1953 Evinrude 15hp 15012 water pump question

[bob1123]

I recently got a 1953 15hp evinrude 15012 from a friend. He got it last year with a boat. He claimed that he got the motor to start earlier this spring but noticed immediately it wasn't pumping water and shut it off. He never messed with the motor after that. There are no signs of overheating anywhere on the powerhead. I pulled the lower unit and the impeller seems like it's relatively new and very pliable. I took my air compressor and blew air through the water tube. I could feel air coming out of the exhaust. These motors don't have thermostats. I'm sorta at a loss as to why it wouldn't be pumping water. The grommet on the water tube looked a little pushed in when I dropped the lower unit. Maybe it was leaking around the grommet? Any ideas?

Other details about the motor:
-Aside from missing two small parts that latch the cowl (part #203420), the motor looks complete and doesn't seem like it's sat for a long time.
-Has decent compression, both cylinders in the mid 90s.
-lower unit seem fine, no water in the lower.
-sparks on each cylinder, but a bit weak on the bottom when compared to the top. I'll dig into the ignition tomorrow.

Looking forward to working on an old pressure tank motor!

 

[merkdawg0084]

If you’ve already took lower unit apart, then replace impeller. There are a couple links out there that will show you how to change that motor over to a fuel pump if you decide to. Leeroy’s Ramblings is a good site too.

 

[F_R]

How deep did he have it in the water? Pump must be submerged. A pail doesn't get it.

 

[bob1123]

merkdawg0084:
I'm not sure if I want to convert the motor to a fuel pump or not yet. It came with a pretty nice pressure tank, and because this is my only motor that needs 24:1 I'll need to keep a separate tank for it anyway. Might just stick with the pressure tank for now.

F_R:
I guess I don't really know the guy that well lol. He also had a QD-17 that he claimed to tank test. I was really wondering if there is anything else about these old motors that might cause water not to pump. I've heard some people say that the two seals between the powerhead and exhaust housing are problematic on these motors, but I'm not sure how that would cause one not to pump (I'd think in that case water would be coming out of the top of the exhaust housing).

 

[F_R]

You mean the two gaskets? As you surmised, the worst they can do is spray water out, not prevent pumping.

 

[bob1123]

Finally got my new water pump installed. After some considerable pulling and fiddling I got the motor running and it pumps water no problem! It does run a little rough though. Probably in need of a carb kit.

I do have one question. The motor jerks every five seconds or so. Sorta like a stutter. It's enough to kill the motor when it idles down low. Thought it was a mixture issue, but adjusting needles didn't sem to do much. Then I thought it was maybe the flywheel touching the coils so I pulled the flywheel and double checked. Definitely not hitting the coils. In the end I figured it was probably carb related and I just let the motor run.

After I was done running the motor I disconnected the fuel line (to run out the carb) and noticed that the jerk every five seconds or so happened at the same time that the air line to the pressure tank pulsed. I don't know a whole lot about these pressure tanks, other that in general the leaf valves in the intake pressurize the tank. Should the air line be pulsing so infrequently? Should it coincide with the noticeable jerk was mentioning earlier? I also noticed that the pulse coming from the connector included some mist. I assume that's normal and just fuel/air?

 

[racerone]

Often referred to as a lean sneeze.-----Open low speed mixture screw 1/8th turn at a time.-----And it could be that throttle plate opens too early.

 

[F_R]

A "lean sneeze" is fuel igniting in the crankcase, usually due to carb's slow speed needle adjustment being too lean. During the sneeze the explosion in the crankcase causes a higher than normal pressure pulse in the crankcase. You see that high pressure pulse blowing out the disconnected fuel connector. All is well and normal with that part of question. Now adjust or repair the carb to stop the sneezing.

 

[bob1123]

Before I tried to start it up I turned the high speed needle out a full turn and the low speed needle out one and a half turns from a light seat. When the motor was running I tried to turn out the mixture screws and the sneeze/jerk didn't really go away. I probably ran the motor for 7 minutes in total. Plugs were black, mixed oil at 20:1.

I'll order a carb kit. Would the packing be bad around the needles?

 

[racerone]

If throttle plate is open slightly at idle the motor will do the " lean sneeze " thing.----Check throttle plate timing.

 

[F_R]

If it isn't the simple stuff we've been mentioning, then you have to move on to less-common stuff. Like slow speed needle tip twisted off in the carb body. Or plugged idle ports (under the welsh plug). Or crankcase leaks (worn bearings or seals) Etc., ect. But check the simple stuff first.

 

[bob1123]

Thanks for all the suggestions! This is my first time working on a 50's motor. I love how almost everything on the motor is metal!

Checked the throttle plate. When the motor is at idle the throttle plate is closed. The plate only opens when the motors is in forward and the throttle is past "Fast" on the tiller handle.

Pulled both mixture needles. Neither one looks broken. The needles were however a little loose. I tightened the nuts a little. I'll see if that makes any difference tomorrow. I reset both needles, one and a half turns out on the low speed one turn out on the high speed.

 

[BUSTER7]

merkdawg0084:
I'm not sure if I want to convert the motor to a fuel pump or not yet. It came with a pretty nice pressure tank, and because this is my only motor that needs 24:1 I'll need to keep a separate tank for it anyway. Might just stick with the pressure tank for now.

F_R:
I guess I don't really know the guy that well lol. He also had a QD-17 that he claimed to tank test. I was really wondering if there is anything else about these old motors that might cause water not to pump. I've heard some people say that the two seals between the powerhead and exhaust housing are problematic on these motors, but I'm not sure how that would cause one not to pump (I'd think in that case water would be coming out of the top of the exhaust housing).

Bob1123, I had a question about the 24:1 fuel mix ratio. The reason I ask is I'm currently working on a 1954 Johnson 5.5 HP which calls for 1/2 pint of oil per gallon of gasoline (16:1). Are you certain your 1953 is calling for a 24:1 ratio? Buster7

 

[Crosbyman]

"Checked the throttle plate. When the motor is at idle the throttle plate is closed. The plate only opens when the motors is in forward and the throttle is past "Fast" on the tiller handle."

the plate should start to open when you cross START on the tiller if not you may to adjust he cam follower underthe flywheel it is suppose to push the carb throttle lever at the correct time

 

[Crosbyman]

see pic

 

[Crosbyman]

btw.... see johnson service manual if you dont have it . you can print series of pages to PDF files for safe keeping

Boatinfo - 1922-1964 Johnson Service Manual

 

[bob1123]

Buster7:
I don't have an owner's manual for this motor. I did some googling and it seems most forum posts/sources I could find recommended 24:1 with modern TCW3. I decided to bump it up to 20:1 just to be on the safe side.

Crosbyman:
Great catch! The throttle cam was way off! I adjusted it so that the butterfly barely opens when the cam follower passes the mark on the throttle cam. Looks like someone broke the throttle cam at some point, silver soldered it back together, and didn't adjust it properly when they reinstalled it. I'll test it in the can again when the weather clears (snow on the ground at the moment).

 

[Crosbyman]

good news...

snow ?...hum..... 14C in Montreal today

 

[racerone]

Post #7 suggested checking throttle plate opening.

 

[bob1123]

racerone:
I misunderstood your message at first and only checked that the throttle plate was closed at idle. My throttle plate stayed closed way past the mark on the throttle cam. In fact, the throttle cam was soo off that the throttle didn't start to open until I put the motor in gear and pushed the throttle past "Fast". Should be adjusted correctly now, I had to pull the throttle cam almost all the way out and retighten the bolts under the ignition plate. Thanks for the advice!

Waiting till it's above freezing again to test.