Evinrude 7.5 overheats

[Joey One]

My '82 Yachtwin 7.5 HP Model E8SLRCTA, 25", overheats badly shortly after starting. No water from the pisser at idle, but good water flow at 1/4 throttle.<br />Removed thermostat and connected water hose to pisser tube; good flow from water inlet and exhaust<br />opening. What do I do now?

 

[DHPMARINE]

Re: Evinrude 7.5 overheats

Start with a new waterpump.Repeated overheats will greatly shorten your motor life.The good water flow you see at 1/4 throttle is not a true sign.<br /><br />DHP

 

[Joey One]

Re: Evinrude 7.5 overheats

OK. I ordered a water pump kit and gasget set. The manual doesn't specifically say so; but I gather from this forum that I can get in trouble if the water tube does not stay in the powerhead. Are there any tricks to be sure that this water tube stays in?

 

[Chinewalker]

Re: Evinrude 7.5 overheats

Hi Joey,<br /> The watertube doesn't generally come out of that powerhead very easily. It has a lip on the top, under which rests a rubber grommet. You'd have to pull awfully hard to pull it through the hole it's sitting in...<br />- Scott

 

[rwcreigh1]

Re: Evinrude 7.5 overheats

i just replaced my 1894 35hp waterpump.the water tube did pull out but all i had to do was use a flshlight ,line the tube up and thats it.unless yours is different it should not be a problem.good luck

 

[TTravis]

Re: Evinrude 7.5 overheats

I just had a similar experience with an older Lightwin 3 HP. It turned out that I had major blockage in my water passageways. My old motor was used in a river and I think it was plugged up with mud or silt. Basically water was getting pumped up into the powerhead but it ran into a dead end and had no place to go.<br /><br />Check this out to see if it gives you any ideas. It's not the same motor but the problem may be the same.<br /><br /> http://www.outboard-boat-motor-repa... Johnson 3 HP 1952-1967 Water Circulation.htm <br /><br />Tom Travis

 

[Xcusme]

Re: Evinrude 7.5 overheats

Originally posted by richard 1:<br /> i just replaced my 1894 35hp waterpump.the water tube did pull out but all i had to do was use a flshlight ,line the tube up and thats it.unless yours is different it should not be a problem.good luck

WOW!! a 111 year old water pump impeller! Now that's what I call durability.<br />( We know what you ment, I just couldn't pass up the chance.... )

 

[Joey One]

Re: Evinrude 7.5 overheats

Right. The impeller only had 2 vanes left, out of six. Three vanes were trapped in the pump outlet.<br />Following the manual and kit instructions, I rebuilt the pump.<br />But I'm dismayed: I can't get the gearcase to fully seat with the exhaust housing. There is a metallic clunk when the gearcase is about 1/2" from the housing. <br />The water tube is OK; motor turns when prop is turned; gearshift works in F,N &R, but not smoothly.<br />I used the 3 mounting bolts to apply a very strong force. The shift rod and the driveshaft are in the gearcase correctly(I marked them); the shift has the flat side to Port(I drew a picture).<br />What's wrong?

 

[Xcusme]

Re: Evinrude 7.5 overheats

OK, lets do the math, 2 vanes still on old impeller, 3 in outlet, that's 5. Where's the last one?? You don't want it to end up in the powerhead, blocking water flow.<br />If things are lined up properly, the watertube should enter the rubber grommet at the water pump, the drive shaft should enter the bottom of the crankshaft. You should not have to resort to using the mounting bolts to pull everything together.<br />Drop the lower unit. Turn the driveshaft clockwise, you should feel resistance. That's the impeller resisting the rotation of the driveshaft. This tells you the impeller key is inserted. If the driveshaft turns with little resistance, the key is missing. Grease the upper driveshaft splines only, not the top of the driveshhaft. re-install lower unit. Align water tube into grommet,and shifter rod. When you feel drive shaft contact crank, slowly rotate flywheel clockwise. Drive shaft should enter bottom of crank. When lower unit is flush with middle section, replace mounting bolts.

 

[Joey One]

Re: Evinrude 7.5 overheats

I found the missing impeller vane in the exhaust housing. I guess it went thru the power-head or fell<br />out of the copper water tube upon dissembly.<br />Still unable to get the gearcase seated. Worked on it for 2 hours this morning. I noticed the top end of the shift rod was badly marked, as if trying to <br />push it into a cocked bevel gear.<br />Is it possible for the upper bevel gear to get cocked; and what do I do about it?

 

[Xcusme]

Re: Evinrude 7.5 overheats

Ok, I think I know what's going on here. The gear shift lever operates 2 small (bevel gears) gears ( this assembly is just below the carb). The flat side of the upper end of the gear shift rod engages the lower gear. The motor's forward-neutral-reverse is shifted when the shift rod is rotated by the lever and gear combo. If you were in neutral gear when you dropped the lower unit, the gear shift lever should be in the straight up (neutral position) upon re-assembly of the lower unit. If the gear shift lever is not in neutral position, the flat side at the upper shift rod end will not engage the lower gear as you describe. To answer your question about the gear being 'cocked'. No, not really, the lower gear is riding in it's housing and is being held in position by the the shift shaft gear. <br /><br />The only other possibility is the other end of the shift rod (lower end). If the rod was lifted out of the lower unit, it may have allowed the 'shift cam' to disengage from the plunger pin in the lower unit.<br /><br />As a side note, did you at any time remove the shift rod from the lower unit? Did you manually rotate the gear shift rod when you had the lower unit down?

 

[Joey One]

Re: Evinrude 7.5 overheats

Thanks for the ideas, guys. Everything is together and running cool. The upper bevel gear for the shift rod was floppy; either cocked or out of line. I finally turned the motor upside-down on a towel; centered the bevel gear with a rifle cleaning rod; then jiggled the F-N-R handle until the shift rod fell-in. I guess I wont know why the bevel gear was floppy until I remove the power head someday; but then I'm not going offshore in the near future.