90 hp 1988 head gasket replacment water on plug.

[peter wickham]

outboard has recently developed water in one cylinder. was slow to run properly on initial start on two occasions and on last use would only run on 3 cylinders till i changed plug. (found water on plug). ran ok for rest of trip. But removed head after flushing and found signs of water in cylinder. Gasket looks ok head looks ok and cylinders look ok. I am hoping that the problem is the gasket, but as it is a new problem and only a minor leak its not yet showing on head gasket. Have cleaned everyting up ready to reassemble. What is the head tension and also I have read to use a sealer on gasket, but in this forum it said not to use sealer. I was going to use Hylomar. Now Im not sure. I am also unsure of my diagnosis. Prior to this problem a thermostat was stuck open and was replaced, and also the water pump impeller replaced. [minor rust stain in cylinder]**:juggle:

 

[wkuadam07]

Re: 90 hp 1988 head gasket replacment water on plug.

Look in a manual for the bolt tightening torque, that's the best bet there, but may i suggest a leak down test? Harbor freight leak down testors are pretty darn cheap, and could save a lot of headache and wasted parts in your case. Probably would have been a more helpful suggestion before you took it apart, but i would do a leakdown test after assembly to make sure that everything is in good shape.

 

[175se]

Re: 90 hp 1988 head gasket replacment water on plug.

is it a bubbleback motor? if it is it may be the inner exhaust, sometimes the gasket or the bolts come loose. which cyl is taking on water? did you check to see if the head was warped?

 

[emdsapmgr]

Re: 90 hp 1988 head gasket replacment water on plug.

You've done the correct thing first-check the head gaskets for a possible leak around the seal ring for each cyl. Head gaskets typically start to leak if an engine was recently overheated. Sounds like you are comfortable with your head gaskets, so on to the next possibility: An exhaust gasket leak can permit water to get ingested into the exhaust chest of the powerhead. Usually exhaust water leaks tend to affect the lower cyls first. Your engine has a flatback exhaust-not too difficult to remove/replace.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

Have taken the other head off and it is also showing signs of water intrusion on lower cylinder and the gasket is starting to blow. Next i will take off the domed cover between heads. Is there anything I can do to avoid breaking bolts? What will i find under this cover? What is a water leak tester? AND THANKS

 

[emdsapmgr]

Re: 90 hp 1988 head gasket replacment water on plug.

You may not have the engine you think you have. The 90 hp engines have a flat exhaust manifold. The high perf engines have the bubble back exhaust manifolds. Sounds as if that's the manifold(s) on yours. So, you have a 110 hp model-possibly with an 88 hp cowling. The 88 engines came with the conventional fuel pump. The 110 model came with the more expensive VRO combination fuel/oil pump. Probably good for you, as these engines have higher compr heads, larger carbs, in addition to the bubble back (tuned) exhaust system. There is an inner and the outer manifold. Hopefully you won't have any problems getting the covers/manifolds off. The bolts are not that tight. Only bolt removal problem would be if this engine was run in saltwater.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

The exhaust is definitely domed the model no indicates a 90. Saw a video of a 110hp on utube and it looks like mine. Ihave now removed manifold and the domed cover and am concerned about a pit mark in exhaust port about 3mm deep. Could this be corrosion into the water jacket. Also I dont need the power or high performance of this motor. Its fitted to a fishing boat and not necessary can the flat manifold quieten this motor down, and would it fit. I have been offered a 90 hp of about the same vintage so parts shouldnt be a problem

 

[racerone]

Re: 90 hp 1988 head gasket replacment water on plug.

Not unusual to see a casting cavity in the block at the exhaust ports.-Not likely corrosion there.--No difference in noise levels between the 2 covers.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

by quietening i mean smooth out the power as it now seems to hit the power band and take off and there is no happy medium and im up and down on throttle much more than i should be. the advice is much appreciated.

 

[emdsapmgr]

Re: 90 hp 1988 head gasket replacment water on plug.

Not sure just where your pit is from your description. Is it part of the block or part of either manifold? Anyway- you can attach a pic?
If the pit is on the inner manifold, does it go all the way thru the casting? That could account for the water intrusion.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

the pit is in the exhaust port in the block on the crankshaft side. Are there water galleries in that area? No sign of water there

 

[racerone]

Re: 90 hp 1988 head gasket replacment water on plug.

Casting cavities in the exhaust area port are fairly common !----Post pictures so we can be clear on this.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

Thanks all this forum is excellent ill tell my friends

 

[emdsapmgr]

Re: 90 hp 1988 head gasket replacment water on plug.

Agree. There is no water jacket around this flaw-should be exhaust only, so should not be any source for ingested water.

 

[peter wickham]

Re: 90 hp 1988 head gasket replacment water on plug.

I have fitted exhaust gaskets for 110 hp and replaced head gaskets tested and running ok. When flushing motor I noticed water from the jet was cool compared to the water from the leg is this normal.
Thanks to all the help from this forum its excellent.The main reason for water in cylinders was the incorrect exhaust gasket fitted by a previous repairer see photo. Wasnt noticable until a thermostat stuck open was replaced, could the new thermostat increase pressure and make the leak worse.

 

[emdsapmgr]

Re: 90 hp 1988 head gasket replacment water on plug.

It's possible the prior owner also thought it was a 90, so ordered the 90 hp inner exhaust gasket-wrong for a bubble back high perf engine.