Logo
FULL SITE MENU

Water in #3 cylinder - 1994 Johnson 155 commercial

mstahl1171

mstahl1171

Contributing Member
I was planing to go fishing today but no joy! Motor idled fine but when I went power up...no power...turned around and pulled the plugs. Found #3 plug wet with water. Did a compression test and all the cylinders were between 85-92 psi. My question is this....am I correct in assuming that the head gasket is blown? Is there another test I should do before I begin the tear down?

Mark
 
Compression would most likely be down if a head gasket was blown.

Where else can water enter? Gasoline source.

Check that first. Easiest and cheapest checks FIRST!
 
I forgot to mention that I did check the fuel source...water separator was free of water. I also drained the carb bowl. I removed the spark plug and ran the motor on 5 cylinders....water / fuel mix coming out of # 3....plug is milky white in color.
 
If the fuel supply was contaminated, "all" carburetors would be affected.

Remove the cylinder head in order to inspect the gasket, sealing surfaces of the head and block, piston, etc. A gasket just starting to fail could allow a fine spray of water enter the cylinder and at the same time not be bad enough to have a large effect on the compression.
 
joereeves said:
If the fuel supply was contaminated, "all" carburetors would be affected.

Remove the cylinder head in order to inspect the gasket, sealing surfaces of the head and block, piston, etc. A gasket just starting to fail could allow a fine spray of water enter the cylinder and at the same time not be bad enough to have a large effect on the compression.
Click to expand...

Absolutely true. But I have learned not to trust what is posted here by the OPs. You can never tell if what they are posting is the "way it is".
He could have been an extreme noobie, and only noticed the water on #3...

Who knows.
 
When I ran the motor on 5 cylinders...with number 3 open....water was spraying out at a good rate. Not enough to get hydro-lock but would put plenty of water droplets in the palm of my hand. I then pulled the boat, cleaned out the cylinder with compress air and did a compression test without oil the first few times and with oil afterwards....not much change in the compression. 86 psi without oil. 92 psi with oil. I'll pull the head and check the gasket. that would be a cheap fix...if there is such a thing...lol. If I find nothing I will check the exhaust gasket, or should I just plan to do all the gaskets? I hate to tear down the whole motor. I'm of the school....if it ain't broke...don't fix it...lol
 
Can you post the exact model # of this motor ?? I can't find a 155 hp for 1994. Read post # 5 again.............
 
Last edited:
So I ordered new head gaskets and the Exhaust Cover Gaskets. I will pull apart the head this evening. I did notice that the seam between the block and the head around the area of the #3 cylinder is very crusty looking. Looks the the gasket is coming apart and crusty looking. The port cylinder bank looks clean and tight. I'll keep you posted.
 
So I was able to get the head off last night. Definetly the head gasket. I did break off 2 head bolts...around #3 cylinder. The bolts were corroded really bad into the block. Whats the best way to remove now? I have about 1/2" sticking out of the block on one. the other is only about 1/4" out of the block. I was thinking a propane torch to heat, PB Blaster and lots of luck. Is it better to just drill out and re-tap?

If you follow the circle pattern for the bolts..it would be #1 and #3. The gasket also was leaking in these same spots...ugh!
 
If you use heat, try Mapp Gas or Acy/Oxy. Propane won't cut it. When you apply the heat use a vice grip on the bolt and rock it slowly back and forth. Patience !!! Don't heat the bolt. Heat the area in the block around it.
 
Thanks Boobie. I bought 2 bottles of MAP gas to heat up. One bolt I will have to drill out since there is not enough bolt sticking out of the block...oh joy!

Also went and pulled the exhaust cover...the gaskets were also bad. Also found the water deflectors along the cylinder walls were all but gone too. So this operation was long over due.
 
Update.....Well despite all my best efforts to remove the broken bolts with heat...no joy. I ended up grinding flat the bolts. Drilled a hole in the center and the progressed up in drill sizes. That worked fine until I broke off a 1/4" drill bit in the #3 bolt...ugh. Resorted to using Alum / Water mix and heat to remove the bolts. It took 12 hours but I was able to desolve away the old bolts, retap the threads and install a new head gasket and exhaust gaskets. Cylinders 1,3 & 5 now have 90 psi...yeah!! Makes me want to do cylinders 2,4 & 6 but after this last adventure...I'll leave well enough alone. So far so good. Ran the motor on a 100 gallon test tank yesterday afternoon in the driveway for almost 2 hours..neighbors were not thrilled. Checked the torque on all the head bolts afterwards. I will tough up the bottom paint tonight and splash Tuesday. Fingers Crossed... :D
 
Well...after a few days of running, all seems well. Thanks again to everyone for their help and support. I'm calling this one done!!
 
Back
Top