Circulating pump
 

Ok I just got home with my new/used 2000 28.8 Sunsation with 70 hours. when i was tuning it up for summer use, I hooked up the hose, and when i turned it off from running the engine, the lower pump hole was leaking out fresh water. I was told i can just RTV the hole up? I am going to install a new raw water pump and circulating pump now. But I would like to know can you really just plug up the seep holes?


Thanks!

No! If you plug the hole the water will go through the bearing.

CAPO71,

Secretformula has it right... Presently the seal on the pump is gone, thus the water, and the next thing will be the bearing...
Looks like it's time for a bypass kit and eliminate the problem
from ever happening again, not to mention the cost of pumps
on an ongoine basis... Stainless Marine does a really nice job
and I have used their products on the past three boats with no problems... :) :) :)

Karl

How exactly does this water by-pass work/ do I replace the water pump with a by-pass tube and what will pump the water? Just the raw water pump?

CAPO71,

Exactly, the raw H2O pump does a fine job, and in many cases better than needed, unless you have a closed cooling system...
Just an fyi, here is the URL for Stainless Marine... They are very good and if you have questions they are also quite knowledgable... www.stainlessmarine.com

Karl:) :)

PS... If you do have a closed cooling system then you will need to keep the circulating pump...

It seems that many of the mercury circulating pumps fail very early. I have twin 385 mpi's with 50 fresh water hours on them and both of my pumps leak. I have talked to a number of other mercury owners with the same problem.

Does Mercury have a class problem? If not, why failures at this low number of hours.

How many members are experiencing these failures?

Dave

When you hook up the crossover, what do you do with the belt? get a different size belt for the -minus water pump pulley?

capo71- crossover off my 454 mag allready has pressure relieve if it fits make me offer.James

Could high water pressure be the cause of so many circulating pumps leaking?
Dan

candyman

high water pressure, spikes in water pressure, and dirt or contamination between the shaft and seal are the main reasons for bad seals in my opinion.

CAPO71,

You have it now... It's just a shorter belt... Not sure of your application but I can pull one of the spares out of the truck and let you know the length... It's the alternator belt unless this is the last thing to go...

Karl

PS... If you have a singel the one listed above will do the job including the thermostat bypass to wet the headers...

Thunder1,

would that (above) setup work with a 174 B&M ??

hi-perf-2000,

Yep... I have them on 525-SC's and have also used the same
bypass on the a 174 blower with an "automotive replacement
intake"... That would be the $300 vs. the $1500 version replacement... Go for it...

Karl

hi-perf-2000,

Sorry, I forgot to mention that re-plumbing the headers is something that may have to be done depending on whether
you have stock Mercruiser/Gil application or otherwise... It eliminates the need for two hoses, which came from the old
thermostat housing, and using a singular hose down to the header water inlet...

Karl

I am running stainless marine exhuast...so i should already be plummed correctly.

Are you saying that i need a different "automotive" intake manifold to adapt the themostat housing???

hi-perf-2000,

Nope... It will work fine for you... What I meant is that if an intake for the blower fails, that would be a water leak from corosion, that the much cheaper auto intake will also work with the bypass shown in this thread... The difference is that they place the thermostat opening in the casting directly under the blower drive snout and the above replacement (Stainless) is the only one that will work... Hope I am a bit clearer this time...

Tnx, Karl:) :)

I think i get it now. The intake i am using does have the thermostat directly under the snout.......and there is an "adapter" type housing that directs it over about 6 inches and then up (to clear the snout).


I've seen many crossovers on N/A motors, but never seen the "pressure relief" as the one pictured above?? What does this do, and what hose gets connected to it??

Mark

Mark,

Relief Valve... I have not seen one built in from the manufacturer but this one has it... The functionality is that the sea pump, depending upon restriction of the engine, coolers and exhaust, will build upwards of 30 lbs. of pressure in the system... It is not desirable to hold this amount of water pressure in the cooling system and this is a good method to eliminate the problem... I would imagine that it would trigger somewhere between 10-15
lbs. but this would depend on the product... The hoses attached would have to vent to the outside of the boat or parallel to the
header intake or output... Transom exit would seem the cleanest...

Karl

CAP071: You probably have the newer serpentine belt set-up (if its a Mag MPI you do). I tried last year to find a cross-over kit but nobody made one. It would need to have an idler pulley to route the belt correctly. I ended up buuing a new circ pump (have been through two on my '99 so far) BAM has a good price on the merc units. My original merc and an aftermarket have failed on me and now I'm on a Merc unit from BAM. One year and so far so good...