Water-pump service Johnnyrude 70

[Swedish_sailor]

Hi,

I have not been here for a while, so long I forgot my old alias... I have an old (-97) Johnson 3-cyl 2-stroke. 10 years ago I had to exchange the lower unit due to a warped propellar axis and destroyed bearings. I found a -93 Evinrude LU in good shape which I painted white and have used ever since. When I got it I also got a new water-pump kit from a friend (GLM), which i mounted. I have not used the boat much maybe 150h since then, only in fresh water. Anyway I feel that impeller change is long overdue. I don’t have access to the motor right now, so I checked my old box with parts and found two old water-pumps (original for the 97 LU and 93 LU I think). They are not identical, the -97 is black and has the metal part of the pump in which the impeller goes made from one piece of metal, the 93 is white-ish and had the impeller-housing mad from two metalpieces. The -97 had a 3-wing impeller 432941, no impeller saved from the 93. As far as I remember the GLM kit had a 6 wing impeller, and the pump impeller-housing made from 2metal pieces, general feeling was not so good quality, but I mounted the entire kit anyway as it was new and I was in a rush to get the engine going. Now I was thinking of using the original pump from the 97 LU with a new impeller, but I thing they had installed the wrong type before (432941) as it seems to be intended for smaller engines? Is the correct impeller 396725? Do you guys agree to use the original pump instead of the GLM currently on the engine?

 

[Mohawkmtrs]

Got a model/serial number?

 

[racerone]

The 6 vane impeller is correct.-----And some of the early 70 HP motors did leave the factory with a 3 vane impeller.-----2 piece or one piece metal cup makes no difference in the way the pump works.-----Make sure you get the latest water pump kit that has IMPORTANT instructions.

 

[Swedish_sailor]

Thanks for the responses! I checked further and I can see that there are differences in the metal-plate below the pump, the leftmost is the pump and plate from the -97 pump which had a 3-vane impeller and the rightmost one is the -93 pump, original to my LU, which used a 6-vane impeller. I guess any of them will work fine and pump roughly the same amount of water... Maybe better to use the 6-vane one. What is normally included in the kit, impeller and O-rings?

 

[racerone]

The latest factory kit 432955 has all the parts / instructions you would need for a proper service.------No need to guess or make assumptions.

 

[Swedish_sailor]

Right, that kit in principal contains the complete water-pump if I understand correct. Are you saying that the correct procedure is to exchange the complete water pump assembly every time an impeller shall be exchanged, say every 2-3 years for normal usage? Never correct to just exchange impeller only? Just trying to understand the normal service procedure. Here the impeller cost around $20 and kit $100, but if the entire pump needs replacement to be on the safeside I will do so.

Thanks for your feedback.

 

[racerone]

Normally the impeller needs to be changed !----But this kit has all the instruction to modify the cooling system If that has not been done.----Sorry I can not see your motor.-----Can not see your tool box or experience with this type of motor.

 

[Swedish_sailor]

Thanks! I understand you cannot judge my capabillity and recommends the safe route. Regarding tools and doing thepractical work as such it is no problem, I`m quite used to do mechanical work on motorcycles, cars etc. I have replaced the waterpump before, using a complete kit, as I had one, and it worked well for many years, and still does, never had any cooling issues, but even if boat has not been used much I feelit is time to exchange the impeller, easiest us if course to just change the impeller in the currently used waterpump, but ifsome important upgrade is made maybe it isworth to buy a complete kit. If you have timeto explain what modification has been done it would be interesting to know. Water overhere is quite cold even in the middle of summer so cooling is likely not an issue, but modification may nit relateto cooling capacity I guess. Thanks for your input.

 

[racerone]

On another ( competitive ) website.-------The kit has the complete list of parts and the instruction sheet that you could look at.----As I say I can not see your motor to see it's condition or know the history of it.

 

[Swedish_sailor]

Thanks, took a look at the instruction and realized I made the t-stat updates 10 years ago when mounting the GLM kit, which had it included. If all other things look ok without exessive wear when I pull it apart Ill just change the impellar, otherwise I go for the full kit as suggested. Just out of curiosity, what is the reason for the t-stat update?