Motor running hot after decarb

[boat_beginner]

I tried the decarb method (1 can of seafoam in 1 gallon gas) to my 1973 85hp evinrude model 85393M, and about 5-10 min in the overheat alarm went off. So I tried running regular gas through it with the proper mix, and it's still doin the same thing. Has anyone else ever had any problems with their motor running hot after the decarb method? Or have any clues as to why it's doing this?
I replaced the water impeller the beginning of the year, and only ran it about 6 times in the new impeller. It seems like it's not pumping water all the sudden.

 

[boat_beginner]

Re: Motor running hot after decarb

Well, I pulled the lower unit and the water impeller was destroyed, as I expected, and the plastic housing around the impeller is melted also. So that brings a few questions.
One, could the high concentration of seafoam caused the motor to overheat and burn up the impeller? I was running the motor in a barrel of water when useing the seafoam, if that makes a difference.
And two, I noticed the exhaust housing is plumb full of carbon, about 3/16 of an inch worth. Could I spray some seafoam or other cleaner in there to clean it out before I put the lower unit back on? I can see the crankshaft in there, and was unsure of what to spray in there to scrub it out other than seafoam.

 

[emdsapmgr]

Re: Motor running hot after decarb

Doubt that your seafoam contributed to the overheat. It's possible the engine overheated in the barrel. The hot engine exhaust exits in that barrel and after some time running-that water in the barrel will quickly heat up, and significantly. Remember that's the water that gets sucked back up into the water pump. Whenever running an engine in a barrel, be sure to turn the hose on full in the barrel while it's running. Let it overflow. That will usually introduce enough fresh cool water that it won't overheat, but you'll have to watch it in a small barrel. I wouldn't think you will need to clean the exhaust tube. It's just going to get carboned up the next time you go boating.

 

[Bob_VT]

Re: Motor running hot after decarb

No the decarb would not have any effect on the impeller however, all sorts of carbon and crust could be expelled from the exhaust.

If your impeller housing is showing signs of being melted then I imagine the stainless steel cup the impeller rides inside of is probably coated with black rubber. It's time to get the kit and replace the impeller and the cup. If it was in a barrel or even in the water.....I bet the intake got blocked. The exhaust carbon residue in the mid section will actually clean itself out when you are under power and wide open. It (the carbon) builds up more at idle and trolling.

 

[boat_beginner]

Re: Motor running hot after decarb

Apprectate the help Bob.
And the stainless cup does have rubber melted to it, so I will need the complete rebuild kit for it.

 

[Bob_VT]

Re: Motor running hot after decarb

Yup, you will never clean out that cup and restore the smooth finish. Here is the link..... now if the plastic is melted be sure to order a kit with the housing Outboard Parts, Outboard Motor Parts, All Brands - iboats

 

[boat_beginner]

Re: Motor running hot after decarb

Yup, you will never clean out that cup and restore the smooth finish. Here is the link..... now if the plastic is melted be sure to order a kit with the housing Outboard Parts, Outboard Motor Parts, All Brands - iboats

sure appreciate it, i do need both, and they are on order.

 

[clanton]

Re: Motor running hot after decarb

What about the exhaust housing gasket/seal?

 

[boat_beginner]

Re: Motor running hot after decarb

I will have to check that n see what it looks like and order that too if needed. Thanks for pointing that out.