'59 35hp thermostat/flushing question big twin

[pcrussell50]

'59 35hp, rds21b...

has a water "riser", with what appears to be the place where the thermostat goes, at the top of the tower. only whoever maintained it before, removed the thermostat. so i have two questions:

1] was it smart to remove the 'stat? seems like maybe not. auto engines wear more rapidly when they're too cool...not as sure about outboards.

2] but if i do use a thermostat, will it ever open when i'm flushing out the engine with cool garden hose water? if not, then you never really do flush out the whole head, do you?

btw, i've been putting the words "big twin" in my subject lines to make sure they show up if someone searches using "big twin". i learned a lot by doing that myself.

-peter

 

[rolmops]

Re: '59 35hp thermostat/flushing question big twin

Until 1957 none of the big twins had a thermostat and judging by the amount of them that are still around,it did not hurt them a bit.Thermostats increased the fuel efficiency a bit but they did not extend the life of the engine.
Although you should be able to flush the engine with a thermostat,you will have far more water running through without one.
About 12 years ago, I got my first outboard and started to take it apart to make it run better.ending up doing very bad damage to perfectly fine parts and I paid prime dollar to replace what was good before I touched it.This website was heaven sent,because it taught me to see the difference between eagerly "repairing" and effectively repairing.
The 4 things that you should mostly be involved with are the coils and points,the lower unit and the carburetor.These are usually the cause of trouble.All the rest is mostly an after thought.
You may want to pick up a parts big twin and rip into it,thereby learning about all the pitfalls and gain a pile of good parts into the bargain.

 

[F_R]

Re: '59 35hp thermostat/flushing question big twin

The '59 35hp not only is designed to run with a thermostat, it has a recirculating cooling system. That includes a much larger water pump than the non-'stat models. The 'stat is part of the system and should be there.

When the 'stat is closed, the water goes back to the pump and recirculates till the 'stat opens, then the hot water is discharged and replaced with new lake water. This is a continuing operation, going on constantly whenever the motor is running. the 'stat continulally sensing the temperature and opening or closing as necessary to maintain the proper temperature. It will run much better at the proper temp.

There is some water bypassing the 'stat even when it is closed, so fresh water flushing still gets the whole system. That is not a problem.

Hopefully, whoever removed the 'stat left the plastic housing and check valve in there. Those are vital parts to the system and it will never work or cool properly without them. And of course, they have to be in there before you can install a new thermostat. I wish people wouldn't just start throwing parts away that are there for a purpose.

 

[coolguy147]

Re: '59 35hp thermostat/flushing question big twin

yup i got a 59 evinrude the first year they came with the t stat in the 10hp and other models i believe. cant say i really noticed improvement in anything since i didnt test it out much witht eh old t stat. which was thansk god stuck open instead of closed thats the only worry i have about them. dont wanna ovr heat the motor. but ya i hear u need one for less carbon build up so i guess in a way it does extend the life?


man ppl were smart back then about the recirucalting and other stuff lol im learning not designing

 

[pcrussell50]

Re: '59 35hp thermostat/flushing question big twin

Hopefully, whoever removed the 'stat left the plastic housing and check valve in there. Those are vital parts to the system and it will never work or cool properly without them. And of course, they have to be in there before you can install a new thermostat. I wish people wouldn't just start throwing parts away that are there for a purpose.

well damn...not sure those other parts are still there, and i'm out of town. i suppose since i ordered the factory parts manual, it will show these parts. do you think they will still be available?

-peter

 

[F_R]

Re: '59 35hp thermostat/flushing question big twin

Without actually looking them up, I would assume they are available. They made tons of those motors (literally).

 

[1946Zephyr]

Re: '59 35hp thermostat/flushing question big twin

Yea, parts should be readily available at the local marine dealor. They'll even have an exploded diagram for you to look at, so you can see that all your parts are there.

F_R is right on the money about needing it. They are a different system than the '57's, even though I think the '57's are just as good.

 

[pcrussell50]

Re: '59 35hp thermostat/flushing question big twin

just revisiting this to close it out...my local dealer, generic, not OMC-only, happens to like big twins. he knows how to find old parts better than i do. i ordered the spring and plastic parts, and a thermostat from him back shortly after christmas. shamefully, i only got around installing them all a couple of weeks ago. turns out, the person who removed the thermostat from my engine did indeed leave the spring and plunger and plastic casing in place, so i ended up not needing those things, just installed the t-stat and off i went.

i don't know if i can really tell or not, but seem like it might run a little better. not a very tech'y answer, i know

lovin' my big twin though. bought it used a year ago, and pretty much only changed the old impeller. i haven't even checked or set the points. runs too well, and i don't want to mess it up. i'll probably seafoam it just to make sure the carbon situation is ok, but really, it runs great.

thanks all.

-peter