Head Gasket Check

[jeffhvaughn]

is there an easy way to determine if head gasket REALLY needs replacing before you go in and inspect/replace it?

 

[jasonbailey]

Re: Head Gasket Check

Low compression on one or more cylinders.

 

[roscoe]

Re: Head Gasket Check

One or more sparkplugs that look to have been steam cleaned.

 

[jeffhvaughn]

Re: Head Gasket Check

thanks... it is a 1998 Force 120hp (no that isn't the problem )

i did a compression check...

125
145
145
145

This is what it was when it was running "normal" as well. So does this mean, there is not a head gasket problem?

 

[imported_LakeRunner]

Re: Head Gasket Check

Could be a stuck ring but the plug will tell you what the condition is of the cylinder is. Check it and report back.

 

[jeffhvaughn]

Re: Head Gasket Check

plug is not black like bottom 2 plugs... top 2 plugs have a light brown (almost cream) sludge on them....

 

[imported_LakeRunner]

Re: Head Gasket Check

Milky oil says water is getting into the cylinder, head gasket would be the first thing to check. You should also check for a cracked riser. The compression numbers are too close to say that it is definetly the head gasket. A black wet glazed colored plug is caused by the burned oil that is leaking past the piston rings or valve guides and burning in the cylinder. This engine will have blue smoke coming out of the exhaust. It is a sign that the engine will need rebuilding. Two strokes that have this color spark plug are burning the transmission oil from the crankcase. If new spark plugs are installed they will foul also and quit working. Water cannot be compressed, so if you only have a minor amount of water right now, the leak is only beginning. If it gets worse the water may seize a piston causing it to break a rod, bearing, or worse the block and crank.

 

[jasonbailey]

Re: Head Gasket Check

Two strokes that have this color spark plug are burning the transmission oil from the crankcase.

I don't understand this statement. How can transmission oil get into the crankcase of a two stroke? My two stroke O/B has oil in the lower unit, but is seperate. I thought a black plug is what you are supposed to have on a two stroke.

 

[roscoe]

Re: Head Gasket Check

I don't understand your comments either, rtevans.

Valve guides, transmission oil from the crankcase?

 

[jeffhvaughn]

Re: Head Gasket Check

Well, I did get to pull the head off and inspect...

definate sign of water on top 2 cyclinders. Brown creamy sludge with the occasional clear water droplet...

No signs of cracks or erosions... Only sign of what could have allowed a breach of water is the head gasket itself... Although no cracks or tears, there was a lot of dried gunk on it. I did replace this head gasket a couple of years ago, and when I did, I used a gasket sealer, but probably shouldn't have... could this be what allowed the water to come through?

Attached is a picture of the head gasket...

Any comments on the picture? Also, when putting the new gasket on, I assume I should not use the gasket sealant, correct? What other things should I keep in mind? Anything I should do while the head is off?

 

[jasonbailey]

Re: Head Gasket Check

Don't use a sealer on the head gasket. That could be the source of your problem. Put a new head gasket on recheck the compression and I bet that 125psi will come up. If it does, than I would say that was the source of your problem.

 

[jeffhvaughn]

Re: Head Gasket Check

thanks... as far as the bolts... should I replace them? This will be the 2nd time I have done this job, but they do appear to be in decent shape.
also, does anyone know the torque sequence for the bolts... I know the torque should be 18.75 ft/lbs OR 225 in/lbs... 1998 Force 120hp

thanks!

 

[jasonbailey]

Re: Head Gasket Check

Replace the bolts. Always use new headbolts. Cheap insurance. As far as the torque settings they should be in the Clymer or Seloc manual. My 75HP Chrysler were 220 inch pounds.

 

[imported_LakeRunner]

Re: Head Gasket Check

Sorry, some of the verbage was taken from an inboard engine post. I should have cleaned it up a little better. The gist was that water can also infiltrate thru the riser tubes. Since I work on both 2 and 4 strokes, I tend to generalize a bit.

 

[roscoe]

Re: Head Gasket Check

Ok, that explains it.