1979 Evinrude 140 Missing Thermostats?

[Theoutdoorsman]

While servicing the powerhead, the service manual suggests replacing the thermostats. Upon removing the cover, and to my surprise.............no thermostats were installed!!! How likely is it, that this may have contributed to the failure of the powerhead? Until now, all I can say is, carbon build up led to stuck piston rings in the #1 cylinder. If the powerhead was running below temperature, would this possibly cause additional accumulation of carbon deposits? Any thoughts?

[Theoutdoorsman]

Also, someone please tell me that this IS the correct manor in which things are to be installed. If I'm reading the manual right, this should be correct. I just want to be certain before I put the power head in place. Thanks..............ALAN

[KYHunter2]

Looks correct , as long as you install the springs on the end of the valves .

And the gaskets , that go on the thermo's.

And used gasket sealer ,on the gaskets.

KYHunter

[Tom Scully]

Running without the thermostats will definetly lead to excess carbon build up.

[johnny whaler]

My mechanic on my 1978 told me that I didn't need the thermostat on my 35HP. It was stuck. He told me most people just don't use one on the older engines. Could this be the cause of me fouling plugs like crazy now?

[emdsapmgr]

There are two very small holes toward the center of that valve body. These two holes must be open or the engine will overheat. Once reason folks take the thermostats out, is that the holes plug up and the engine runs hot-even with new thermostats. Scully is right. Also, to reduce carbon deposits (due to today's gas) I would run a can of engine tuner through the engine on an annual basis.

[Theoutdoorsman]

Thanks for the information gentlemen!!!! Also, the two small holes in the adapter plate........... What exactly is their purpose? I wondered about while cleaning it. Everything cleaned up nicely. What type tuner would you recommend? Is this tuner designed to clean and flush the water jackets as well? Thanks again guys/gals...................ALAN

[Theoutdoorsman]

Now all this has me wandering???............ The powerhead failed because of stuck/broken rings in the number one cylinder due to excess carbon buildup. If indeed the missing thermostats contributed the excess carbon buildup, due to the motor operating at temps much cooler than it was designed for, would it also be safe to say that this might also be the reason for the temp sensors not warning me of a possible overheating problem? I plan to remove and test the sensors prior to turning the key on the rebuild........no doubt! But now I'm wandering if the overcooling of the powerhead, due to the lack of thermostats, might have prevented the sensors from getting to the proper temperature to open and ground out, triggering the warning buzzer in the controls, and not warn me of a possible problem? Any thoughts on this? Just brainstorming here, but how likely would this be?

[tiller7104]

I have heard it on Iboats and I am a firm believer.....running an outboard without therostats is just as bad as running with bad ones..Cold engine is horrible for incomplete combustion..Hence carbon build up and stuck rings etc. Try some Deep Creep and reinstal the thermostat!! Go to FAQ and due the perscribed decarb....I bet you will see a huge difference

[fireman57]

Without the stats in you definitely wil run cooler but you also may not be filling the cooling system totally because the stats build up the proper pressure to fill all passages. If they are not all filled you may be running one or more cylinders a lot cooler or hotter than the others. Two different temperatures lead to bigger problems.

[KYHunter2]

No, the engine tuner , does about the same as the sea foam in gas.

It has nothing to do with the cooling system .

The best way to be sure all cooling passages are clean , is to remove water jacket covers and exhaust cover plates , and thoroughly clean.

As well as the cooling passages in the heads.

IMHO, a must whenever rebuilding a powerhead.

Cover all bases , so to speak.

KYhunter

[Theoutdoorsman]

No, the engine tuner , does about the same as the sea foam in gas.

It has nothing to do with the cooling system .

The best way to be sure all cooling passages are clean , is to remove water jacket covers and exhaust cover plates , and thoroughly clean.

As well as the cooling passages in the heads.

IMHO, a must whenever rebuilding a powerhead.

Cover all bases , so to speak.

KYhunter

I noticed, whenever I pulled the head covers off, that they were PACKED to the gills with white chalky deposits. I don't think ANY water could have possibly penetrated this stuff !!! Is there anything that can be done to help alleviate the build up of these deposits in the future. Maybe something I can flush the cooling system with anually that won't destroy or eat at the gasket material or sealer? Also, might it be a good idea to bore the holes in that adapter plate to a slightly larger diameter, maybe twice the size?

[clint]

Is your engine used in fresh water or salt? Do you trailer boat and flush out with muffs and fresh water at the end of the day? If you dock the boat it is tough task to flush engine even though you can with tight muffs attached to motor and lower it into water and start for 5 minutes till water from pee hole is exiting fresh water. Remember you had alot of hours on those heads and alot of crappy water go thru and accumulate thru the years and when winter storage it drys up and hardens till the spring.
Clint 8)

[Tom Scully]

Try a product called Salt Away, I have had good results with it keeping deposits to a minimum.

[Theoutdoorsman]

Is your engine used in fresh water or salt? Do you trailer boat and flush out with muffs and fresh water at the end of the day? If you dock the boat it is tough task to flush engine even though you can with tight muffs attached to motor and lower it into water and start for 5 minutes till water from pee hole is exiting fresh water. Remember you had alot of hours on those heads and alot of crappy water go thru and accumulate thru the years and when winter storage it drys up and hardens till the spring.
Clint 8)

The motor will be used in only a fresh water environment. Too, I have never flushed the motor on muffs at the end of the day, although now, I can see the need for it. I'll definitely try the above mentioned product to keep the deposits at bay. Is it available at any local hardware store or is this normally found at the marine shops? What meathod is used to administer the product? Thanks for the tip!!!

[Theoutdoorsman]

Is your engine used in fresh water or salt? Do you trailer boat and flush out with muffs and fresh water at the end of the day? If you dock the boat it is tough task to flush engine even though you can with tight muffs attached to motor and lower it into water and start for 5 minutes till water from pee hole is exiting fresh water. Remember you had alot of hours on those heads and alot of crappy water go thru and accumulate thru the years and when winter storage it drys up and hardens till the spring.
Clint 8)

The motor will be used in only a fresh water environment. Too, I have never flushed the motor on muffs at the end of the day, although now, I can see the need for it. I'll definitely try the above mentioned product to keep the deposits at bay. Is it available at any local hardware store or is this normally found at the marine shops? What meathod is used to administer the product? Anyone else have anything they like to use?Thanks for the tip!!!

[KYHunter2]

If it is and has been a fresh water motor.

No need to flush at end of the day , unless , I guess , your running in awefully nasty water.

Over time , they all get that build up , be it calcium, lime, whatever it is.

I just pull the water jacket covers every few years and inspect/ clean.

But, I can be a little too particular at times.

Cheap insurance , none -the - less.

KYHunter

[Theoutdoorsman]

True.............Thank you!! What can you tell me about dropping this lower unit to install a water pump kit? That's my next biggest thing right now and I don't know squat about how to do this. Thanks again.............ALAN