1961 lark III question

[thefairlaneman]

IM looking at a 61 lark III and the guy had it serviced and spent over 600.00 on it . He said the overheat light came on and he shut it down but he knows its getting plenty of cooling water from new impellar. What should I assume to check. ? thanks

 

[tashasdaddy]

Re: 1961 lark III question

what hp? my 58 35 i went thru 2 impellers in a week, bad impellers. depends on which motor, as some did not have tstats.

 

[F_R]

Re: 1961 lark III question

A new impeller in a worn-out housing doesn't help much. The first place to look in an overheating condition is always the water pump. Also, on that motor, people seem to enjoy removing the thermostat and all the other guts in the thermostat cavity. That just don't get it.

 

[thefairlaneman]

Re: 1961 lark III question

The engine is a 40hp/ He said he thought his heavy old wooden boat was part of the issue. Hereplaved the prop also but sid he though it wasnt right for his boat. thanks

 

[jay_merrill]

Re: 1961 lark III question

Just out of curiosity, why is removing a thermostat such a terrible thing to do - assuming, of course, that the motor is not being used somewhere with water that is cold enough to cool the motor too much.

PS: Props for that engine were commonly available in pitch range from 10.5" to 14." While I don't think OMC/Bombardier stocks all of them (if any) these days, you can still buy the props from Michigan Wheel as part of the Michigan Match series. Ther should be enough selection in this range to get your motor into the proper operating range.

On the overheating, I would be inclined to look at the possibility of water passage problems if it is felt that the impeller was OK. The 40hp Larks are of the "Super Quiet" variety and have two water tubes running from the water pump housing. I would start with something as basic as making sure that both tubes are properly seated in the pump housing. I don't know these motors as well as I do some of the other OMCs but, if they are like many others, there are rubber bushings at each end of the water tubes. Check to make sure those are in place and in good shape. A common problem (at least in my experience) is for the tube to catch the inside surface of the bushing as it is being installed, rolling the bushing inward and causing a restriction as the rubber "bubbles" inward. One way to overcome this is to put a small amount of lube on the outside of the tube end before inserting it into the bushing.

 

[tashasdaddy]

Re: 1961 lark III question

"A common problem (at least in my experience) is for the tube to catch the inside surface of the bushing as it is being installed, rolling the bushing inward and causing a restriction as the rubber "bubbles" inward."

there reason for not running without the tstat, is the motor is designed to operate at that temperature. running cooler cause carbon build up, not burning fuel efficiently. and other problems in the long run.

the bean counters would not let them put it in, if it wasn't necessary.

 

[Chris1956]

Re: 1961 lark III question

Fairlaneman, Why is it that you are drawn to such an old motor? It is a good design, however, it is so old that parts are becoming scarse, and no one will work on them. It will be better to get a newer outboard, with a simple, reliable charging system, versus that old, bulky prestolite generator/mechanical regulator.

 

[tashasdaddy]

Re: 1961 lark III question

because he has a vintage boat.

 

[F_R]

Re: 1961 lark III question

jay merrill,
"Just out of curiosity, why is removing a thermostat such a terrible thing to do - assuming, of course, that the motor is not being used somewhere with water that is cold enough to cool the motor too much."

I didn't say removing the thermostat, I said removing the thermostat and all the guts, meaning the thermostat housing and relief valve below that.

Understanding the system will explain why: That motor has a recirculating cooling system where the water pump supplies water to the powerhead through the "up" tube. The water circulates in the powerhead and absorbs heat, then is presented to the thermostat. If the 'stat says it is warm enough, it opens and the water is discharged and replaced with cool water from the pump.

However, if the water is not warm enough, the 'stat remains closed and the increased pressure ahead of it forces the relief valve off it's seat and the water goes back down through the second pipe to the water pump, where the pump recirculates it back up to the powerhead, going 'round and 'round until it gets warm enough to open the 'stat. The thermostat is constantly monitoring the temp and opening and closing as necessary to maintain the proper temp.

So, if the relief valve is missing, the water is free-flow back to the pump all the time, recirculating when it should be discharged and replaced with cool water, thus getting hotter and hotter.

AND there is another thing. If the relief valve is missing, exhaust can blow down the second pipe to the water pump also. It's a very effective water pump, but a lousy exhaust pump. The exhaust kills the pumping action.

Frank

 

[jay_merrill]

Re: 1961 lark III question

Thanks FR - a knowlegable answer. I have owned a 60s Superquiet 40 but really wasn't working on outboards at the time so there are things about it that I don't know. Here in south Louisiana, thermostats are often removed when they malfunction and left out because the water temperature doesn't generally get very cold.

 

[jay_merrill]

Re: 1961 lark III question

Chris, people buy older motors for a number of reasons from pure enjoyment of owning something unusual to practicality.

I bought my first '58 Evinrude Bigtwin (35hp) just for fun. I saw it on Ebay and got a kick out of it because my first outboard as a kid was a '57 5.5hp. When I started buying parts to refurbish it, my local OMC dealer took an interest in the hobby. As a matter of complete happenstance, someone came in during that time period with a tiller version of the same motor to trade for something newer. My dealer gave him 100 bucks for the motor just because he knew I would buy it in a heartbeat, which I did. Both of the motors ended up on the back of a 15' trihull and I had a blast with it - both in running around the bayou and chatting with the old timers at the boat launch, who always wanted to know all about them and tell me stories of ones that they had owned. Since boating is largely a social activity to me, I loved that part of using them.

As to practicality, it has been my experience that these motors are very relaible when properly refurbished and/or repaired. They are very simple so there isn't all that much to go wrong. There is also a much greater parts availabilty than some realize because the basic designs during that era changed very little over long periods of time. That means that there has been a large enough population of the motors in active use to justify supplying new parts. As time goes on that is becoming less true but I still find that I can get just about any aprt that I need for mine.

Another factor that may just be unique to me is that I just get a huge kick out of towing someone with a $17,000 outboard in with my old motors! The whole idea of an outboard motor costing as much as a few new cars is just plain dumb to me but, perhaps that is just because I am becoming an "old dog." So, when the occassional young one snickers at my old Rudes, and I end up towing him in 6 hours later (yes, that has actually happened a couple of times), I just smile and salute Ole & Ralph Evinrude!

 

[tashasdaddy]

Re: 1961 lark III question

i agree with Jay, i've towed many boats with my mature motors. also it so great to watch the high monthly payment boats nearly kill a battery trying to start them, and my mature motor starts the first bump.

 

[jay_merrill]

Re: 1961 lark III question

LOL! My idea of a "payment" is the launch fee or how much gas I'm willing to burn up that day!

 

[Evinrude Boater]

Re: 1961 lark III question

I don't think I spent more than $500 last summer on boating with my 1968 Alpex Sea Aira and 1964 Evinrude 75hp. $100/month, that's a luxury I can afford. Next year I should have a Dolphin with a 1960 40hp Lark.

 

[thefairlaneman]

Re: 1961 lark III question

I am excited about having it in the water this spring. Crusin in a classic (cheap but still a classic) I will see time stop and roll back to 1961.Maybe some early sixties music to go along. I dont drink so the beer has to be out.

 

[CATransplant]

Re: 1961 lark III question

i agree with Jay, i've towed many boats with my mature motors. also it so great to watch the high monthly payment boats nearly kill a battery trying to start them, and my mature motor starts the first bump.

Yup...so have I. It's always rewarding. Another thing about the old-timers is that when you do need to fix them, you can actually do it yourself. Compared to today's modern outboards, it's a snap. You can't just change coils on a new outboard's ignition system. It's run by a computer, for pete's sake.

My old RDS-20 ('58 35hp) ran like a clock. I did have one situation, though, where the old connector from the remote electric cable didn't have a good connection. But I wanted to go fishing. So, I pulled down the flap on the front of the cowling and rope-started it. Try that with today's outboards of a similar size.

 

[jay_merrill]

Re: 1961 lark III question

Yup, and here's another one - my very nice boss gave me a really nice bonus this past January. So, I'm sitting there contemplating my unexpected windfall with thoughts of all of the boat toys I could go out and buy for cash. In the end, I thought, "nah, its going in the bank!" My old motors still get me to the fish very reliably and if my broker is as good as he has been in the past, retirement is going to be just a little easier!

 

[HighTrim]

Re: 1961 lark III question

Just adding to what FR was saying about the importance of the tstat in the cooling system, you have to remember that pistons actually twist off round when running. That being said, the t stat is required to keep the outer wall surrounding the steel cylinder, and the cylinder wall itself at a temperature to compensate for the distortion. With the t stat removed, the difference in temperature between the inside of the cylinder and the water jacket quickly reaches a point where you have an oblong piston running up and down a round cylinder, or vica versa. Basically when removing the t stat, the piston and cylinder wall could be damaged severely in a fairly short period of time.