Evinrude 1973 50 h.p. Overheats

[BuzzM]

My 1973 Evinrude 50 h.p. still overheats with a new waterpump. ( no water flows from upper exhaust port,as it did previously)I cannot find the thermostat and was told the powerhead needs to be removed to find it. I HOPE this is inaccurate. Any ideas?

 

[DJ]

Re: Evinrude 1973 50 h.p. Overheats

osprey,<br /><br />I believe your thermostat is on the head. Look for a small plate covering it.

 

[OBJ]

Re: Evinrude 1973 50 h.p. Overheats

The t-stat is located under the head cover which is the plate attached to the front of the head. Has about 14 or so bolts holding it in place. The T-stat is at the bottom when the cover is removed. The bottom bolts are a pain to get to but you don't have to pull the power head to get to it. The bolts are 1/4 with 7/16 wrench heads. If ya' get into it, just remember that when your reinstall the plate cover, work from the middle out when tightenig the bolts. May save a leak.

 

[BuzzM]

Re: Evinrude 1973 50 h.p. Overheats

I verified the water pump is installed correctly and ran a water hose into the pickup tube to dislodge any obstuctions ( dirt dobbers, fireants, etc) with no visible results. Water is ejected through the housing, but not through the upper exhaust ports. Would this confirm a bad thermostat or could there also be another problem ( blockage in water jacket, blown headgasket). The thing starts fine and runs well until the horn goes off.<br />I really don't want to pull the powerhead. I can't get the bottom bolts out of the water jacket cover without doing so. Any help is appreciated. thx

 

[OBJ]

Re: Evinrude 1973 50 h.p. Overheats

Hi again osprey....<br /><br />You probably won't get any water through the upper ports, I'm taking for granted you mean the exhaust releif ports right under the engine pan, until the t-stat opens. This will be just a "dribble" at that or a misty spray. I'm not sure why you can't get to the lower bolts on the cover plate. Are they just "stuck" are you not able to get a wrench on them?

 

[BuzzM]

Re: Evinrude 1973 50 h.p. Overheats

I appreciate the quick response. Actually, I can get a wrench on them and have loosened the water jacket bolts. The problem is there is very little clearance at the bottom, so the bolt cannot come out far enough to clear the edge that comes up a<br />couple of inches. The ones above the bottom row can just squeeze out. It appears that the powehead can come off without disturbing the carbs so that may be my next move. I am a little intimidated by the powerpack wires, adjustment stuff, etc. thx again

 

[papasage]

Re: Evinrude 1973 50 h.p. Overheats

take the bottom cover loose . it will move bac kand down enough to git the bolts out. papasage

 

[OBJ]

Re: Evinrude 1973 50 h.p. Overheats

Papasage has the answer. Loosen the lower pan bolts and get a little more room. Pulling the head is a pain.

 

[BuzzM]

Re: Evinrude 1973 50 h.p. Overheats

I know I am sounding like an idiot.. but the engine pan appears to be a solid casting complete with the support pillars for the powerhead mounts. I don't think it will move or " split" in half. I am going to try this again, but the clearance for those bottom bolts is less than 1/4 ". It is getting hot here in Dallas so I may get after ir with a sledge hammer. The manual indicates powerhead removal to get to the thermostat. But, there is usually an alternative appraoch. Thanks for the support anyway.

 

[DJ]

Re: Evinrude 1973 50 h.p. Overheats

It will seperate. Look for the bolts on the front of the lower cover that face forward. I think there are four. That will remove the smaller lower cowl (just above exhaust relief holes) and allow access to some of the bolts that hold the mid section cowl in place.

 

[papasage]

Re: Evinrude 1973 50 h.p. Overheats

they are 4 bolts that can be taken out . this will not take the bottom pan off but will let it move enough to git to the bolts .not easey but i think it will work. there is a cover on the frunt that has 2 flathead scerws you may have to take off. papasage

 

[BuzzM]

Re: Evinrude 1973 50 h.p. Overheats

The story continues..been too hot to mess with the water jacket cover. I took another look at impellor and ntoiced that all vains except one was turned in the proper direction. Probably no big deal. I used blue silicone to seal pump body to the plate this time and was extra careful to get tube into the grommet. Started it.. ran great, but seemed a lot of water was coming out around the " collar " above the lower unit, and the " pee" hole. But, a little water was coming out of the exhaust ports at the top and it did not sound the hot horn. Thought it was finally fixed. The I put it in forward gear briefly and killed it since some of the water sloshed out of the tank. Restarted it, and put in reverse for a couple of seconds. I restarted and let it idle. After a couple of minutes , the hot horn sounded.It looked like water was not flowing through the system, again.<br />I dropped the unit and could find nothing wrong with the impellor, housing or anything. I did not put sealant on the bottom of the pump plate or bewteen the gearcase housing and lower unit. I did not use any sealant on the grommets and am beginning to think that water is leaking from the pump grommet at the pickup tube. The inner diameter of the tube is not perectly round. Looks like it has a slight indentation.<br />Any thoughts before I give up and take it to a shop?

 

[papasage]

Re: Evinrude 1973 50 h.p. Overheats

make sure the key is in the impeller.tube is in the rubber gromet . the plate under the pump gits to much wear it want pump right . change the thermostat .papasage

 

[Droll]

Re: Evinrude 1973 50 h.p. Overheats

Got the same problem on my 1971 50hp , the "Pressure release valve" was "missing".<br />The engine was runnig ,but after some time on idle ,the alarm started .<br />Hopefully my part arrives this sweek .

 

[Jay Squelch]

Re: Evinrude 1973 50 h.p. Overheats

Did you get your overheating problems sorted out?<br />I recently went through a similar nightmare with may 1981 60 horse. I turned out to be the rubber gromet between the powerhead and the water tube. this requires removal of the powerhead and adapter assembly. If the motor is saltwater, this process is very difficult as you can expect a lot of broken bolts. They now make a platic grommet which does not corrode.