water leak from motor

True North

True North

Member
Sep 11, 2012
165
Live: DeWitt, MI,West Michigan (Ludington)
Boat Info
2005 SR 260DA
350 MAG MPI
Bravo 3
Engines
(1) 350 MAG MPI w/Bravo III
new to me boat has sprung a leak (2005 SR 260DA with 350 MAG MPI, B3). After close review I am able to determine where it is coming from, however I'm not sure how to go about repairing it. I forgot to take a pic and the boat is now 150 miles away again, so pls bear with me+ I am just now getting familiar with the boat since I have only had it since July 3rd :)

It is on the starboard side of the motor, on the bottom of the block, down low, right above the oil pan, centrally located, right behind (aft) of the fuel pump/filter "black box". It looks like the older style freeze plugs. It's got a threaded brass part that looks like it's screwed into the block, but has a small diameter hose leading from it. It sits behind a bunch of other water hoses (larger ones). It appears there is one similar to it on the port side of the motor as well. I assume it is part of the cooling system (fresh water cooled). It only leaks when the boat is running i.e. circulating cooling water. I verified it both on the muffs on the trailer and in the water. I can't tell for certain if it is actually leaking from the threads into the block (it appears there may be some type of plumbers putty or some sort of sealer on it) or the hose that is attached to it. There are no hose clamps on either one (port or starboard) so my guess is not a high pressure water route or forgot to put clamps on from the factory??? I will have to remove other hoses in front of it to gain proper access.

So who can tell me what those are and how I should go about trying to repair it? I'm worried about if it is a cross-threaded situation of a plug from the factory-boat only has 300 hours on it. It didn't leak during sea-trial??? It causes enough water in the bilge to run the bilge pump every so often. I have continued to use it with the leak as it doesn't appear to be impacting operating temp. Does anybody have a water-cooling diagram resource of what this could be?

Sorry so detailed, but without a pic wanted to provide as much info. Thank you in advance.
 
That is an engine block drain hose. It has a quick connect in it. No hose clamp. If you disconnect the small diameter hose, you will have a 1/4” diameter open port right into the coolant circulating around the cylinders. It will be a big leak with the engine running.

If you really are fresh water cooled, there will be antifreeze leaking from there. If you are raw water cooled, it will be sea water.
 
so just to clarify.....it is raw water cooled i.e. circulates water from the lake (fresh water not sea water ;)
The hose is still connected to it, but I can't see well enough to determine exactly where the water is leaking from (other hoses in the way). Is that part of the drain system for winterization? I haven't looked into winterization processes yet, but it was my understanding from previous owner that this motor was a simple drain (blue plastic valve) on the lower front port side) to drain the water? I can look into that closer to the time, but what is the purpose of this quick connect connection and how should I go about gaining access to it to trouble shoot further? Thank you.
 
good point regarding winterization, however 1) I have access to heated storage for the winter so not sure if it is necessary to change over the system right now, 2) that doesn't assist me with repairing my leak. So that plug/fitting on the block that has the hose leading away from it, where does it circulate to and what does it do? Is it just a "drain" from circulated water through the block? Where does that circulated water go from there? I didn't look at it that closely as I was pressed for time when I was troubleshooting the leak. Again, trying to gain knowledge so I can perform the repair this next weekend when I am back at the boat. Thank you.
 
so blocking it off i.e. not having a hose from that fitting will have no negative consequences in blocking it off? Why is there even this system in place if it is not needed? I will plan to plug it as you say, hopefully it is not a stripped thread situation that is causing the leak in the first place. I will report back if I run into trouble when I work on it this weekend. Thank you for the info!
 
It's an iron block with pipe threads, damn near impossible to strip. It's the fitting that screws into it that you may have a problem with. Don't use a brass plug with the inverted hex that you'll need a hex bit for, get a brass plug you can put a socket on.
 
Definitely set it up for easy access. Those plugs/valves should be remove annually to allow sediments to drain. Otherwise sediment will build up in the cooling passages causing hot spots in the block and possible overheating.
 
understand, that is how all my other boat motors (mercruisers and OMC's) were, but why is there a hose connected with a passageway then to allow water to circulate through? That is what's not making sense to me at this point. I wish I would have paid closer attention to see where that hose leading from there routed through???
 
Generally speaking the boat comes from the mfg with plugs or a Petcock. The hose was probably some previous owners attempt to simplify winterizing?????
 
Sounds like that is part of the quick drain kit - there should be a knob on front of engine that you turn, it drains the water out and you give it a pump or two to blow the rest of the water out with air. Problem is with the additional hoses and plastic fittings they eventually leak. Replacing the leaking fittings with the traditional block plugs won't hurt anything, just won't be able to use the quick drain kit to winterize.
 
perfect thank you. Anybody with any plumbing/mercruiser expertise tell me if I should use any type of teflon tape or pipe putty on the threads that should be used with the high temps noted on the engine block?
 
Brass plugs are generally self sealing but Teflon tape or paste would not hurt anything would facilitate removal when nec.
 
The other end of the small hose is attached to the drain manifold which runs underneath the crankshaft pulley. Very difficult to access. The manifold has barbs on the end where the hoses attach so you basically have to cut the hoses off. Even with the clamps removed, the hoses are nearly impossible to be pulled off of the manifold.
 
Be very careful with the plastic manifold. Especially when installing the small blue plastic drain plug, do not overtighten it,,,the housing can break and cannot be repaired.
 
ok, sorry, I need to revisit this as I have more questions than answers. I was able to get to the boat this weekend and this is what I found.
10123.gif

Part #18 (push lock fitting) had water squirting from it on the starboard side-down low aft of the fuel filter area. After removing and reconnecting multiple times without any improvement I noticed that it was cracked on the neck. I inadvertently broke it off with the neck still inside the hose (I have since removed the remnants). The water circulates from the hose INTO the lower block at that fitting (push lock clips onto the male connector engine block) (I thought the water was pumping out of the block into the hose), therefore I had water spraying into my bilge when the motor was on because I could not reconnect due to broken fitting (part 18). So one fix is to replace the fitting and hopefully it will "clip" back on the male connector and all will be good, but I am having a hard time getting a part that will arrive before next weekend. Others have suggested removing the male connector on the block with a plug, but I have concerns that if that hose feeds water to the block that I will be bypassing a vital cooling component? In addition, how would I shut off the water flow coming from the hose (see part #10) as I could not find any valve shut off along that line??? I would love it if there was a resource (diagram, weblink, etc.) that showed in detail how the fresh water circulates through the cooling system. This system seems a bit more elaborate than what was on the older 4.3L alpha system. Thanks in advance for your information.
 
Crazy amount of plumbing with many plastic parts that can fail all for the purpose of making winterization easy.

Besides the plastic parts getting old and brittle, sediment from the block drains clog those lines and make draining incomplete
 
Scoflaw- understand and agree completely, but what about my concerns with shutting off the water flow? Will shutting off that section of cooling have any negative impact? How do I shut off the water flow from the "feeder hose" part #10 above into the block? It's obviously designed to allow water flow through there for a reason??? Thank you
 
You must log in or register to reply here.

Forum statistics

Threads
113,171
Messages
1,427,819
Members
61,081
Latest member
Agent360
Back
Top