115 Johnson overheat

[surrender]

1983 115 that has new waterpump kit but not much other history. Overheat alarm sounds and heads are very hot to the touch after just a few minutes of running at idle in the water. Water coming from pee hole is very cold cold( seawater temp is around 48). T- Stats are supposed to be new. Took apart t-stat housing and was all dry. both hoses at lower end of heads have no water flow, yet have good flow through pee hole. Where is my blockage. this is a friends motor so I dont know anyother history except the heads were recently removed and water deflectors were said to be in right place. So salt blockage was found but was all cleaned. Ran engine on muffs with t-stat housing removed and water came out pee hose but area around and in housing was dry.

 

[wilde1j]

Re: 115 Johnson overheat

Drop lower unit, remove stats and force water through the water pump outlet tube which goes up to the block. Sounds like debris has lodged in the heads or block killing circulation. You can try compressed air also.

 

[78 mckee]

Re: 115 Johnson overheat

Another thing that may cause this problem is exhaust gases getting into the water jacket due to a failure of a gasket that separates the water from the exhaust at the inner exhaust cover. The exhaust will displace the water and keep it from circulating around the cylinders. Cool water from the pump will still make it to the water pump indicator line but will not circulate.

 

[emdsapmgr]

Re: 115 Johnson overheat

You can have cool water out of the telltale and still overheat at idle. If the cooling water can't escape the block (dump back down into the midsection) it will overheat at idle. Usually, thermostats which are stuck closed will cause this problem. I'd want to see some receipt to validate the stats are really new.... In the thermostat housing there is a plastic plate, called a valve body. This body should have two small pinholes in it. They must be open for hot water to bleed to the back side of the stats to get them to open. If these holes are plugged, it will overheat at idle. If the holes are open, but still overheating, I'd pull the outer head covers off the heads (not need to pull the heads off) and inspect the water passages inside. They may be partially blocked.

 

[surrender]

Re: 115 Johnson overheat

78 Mckee, (nice I have one too, 87 offshore) my buddy called and he has pulled the exhaust cover and plate and I am going to look at that today.

Emdsapmgr, we pulled the t-stat housing and it,s new along with the stats. What is weird is the whole compartment behind the stats is dry and the hoses going to the heads are dry. No water is getting to either side of the stats, yet it is flowing great out the tell tale. When the heads were off I saw the blockages and they were cleaned out and the diverters looked to be in the right place. I think we will drop the lower unit and try to see if we can get water to flow up the tube.

 

[78 mckee]

Re: 115 Johnson overheat

What can happen with the gaskets is that the gasket surface that is exposed between the webs that mate-up can dry and shrink over time and when they do the gasket pulls out from between the mating srfaces and allow exhaust gases to infiltrate the water jacket. I have seen this several times. I actually have one of the gaskets up at our cottage that was taken off of a 35 hp Evinrude with this problem. I'll have to get photos posted sometime when we get back up there this season.

Love my Mckee, have had it since '86.

 

[emdsapmgr]

Re: 115 Johnson overheat

Pull the head covers off the outside of the heads and have a look. Were the holes open in the valve body?

 

[Fed]

Re: 115 Johnson overheat

The diverters may be in place but they are there to stop the water taking a 'short cut' between the cylinders, instead forcing the water to go up and over the top cylinder then back down & out.
The diverers swell up & block this up/down circulation where they should only block between cylinder circulation.
Search the site for diverters or deflectors there are a few very good pictures showing problems.

 

[emdsapmgr]

Re: 115 Johnson overheat

Here is a picture of a correct water diverter, and one that is misplaced. The one in the center of the picture is correct, the one to the far right is out of position.

 

[emdsapmgr]

Re: 115 Johnson overheat

This is a duplicated post, disregard.

 

[mkay]

Re: 115 Johnson overheat

Some common problems when a water pump has been changed is either a misalignment of the inner exhaust tube seal ring to lower unit as the lower unit is lifted and bolted up to the outer housing or an old pitted seal.The seal is pretty soft and easily damaged.This is more common because most people put the engine in the tilt position to make the job easier. If the seal doesn't mate properly it can cause hot exhaust gases to leak into the area above the tranny heat up the new water pump and transmission housing causing the internal tranny pressure to rise and cause a leak of transmission lube into the exhaust system. You will see the oil smoke. If the old seal shows pitting new seals are available. It should be attached to the inner exhaust housing with an adhesive. After allowing it to set a while the lower unit can be lifted into place, but it is a good idea to lube the exposed mating surface of the new seal with a small amount of grease to facilitate it entering the sealing surface on the lower unit. Bolt up is often done with the engine in tilt position which makes life easier. Once the drive shaft splines enter the power head you can generally loosely attach the lower unit to the outer exhaust housing with the four side mounting bolts leaving enough gap between the lower unit and the outer exhaust housing to peek through the gap of about 3/8 inch with a small flashlight and make sure the water tubes and the inner exhaust seal are properly lined up. At this point to facilitate the alignment it is a good idea to lower the engine into its running position and rock the lower unit back and forth just a tiny bit to let everything align. Recheck the alignment. Then it is just a matter of slowly tightening the bolts in a balanced manner to close up the gap. In those engines without a gasket between the lower unit and the outer exhaust housing water may leak between the two surfaces especially if you run it on a garden hose. Evinrude called for use of a sealant in that area, but it is not really necessary. As long as steam and then hot water exits the rear ports after a few seconds no problem, but it is a good idea to check the power head temp as the engine warms up; a small inexpensive non contacting infrared sensor works well if you get it close to the heads. These engines should regulate between 120 and 150 degrees F depending upon how hard they are being run.