TOPIC: Cooling discharge?

Continuing saga with the '77 140hp Evinrude.
Overheating bad. Had it running and then shut it down because the heads were getting really hot and there was no water circulating.
I know the impeller is good, just rebuilt it.
Removed the two small hoses from the heads to the thermostat housing and while the motor was running water was flowing out the connections so there is water circulating through the block.
Problem is that the water is not discharging therefor not letting the cooling water circulate.
Removed the thermostat housing, the stats were a little gummy so I cooked them. One opened at 140 deg, the other opened around 165 deg. The springs and seals are all good.
I tried backflushing through the two holes in the shaft housing where I assume water should be discharged but I just get back pressure.
Any opins of why water is going in but not coming out. With this happening there must be an airlock issue causing overheating. I do not want to run without the thermostats but can if necessary
I see nowhere for the water to go once it enters the thermostat housing.
Mentioning that the impeller housing had a small 1/8" hole in the top which I assumed was some sort of pressure relief. I've never seen that on all the rebuilds I've done before.
Also mention that one of the plastic plungers looks like it had melted somewhat. It still seals good but what would cause that?
OPINs?



PS> I did drill three large holes in the lower cowl to get to the thermostat housing bolts

I may be wrong, but if the 140 works like my old 85 only enough water spits out those 2 holes to let you know water is circulating. Most of the water exits thru the prop with the exhaust.

Ya Doug, My '76 85hp Johnson is like that. Runs warm but I can still hold my hand on the heads. This baby gets HOT!
No water comes out of the exhaust either. Something is plugged up somewhere. Any JEGO gurus know what is hiding under that exhaust "bubble"?

Sorry Cal can't help on this one. Too bad we don't hear from Bruce or Scott much any more I'm sure they probably know.

Bob

Hey Bob, not a problem we can't solve. About a half hour before I opened your post I had that 140hp running like a top.
I found some blocked passages in the thermostat housing. Two small holes that I suspect were air bleed were plugged up.
Installed two new thermostats and backflushed the pump and heads. The discharge hole from the stats was also gunked up. New gaskets etc. Started it up and a few seconds water was flowing
So much for a free motor.
Rebuilt starter, new key switch, new start solenoid, rebuilt fuel pump, impeller. rebuilt carbs.
Hoping some decent running will improve the compression once the carbon loosens up.
She's a gas hog four sure. I had a gallon milk jug half full hanging on the stand alongside the motor, ran for a few minutes or longer to make sure it wasn't overheating, started running bad.....sucked up the entire half gallon.

There is a reason they put big gas tanks in boats that can handle big motors!!
Bill

What about small boats with big motors. Recommended 85hp which is on the boat now. We'll see how it performs this spring. The 140hp is for stupid people to swap. Just a matter of time before I change over.
I installed an onboard 18 gallon tank which should get me a few miles from home then I always carry a red gallon ERA laundry soap container as a "get me home".

Ok glad it's running great now. Yeah this '67 80hp isn't much for good mileage either. If I could find maybe an '80 something 80hp that I could adapt the current '67 cover on it would be more powerful and a lot more fuel efficient.

Bob

There is a reason I have 2 12 gallon tanks for my 115 Merc. It isn't quite as thirsty as my old '63 merc 85 hp, but it can hold it's own if you cruise wide open. I usually cruise about 2/3 throttle and I get the same speed as wide open on the 85, but save about 1/3 the fuel.
Bill

Nice work. You are like Sherlock Holmes chasing down those mysterious problems. Do you think maybe some of the rings are stuck giving you low compression? Wonder if that motor got overheated before you got it? Love the sound and power of those v-4’s. I have skied behind many and they all seem like stump pullers. Someone had a 140 on there gt150 bond boat because he barefoot skied doing deep water starts. Pretty darn quick. You may need the 140 once you finish placing that entire redwood tree on board. Built in floatation is pretty smart! Can’t wait to see this summer.., from 6 feet away of course.

Yes Mark, I suspect the motor is pretty carboned up. When weather warms up I'll run it with SeaFoam to help loosen things up.
It DID overheat, pretty obvious just from looking at it. The wire from the starboard heat sensor was melted at the head. The starboard cylinder head was replaced at one time, there are new head gaskets in place. Had to retorque them both. What surprises me is how easy it starts. Past experience was that if the compression was really low, even in one cylinder they are a bear to start.
Bill, WOT on those "stump pullers" like you said doesn't get you any more speed, but the hole shot to plane is a lot quicker, not as quick as Mark but adequate. Usually for me a good cruise speed is around 23 mph. A more aggressive prop with more hp can put that target in range with much lower RPM ergo saving gas.

Hey Cal what's the weight on that 140? It really doesn't look like it could weigh more than my '67 85hp. My Wagemaker is rated for 100hp but I'm sure that's due to the weight of a 100hp at the time vice actual hp. I've been afraid to try and put anything bigger than an 85 on there due to the weight. The transom is still original and don't know how much it can take. The plywood is bone dry but Dad said he thought it was shot, didn't look like that to me.


So anyway, I wanted more than 23 mph wot with the '59 fat fifty on it hence the '67 85 hidden in the '61 housing. The 85 definitely isn't at it's peak compression, I think when I first got it, it was 90/95. I haven't run it in a year and half so not sure what it's at now. Been running Seafoam in every tank since I did all that switching. I could do a rebuild maybe to bring it back but I figured a much newer model would be more efficient and still get some more mph out of her.

Bob

Specs say the 140 is 326# and the 85 is 270#. I suspect the 85 is somewhat heavier than that. If you look at the pictures you can see that the 140 LU is quite a bit beefier, larger supports, gearcase, et al. Don't know how much and extra 50# would affect performance.
The first Tomahawk I had and put the 135hp on ran beautifully but when standing still you had to be very careful not to get too close to the transom cuz water would come in the motorwell drain holes.
The 15' Tomahawk on a good day would do 47/48mph on a straight run GPS. Only did that once though just to see what she would do.
The wood wagemaker more than likely weighs much more than the glass.
The motor covers are exchangeable, same size, same lockdowns.

Good to know about the cover. My Wagemaker is 1040 lbs no engine. Completely forgot to look at the lower unit, was focused on the top end. lol

Bob

Add the weight of power trim/tilt to the 85 and they are very close.

Yah, that's what I'm thinking too. Won't mean much for now since the 140 is a backup sitting on it's stand.