Johnson 6 Hp 4 Stroke not moving water??

[MahtyMaht]

It's a J6R4SRC, and it suddenly quit peeing. I looked at the impeller, and it's fine, I ran a weedwhacker line into the pee hole and it felt clean, no dirt dobbers, etc. Popped the top off the thermostat housing, and there's a rubber diaphram in there that was torn, so I though, "Bang! Gotcha!" ordered up a new one, installed it, slapped it on the boat and still bupkiss. WTF?!?! Now it appears that I'm going to have to actually understand how the durned thang works. Anybody got an idea? It appears to be on the downstream side of the engine, but I don't see what the diaphram actually does. It has a small spring in a plastic cup, then a vernatherm, then the diaphram, then a bigger spring, then the cover. When I look at the exploded view on the BRP Johnson site for my model, they show a spacer above the diaphram mine doesn't use. Otherwise, the parts look the same. I got nothin' here............

 

[oldboat1]

Does the motor overheat? Believe there is a flushing plug in the t.stat housing -- If so, consider flushing down and out. May clear the tell tale. If a salt water motor, flushing is very important -- any visible corrosion or salt build up in the t.stat housing?

 

[MahtyMaht]

The motor spent it's last 5 seasons in Maine, where it did occasionally take a turn down the Kennebec to Small Point, or put in at Harpswell and cruise into Caso Bay. It always got a freshwater trash can run afterwards. There was some small amount of corrosion under the housing cover, and there is a flushing hole, although I don't have an adaptor. I have been running it around in a pond much further south, now that I've moved, and it's never overheated, but I don't really run it long enough. I tested the vernatherm when it was out, and it got longer in a pan of water. I also put a hand drill on the drive shaft and stuck the lower unit in the tub to test the pump, and it was fine. I'll rig a hose flush and try that, but I'm skeptical, as I have always kept it in the house so it wouldn't freeze or get dirt dobbers........

 

[oldboat1]

sounds like the motor has had great care. If the tell tale has you bugged, try spraying some carb clean and/or some WD-40 or similar up there with the wand, then run it in fresh water -- repeat if needed. Chances are, it's just a blockage at the tell tale. If the t.stat is assembled according to the diagram, try it and check for leaks. Run it out a while. You might like to get an infrared temp gun to check head temp, if you want to be a little more exacting than the hands-on method.

 

[MahtyMaht]

So apparently, water comes out of the engine to the top of that diaphram, and when the vernatherm expands, it backs down out of the center hole of the diaphram, and lets water move out the telltale. It always squirted before, I think it's supposed to squirt, I'm obsessed with it's squirtilalation, and squirt it must! I don't see how that diaphram tore, either - It was so new when I got it, I put it thru the whole breakin protocol. What a nuisance that was.The water pump can't really produce much pressure, can it? I got a Multimeter with a t-couple if I wanted a good temp number. I just want to fix the squirt............

 

[oldboat1]

scaring me now, MahtyMaht. Would have to look at the water passages on that model, and placement of the tell tale elbow, but should work independently of the t.stat. Water flows past the t.stat (vernatherm) when you start the engine -- i.e., water flow isn't blocked waiting for the t.stat to open. On that note, good to check the area around the thermostat housing to make sure bypass passages are open, not salted in. But if no water was flowing until the thermostat opens, the motor would be overheating -- and yours apparently isn't. Maybe you've done it already, but could just remove the assembly and replace the cover, then try it. I haven't checked a parts diagram for your motor, but if the elbow for your tell tale is in the exhaust cover, could remove the cover and check for blockage there.

 

[MahtyMaht]

Success at last! I pulled the carb to get access to this weird little aluminum housing that's bolted to the underside of it, The top of this housing has the accelerator pump diaphram and a couple of fuel passages in it, but the underside has a couple of brass water hose nipples in it. Those nipples are aligned. The thru hole MIGHT be 3/32", but weed wacker line is too big, so I ran a 1/16" drill gently in there, and it felt like it hit the blind end of the hole. I turned it acouple of times and it came out with some kind of tan crap in the drill flutes. I did this a couple of times and BAM!, it broke thru! I re-assembled and lit it off in my too short trash can, and voila it's squirting again. I'm tempted to bypass that stupid aluminum housing cause it's the smallest hole the water has to go thru in the whole system, and this is the second time it's caused me problems.