New member with some questions!

Hey y'all I'm a new member here. I have some questions of course but eventually I'll learn a thing or two and hopefully start helping others as well. I don't know much about outboards (yet) but I learn fast.

So I'll get to the point of my thread here:

I have a 1974 Johnson 50 HP outboard, model # 50ESL74M.

First of all, I'd like to get a copy of the FACTORY repair manual. Is that what's listed for sale on the sticky thread, or is that a third-party manual?

Second, I have zero experience working on outboards. Are there any special tools that would be nice to have? I can't imagine anything really. Looking at the engine, it really doesn't look that complicated aside from the mysterious power pack. What does the power pack actually do?

Third, I learned that the key switch/throttle/gearshift assembly is called a control box. Are these specific to each engine model or...? I would assume so, but you know what happens when people assume. I am not sure that mine has an audible alarm in it for overheating. Can anyone confirm this? If so, is there a way to test it?

Fourth, if I decide to sell this engine, what is a good asking price if it was to be in good running condition? I don't actually want to sell it, I'm just curious in case I decide to re-power the boat at a later time.

I just bought this boat a couple weeks ago and the previous owner ran it for me, however he said the carbs need cleaned out or else she will bog down with much throttle. Ain't been out on the water yet to prove/disprove this, but it does seem to start and run alright. The previous owner ran it in a bucket of water for me and it sounded good, and I ran it once more (dry, NO water) for less than 10 seconds at one point as well. Reaosn for the short dry run was i wanted to see if she would fire and come off idle, but didn't want to damage the water pump running it dry. I'm thinking I should probably replace the pump to be safe, as this boat will be taking me into some backwaters and I'd really hate for it to break down out there.

So anyway, I look forward to your replies and will really appreciate any help. With time I hope to become an "answerer" instead of a "questioner" but of course that takes experience, and this forum looked like a great place to start!

Thanks!

I'd say 500 bucks in good running condition for that engine - due to the age, although it might be perfectly good, it just isn't worth very much. If it was in the 25 year old range maybe $1000 in really nice shape, 750 good running condition.

I don't know much about anything with points, made it a point (no pun) to avoid anything back to that era, so will let someone else comment on your power pack.

Carb cleaning - this is typical, you should be able to find rebuild kits (get the ones with floats) and following the procedure is not rocket science. No idea on where you can find a factory repair manual but the Seloc ones tend to cover like 20 years worth of engines and are probably readily available if you just do a search here (ie Johnson 1974 50 HP repair manual)..

Water pump - don't run them out of water, just don't do that .. 10 seconds you might have damaged it or might not have, depends if there was anything left in there to keep the impeller cool or not. These are a commonly replaced part so no worries, checkout this site for parts - they are very common and available aftermarket, one pump fits many in a big HP and year range so readily available, if you don't know when it was last changed get the whole water pump kit (should be like 50 bucks) because it comes with the body and base, later down the road once you know the parts are recent it's OK just to replace the impeller.

Jon

Tools---depends on how involved you intend to get. A multimeter is a big help for testing/troubleshooting electrical systems...If you know how to use it. If not, learn. A DVA meter is a step forward over the plain multimeter, as it is required for working on the ignition system.

A hand impact screwdriver is almost a requirement for anybody working on outboards.

Controls usually fit a range of motors, but certainly are not universal. The correct one for your motor does have an overheat alarm horn.

A power pack is the very heart of the ignition system. Contains a storage capacitor and some electronic switches. The service manual you are thinking of buying will explain how it works, but the test procedures are obsolete. Fortunately those are on-line.

If it still has the original aluminum water pump housing, replace the whole pump kit. If that has already been done, just replace the impeller.

Okay great, thanks guys. So are the manuals available on this site factory manuals, or third party? I just haven't had good experiences with third party manuals and would like as much information as possible. I ain't scared to work on anything, but it sure does help to have accurate and detailed information on hand! Saves me multiple trips to buy parts, if nothing else.

For the carbs I planned on doing a rebuild anyway, thanks for the recommendation on which kit to get (with floats). Should I run ethanol-free fuel in this motor, or is the standard junk okay? I don't know what happened to the carbs to begin with, so I'm assuming the worst and going with the fact that they're probably gummed up from sitting unused with fuel in them.

I will replace the entire water pump as recommended. I don't think I damaged it but who knows... I know a lot of guys end up replacing them every few years so I planned on replacing mine as well.

I know how to use a multimeter, I work with industrial control systems so that is no problem. I'll look into the DVA meters as well.

The overheat alarm... can I test that somehow? I presume the manual will tell me. Is there a place on these engines I could tap in a water temp gauge? How bout a tachometer?

And the power pack, thanks for the info. Doesn't sound real complicated. Anyhow, I have to run since I'm at work but I'll be back on here later. Thanks for the help everyone, more info is always welcome! Sorry for any stupid questions lol.

OK, now knowing your occupation, perhaps you already have a DVA? That is a fancy name for a peak-reading voltmeter. The pulses come too fast for an ordinary multimeter to grab and display them properly. The DVA displays the peaks....but you already know that.

You can test the horn by grounding the tan lead (ignition key on), going to the sensor in the cylinder head. Horn should blow. But understand that tests the horn circuit but not the sensor.

Most aftermarket temp gauges use a heat sensor that goes under a head bolt.

No such thing as a stupid question. Well, maybe there is, but there are stupid answers also.


EDIT: marineengne sells both factory and aftermarket manuals. The factory one you get may be a copy.

On the manuals, something to mention - it may not apply so much to your engine, but often you want the aftermarket manual because they explain things in simpler English assuming that you are working with standard tools (ie "remove flywheel with crows foot puller available at most auto-parts stores" and not "remove flywheel with OMC tool #XXXXXX").

Jon

I'll still stick with the OEM factory service manuals as they are the most accurate.

fdrgator said:

OK, now knowing your occupation, perhaps you already have a DVA? That is a fancy name for a peak-reading voltmeter. The pulses come too fast for an ordinary multimeter to grab and display them properly. The DVA displays the peaks....but you already know that.

You can test the horn by grounding the tan lead (ignition key on), going to the sensor in the cylinder head. Horn should blow. But understand that tests the horn circuit but not the sensor.

Most aftermarket temp gauges use a heat sensor that goes under a head bolt.

No such thing as a stupid question. Well, maybe there is, but there are stupid answers also.


EDIT: marineengne sells both factory and aftermarket manuals. The factory one you get may be a copy.

Click to expand...

Unfortunately I don't have a DVA but I can get one easily enough. I've been thinking about buying an oscilloscope which should also do the trick, but that would be a personal purchase (i.e. not for my job) since I also repair my own electronics when possible. Either way, I'll equip myself accordingly.

I'll look for the tan wire and test it. To test the switch itself, I'm thinking I'll just pull the temperature switch out and stick it in a pot of boiling water while monitoring for contact closure and watching water temp with an IR thermometer.

Good point on the aftermarket manual!! Didn't think of that, perhaps it would be simpler.

I have a question about control boxes... mine seems to be in okay condition but from my research there are little parts in there that sometimes break. Let's say I needed to replace it at some point. Do I need one specific to my engine (ESL74M) or can I use one from any Johnson, or only certain year ranges or...?? Mine has the big red plug on the engine harness, so I'm guessing that only certain years had that.

As for stupid questions... I try to do as much research on my own before asking questions so I don't sound like an idiot. Anything beyond that is just cause I'm a newbie to the marine world, having only owned one boat before and that was just a bare bones fiberglass v-hull with a 25 Johnson tiller steer that I sold after not having the dedication to work on it. Mainly due to having other projects going at the time. That was when I was 16 or so... I'm 30 now so it's been a while!

Thanks guys!

Well, yesterday I pulled the carbs apart and found... brand new rebuild kits already installed! Grrr... I said screw it and cleaned/rebuilt them again anyway. Didn't find anything dirty, it was all nice and clean. Now I'm thinking since the carbs were clear than I might have a fuel delivery issue and a carb adjustment issue. She stalls at idle and surges at full throttle, so I think I need to put her in the water and adjust the idle mixture (the only adjustment on the carb) til she idles. For the surging at full throttle, I checked the filter on the side of the fuel pump and only found a bug and some little bits of trash, it was nowhere near blocked but I blew it out anyway. I think the fuel pump might be failing, or perhaps I have a partial blockage or have a hose coming apart somewhere. I'm gonna take it out today and see what happens if I squeeze the primer bulb as it's surging.

I also grounded the tan wire at the cylinder head and was happy to hear the alarm horn sounding at the control box. Without a manual it wasn't immediately obvious how the cylinder head temp sensor comes out, so I didn't get to test it in boiling water like I wanted to... maybe I'll just take the sensor out and put in a gauge instead since the wire coming from the sensor has seen better days.

Anybody that can answer my question about control boxes? I found out while I was on the water that I need to replace at least the key switch portion of it... the keys fall out of the switch while underway.

Removing the heat sensor is an exercise in futility. Let's say you do pull it and test it and it is ok. That doesn't prove it will be ok the next time it is heated. But if you want to pull it anyway, you have to remove the cover plate. Then pull it out. Problem is, just pulling it out by the wire can destroy it. So....if you are going to do all that, you might as well put in a new one and be done with it.

Control SHOULD work if it has a red plug. Unless there is a "gotcha" that I'm forgetting. Replacement switch is available here at marineengine.

fdrgator said:

Removing the heat sensor is an exercise in futility. Let's say you do pull it and test it and it is ok. That doesn't prove it will be ok the next time it is heated. But if you want to pull it anyway, you have to remove the cover plate. Then pull it out. Problem is, just pulling it out by the wire can destroy it. So....if you are going to do all that, you might as well put in a new one and be done with it.

Control SHOULD work if it has a red plug. Unless there is a "gotcha" that I'm forgetting. Replacement switch is available here at marineengine.

Click to expand...

Okay, thanks. I'll check a few things out today after work.

Well, found out what's wrong. Top cylinder had 90 PSI compression, lower had 60. Thinking I might just find a 25hp motor, but I need one that's set up for remote steer since my boat has a center console. Probably gonna end up costing me the same as trying to find parts to rebuild the 50 horse.