pan easier than flipping it around, or drop it under the pan?

I've run them backwards on a reverse rotation motor. As long as the pulley spins it will pump.

Sorry Randy as of right now the pieces to the motor are in three different States. It's really not a big deal to flip the pump and it will make it much easier running the water to the coolers and back into the motor. I have lots of room in front of the motor I can literally sit down in the Bildge in front of the motor so that's not of any concern. If I get some spare time in the next few weeks I'll mock it up on a spare block and post some pics.

What about moving it to the other side of the engine. I've done that before in some twin engine cats where the engine was really close to the tunnel.
Eddie

Idea went through my head. Then what do I do with the dry sump pump? I was thinking drive the oil pump off the Jesel belt because they make a drive but I don't think I could run the front mount distributor... I don't know ill try to call Jesel and maybe re-visit that idea.

Sorry, didn't realize it was dry sump.
Hardin has a dry sump pump mount to go on the other side. I've used it before as well. I think it was originally done for 36 Nortech cats. That's what I used it on. One engine had the water pump and dry sump pump where they normally go, and the other engine had them the reverse of that so that the water pump was away from the tunnel and on the outsides of the boat.