1970 115hp overheat light on

I have a 1970 115hp Envinrude. The overheat light turned on and I am not sure what to do. I just bought this boat a few weeks ago and the first couple of times I used it, no light. I then put my first fuel/oil mixture in and now I get the oveheat light. I used some cheap oil at Check Auto. <br /><br />Could using a none "name" brand oil cause overheating?<br /><br />I bought a book and realize that it could be the impeller, the water pump, or a thermostat, or maybe the oil.<br /><br />What do you all think? I also bought muffs and put those one and water comes out the pee holes but not out of the stem (there are 2 holes where water is supposed to "shoot" out).<br /><br />I would appreciate all the input you all can give me.<br /><br />Thanks,<br /><br />RIck

Re: 1970 115hp overheat light on

First off tell us what type of oil you mixed with the fuel.Was it TCW3 rated two cylcle oil?Did you mix it 50:1 ratio using 87-93 octane gasoline?<br /><br />The two holes on the upper mid-section of your engine will not usually discharge a mentionable amount of water while running on the hose.Once the engine is up to speed in water,the pressure bypass valve should open and that's when you'll see it discharge.<br /><br />Once you post back with some feedback on the first few questions ,we'll be able to better steer you toward a plan of attack with your overheat light issue.

Re: 1970 115hp overheat light on

I used Valvoline 2-stroke oil with the TCW3 rating. I used 87 octane fuel.<br />I first mixed 1 quart per 6 gallons in 2 tanks. I then ran 3 gallons thru it and my red overheat light came on. I made a few phone calls to get the correct mixure. I then poured out the remaining 3 gallons into a bucket and transferred 3 gallons from my other 6 gallon tank and then filled both tanks with gas. I thought this should break a 100:1 mixure into a 50:1 by splitting the 6 gallon tank.<br /><br />Thanks,<br /><br />Rick

Re: 1970 115hp overheat light on

New boat/motor to you??? I would check the impellar!!! It may be old and is finally just about dead!<br /><br />Don't run it until you have checked that lower impellar. Was there water streaming out of the telltail hole?<br /><br />Bob

Re: 1970 115hp overheat light on

This is all new to me. I did check the impellar but I am not sure exactly what I should be checking. It looked good to me. What is the telltail hole?<br /><br />Rick

Re: 1970 115hp overheat light on

raxel,Not to insult you intelligence,but do you realize that Bob_VT is refering to the waterpump impeller and not the propeller.This is a rubber pump part within engines lower unit assembly and will require some mechanical skills to service.First thing I would recommend you do is to obrtain an engine specific manual if you plan to troubleshoot your issue and do the necessary maintenance yourself.Any of the members here then will be glad to assist with the procedure in servicing the cooling system of your engine.<br /><br />Reason I wanted to narrow down the type and ratio of oil you used on your first mix ,is to determine whether we are chasing a failing cooling system component issue or one that is lubrication related.If it's the latter ,the first procedure you should concern yourself with is a compression test.If that checks out fine ,then I would suspect your engine is due for a waterpump kit replacement as well as a new T/stat and insure that the poppet valve(water pressure bypass) is working properly. Good luck

Re: 1970 115hp overheat light on

OB,<br />I did drop the lower unit and check the impeller...I was saying that it looked ok to me...but I am not sure what a bad one looks like. As stated in my first post, I did buy a manual.<br /><br />How can I narrow this down to a cooling or lubrication problem?<br /><br />How do I know if its a water pump problem or a impeller problem or a t/stat problem. The books do not go into troubleshooting these. They only show how to replace them if the are bad. I am not sure if mine are bad????<br /><br />Rick

Re: 1970 115hp overheat light on

Sorry for my misread.You can observe the impeller to see if it has taken a set by whether it remains in a spiral shape when removed.It should flex back to a star shape if it still has its original elasticity.Also observe whether the impeller cup and back plate are grooved from use as they will tend to become this way over use from the crude sediment in the water that runs through the pump.This will also reduce the pumps volume capacity.The waterpump discharge tube seal is also an item you'll want to insure is inplace and sealing as this is what transfers the water from the pump to the engine block.<br /><br />The T/stat assy. is a very important aspect of the cooling system and is prone to crusty deposits which cause them to stick and not operate freely.Best to just replace with new after removing the present one.Same with the poppet valve or (water pressure bypass) valve as they also tend to become encrusted over time and don't open freely and smoothly.Your engine also has water deflectors that can become deformed and cause water jacket restrictions as well.<br /><br />Before digging too deep into a possible cooling issue though,you need to be able to determine that the engine is in fact overheating and its not just a malfuntion of the temp sending unit that initiates the light.You can determine this a few ways.One is by performing a touch check of the head covers and block after a run .The best way is to obtain either a 163 degree thermo melt stik and marking several locations of the engine block and heads or getting ahold of a hand held temp gun.Good luck and let us know what your findings are.<br /><br />Again,sorry for any misunderstanding on my part.

Re: 1970 115hp overheat light on

No problem with the misunderstanding... I did do the touch test and it was HOT...I noticed a couple of wires that were touching the engine were melting...luckily it had a protected sleeve over them...<br /><br />I will take the impeller out again...if my memory serves me right I think the impeller did not go back to a star shape...but I will look at it again. <br /><br />Rick

Re: 1970 115hp overheat light on

I checked the impeller and when I took it out of the housing it stayed in the same shape as it was inside the housing. The impeller was "stuck" in the spiral shape.<br /><br />rick

Re: 1970 115hp overheat light on

Be a good idea to install a new pump kit.Once the impellers take a good set ,they lose efficieny and don't move the volume of water they once did.Always a good practice the install a new T/stat assy along with the waterpump.