Johnson 15 new w/p and thermostat - no water

[Grant Brown]

1982 tiller rope start 15"
J15RCNC
I bought this so my 10 year old son and I would have a winter project.
Winter is almost over and after rebuilding the water pump and installing a new thermostat I still don't have any water out the tell tale. It might drip a drop or two, but I shut it down really quick.
The thermostat jacket was full of corrosion and salt but I cleaned it out really good. My gut says it's blocked somewhere in the block or head.
What techniques should I use to clean it out? I read about using a hose and reducer to attach to the copper water pump pipe, I have also heard about weed eater string cleaning it out. I even had a guy tell me to pull the leg, tip it upside down then pour muratic acid down the copper tube.
What is the best way to proceed. We've done well so far but I'm worried that the boy will start to lose interest unless we can get this thing pumping water soon.
Grant
White Rock, BC

 

[raczekp1]

Re: Johnson 15 new w/p and thermostat - no water

the best way is to take out powerhead out,there at upper part of water pipe is a grommet-its blocking water very often

while the powerhead yo should take out the head, clean salt, flatten the head surface and install new head gasket,

to yake out powerhead is only 30 min work(6 bolts under cowl, 3 bolts inside cowl. chocke lever out , starter out and tie with tape, fuel pump filter out-grab powerhead and lift, if resist there si a gasket between powerhead and midsection-just t break tesion)

 

[Johny25]

Re: Johnson 15 new w/p and thermostat - no water

Have you pulled the tell tale line off and made sure the hose wasn't plugged? Sometimes the hose gets crimped or has junk in it. Pull it off at the motor and see if she is pumping water there before removing the powerhead.

 

[Grant Brown]

Re: Johnson 15 new w/p and thermostat - no water

I had the powerhead off to remove the stuck driveshaft and I replaced the upper grommet then.
I cleaned the t stat housing and passages in the head. Hate to take it apart again but maybe I ought to pull the head too and clear the passages in the block. It's a 1982 and I think I need to pull the power head to get at the lower head bolts. Oh well...
I ran a wire up the tell tale, had a piece of seaweed in stuck in one years ago and learned the lesson then.

 

[Rick.]

Re: Johnson 15 new w/p and thermostat - no water

First thing is to make certain the lower unit is well submerged. Many times that's the reason for no water at the tell tale. Sometimes the tell tale hose is simply plugged so check that too. If that isn't the problem you can drop the lower unit and make a hose connection to the water tube and see if you get flow from the tell tale. If your still not getting flow then I would pull the head and start picking away at the passages until water starts to flow at a good rate. You can remove the head without pulling the engine. Do not use muratic acid as it will destroy the aluminum. Best of luck. Rick.

 

[Beek14]

Re: Johnson 15 new w/p and thermostat - no water

Just curious. Did you replace only the impeller? Or did you put in a kit with the plate, impeller, and pump housing? I've had projects where I put only the impeller in thinking that the other parts were good, and had no water coming out. After frustration and headaches, I installed a whole kit with the plate and housing and sure enough, water flowed perfectly..

 

[Grant Brown]

Re: Johnson 15 new w/p and thermostat - no water

I did the whole kit. New impeller housing etc. I made sure and used the correct parts from the kit to match the ones that were on he original.

 

[Grant Brown]

Re: Johnson 15 new w/p and thermostat - no water

I pulled it all apart on the weekend to be sure, when I finally got close to removing the head I decided to remove the tell tale outlet (the threaded plastic 90). Turns out the water passage was plugged from there though to where it exits the powerhead. A huge plug of grayish white salt and sand, took some digging and scraping but I got it all out. I blew through the passages and all seems clear now!
Picking up some gaskets tomorrow and should be good to go.
Thanks for all that offered advise, this site is awesome!

 

[Grant Brown]

Re: Johnson 15 new w/p and thermostat - no water

Now I am having trouble getting the L/U reinstalled. I cant seem to get the connector on the shift shaft to join the top part. Bolt is out, seems to be spread open, but it seems like it just wont join. Something else maybe?

 

[Johny25]

Re: Johnson 15 new w/p and thermostat - no water

Do you have it in forward gear while connecting it? If not, then try it that way. This will drop the shifter down so you can connect it. Then you can put it into neutral as you push the units together to mate.

 

[AlTn]

Re: Johnson 15 new w/p and thermostat - no water

shift lever in fwd....lower shift rod all the way up is fwd too....you may have to use needle nosed vice grips to reach in and insert the lower shift rod into the connector and make sure you have a clear passageway for the 3/8'" connector screw to screw into the opposite side of the connector...much easier if the engine is at a 45 deg. or greater tilt...might have to call on that 10 yr. old helper