1963 75hp Break-In: The Saga Continues

[yorab]

Motor in signature. Trying to get this thing broken in after a complete rebuild. FSM says to run for 1 hr at approximately 3000 rpm. I did that for 40 minutes yesterday but ran into a problem with my ignition coil. I got that fixed and continued the break-in process today. I ran it for 20 more minutes at 3000 rpm. Smooth as can be.

Then, the FSM says to run at 4000 rpm for the 2nd hour and occasionally run full throttle for 1-2 minutes during that 2nd hour. It ran well at 4000 rpm. The first time that I gave it full throttle, things seemed fine. It topped out at 4950 rpm with the 10 X 9 1/4 prop. After a little less than a minute at full throttle, the sound of the motor changed. It didn't sound catastrophic or anything, just different. So I eased back on the throttle. As soon as I eased back, the motor died. The motor felt very hot, like it did a few weeks ago when I tried to run it with the water pipes reversed.

After letting it cool, I started it up again. Seemed to run well, but I noticed that very little, if any water was ejecting from the exhaust relief port. It was a different story yesterday. Here's a video that I took yesterday of the port with the thermostat closed:

http://www.flickr.com/photos/jmm741/5694560603/in/photostream

And here is the water ejecting with the thermostat open:

http://www.flickr.com/photos/jmm741/5694558957/in/photostream

And now, here is the relief port today after the motor shut off:

http://www.flickr.com/photos/29072032@N05/5694568535/in/photostream

I thought that maybe the key had sheared off of the impeller, so after letting it cool again, I restarted and checked for water flow from the starboard cylinder bank to the water choke. Looked good. Here's the video:

http://www.flickr.com/photos/29072032@N05/5694566851/in/photostream

So I'm getting good water flow, but the top of the motor is still getting very hot. I also noticed a water leak near the junction of the thermostat housing, adapter plate, and exhaust cover plate. Here's a video of that:

http://s952.photobucket.com/albums/ae10/yorab/?action=view&current=Leak.mp4

So, in summary, the motor ran great at 3000 and at 4000 rpm. After about a minute of full throttle, the sound of the motor changed so I eased back on the throttle and it died. It felt very hot on the top of the powerhead. After cooling, the motor started right back up but it seems as though water is not ejecting from the relief port like it did prior to the shut down. However, water is flowing from the top of the cylinder bank to the water choke just fine. There is also water leaking near the bottom of the exhaust cover plate.

Perhaps the vernatherm is not opening properly. This would mean that water is still circulating through the motor (as shown in the video) but cool water is not being introduced since hot water is not being expelled. The vernatherm that I used was NOS, so I assumed it was good. I could try to replace it with my old vernatherm that was only used a few hours before my rebuild.

Any ideas of how I can be sure that enough cooling water is making it to the powerhead? Do the exhaust cover plate bolts usually need to be retorqued after a heating cycle? I don't remember reading that in the FSM. I'll check the torque on those tomorrow.

 

[hidef]

Re: 1963 75hp Break-In: The Saga Continues

I would check the torque on all of your bolts after running it and you should re-torque after it is broken in including checking the torque on the fly wheel. Bolts and nuts can loosen due to vibration. Your vernatherm could be bad or you have a blockage if I were you I would take a look at it. Don't rule out anything including dropping leg and checking everything down there again.

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

So after sleeping well and thinking about this, I have a plan. I'll first check the torque on the exhaust cover plate bolts. I need to stop that leak first and foremost. I'll also check the other powerhead bolts as well. I've already retorqued the head bolts. Then I'll buy an infrared thermometer. That way, if the motor "seems" to be too hot, I'll know for sure whether it is. Does anybody know the typical operating temps for the top of the powerhead for this motor? This might be in the FSM, but I don't have that with me now. Is there an absolute max temperature that it can run at?

I also realized that when I checked for water ejecting from the relief port yesterday, I did so just after the motor was restarted after a cooling period. It takes a bit of time for the water to fill the powerhead before water is ejected. You can see this pretty clearly in the video of the water flowing out of the choke hose.

Perhaps water is flowing correctly through the motor and my opinion of what is "too hot" may not be so accurate. Again, I'll get a thermometer and find out for sure what the temperature is. I suppose that as long as the motor is not getting too hot, then it doesn't matter how much water is ejecting from the relief port. It would be strange though, if the amount of water being ejected changed drastically from one day to the next. Something must have changed if that is the case. It could be that the leak that I have is an outlet for the water to go and therefore less water gets ejected from the relief port.

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

Good point on the flywheel nut, hidef. I would have overlooked that. I'll check for flow at the bottom of the cylinder heads near at the thermostat housing connections to rule out any blockages.

 

[Willyclay]

Re: 1963 75hp Break-In: The Saga Continues

Then I'll buy an infrared thermometer. That way, if the motor "seems" to be too hot, I'll know for sure whether it is. Does anybody know the typical operating temps for the top of the powerhead for this motor? This might be in the FSM, but I don't have that with me now. Is there an absolute max temperature that it can run at?

Harbor Freight IF thermometer sale priced around $27.00USD. Normal operating temps should be 130-150F. Something is wrong if temp exceeds 170F. Did you get any overheat indications (i.e. light, horn, buzzer, etc.) other than the hand-test? Good luck!

 

[F_R]

Re: 1963 75hp Break-In: The Saga Continues

I'm sure you realize that the thermostat constantly samples the water temperature and opens and closes as necessary to maintain proper temperature? It is not a matter of open or closed and staying that way. In fact, a normally operating pump on those motors will supply enough water that the 'stat may not open at all at idle speed.

But we still don't know why it conked out, do we? The water inlet screen isn't missing is it? That'll do it.

 

[Willyclay]

Re: 1963 75hp Break-In: The Saga Continues

You might consider installing a T-fitting in the cooling water supply line to the choke and temporarily or permanently connect a water pressure gauge so you can gather some real data on what's happening inside your motor. I tried the OMC water temperature gauge kit on my 1962 model but did not have much confidence in it. Good luck!

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

Okay guys. All is good. First, I had to stop the water leak that I saw. I removed the lower rear motor cover and thermostat housing in order to access the powerhead-to-adapter-plate bolts as well as the exhaust cover bolts. The powerhead-to-adapter-plate bolts were okay. The exhaust cover bolts needed to be retorqued. I believe that this was the cause of water pooling on top of the thermostat housing bracket in the spots shown with the screwdriver in the pics. I retorqued the rest of the powerhead bolts while I was at it.

Upon removing the ignition coil that mounts to the lower rear motor cover on my motor, I noticed that the resistor wire to the positive terminal was not tight. I had just replaced the coil and I must have somehow forgot to tighten down the nut. This is most likely the reason that the sound of the motor changed at full throttle.

I started up the motor on the flusher attachment and checked for flow from the head-to-thermostat-housing hoses. Water flow was good as shown in the video:

http://s952.photobucket.com/albums/ae10/yorab/?action=view&current=DSCF0174.mp4

I also replaced the Vernatherm. After restarting at the lake, I again noticed that little, if any, water was ejecting from the relief port for the first few minutes after starting contrary to how it acted just a few days ago. I bought an IR thermometer so that I could get an accurate reading of powerhead temperature. The top of the cylinder bank reached 190 and the top of the starboard head reached 206. I was just about to shut it down when the thermostat opened. It was quite obvious. The sound of the motor changed slightly and much more exhaust gas (or possibly steam) was ejected from the above-water relief port. Water also spewed from the relief port--just as much as a few days ago. The power head temps began to drop. The temperature varied by location, but it went down to about 150 at the cylinder bank and about 160 at the head. The thermostat closed again and the cycle repeated at pretty much the same temps. I know that 206 is a bit high but as long as the Vernatherm opens and the powerhead cools consistently, should this be a problem?

I also noticed a bit of fuel behind the carb down in the valley between the carb and crankcase. I checked all the bolts and the hoses. All seemed good. Could this be from gas ejecting from the carb throats? I think I read on here somewhere that if you hold a business card above the throat, it should get a slight mist covering after some time. Or perhaps that only happens when there is a problem with a reed valve? I can't remember for sure. Any ideas?

I finally had good enough weather to complete 4 hours of break-in. The only other requirements left are to avoid continuous full throttle operation for "the next few hours" and to double the oil for the first ten hours. I'll post back to my rebuild thread with updates, pics and videos.

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

I forgot to mention that the intake screen is on there.

 

[hidef]

Re: 1963 75hp Break-In: The Saga Continues

It sounds goods in your video. Looks like you have solved everything. Once you have broken in you should go back and re-torque everything one last time. Although they say that engine can run on 50:1 if you are concerned about the operation temps when running slow you could run it 40:1. The extra oil won't hurt it and you would have the comfort of knowing everything is well lubricated. The T-Stats should be forced open by water pressure when running at speed so the heads and block should stay in 150-160 range. It is nice to see these old outboards being restored and used you have done an excellent job on the rebuild.

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

Thanks hidef. I'll take your advice and retorque once again after the rebuild.

Now I just need to figure out where the fuel is coming from. It could have something to do with tilting the motor with the fuel bowl full after a run but I'm not sure.

BTW, love your tag line "Speed costs..."

 

[hidef]

Re: 1963 75hp Break-In: The Saga Continues

Also do you unplug the fuel line when your not running the outboard? That can cause gasoline to leak out of the carbs also. It has been years since I have ran an old 75 but as I remember there was always a little oil and and gas sludge under the carbs. These things are pre BP (before pollution) and are not the cleanest things around.

Whatever you do don't run the carbs dry of gas to stop a little leakage. That is hard on the engine. I hate when people run two strokes out of fuel needlessly. Better to drain the bowls and clean up the mess afterwards.

 

[yorab]

Re: 1963 75hp Break-In: The Saga Continues

I always unplug the fuel line at the fuel tank but I leave it connected at the motor so that fuel doesn't back down the motor-connector-to-fuel-pump line and leak into the splash well. I've cleaned up the small amount of fuel behind the carb and I'll check it out this weekend when I get a chance to run it some more. It seems as though it must be coming from the supply line that connects to the back of the carb based on the location of the puddle, but the hose and clamp seem fine.

 

[Willyclay]

Re: 1963 75hp Break-In: The Saga Continues

Normal operating temps should be 130-150F. Something is wrong if temp exceeds 170F.

These are "expelled water temperatures at the exhaust bypass outlet". Sorry I was not more specific with my initial post. Agree with member hidef that these great old motors were kinda oily/messy in the front cowling area. Just keep an eye open for leaks. The good news is the only pressurized fuel hose is the short one from the fuel pump to the carb.