1960 Johnson 40hp Water Pump Problems

AMD_237 · Oct 26, 2008

I have been fixing up a 1960 40hp Johnson that had sat around at the previous owner's house for 7-8 years. I put in a new carb kit, fuel pump kit and done general cleaning of the exhaust manifold and other things that I thought would help it run. The problem I am having now is running the motor because when I start it, all I see is smoke out of the exhaust and no water. This I take it means the water pump isn't getting water to cool the engine off. (I'm running it in a 55 gallon drum) I took the pump apart and the impeller looks worn but not terrible. The seals and grommets and stuff could need replaced but my question is, is a water pump supposed to be completely sealed to create a vacuum for the water to flow? I guess I'm just confused on what I should do to fix it besides put a new impeller in it and hope. When I took the pump off, it didn't have any gaskets or sealer to keep it sealed so I didn't know what to do and/or where to put gaskets, sealants or seals, etc. Any info would be wonderful. Thanks!

1946Zephyr · Oct 26, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Puting a small bead of sealer would not be a bad idea. Infact, it would only help the waterpump work better. One thing I would check, is the Thermostat. There is a wedged shape plate on top of the head and that is where it is located. There are three screws that attach it. If you pull the thermostat out and start it up, you should see water come flowing out of there. If not, then your pump is not getting water up there.

There are other things to look for too, when you have it apart. Run water up into the water tubes (that go into the water pump housing)and see if it flows freely through the cooling system. Sometimes, (especially on motors that have been run in salt water) there will be sections of the water tubes that corrode shut.

That should be about all you need to make it happen. If you have any questions, we're here to help.

Leon

AMD_237 · Oct 26, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Thanks a lot for the reply. I have had the thermostat out and run the motor. No water only smoke out of the thermostat housing. I did buy a new thermostat but I did that as a precaution and haven't installed it yet I want to get the water passing through while the engine is running first. I did buy a new impeller as well but have been hesitant to install it until I found out a little more info about how the water pumps in these motors work and about what to do to make them work (or work more efficiently). I have put a garden house on the tube in the lower unit and the water will run out of the thermostat housing then, just not when the motor is running and water pump installed.

1946Zephyr · Oct 26, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Excellent! Sounds like you know your **** pretty good so far.

So the water flows free and you're ready for a new thermostat.

All you need to do is bolt that water pump assembly back together and you're set.

You may as well install a new seal, below the water pump assembly, while it's apart. This seal is for the lower unit and often times goes out, just like any other.

Turn the shaft in the direction the motor turns while you lower the pump housing down and that will make the job a bit easier.

While the lower unit is off, it is also good to check the drain holes and make sure they're totally cleaned out. All kinds of crap loves to settle there.

When you bolt the lower unit back on, use a light coat of grease, where the water tubes go into the water pump housing and coat the o-ring on the top of the shaft.

Leon

AMD_237 · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Sounds good I will try putting it back together and if I run into any difficulties I'll be sure to ask. I'll let you know how it goes. Just one more question...on this motor there is no peehole or tube or whatever for the water to flow out of so you can make sure water is circulating while it is running and while the thermostat is installed. Where am I looking for the water to flow out of while it's running in my 55 gallon drum? There's a large exhaust valve under the powerhead but didn't know if that was for exhaust gases or water or both. Thanks again and I'll let you know how it goes!

1946Zephyr · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

The water should shoot out the exhaust outlet.

F_R · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

The amount of water out the outlet varies according to whether the thermostat is open or closed. But there should always be some spray, even if it is closed. In actual use on a boat, the thermostat is constantly sampling the temperature and opening and closing as required to maintain the temp.

Since you took the 'stat out, I assume the plastic 'stat housing and check valve are in there. Some people yank those out also and toss them. Mistake! It won't work right with those parts missing.

AMD_237 · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

I installed the new impeller and put sealer around the housing and grease on the seals. It seems like i did everything correctly. I am really getting frustrated. It just ran for several seconds with the 'stat cover off and all I got was white smoke. No water out any hole at all. The odd thing that I noticed was that the propeller may be moving when it starts even though it is in neutral. I have no idea if that will affect the water pump but I just cannot get suction of the water into the motor. Anyone have any ideas or tests I can perform to diagnose this? I sure would appreciate it. Thanks.

freddyray21 · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

those need to be in the water far up the leg. You also need to put the stat housing on as without it is sucking air. Put the new thermostat in and forget that part. Like FR says you should have water of some sort all the time whether the thermostat is open or not.

asdasc · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Are you running it in the water (lake), or in a test bucket, or with the 'muffs' on with a garden hose? The muffs should work well. When I first tried a tub of water on a test stand, I was surprised how deep the water needed to be. It has to be up to the level of the impeller or just a little higher. It won't self prime, the water has to be up there.

It sounds like everything else should be good.

James R · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

One point that seems to have been missed.Is the plate or the pump housing scored? If either one is scored then water just goes by the impeller and not up the tube. Another point, when the impeller was installed did you rotate the drive shaft in a clockwise motion, looking from the top, as the housing was pressed down over the impeller. If not then the impeller blades are not oriented correctly.

AMD_237 · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Thanks for the feedback guys. I will put the 'stat in and the cover on I just had it off because I was hoping to see some water while it was running. I am running the motor in a 55 gallon drum. I have been putting water just covering the water pump because I didn't want to burn up the new impeller. Should it be even higher than that? I will try putting it deeper maybe that is my problem. If it isn't I'm not sure what I will do then. Maybe my compression isn't up to par. (I'm not sure if that makes any difference to the water pump at all) Alright back to trying it...I'll let you know how it goes. Thanks again!

freddyray21 · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

you need to have it a lot deeper. It should pump then. Those are fickle about how deep they need to be.

Joe Reeves · Oct 27, 2008

Re: 1960 Johnson 40hp Water Pump Problems

The water level must be approximately 2 or 3 inches above the seam where the lower unit bolts up to the long exhaust housing.

AMD_237 · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

I put a lot more water in the barrel, at least 6-7 inches above the impeller like you guys suggested. I also installed the new thermostat. It seemed to run better but I still didn't see much, if any water coming out of the exhaust. Could this be a powerhead/compression/ring problem? I took my spark plugs out and examined them and they were both oil covered after only a few minutes of running. I wonder if maybe it isn't sucking up enough water because the compression isn't there. I have no idea if this even relates to the cooling system. I opened up the 'stat housing after i ran the motor and it seemed a little wet so possibly a little water was circulating. Any thoughts on where I should go now?

Joe Reeves · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

The only mention I see pertaining to compression is a statement "Maybe my compression isn't up to par", then later "I wonder if maybe it isn't sucking up enough water because the compression isn't there."

It would help if you told us just exactly what the compression readings are.

AMD_237 · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

I am not really sure how to get an accurate reading. This motor has pressure release valves in the cylinders when you pull the string to start it. The only way I would know to get an accurate reading would be to run it with the tester hooked up but I didn't think that was the proper way. I'm kind of new with the compression testers and how to do it and get an accurate reading.

freddyray21 · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

don't run more than one post on the same problem already answered in other post. Good to know what the compression is, but would have nothing to do with the water pump working or not.

AMD_237 · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

Okay thanks a lot. Sorry about the other post it was a mistake I meant to type it in this one.

Joe Reeves · Oct 28, 2008

Re: 1960 Johnson 40hp Water Pump Problems

A slightly failing head gasket would allow the combustion to enter the water passageways, and since the power generated by the combustion is greater by far than the water pump pressure, a stalemate condition is generated whereas the water pressure rises to a certain point but can go no further due to the combustion pressure.

Bottom line...... the water would simply sit/pulsate at that point and the engine would overheat.

Temporarily disconnect the relief valve setup by removing the two screws from the stainless steel lever and set that lever aside.

1960 Johnson 40hp Water Pump Problems

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