1981 Johnson Seahorse 35hp Water pump 3X replacement!!!

Hello, I have an 81 Johnson Seahorse 35hp (J35ELCIG) and a few weeks ago installed a new water pump kit I purchased from MarineEngine.com ( PN 0393630)
. This is the 2nd kit in 2 months that I have installed. Well, yesterday my motor overheated yet again. I was riding just fine and it started bogging down and shut off and overheated. So I will be ordering another kit :thumbsdown1: and installing it soon.


My question is, could there be some other reason why the pump stops working? As far as I know there are not any obstructions in the water lines but does anyone have any suggestions on what is going on with this thing? Should I do a complete flush of the motor? I was in a salt water inlet yesterday so it now has saltwater in it which is also scaring me because I am unable to flush it until I get a new kit.

After you dismantled the original kit did you notice any thing wrong with the impeller? After you took replacement kit #1 off was there anything wrong? same with #2? Has marine engine offered any assistance?

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Originally Posted by ChampioNman

After you dismantled the original kit did you notice any thing wrong with the impeller? After you took replacement kit #1 off was there anything wrong? same with #2? Has marine engine offered any assistance?

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No sir other than the fact both times the impeller (s) and the plastic housings were disintigrated/melted. I will take photos today when I dismantle it and try to post.

Here is the impeller and casing, melted again. I am contemplating removing the water jacket and checking the thermostat, could it be possible my thermostat is frozen up causing a water restriction? Last I saw it was peeing but it did seem to be a trickle and not a full, steady flow like it did when I bought it last year.

(My original issue was caused when riding on Lake Waccamaw last year, there are shallow areas in the lake. One of my intake screens had some damage and when I rode through some vegetation it sucked some up. Some of it wrapped around the foot and I did not notice it but it stopped water from coming in and it overheated.)

On the original were any impeller vanes missing? I'd drop the lower and remove the thermostat and hook a hose up to the water tube and flush it from the water tube. Have you replaced the inlet screens and flushed that area. It definitely looks like it isn't picking up the water and priming properly.
If you haven't ordered the replacement yet you may want to order the Sierra kit instead of the OEM kit.

are you one of those who always crank the motor on the trailer BEFORE you back the boat into the water?I shake my head every time I see that happen,and that's too often.

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Originally Posted by swamprat

are you one of those who always crank the motor on the trailer BEFORE you back the boat into the water?I shake my head every time I see that happen,and that's too often.

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Negative, I loop the end of rope to my trailer wench and back it in. I am not one of "those"....I know better :laugh:

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Originally Posted by ChampioNman

On the original were any impeller vanes missing? I'd drop the lower and remove the thermostat and hook a hose up to the water tube and flush it from the water tube. Have you replaced the inlet screens and flushed that area. It definitely looks like it isn't picking up the water and priming properly.
If you haven't ordered the replacement yet you may want to order the Sierra kit instead of the OEM kit.

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Each impeller I have put in I inspected them, there were no vanes missing. It has new inlet screens. I am pretty sure I found the issue. From your reply I opened both the exhaust and head manifolds... The thermostat is shot, stuck. I put the old one in boiling water and it did not open. So...Just ordered a new thermostat, exhaust and head gasket, and thermostat gasket. Will take the opportunity to clean, remove deposits and fully flush everything as you said. I will cross my fingers...but this should hopefully do the trick. The motor pushes my little 14" Eldocraft really well, over 30mph when running right.

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Originally Posted by Carolinaoutdoors

Negative, I loop the end of rope to my trailer wench and back it in. I am not one of "those"....I know better :laugh:

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Good,,,I have seen people ruin impellers this way...Good luck

It looks to me like that impeller melted down due to lack of water getting to it. If it was simply a loose vain, bad thermostat, or other obstruction then the impeller would probably still look fine even though it was overheating.

I would look more into how you are flushing the engine and see if that is somehow contributing the the deterioration of the impeller. If you have added any transducers or other items to the back of the boat make sure they are not obstructing the path of the water to the engine. Also make sure the new inlet screens are installed facing the right direction.

Look to see if your lower unit has 2 small holes on each side of the gearcase at the underside of the anti-ventilation plate. If so, you have to tape those 4 holes up before flushing the motor or they will suck air and not allow the impeller to prime. If you flush in a tub, you have to submerge the gearcase at least just above where it meets the exhaust housing or the impeller could run dry.

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Originally Posted by SEAHORSE

Look to see if your lower unit has 2 small holes on each side of the gearcase at the underside of the anti-ventilation plate. If so, you have to tape those 4 holes up before flushing the motor or they will suck air and not allow the impeller to prime. If you flush in a tub, you have to submerge the gearcase at least just above where it meets the exhaust housing or the impeller could run dry.

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Yes, there are indeed 4 holes as you stated. Why are they there? I figured they were manufactured that way so I haven't sealed them. I have noticed water comes out of them before when lifting the motor from the water but never thought of sealing them up.

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Originally Posted by Evinrude57

It looks to me like that impeller melted down due to lack of water getting to it. If it was simply a loose vain, bad thermostat, or other obstruction then the impeller would probably still look fine even though it was overheating.

I would look more into how you are flushing the engine and see if that is somehow contributing the the deterioration of the impeller. If you have added any transducers or other items to the back of the boat make sure they are not obstructing the path of the water to the engine. Also make sure the new inlet screens are installed facing the right direction.

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I don't have any other obstruction that I know of and I have the inlet screens facing forward to channel water in. I am just hopeful that a stuck closed thermostat and new gaskets, cleaned water jacket will do the trick.

tape the holes shut when using the flusher, then remove tape when done

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Originally Posted by SEAHORSE

tape the holes shut when using the flusher, then remove tape when done

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Oh thank God I asked. I was going to use some gorilla tape to make sure it doesn't come off when I get it back running. :nanner: :laugh: Thank you for clarifying.