Logo
FULL SITE MENU

Late 70s new water pump not working 35hp

T

toqwik

Member
I have what I think is a 1978 Johnson Seahorse 35 I am having issues with. I have owned the boat for about a year with a friend owning it for quite a few years prior with no issues. A friend cane to visit and took the boat for a joy ride. the boat came home on the trolling motor. Took it to the shop and the water pump was trashed and it blew the headgasket. Took it to a certified Johnson dealer and had a new head gasket installed with a new water pump and housing installed. I took it out a few tines and it ran great as always. I went to take it out one day and all was fine. I looked back and the water pump was not peeing. I went to shut it off but it quit before I hit the switch. Towed it home not attempting to start it. Went down the next morning and it started right up but no water pumping. This happened a few months ago and I start it every weekend but nothing. I live on a lake with alot of grass, Unfortuantelly the spe******t who fixed it is now fighting cancer and not working. I have blown through the pee hole and it is clear and when I pull the motor up out of the water alot of water runs out of the motor, I dont have a screw in compression guage but have an old school push in type. Used it by myself and they both showed ok over 100lbs. When it blew last time only 60lbs from 1 cylinder. Nothing comes out of the pee line or the exhaust but vapor. Where do I need to start finding why this new pump isnt working?
 
Toqwik, check to see if the impeller pieces are plugging something, they may be floating around in there. Gotta blow or flush things out. If the paint on the head is discolored it may have gotten too hot so your motor is on a downslide. Should be easy to tell with white paint......I am so sorry if thats the case.
 
The head is slightly discolored from where it overheated last time but the motor still runs fine, shifts fine, just no water pumping.
 
A engine in that time period should have a metal plate attached to the port (left) transom bracket that contains the "Model" & serial numbers.... also a quarter size core plug (looks like a small freeze out plug) would be somewhere on the powerhead that possibly has those same numbers imprinted. If so.... What is the model number?

There is a old saying, in poor taste perhaps, but still a true one... that you can loan your wife to a friend... BUT... never your boat. Your wife will come back, good as new... but your boat? Well, you know how that story ends! Actually there is no such thing as a friend so good that one should feel obligated to loan his boat to.

That engine has been ran without water to a point whereas it got so hot that the pistons seized to the cylinder walls, hot enough to have the aluminum castings separate from the steel cylinder wall sleeves, hot enough to warp the cylinder head.

You mention that the engine quit before you could hit the switch... that indicates to me that the engine is an electric start model (battery equipped), and as such... you could easily install a temperature gauge assembly on that rig.

What did your mechanic say about the above possibilities? Are you mechanically inclined that you could do the work yourself?... It's a pretty basic non complex, non complicated engine.

In its present condition, you can't hurt it. Make notes, take pictures before removing anything is a good idea. If step by step instructions is needed, we're capable of that. It doesn't require rocket science mentality.

Present possible causes.....
1 - The replaced water pump failed for some reason... requires dismantling for inspection.
2 - The previous water pump impeller broke up and is up that tube blocking the passageway somewhere.
3 - The head is warped.... check it with a straight edge for light showing under it, near the center usually.
4 - Powerhead damage not evident/overlooked on previous water pump/head gasket installation.
5 - Head bolts not torqued to proper specifications or proper sequence (see below)

The 10 head bolts in that era/hp were 18 to 20 foot pounds and torqued in the following sequence whereas each number indicates a bolt.

9....10
5.....6
1.....2
4.....3
8.....7

Let us know what you find.
 
Joe, he said he took it to be repaired at a certified Johnson dealer. Its possible they missed something, right? Sometimes the dealers make mistakes, like everyone else. Nobody's perfect. We just try to be as good as our skills and patience allow.
 
Last edited:
Thanks for the replies on my receipt from the repair itlists the model as 35E77h. Trust me I never loan my boat. He just took it upon himself Togo for a ride. Compression at service was 145 in both holes. I am not afraid to tear it apart just can’t believe the impeller failed but I am not a marine mechanic by any means.
 
toqwik said:
..... just can’t believe the impeller failed ......
Click to expand...
I'm thinking Tim has the right suggestion. When you're original impeller failed it's possible it sent pieces of rubber shrapnel into the engine and now that is blocking passages. So, it's entirely possible the pump is working just fine, the problem is the water can't flow to where it's needed.
 
35E77H is a 1977 Johnson, short shaft (15" high transom). However it could have been extended to 20" since its manufacture. Check to see if that is indeed the number on the engine's ID plate when you have a chance.

Since you've already had the engine to a mechanic, I assume that a warranty of some kind exists. Perhaps it would be better to simply take it back to him. It's always possible that something has been overlooked.

The following is simply for your benefit should you decide to take a look on your own... BUT... keep in mind that it would cancel out any warranty the mechanic may have implied.

The side plate on the long exhaust housing between the powerhead and the lower unit... the plate held on with two screws is the access plate to the shift rod. Remove it, then remove the bottom 3/8" hex bolt from the brass shift lever. When reinstalling that bolt, make sure that the groove in the shift rod is aligned with the threaded hole in the connector.... Remove the lower unit. The retaining bolts are obvious.

Dismantle and inspect the water pump.... the water tube is removable from the upper grommet (note which way any curvature of the tube may face). A piece of single strand steel wire with a 90 degree or hook at its end usually proves to be efficient in finding and removing broken pieces of the impeller if they exist.
 
I finally tore it down this weekend and found what I expected. It looks like the impeller failed and parts of it lodged in the brass tube. Housing bubbled and melted. I had to pull the shaft out of the lower unit and beat on the impeller for about an hour to get the impeller off. Why would this happen, heat? I had a new impeller and it dropped on the shaft perfectly. I need to replace the housing so I did not reassemble the pump. How can I check to make sure there isn’t any pieces stuck in the motor or the foot. Even the new metal cup in the housing was covered in melted rubber. Any reassembly tips, should I use any sealant?
 
You said it yourself, you live on a lake with a lot of grass. That motor is probably among the worst choice for such conditions. Weeds/grass block the water intake holes, so water does not get to the pump. When the pump runs dry, the impeller melts. The only real cure is get a different motor or stay out of that weedy lake. OMC fixed the water intake problem around 1984-ish when they put the water intakes on the sides of the gearcase.
 
Gator is right about the weeds, but not a problem at all where we boat. Lake Superior, as well as the Ontario lakes we boat are oligotropic or late stage mesotropic......little or very few weeds. My 1st question is that when the motor seized was there weeds on the intake plugging it off? If not, then there was something else that caused the pump to quit. Also, second question: When your careless friend took it out and toasted it, did he admit to picking up weeds? Thirdly, its likely after a second overheat of this severity, there has been major motor damage, so its worth doing another compression test before you move on.
 
Last edited:
I guess no weeds might be nice for motors, but if you want to see weeds come to Florida---we can show you weeds. Anyhoo, the first new 35hp motor we sold of that design came back after the first weekend. Totally fried. Evinrude gave him a new powerhead, but it didn't take long to cook that one either. OMC thought they later fixed the problem with grooves across the water inlet holes, but they still burned up. We actually stopped selling any more 35's to fresh-water fishermen. Mercury dealers were happy. Gotta say though, I have one of the newer ones with inlets on the sides and am very happy with it.
 
So, Gator, would there be evidence of weeds causing the problem, as I suspected? Yes those grooves were a novel idea, but certainly not effective.
 
Well they don't call them hayfields for nothing. Sure, you are shoving a big gob of weeds along ahead of the motor and there isn't a lot of doubt. In all fairness though, the state has done a lot of progress in eliminating some of them. Back in "The Day", water hyacinths would get so matted that you couldn't even get through them. Don't see a lot of them any more. And then there was the hydrilla too.
 

Attachments

  • Gulfliner on Panasofkee 2.jpg
    Gulfliner on Panasofkee 2.jpg
    95.4 KB · Views: 57
Holy cow. I can't hardy believe that. We drink the water directly from our lakes in NW Ontario. Such a huge difference. Here is one pristine lake. 300 feet max with average depth around 70 feet. You can see bottom at 12 to 15 feet.
 
Last edited:
Back
Top