1980 85hp Johnson - Water in Plug?

[TexAcoon]

Noticed my engine does not like to idle very well and decided to replace the plugs. Replaced the plugs and then tested the engine on a local lake and found it ran a little better but would not idle correctly ..

After talking to one person - I decided to replace the plugs again with a standard plug verses one with a heat range of 10. However, when removing the plugs, I found one of the four cylinders the plug did not have a light oil burn being a two stroke .. The plug actually had traces of water deposits on the plug as if it was not firing...

At this time I am wondering if I have a cyl head crake OR blown head gasket leaking water into the the one cylinder...

Did not smell of fuel .. Have not checked the coil to see what the ohm rating was .. AGAIN not sure what the ohm rating is...

Figured I would ask before guessing at what this could actually be .....

 

[mamm7215]

Re: 1980 85hp Johnson - Water in Plug?

Compression test first...

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

What should the pressures of the compression test be? ....

Thanks!

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

Not sure of Johnson cylinder numbers - let's start with the following:

Facing rear of engine (back of boat):

1) Left Bank "Top" Cyl = 74lbs
2) Left Bank "Bottom" Cyl - 74lbs
3) Right Bank "Top" Cyl = 35lbs
4) Right Bank "Bottom" Cyl = 74lbs

Item 3 was very low being 35lbs ...
However, if each of the cyl's were suppose to be a higher compression, I am a little concerned of the overall health of my motor.

 

[Daviet]

Re: 1980 85hp Johnson - Water in Plug?

The compression is not great, but 35# is really low.
I would pull that cylinder head and check the cylinder and piston for damage, if no damage is found install a new cylinder head gasket and recheck the compression. If the compression comes up think about replacing the other head gasket and then do a decarb on the engine and see if the compression comes up some.

 

[ezeke]

Re: 1980 85hp Johnson - Water in Plug?

Pull the cylinder head and inspect - just the 10 larger screws. You may have only blown the head gasket.

The other readings are too consistent for abnormal wear and could just be your method or the gauge.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

What SHOULD my REAL compression rating be?

 

[ezeke]

Re: 1980 85hp Johnson - Water in Plug?

Test with all plugs out, warm engine, screw in gauge with 14mm short. Battery should be fully charged. be as consistent as possible. Normally, look for readings within 10% of each other and well above 100 on that engine.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

WOW! .. That's a bit out of spec then ....
In most cases one would think cyl pressures would be 95 or above ...

Grant you the engine was cold yet met other requirements ..
Seems there might be a little ring leakage in the compression or small amount of blow by in the gaskets.

Will look at removing the head this evening and see what the verdict is.

Thanks!

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

Placing the head gasket on a green back ground should help you visualize my finding.

1) Center and top portion of the gasket is shot.

2) Seems someone has been in this top end before and reused the gasket by adding some sort of sealant on the gasket to seal gasket to the head and block.

3) When removing the head bolts the bolting did not seem tight.

4) Each cylinder and piston tops - look clean, shiny with no scratches. So all is good there. Not to say the rings are worn ..

Need to know what the torque values are for the head bolts - Hopefully one of you will let me know what the value is.

My compression gauge should be replaced .. Not sure just how good it is after being about 30 years old. Yet it seems to hold pressure and not leak out until I push the pressure release button. LOL! ..

So I figure with the other three cylinders reading the same values, and finding the weak cylinder breached by bad gasket allowing some water flowing into it .. I would expect replacing the head gasket will be my final fix ..

Any suggestions?

 

[ezeke]

Re: 1980 85hp Johnson - Water in Plug?

New gasket, tab at top away from exhaust cover
Gasket sealing compound
18-20 Foot pounds
Check the water passage deflectors while you have the cover off.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

New gasket, tab at top away from exhaust cover
Gasket sealing compound
18-20 Foot pounds
Check the water passage deflectors while you have the cover off.

The Water Passage Deflectors are listed in the "yellow" Items "A" ?

Thanks for the feedback ..

 

[ezeke]

Re: 1980 85hp Johnson - Water in Plug?

The Water Passage Deflectors are listed in the "yellow" Items "A" ? ...........

Yes, they are pieces of hose that direct the flow of water around the cylinders as indicated by the small arrows.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

Ok took a look at both deflectors on the Starboard side ... (bad head gasket)

They are there, yet kind of picked on the upper one a little. Seems to be soft and when picking at it seems to shed a little rubber ..

Is this something special or fuel type hose is all that's needed for replacement?

What is recommended for head gasket sealant?

 

[ezeke]

Re: 1980 85hp Johnson - Water in Plug?

The hose has to be fairly rigid and have a diameter somewhat larger than 3/8. The inside diameter should be less than 1/8. You may find it simpler to just get the OE or aftermarket part.

If the deflector weakens it can cause an overheat or worse and in extreme cases cause the cylinder liner to separate, destroying the engine block.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

I would rather be proactive and replace these two deflectors while the head is off ... Rather be safe than sorry and from what I have seen on the outside of the engine ..

Some of the protective wiring shelding has melted to the block in some spots .. Apparently this was before my ownership .. Yet it does bother me why it may have heated enough to cause the rubber (plastic) wire sheilds to melt in spots.. I have checked for any wire insulation melting exposing bare wire .. Nothing found yet did add electrical tape as additional protection to the sheilding.

Great photos! bad for the owner(s) ..

 

[Fed]

Re: 1980 85hp Johnson - Water in Plug?

The Water Passage Deflectors are listed in the "yellow" Items "A" ?

That's them, they are there to stop the water taking a shortcut between the cylinders, they force the water to go up one side, over the top cylinder and back down the other side.
What goes wrong is that corrosion and swelling squeezes them out into the desired path of the water which will cause overheating at higher RPM.

 

[Fed]

Re: 1980 85hp Johnson - Water in Plug?

I didn't mean to repeat you ezeke, I posted after post #12 but was off doing other things while the thread was going forward without me. LOL

 

[boobie]

Re: 1980 85hp Johnson - Water in Plug?

I have about 5 or 6 different compression gauges in my tool collection. I can take and try all of them on the same mtr,same cyl and get different readings on all of them. What you always have to remember is the % difference between the cylinders. Like I've always said, compression gauges very from state to state. LOL.

 

[TexAcoon]

Re: 1980 85hp Johnson - Water in Plug?

I can believe that .... Not being a calibrated tool I'm sure they do vary .. However, I agree with what you say about the percentage between cyls ...

Overall the three cyls looked good for being within reason of each other .. Just the one odd ball had a major head gasket leak ..

Decided since I'm working on replacing my water deflectors in the engine .. and being in it for the first time .. Figured I would spend a little time and money as a precaution and replace not only the water deflectors and buy a complete thermostat kit to boot .. The water pump is doing a fine job when running. Peep hole is spitting out more water than one could imagine .. There again it could have been the help of the piston's compression ..LOL! ..

Figured once all this is done and completed, I'll be able to take it to my local lake and give her a try and watch the water pumping out the shaft on first start and run ... Will park the boat for winter in about a month or two and then plan on replacing the water pump for grinns and giggles for next year run ... Not to mention a new prop ..

Hopefully this will be a good engine for the next couple of years not running in the salt and running only in fresh water..