Johnson V4 Which way does the water flow???? 1975 Johnson 85 HP

[rctownes]

1975 Johnson 85 HP (85ESL75)

I replaced the impeller but still had no water coming out the ports just below the outside cover when running on muffs. Took thermostat (vernatherm) assembly off and found some junk in there so I bought new vernatherm/thermostat. Before I put the thermostat assy back on I thought I'd submerge the foot in a drum of water and run it again. I was expecting to see water coming out the tubes near the bottom of the heads but I got nothing.

I am trying to get an idea first of the flow of water. Does it go from impeller, thru the water passages in the heads, out to the thermostat, and then out the exhaust ports? Will running it without the thermostat in there somehow cause the pump not to "prime"? I am at a loss to explain why I'm not getting water to the engine. This model h as two water tubes coming off the impeller housing. It's a PITA to get them lined up when putting the lower unit back on but I'm pretty sure they are. At least one of them is for sure. I assume one water tube goes to each side of the engine (one tube per two cylinders?).

Anyone who can shed some light on exactly how this works and what might be causing the problem would be appreciated.

Attaches a pic of the engine in its current state for whatever it's worth. I have labeled it A,B,C,D to show how I think the flow of water goes. Please correct me if I'm wrong.

 

[Bosunsmate]

You should put a bolt in that missing hole for starters
Have a read of this, im not sure abot the specifics on that motor, ive only worked on a 82 v4
http://forums.iboats.com/forum/engi...aq/228380-johnson-evinrude-adding-a-tell-tale

 

[emdsapmgr]

You are working on an early crossflow engine, with the single vernatherm thermostat. These engines don't put out much water at all from the two exhaust relief holes, like the later models with dual thermostats. Completely different cooling systems. Here's, your test. Start the engine cold. Hold the palm of your hand back by the two exhaust relief ports. After about a minute, the vernatherm will open and water droplets will form on the palm of your hand. That's normal and a good thing. If that happens, you are good to go.

 

[F_R]

Water leaves the pump and flows up through one water tube to the powerhead. Upon passing through the powerhead, it exits through the two big hoses and is presented to the vernatherm for sampling. If the vernatherm decides it is too cool, the water is forced through the relief valve next to it and returns to the pump inlet side via the second water tube, and is recirculated until it is warm enough. However, a small mount of water is also discharged to cool the exhaust.

Once the vernatherm says it is warm enough, it opens the valve with the heavy spring, and water exits out the exhaust instead of returning to the pump.

It is NOT an either-or condition. The vernatherm is constantly sampling the water and opening or closing as necessary to maintain proper engine temp.

Now.......having said all that, if you run it with the thermostat assembly removed, AIR can pass through the second tube, down to the water pump. That kills the prime of the pump and it may not work at all.

A common reason for pumps not working is trying to run it in a tub of water that is not deep enough. The water pump needs to be submerged before starting the engine. Furhermore, all the exhaust and turbulence can interfere with the pump getting the water it needs. You didn't say you are doing this, but just so others know, you cannot test a water pump by running on muffs. The muffs/hose supplies water whether the pump works or not.

Finally, there are two plastic guide tubes to make it easier to hit the grommet holes when reinstalling the lower unit. Are you using them? They usually shinny up the water tubes and have to be retracted and inserted into the pump.

 

[rctownes]

Thanks everyone it's working now. Just as emdsapmgr stated, I needed to put the thermostat assembly in in order to allow the pump to circulate the water. I did leave the hoses coming from the heads detatched just to confirm water flow and got soaked, so it's good. Attached the hoses and started getting water flow from ports once the engine got warm.

Thanks F_R for the explanation of the water flow. I do have the engine submerged in a 55 gal drum and I have the water level well over the intake for the water.

Thanks All!