88 hp Johnson - Overheated & leaking water

[dhardin78737]

1992 88 hp johnson overheated on lake last time out. Water wasn't pumping out of motor, buzzer was going off but by the time I heard it, the engine overheated.<br /><br />Checked water pump impeller - ok. Checked water line and found out that line was clogged with ants and ant larvae. Cleaned all out but now water is leaking from motor - from bolts holding a large plastic cover on back side of motor where water water line comes out of the motor. Have manual but couldn't find what this is.<br /><br />Have a bad feeling - can someone help give me an idea what this is that's leaking and the severity of the problem?

 

[Daniel Beckman]

Re: 88 hp Johnson - Overheated & leaking water

Are you sure you did get all the clogg out.<br />Had almost the same prob this summer.<br />Had to clean it out several times.<br />Did release the lower unit and put a hose direct to the water line that goes up inside the engine.<br />Release the pee hole and the short hose between the pee hole and the engine so the water easy could get out. <br />Also had to take the thermostats away (was clogg there to)<br />Then let the water flush thuru the engine real good (did flush mine for about an hour to be sure.<br />It can be mutch more clogg in there then you even could think about....<br />Think the major prob on my engine was the clogg at the stats.

 

[dhardin78737]

Re: 88 hp Johnson - Overheated & leaking water

Thanks for reply - no, I am not sure all the clog is out. Every once in a while, would still see ants coming out. I will pull thermostats and see....now all I have to do is find the thermostats.

 

[z71crazyman]

Re: 88 hp Johnson - Overheated & leaking water

You could also need to replace the paper gasket that is right above the head where the hose meets the engine at the bottom. It cost me less than 5 dollars at autozone for a roll of paper gasket. Just trace the head cap and then use a hammer on the bolt holes and one bolt and a razor to cut the temperature gauge. <br />Good luck

 

[Solittle]

Re: 88 hp Johnson - Overheated & leaking water

Do all of the above & replace the water pump. You can't tell how good the impeller is pumping by looking at it.

 

[Jack Shellac]

Re: 88 hp Johnson - Overheated & leaking water

The plastic cover you mention is the thermostat housing [and pressure relief valves]. It's something of a chore to get it off, but it can be done. Not difficult, just hard to get to two of the bolts. I would suggest that while you have it off, go ahead and replace the thermos. I've had best luck with OMC replacement thermos.

 

[dhardin78737]

Re: 88 hp Johnson - Overheated & leaking water

Looking for the thermostat, I took the cover off that is between the two sets of cylinders. Come to find out that this is the exhaust cover....no thermos in there obviously (This is the same cover that was leaking water).<br /> <br />2 questions:<br /><br />1. Anything special about getting this exhaust cover back on correctly....besides replacing the gaskets which I am ordering? How important is it to get surface of cover sparkling clean before putting back on?<br /><br />2. Do I have to take the cylinder head off to find thermos? In book it looks like thermos should be right above top spark plug on each side.<br /><br />HELP!

 

[Jack Shellac]

Re: 88 hp Johnson - Overheated & leaking water

Drew: Your thermostats are in a hard plastic housing that is located at the bottom rear of the motor powerhead between the cylinder banks. There is a short rubber hose from each cylinder bank clamped to the top of the housing. It's not very big, about 4"w x 2" d. Held on by 3 machine screws. I misunderstood what you were describing before.

 

[DJ]

Re: 88 hp Johnson - Overheated & leaking water

If the engine got that hot, I would suspect you may have popped the head gaskets too.

 

[dhardin78737]

Re: 88 hp Johnson - Overheated & leaking water

Jack - I know I am probably blind and you have been incredibly patient, but I can't find it. If I am standing behind the motor looking at the cylinder banks on each side, there are two hoses coming off the bottom of each cylinder bank but they go right into the cylinder bank via a 3/4" nozzel. The two hoses I am looking at are about 3/4" dia., 4" long and seem more like air hoses than water hoses.<br /><br />another dumb question related to next email - where do you find the head gaskets. Would this require taking cylinder cover off of cylinder banks? What are the signs if you did blow a head gasket?<br /><br />Thanks for all the help so far.

 

[DJ]

Re: 88 hp Johnson - Overheated & leaking water

Drew,<br /><br />The two hoses come off of the cylinder heads and go down (at an angle) and are connected to the thermostat/poppet valve block. The hoses simply connect the thermostat block to the heads. The block is held on by three bolts. It is at the very base of the engine.<br /><br />Yes, the heads will have to come off to replace the gaskets. Note, the cylinder head bolts are the LARGER bolts around the outside of the cylinder heads.<br /><br />A head gasket failure will USUALLY show up by washing down the spark plug(s). They will look very clean, almost new.

 

[dhardin78737]

Re: 88 hp Johnson - Overheated & leaking water

DJ & Jack - Jackpot! Finally found housing for thermos. Will try to get them out today or tomorrow. As far as the head gasket - I checked the spark plugs and they definately are not clean but I do have crusty white stuff on the outside where the gasket is indicating leakage of some type.<br /><br />As a rookie, do you think I am ok replacing head gaskets myself?<br /><br />Thanks a bunch for all your help

 

[G DANE]

Re: 88 hp Johnson - Overheated & leaking water

A little crusty white stuff is normal for salt water motors, thats sweating. As long as it isnt leaking and compression is fine, no reason to pull heads.