Overheating while trolling w/ a 59 35HP Lark?

[clarky711]

Greetings,

I was out fishing last night in the harbor and after dark I decided to do some very slow trolling on the way back. After about 15 minutes or so of this very very slow trolling the engine starting bogging down and then stalled. I could hear the engine ticking from heat and it was smoking a little. It was very hot and it was overheating.

I took the cover off and waited a while, then she started back up and I took her at 1/2 and then full throttle in the harbor to get water back into the engine. She was fine and cooled down imediately.

I don't think any real damage occured, but I learned my lesson: very slow speeds don't suck up enough for my 1959 Evinrude Lark 35 HP. Is this common? This engine has a weird water intake built into the lower unit. I checked the screen when the boat was out of the water and it wasn't clogged. What do you think??? Thanks.

Mike

 

[BaitThrower]

Re: Overheating while trolling w/ a 59 35HP Lark?

When was lat time water pump impeller and thermostat where changed?
Could be restricted flow of cooling water somewhere, that is more evident at low speed where not as much water pressure is available to push past it?

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

I changed the impellor about 2 months ago, but didn't change the thermostat. Could that be the issue? I didn't even know that there was one to change on this engine.

 

[tashasdaddy]

Re: Overheating while trolling w/ a 59 35HP Lark?

should be on top of the cylinder head, 2 or 3 small bolts.

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

ok, is there an easy way to test the thermostat out?

and which brand is better Sierra or Mallory as they are the same price? I have a feeling it really doesn't matter, but I figured I'd ask? Thanks.

Mike

 

[F_R]

Re: Overheating while trolling w/ a 59 35HP Lark?

If your problem is only at idle, I doubt very seriously the thermostat is the problem. The 'stat will be closed most of the time at idle anyway, unless you are in very warm water.

Your water pump housing is probably worn out. How did it look?

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

the water temps up here are around 72-75 degrees F. I doubt that would be too warm to cause concerns.

as for the housing, to my unexperience eye it didn't seem too bad. there was no noticable gouges/cracks, and I replaced some of the seals that came with the sierra kit. i've been using the engine a lot since the replacement a few months ago and never had a problem.

So I'm gathering that I should be able to troll for a long time and not have any overheating issues right?

 

[CATransplant]

Re: Overheating while trolling w/ a 59 35HP Lark?

Yes. You should be able to troll with that outboard at a slow tickover without any problems with overheating. I used to troll with my 58 for hours, and never had a lick of trouble.

When you reassembled the lower unit, did the water tubes go cleanly into the grommets on the water pump? They sometimes fold the grommet, which severely lowers water flow.

At an idle, you should be seeing a decent amount of water coming out of the exhaust relief hole in the midsection, along with some exhaust. What are you observing?

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

everything seemed to go in right, and like I've said, I haven't had any problem like this in a few months since the install.

I'll check out how much water is coming out of the exhuast tube, but from what I remember, it never reallly was that much...

Mike

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

Ok, well I was out last night and this morning fishing a bunch and no more problems. but I haven't trolled anymore. And I checked to make sure there was water spitting out of the exhuast tube while it was idling (engine was fully warmed up) and it was spitting out a good amount.

I'm not sure what else it could be. Maybe there was some weeds or something blocking the intake? Again, this engine has a wierd intake that is almost like a 1/4 screened tube on the lower unit...

Any other ideas, or should I just forget about it? Thanks.

Mike

 

[tashasdaddy]

Re: Overheating while trolling w/ a 59 35HP Lark?

very normal intake for that vintage motor, some of the newer small motors still use that type intake.

 

[CATransplant]

Re: Overheating while trolling w/ a 59 35HP Lark?

Well, if it's behaving now, it probably was weeds blocking the intake. Pretty common when you're trolling to pass through some weeds and clog things up. Once you ran faster after restarting, off the weeds came.

I make it a point, while trolling, to glance at the output of the telltale or exhaust relief every few minutes. Can't hurt.

 

[clarky711]

Re: Overheating while trolling w/ a 59 35HP Lark?

very normal intake for that vintage motor, some of the newer small motors still use that type intake.

ya, I guess I just meant compared to most newer engines today.

CA Transplant, I'll see what happpens, but I'll be sure to check on the output more often when playing in the weeds...

hopefully it's not a big deal!

 

[BaitThrower]

Re: Overheating while trolling w/ a 59 35HP Lark?

Good to hear it all seems normal again. As a side note, it's a good idea to check the thermostat and replace every couple seasons anyway