Clogged water tube on 30hp Mercury 4 stroke

island561 · #1 March 21st, 2007, 08:56 PM

I've got a 30hp Merucry 4 stroke with a water tube that seems to be completely blocked at the powerhead. I'm not yet ready to give up and pull the powerhead until i'm sure nothing else can be done. With the thermostat removed, water forced in through a hose only comes back out the flush port. Water forced through a hose attached directly to the water tube merely comes back out the bottom of the water tube. I have inserted both a coat hanger and a drill bit up the water tube. The tip comes back with a gritty, dark, muddy looking sludge. I did also come up with a couple bits of rubber - which probably came from the impeller. Do I dare keep trying to force the tube open with a drill bit, or hanger? What path does the water follow once it enteres the powerhead at the top of the water tube? Is there a 90degree bend, or is it straight? The mechanic at the merc dealer said it is probably the grommet that connects the water tube at the top has deteriorated. The engine is an '01, and I always flush after use. Thanks for any insight.

Don S · #2 March 21st, 2007, 09:11 PM

Pull the exhaust cover off the port side of the motor and put water to the water tube out of the water pump and see if water gets to the engine.

island561 · #3 March 25th, 2007, 07:48 PM

Quote:

Originally Posted by Don

Pull the exhaust cover off the port side of the motor and put water to the water tube out of the water pump and see if water gets to the engine.

I was finally able to get back to looking into the water problem. At this point, the lower unit is off, and I have checked all parts of the water pump itself, new impeller, gaskets, etc. When I put a hose to the water tube, the water only comes back out the tube, so i know for sure it is clogged. I tried again putting water to it down through the termostat opening - only a tiny dribble comes out the water tube - i guess from my poking/prodding with the drill bit. Is there any way to know what the downside of continuing to probe with a drill bit? I again get little bits of sludge, and rubber. Does the path make a turn where the water tube enters the powerhead? I can't find a specific refernece to it in my manual. Thanks again for any insight

Don S · #4 March 25th, 2007, 08:02 PM

Like I said, pull the exhaust cover. It connects directly to the water tube. Using the wrong kind of oil can really plug those things up.

ronnieboy · #5 March 25th, 2007, 08:05 PM

i have the same motor, 2000, not a problem yet, is the old water pump in one piece? seems like a piece of rubber or plastic has taken up residence where it aint wanted, wouldnt use a drill bit, something softer, plastic rod with chisel point, ron

ronnieboy · #6 March 25th, 2007, 08:07 PM

oh , forgot, i use yamaha ring free in all my fuel, seafoam to. ron

island561 · #7 March 26th, 2007, 07:50 AM

There were a couple of pieces missing from the impeller, which we do suspect as being part of the problem, but I didn't think it would cause complete/total blockage. I've used the recommended mercury oil ever since the motor was new - i've had it since new.

i also flush it each time - local dealer claims if i've used cold, garden hose water to flush it that the thermostat doesn't open, and therefore may not be flushing the water tube, lower end. i've only flused it at the flush port, not with flush ears. Is that possible?- and if so, i guess it could be clogged - i only use it in Florida salt water. I'll try to get to the exhaust cover.

Thanks to both of you. Project will have to wait again till the weekend - work gets in the way.

ronnieboy · #8 March 27th, 2007, 10:41 PM

bet the water pump impellers are the problem, the flusher on the block will clean all the engine, try the ringfree, and seafoam, the cleaner the better. good luck ron