1964 18 hp Evinrude overheated...

[josh6780]

Re: 1964 18 hp Evinrude overheated...

Guys, The very first thing I did to this engine was change the water pump impeller. Very first thing. The housing looks just fine. How can I tell if its bad? This engine overheated with a brand new impeller and like I said before. I checked for blockages and found none. I also was running the motor with no T stat installed when it overheated.

how am I suppose to know if the lower unit is leaking water when it is in the water?

What I will do next as far has the water pump goes, is test the lower unit alone with a drill and see if it pump water.

I think once I solve the water pump problem I will just let the engine run the way it is and see how it does before I go through anymore trouble of ripping the head off or anything.

No one has any comment about water being in the combustion chamber?

 

[samo_ott]

Re: 1964 18 hp Evinrude overheated...

When I test my LU in a bucket with a drill at 330 rpm's the water shot about 8-9" up out of the tube.

 

[jbjennings]

Re: 1964 18 hp Evinrude overheated...

The water in the cylinder could be due to a bad head gasket. I wonder if it's possible the bad head gasket could also be leaking exhaust into your water jackets pushing water away from the head and causing your water flow problem.
Either way, you might as well pull the head and replace the gasket like SamOtt said. You can get a better look at your cylinders and pistons, too. You have to do it anyway and there's no way around it. You should use a straight edge and check for warpage which often occurs after an overheat. Once your new head gasket is in, you can check for compression. I still think if you get 90 on bottom and 60 on top, it's not worth fooling with that powerhead anymore, but hopefully the head gasket will fix your problem with compression, then you can trace your water flow problem. It could be the water tube grommet is pinched, housing is bad, intake screen is a little clogged, etc.
If your head is warped, I believe you can place it on a pane of glass with sandpaper on it and use a figure 8 motion to get it nice and flat.
Good luck,
JBJ

 

[CATransplant]

Re: 1964 18 hp Evinrude overheated...

"No one has any comment about water being in the combustion chamber?
"

Oh, several people have commented on it. It's not a good thing. You really, really need to remove the cylinder head for an inspection. Odds are the head gasket is bad, which was part of the cause of the overheating.

However, from your description of how the piston and rings looked from the bypass or (I hope not) the exhaust cover, you really, really need to inspect the cylinders for damage.

Putting it back together and just running it will get you nowhere, except to further damage your outboard.

Head gaskets are cheap. Thermostat housing gaskets are cheap. If you don't find any damage in the cylinder with the low compression, you can then put the head back on, torquing the bolts down in the proper sequence and to the proper torque, replace the thermostat housing gasket, and go try the outboard again.

As someone else pointed out, if there's damage in that cylinder, forget about that powerhead. Hunt down another good used one on ebay or Craig's list and install it. Or, find another 18 hp outboard and keep the one you have for parts.

But, you really, really need to find out what's going on in that cylinder with the low compression, and the way to do that is to remove the cylinder head.

 

[josh6780]

Re: 1964 18 hp Evinrude overheated...

ok just got done removing the head and inspecting. The wall on the bottom cylinder head is smooth at a baby's bottom. The top one is fine except for there is just a little bit of score right by the port. Could be carbon? Either way I could probably just buff that out. What do yall think about that?

I'm sure yall are right about the head gasket being bad. There was water in both cylinders. More on the bottom than on the top. I don't understand why though cause the bottom was the one with the best pressure. Either way I am going to replace the exhaust and head gaskets.

Next I will test the lower unit.

 

[samo_ott]

Re: 1964 18 hp Evinrude overheated...

Sounds like you're on the right track. Let us know what you find.

 

[Woodstock60]

Re: 1964 18 hp Evinrude overheated...

Now that you have the head off check all around the water jacket and any ports in the head, I don't know if it has tasted salt, but I've seen salt deposits clog up water jackets and blow head gaskets also look for hairline cracks. once you have dropped your lower unit you can determine if the cooling issue is from the top or the lower fairly easy. I know the other guys have already talked about it but I will recap for you. Fill a bucket that your lower unit will fit into with water and drop in LU. Use a half inch drill and attach it to the top of your driveshaft carefully so as not to damage the spline. Turn on the drill (clockwise) and the water should shoot out the top of the water pump at a pretty good force maybe 6 to 10 inches. If that seems ok you need to hook up a water source to the copper tube that feeds the powerhead. I would leave the head off then pack the cylendars with clean papertowels then plastic taped up right to the brim of the cylendar. cover anything exposed that you dont want water in ind turn on the water gently and observe where it comes out. I have seen the copper tube get clogged with debris such as impellar rubber, silicone, sea crap and various flotsam. if the water comes up through the jacket ok on a gentle flow then add water pressure if there is blockage the pressure at the cylendar may still be weak. my guess is blockage that is allowing some water through but not enough.

 

[josh6780]

Re: 1964 18 hp Evinrude overheated...

top

 

[josh6780]

Re: 1964 18 hp Evinrude overheated...

Anyone know the part number for my exhaust gaskets?

If water is clogged somewhere how am I suppose to get it out. See I already pretty much did what you suggested with the water pressure up the tube. I flushed it both ways. I didn't seeme to get an increase of flow with I increased the pressure either.

 

[Woodstock60]

Re: 1964 18 hp Evinrude overheated...

Did the water just flow up and come out the head, or did some leak out back down through the leg as if it were coming out from where the copper tube connects into the head (where the exhaust manifold mates with the head). if you think it may be clogged try sticking a stiff length of copper wire up through the tube to see if you feel anything in there, maybe if there is you can dislodge and push out with water. But more than likely if you believe there may be a blockage in the top end you will have to remove the powerhead to find it. as far as the gaskets go for reassemble, I usually go to the local auto parts place and buy a sheet of gasket material and make my own. I use the old gasket as a template and cut out with an exacto knife.

 

[jack sprat]

Re: 1964 18 hp Evinrude overheated...

pull the head thouroughly clean the block&head loose scale often clogs small water passages and when you stop running they will collect in the bottom of the head.Also the side egxaust cover needs to be pulled to check 6 small water passages the bottom is probably cloged you might be able to run without the t-stat but i have it on good authority that it will cause overheating Ive tried this and to my surprise it runs cooler with it in.My next mods will be to orifice size. Im rebuilding my second 18hp so I can run dual props on my 12'Valco I'll let you know how that goes. I also have pics of the inside if that helps.