Seawater pump 7.4 bravo1

Handsome Transom

Active Member
Jan 26, 2018
563
Penetanguishene Ontario Canada
Boat Info
1989 SeaRay Sundancer 268 454 Bravo
Engines
454 Mercruiser bravo drive
I am going to take care of my seawater pump shortly as a matter of maintenance since our boat us new to us and I don't have any idea when it was last done . Looking for advice on what to get for the job I don't want to cheap out but do not want to replace parts unnecessarily since I have ample water being supplied now. Also should u do it now or wait till haulout
A) impeller only
B) water pump repair kit inckudes plates gaskets seals
C) water pump repair kit includes above parts plus housing
D)water pump (oem)
E)water pump brass
Thanks in advance for your input
 
Since you don’t know the maintenance history I would do C. As far as waiting, hard call, it’s working now but you don’t know how old the impeller is. First sign of a failing water pump is risers getting hot - should be able to lay your hand on them if too hot to do that you are starting to have problems. If risers are cool I might wait.
 
Take the pump out, disassemble and get whatever needs to be replaced.
Ideally that's a nice way to go except I don't want to miss out on any boating this season waiting for parts especially since this is preventative maintenance at this point . If I go this route I'll wait till haulout since it is working well at this point .
 
Since you don’t know the maintenance history I would do C. As far as waiting, hard call, it’s working now but you don’t know how old the impeller is. First sign of a failing water pump is risers getting hot - should be able to lay your hand on them if too hot to do that you are starting to have problems. If risers are cool I might wait.
Thanks I am leaning towards doing it right away since although I seem to have plenty of water being supplied I am in the middle of replacing the upper and lower exhaust tubes and exhaust shutter valves due to a pinhole leak developing in the lower tube . When I removed the lower tube that had the pinhole I was able to rip it wide open along it's seam with my hands it was Original I believe from 89 so could have been caused by age rather than excess heat and inadequate water supply . I have run the boat pretty hard post commissioning in effort to get a good shakedown on items that need attention beyond what I could find with inspection and temp was reading as it should.
 
I used to use the kit that had the impeller, plastic body and o-ring.
Do it now if you have no history, and drain or draw out the oil and change it. It gets contaminated with trace amounts of fuel through the fuel pump diaphragm.
 
I used to use the kit that had the impeller, plastic body and o-ring.
Do it now if you have no history, and drain or draw out the oil and change it. It gets contaminated with trace amounts of fuel through the fuel pump diaphragm.
Thanks I'll do it shortly I have done the oil and outside fluids . The oil I drained looked great nice Amber colour and 0 particulate engine has 700 hrs . I am leaning towards the brass pump because I like the idea of doing the best maintenance possible given our boat will be with us for many years and I don't want parts failing especially where critical parts are concerned . I am wondering if the brass pump is actually any better it costs twice the price as an oem one but guven that i do all my own wrenching if I can spend a few extra bucks on parts I don't mind for peace if mind though I don't want to waste money either
 
Brass pumps are junk. too soft
Too soft? That is something I have not heard before . I guess that should my bump ingest sand or other debris it could in theory score the inner housing but I would think the rubber impeller would take the hit first since it's even softer . There is no strainer on my 268 so the possibility of debris entering is a reality. Would you recommend stainless then? The oem is plastic composite.ny boat is raw water cooled and I am in fresh water Georgian bay Canada. I'll be in the h2o till freeze risk late October unless I can figure out a way to keep running longer without risking freeze damage
 
OEM , that plastic pump is cheap and problem free. Merc went to the brass pump after the plastic and there are countless threads on scoring failures.
 
The raw water pump is more than likely mounted below the waterline. Depending on how the suction hose is routed, it could be a bit tricky to raise it above that level and get it plugged off once disconnected. Something to consider if you haven't already.
 
Thanks I'll do it shortly I have done the oil and outside fluids . The oil I drained looked great nice Amber colour and 0 particulate engine has 700 hrs .

Just to make sure we are on the same page, the oil I am talking about is in the seawater pump. Refill with merc high perf gear oil, the green/blue stuff.
 
Just to make sure we are on the same page, the oil I am talking about is in the seawater pump. Refill with merc high perf gear oil, the green/blue stuff.
I have a bravo drive so no pump in it my raw water pump is on the lower front starboard side of my engine it's inlet is in the drive though . I also have a circulation pump on a pully at the front if the engine .
 
The raw water pump is more than likely mounted below the waterline. Depending on how the suction hose is routed, it could be a bit tricky to raise it above that level and get it plugged off once disconnected. Something to consider if you haven't already.
Yes it is I'll bung it once I get it off the pump. I also plan on bagging the lifted drive for this work since I'll be doing the lower exhaust tubes. Shutter valves and upper tubes. The lower tubes come off what some call the bullhorn where the shutter valves are which is so close to the water line that water comes into the bilge through the little holes where the rubber grommets are which the hinge pins for the shutters go in . Will I be nervous yes . Will I have extra pumps in case you bet. It Will be all well though since bagging the drive will effectively cut off all sources of water into the boat. The risk is a bellows having a hole in it exhaust or gimble bearing. In that case I'll find out pretty quick and have to pull the boat to continue . Thanks for your catching that i could sink.my boat if I was unawere of a few things.
Dave
 
Last edited:
I have a bravo drive so no pump in it my raw water pump is on the lower front starboard side of my engine it's inlet is in the drive though . I also have a circulation pump on a pully at the front if the engine .

Your setup should be a v-belt driven seawater pump. It incorporates a shaft that not only turns the impeller but has a cam lobe on it that
operates the low pressure fuel pump that supplies fuel to the carborator. The pump casting has a chamber that holds mercruiser high performance gear oil for the purposes of lubricating the shaft, seals, cam lobe and fuel pump lever. Some of the pumps have one oil plug in them. If it does, that is the fill level. Some pumps have 2 plugs, if it does, the lower one is the drain and the upper is the fill.
Hopefully you have the later because if you have only the fill plug, then you have to draw the old oil out with a suction gun if draining the oil without taking the pump off the motor. Remove the top plug first (or only plug) when servicing the pump. If more than a trickle of oil runs out,you know that the fuel pump diaphragm has a pin hole in it and is leaking fuel into the pump and must be changed. (Rare) Then go ahead and drain the oil out or remove the pump to install the impeller and just dump the oil out the plug hole. Change the oil with every impeller change as the oil does get mildly contaminated with fuel even without a fuel pump diaphragm leak. The oil will smell like gasoline, that is perfectly normal.
You are a hands on guy so when you take the pump off to replace the impeller, drill and tap a bottom plug hole if you don’t have one. It’s 3/8”-16 and takes the same plugs as you’re lower gear unit on your bravo drive. Then you can change the oil every fall before layup if your not going to change the impeller that season.
That is what I used to do on my boats like that.
 
Last edited:
Didn't think the top of the Y pipes were so close to water line but in that event, don't think a bag over the drive is going to help much unless it can somehow cover the little exh ports on the transom plate too. Let us know how you make out
 
Didn't think the top of the Y pipes were so close to water line but in that event, don't think a bag over the drive is going to help much unless it can somehow cover the little exh ports on the transom plate too. Let us know how you make out
I will I have already had the one lower off and was able to keep up with my onboard bilge pumps without bagging I am hopeful that I can slow it enough to get the shutters changed I'll for sure fill in on this when I do it tomorrow or Tuesday so someone in the future can benefit from my experience good or otherwise.
 
Thanks I'll do it shortly I have done the oil and outside fluids . The oil I drained looked great nice Amber colour and 0 particulate engine has 700 hrs . I am leaning towards the brass pump because I like the idea of doing the best maintenance possible given our boat will be with us for many years and I don't want parts failing especially where critical parts are concerned . I am wondering if the brass pump is actually any better it costs twice the price as an oem one but guven that i do all my own wrenching if I can spend a few extra bucks on parts I don't mind for peace if mind though I don't want to waste money either

IMHO,
“Best maintenance possible” is to replace the whole plastic pump kit every 2-3 years. The plastic pump is well proven design and works well.
When replacing it..ALL of the possible wear parts are brand new again. Change out the oil as previously mentioned at this interval and you’ll be happy..
 

Forum statistics

Threads
112,946
Messages
1,422,777
Members
60,929
Latest member
Henchman
Back
Top