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1982 Johnson 70 hp - No Water Flow

M

Michael Harrison

New member
This clean old engine set on a trailer for most of its life and received little use (only fresh water). It started immediately, but we could only get water flow by revving the engine to 2000+ rpms (I know that is not a great idea without a load but ...) and then hot water only came out of the cowling nipple (none out of the prop). The engine quickly heated up and we shut it off after a 2-3 minutes. Here is what I have done so far:

1) Removed the lower unit and found the water pump and impeller to be in good shape. I plan to replace impeller anyway.
2) Blew compressed air up the copper water tube. Air came out of the cowling nipple, but when I plugged that, there was no air flow coming from the exhaust housing.
3) Removed Exhaust Manifolds and found no obvious blockages. The chambers were reddish in color and mostly clean.

Questions:

1) Could my problem be the thermostat? It doesn't seem like that would that stop water from flowing thru the manifold and out the prop?

2) Can any one describe the water flow thru the crankcase & head? After removing the exhaust manifolds, the only visible place where water could leave the manifold assembly and enter the crankcase/head is a very small 3/16"+ hole at the top of the exhaust manifold "bed" on the side of the crankcase. Is that the only place water leaves the manifolds to enter the block? Where does it come back out? I see where the exhaust manifolds drain into the exhaust housing, but not where water returns from the crankcase/head?

3) Some of the bolts thru the thermostat cover also appear to be head bolts? Can I remove and replace the thermostat cover without affecting the head? If I remove the thermostat cover, do I need to remove the head and install new gaskets?

Thanks,
Michael
 
No head bolts thru the thermostat cover at all.--Just take out the 1/4" bolts( 4 or 5 ) and make 1 new gasket for the cover. Nothing happens to the cylinder head when you take that cover off.--------------Couple of strong springs in there, so take time / work carefully.---------------Did you do all this work with it running on a hose / bucket or boat in the water.---------------In a bucket you need water well above the pump as they are not self priming.---------Sometimes running on a hose the cooling water does strange things !!----Hopefully all this work was not done in a rush and in vain.------Re-assemble and test with boat in the water.
 
Four of the bolts that hold the Thermostat cover on are also head bolts and they are larger than 1/4". The exploded diagram available on this website will show this. There was no lack of water during test and all work was done neatly on a bench. I was hoping someone had experience with these motors and could answer the specific questions in my initial thread above?

Thanks,
Michael
 
Michael -----------You are so wrong it is not even funny !!!!!!!!!!!!!!-------------The cover is independant of the cylinder head.-----------I own about 15 of those 3 cylinder motors and I do have lots of experience.---------When the student is ready and willing the teachers will show up.----------------Please note that the 5 cover bolts for the thermostat housing are a different part # than the 18 cylinderhead bolts !!!!!!!
 
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Racerone, When I got home last night I did confirm that you are right about the thermostat cover, but please go away anyway because you are not helping anyone. I am looking for someone who can answer the specific questions in my first post. Why do you waste your time and mine posting worthless comments? So far you have noted that there are springs under the thermostat cover and questioned whether I tested the engine with water and wondered out loud if my efforts were in vain. Please go share these cutting edge insights with someone else and allow others to actually answer my questions. Thanks, Michael
 
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