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73 Johnson Over heating. Is water pump working

D

Dohar1985

New member
I have a 73 Johnson powershift 2 2 cycle 135 hp. I dropped the lower unit and replaced the water pump impeller and housing. While the lower unit was dropped I used the water hose to blow water up the intake tube as well as the outtake tube. Every thing seemed clean. put everything back together and the engine over heated. Dropped the lower end again and attached pvc pipes to the tubes to help them seat into the housing. (suggestion from a forum I read). put everything back together again and still overheating. This motor does not have a tell tale to see if the water pump is working. I tried disconnecting the hose that goes to the engine but nothing comes out. I was told that it had to be a complete circuit for the water pump to work so this was not a good test. Any other ideas? Not sure if it matters but I have replaced the head gaskets as they were busted. I have tried using muffs as well as a bucket test. Over heats both ways. Only takes about a min for the warning to go off. Any suggestions? Also I have noticed a small amount of oil in the bucket. Is this normal? Any help is much appreciated!!!!!!!!!!!!!!!!!
 
No. Bucket is not big enough. Only about 2 inches above intake. I understand where your going with that but it shouldn't over heat with the muffs.
 
Update: in another forum they suggested the thermostat. After some seek and find I found it. Pulled it out and tested it in some hot water and it opened. So it's good. Held the valve open with the motor running and no water came out. So I assume I have an issue bellow this point. Any suggestions? I am going to check the water pump again tomorrow.
 
Water flows from the water pump to and through the powerhead, then out through the cylinder head hoses to the thermostat. Remove the hoses, then run the engine. If water does not exit the cylinder head hose flanges, the water pump is not supplying water to the powerhead.

NOTE that with the engine positioned upright in a large plastic trash can, the water level must absolutely be at least 4" above the joint where the lower unit attached to the long exhaust housing so as to be above the water pump. The water pump is not self priming and will draw air other wise.

If running on a flushette, the water must be turned on full force!

With all spark plugs removed at the same time, what is the compression psi reading of each cylinder? Is there any traces of water in any of the cylinders?

If "all" of the above checks out to be normal... suspect the water deflectors in the water passages behind the cylinder heads (as follows).

(Water Deflectors)
(J. Reeves)

Water deflectors are actually lengths of 3/8" outside diameter rubber hose, installed between the top cylinder and any cylinder beneath it, and also between the bottom cylinder and the block. The purpose of the deflectors is to have the water follow a definite path around the cylinder walls. Unfortunately the deflectors between the cylinders will at times swell sideways due to either a previous bad overheating problem, or simply due to age and salt corrosion. This causes a water flow restriction which usually allows the water to cool sufficently at low rpms but not at the higher rpms.

This hose material can be purchased reasonably at any automotive parts type store if you care to make your own, or you can purchase individual deflectors at any Evinrude/Johnson dealership at a somewhat higher cost.


Removing and installing them can be a hassle at times, but not always. I use a sharply pointed scribe with about 1/4" of the tip bent at a right angle whereas I can reach in, jab the tip sideways into the rubber, then yank it out. It's necessary to clean the seating surfaces where the ruber contacts the block with a small rat tail file to eliminate salt deposits etc. When installing the new rubber deflector, coat the deflector and the metal surfaces with WD40 which will act as lubrication to allow it to go in as easily as possible.


Make sure that you insert something into that deflector area before cutting and installing the deflectors if you make your own so that you will be certain that they are the right length and also that they will be seated properly. Usually a very small amount will be left extending about the block sealing area..... simply cut the excess off with a single edge razor blade.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1

Now, if that doesn't keep you busy until at least 10:30 am tomorrow, get back to me. :cool:
 
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