1962 18hp Evinrude- is the thermostat working?

[GarageBeers]

Hi there, new thermostat and water pump. Water shoots out the exhaust on startup and while idling but temperature is warm to the touch the entire time. Didnt feel hot/cold/hot/cold. Is this okay? How do I know if the thermostat is working? Water pump seems fine. Hard steady flow. My next idea is to buy an infrared temperature laser gauge to check the cylinder head temp. Worried its getting hot because i cant tell if the thermostat is working

Thanks for any and all help!

 

[LDUBS]

What you describe is 100% normal for my outboard. It starts peeing immediately upon start up. I suppose things could have been different 60 years ago, but it seems I've read here that the tell-tale is not dependent on the thermostat. I;m sure others will confirmed or not.

BTW, if it bothers you, just buy and install a new thermostat & gasket. Or pull the existing one and test it. I suspect the cost of a replacement is relatively low, so if me I would go with a new one. Then no need to buy a fancy laser thermometer.

 

[GarageBeers]

What you describe is 100% normal for my outboard. It starts peeing immediately upon start up. I suppose things could have been different 60 years ago, but it seems I've read here that the tell-tale is not dependent on the thermostat. I;m sure others will confirmed or not.

BTW, if it bothers you, just buy and install a new thermostat & gasket. Or pull the existing one and test it. I suspect the cost of a replacement is relatively low, so if me I would go with a new one. Then no need to buy a fancy laser thermometer.

Hi LDUBS thank you for your response. It is comforting to hear that my situation is similar elsewhere. I know on these old outboards there is no "tell tale" like modern outboards, it just shoots out the main shaft with exhaust, so I didnt want that to be unclear/mistaken. Good to see we are on the same page there

Regarding the thermostat, its brand new and recently ordered as an OMC original piece. So my guesses are: 1- its defective, 2- it hasnt gotten to high enough operating temp to work, or 3- it is working, and a steady flow of warm (not hot) water is normal for these older outboards? Still seems odd that cold water wont pass through after a few seconds. Not sure

I suppose I could boil some water and put the thermostat in and see if it opens. Need to research what temp this thermostat opens at.

 

[Crazyboat]

Well, if it's not overheating it's stuck in the open position, which is better then closed. I'm going way back in my memory for this, but my 74 Johnson 15HP always was warm, never hot to touch. That said, I never held my hand under it longer then it took to rinse the fish off my hands.

 

[airshot]

Been a while since I worked on one that old, but if my memory serves me correctly the water discharge will be warm right away as the water is cooling the exhaust leg which gets warm immediately from exhaust gases. Had a 1964 model and recall the discharge immediately warm. Telltale is a different thing completely, water circulates the head first so it takes time to warm up. Kind of a quick explanation but your good to go.

 

[GarageBeers]

Been a while since I worked on one that old, but if my memory serves me correctly the water discharge will be warm right away as the water is cooling the exhaust leg which gets warm immediately from exhaust gases. Had a 1964 model and recall the discharge immediately warm. Telltale is a different thing completely, water circulates the head first so it takes time to warm up. Kind of a quick explanation but your good to go.

immediately warm, and stayed throughout use? Or eventually shifted between hot/cold as the thermostat opened/closed?

 

[GarageBeers]

*update- this is the thermostat I ordered off MarineEngine, its an OMC part: 5005440 - Thermostat, 143 Degrees. Ill have to shoot the thermostat area with an infrared thermometer to see whats happening with temps I suppose... ill also remove the thermostat and see if water shoots out to verify no blockages prior.

 

[GarageBeers]

Here is the exhaust water flow:

 

[Crazyboat]

The amount of flow is normal above idle amount IMO.

 

[airshot]

The thermostats controls the water temp thru the head, all excess water comes out the exhaust to keep the leg cool. The water coming out might vary some in temp but you won't notice it. Looks like she pumps water well. If it makes you feel better get a temp gun and check the head.

 

[LDUBS]

Hi LDUBS thank you for your response. It is comforting to hear that my situation is similar elsewhere. I know on these old outboards there is no "tell tale" like modern outboards, it just shoots out the main shaft with exhaust, so I didnt want that to be unclear/mistaken. Good to see we are on the same page there

Regarding the thermostat, its brand new and recently ordered as an OMC original piece. So my guesses are: 1- its defective, 2- it hasnt gotten to high enough operating temp to work, or 3- it is working, and a steady flow of warm (not hot) water is normal for these older outboards? Still seems odd that cold water wont pass through after a few seconds. Not sure

I suppose I could boil some water and put the thermostat in and see if it opens. Need to research what temp this thermostat opens at.

Thanks and no worries. I actually thought you were referring to a tell-tail (oops).

 

[GarageBeers]

The thermostats controls the water temp thru the head, all excess water comes out the exhaust to keep the leg cool. The water coming out might vary some in temp but you won't notice it. Looks like she pumps water well. If it makes you feel better get a temp gun and check the head.

Oh wow so there really isnt any water exiting to verify if thermostat works? Just simply measure temps with an infrared thermometer around the head and thermostat housing?

 

[airshot]

Many engines don't have thermostats... Having a thermal temp gun can be very useful but some folks go by touch with their hand..

 

[Pappy]

Easy way to see if the thermostat is working is to lay your hand on the top of the cylinder head at idle. You should be able to hold your hand there no longer that 3-5 seconds before it gets uncomfortably hot. That should be around 135f or so.
The thermostat in this engine warms the powerhead at idle only and does not control the powerhead temperature throughout the RPM/load range.
The exhaust relief should show water flow very quickly as does a more modern overboard indicator or tell tale. They are not dependent on the thermostat opening to operate.

 

[GarageBeers]

Easy way to see if the thermostat is working is to lay your hand on the top of the cylinder head at idle. You should be able to hold your hand there no longer that 3-5 seconds before it gets uncomfortably hot. That should be around 135f or so.
The thermostat in this engine warms the powerhead at idle only and does not control the powerhead temperature throughout the RPM/load range.
The exhaust relief should show water flow very quickly as does a more modern overboard indicator or tell tale. They are not dependent on the thermostat opening to operate.

Great to know, cleared up my confusion! I appreciate it! I will report back with results

 

[Sinkingfast]

Get some temp sticks used for welding. They are like a wax pencil that ya just draw a line where ya want to check the temp. I use 120, 140, 160, 180F. I put 4 marks on the motor and see if or how many marks melt.

 

[GarageBeers]

Get some temp sticks used for welding. They are like a wax pencil that ya just draw a line where ya want to check the temp. I use 120, 140, 160, 180F. I put 4 marks on the motor and see if or how many marks melt.

Oh cool! Great to know. Thanks!