Steaming Outboard

[Elund09]

35 Hp Johnson. The Power Head is a 1980, 35ELCSM, and the Lower Unit is a 1977, 35EL77H.

History;
I overheated this engine. Weeds wraped around the lower unit. I thought I had cleared the weeds and went WOT. Soon I experienced a loss of power. When I backed off, the engine killed and then, Poof! Steam rolled out from under the engine cover. The engine paint blistered and darkened in color.
Compression readings showed 50 psi in both cylinders.

Work Done;
-The head warped, found a used head. Installed head and gasket. Compression readings now at 110 in both cylinders.
-New Thermostat
-New gaskets in exhaust cover
-New spark plugs
* I have not replaced the impeller in the 4 years I've owned this.

All back together and in the water. I have a strong steady stream of water out of the tell tale at any rpm. The water from the exhaust ports is nice and warm, the water from the tell tale is about 50% cooler than the exhaust.

When I'm at an idle everything seems fine. As I add power and increase the rpm I notice that it begins to steam. It looks like a 2 stroke would at 45 deg. outside, but it's 85. It seems to have power loss as well.
There is also some carbon spatter from the steam on my lower unit. This never happened before the overheat. There are pics of this and the holes the steam is comming from.
Could this be an impeller issue? Cracked block perhaps? No sign of dammage to block or cylinders when head was removed.

I'm stumped and getting a bit frustrated. I could sure use some advice, Thanks, Erik

 

[Daviet]

Re: Steaming Outboard

If I read your post correctly, you did some repairs and did NOT replace the water pump after it over heated, correct?
If that is the case, I would pull the lower unit and check and replace the water pump.

 

[1946Zephyr]

Re: Steaming Outboard

Well, I'm amazed that you're getting 110 psi evenly in both cylinders after that incedent. Usually when you overheat an engine this bad, the pistons will end up BADLY scored. I had to rebuild a motor for a guy who had this happen.:redface:

 

[1kruzer1]

Re: Steaming Outboard

If I read your post correctly, you did some repairs and did NOT replace the water pump after it over heated, correct?
If that is the case, I would pull the lower unit and check and replace the water pump.

Agreed. If it ran starved for water long enough to cook the powerhead like that, it fried the waterpump as well. The fact that it seems to pump ok at idle is meaningless. It's common for a worn pump to pump at idle and then loose volume as it revs up. Replace the impeller and if it's housing is not perfect replace that too.

 

[Elund09]

Re: Steaming Outboard

I dropped the lower unit today. The drive shaft spacer was lifted up and off of the impeller housing. It was badly dammaged and if not all of it, part of it had broken off from the rest and was spinning around with the drive shaft.
The impeller had one bad blade barely attached but connected and in the correct possition respectivly. The water tube grommet needs replacing.

I will be replacing the Drive Shaft spacer, Impeller, O-Rings, and Grommets. The Housing is in good condition. I'll post my results after I get her put back together.

If anyone thinks of anything I missed or other things to look at, let me know.
Thanks, Erik

 

[Daviet]

Re: Steaming Outboard

If it were me, I would install a complete water pump kit including the housing. It would be a shame to go through all that work and then find out you had a warped housing.

 

[wilde1j]

Re: Steaming Outboard

The housing and wear plate must have no scoring or the pump won't pump very well. Why cheap out when you have the whole mess apart? The entire pump isn't that expensive.

 

[Elund09]

Re: Steaming Outboard

Replaced all the parts including the housing. There is no longer a steaming issue and there has been no soot observed on the lower unit after operation.

The drive shaft spacer had broken apart and melted around the shaft, getting wedged in a tight space on it's way upward. It's possible the friction here was causing the steam but is certinly the cause of the soot. I'm sure a lack of water into the engine could also cause the engine to begin to overheat, causing steam as well.

Don't be cheap. If you experience an overheat, check the water pump, even if you think you have a good flow. A pro told me I had a good flow of water and it could'nt be the pump.
However, it was a combination of things. The spacer, water tube gromets were leaking, and one of the impeller blades was bad.

I could have avoided all of this had I done an inspection of the lower unit this spring. Proper maitenence is key to keeping a good motor good for years.
I will be inspecting my lower unit every 2 or 3 years from now on.

 

[Daviet]

Re: Steaming Outboard

Glad you got your problem solved.