Timing a 6HP Johnson 1989

[joesnuffy]

That did solve the problem. Motor running on top or bottom cylinder revving up and idling.

I re-did my 90hp 4 Stroke Mercury down here in St Pete a couple years ago. It was a freaking nightmare I purchased the boat knowing it had this issue but the price was right and we wanted a 4 stroke down here after it was said and done it still was a good deal for me. It had great compression but when started it would start re-filling the crankcase with water not fast but gradual enough to drive you nuts. I changed the head-gasket still no go. Changed to a fresh water cylinder head still no go. Finally decided to change the short block to a fresh water short block making the motor like new. That fixed it. When I inspected the old short block I finally found a hole in it from salt water big enough to put a piece of wire through it. I am trying to find the picture of the hole and will post it hopefully later. Just thought I would share.

I will figure out a way to hook up a hose to motor should be pretty easy I had one rigged to the 4hp folding motor.

Thanks,
Joe

[joesnuffy]

Yes I rigged the garden hose started motor and turned on the water engine started misbehaving I then turned off water motor started running correctly. I barely turned it on to just a little water was coming from tell tale. I did it 2 times to confirm.

I will wait for further instructions how to proceed. I think I will call it quits for today on that motor since we have identified the problem and it does get pretty hot around here lol.

I did talk to the owner and I ordered the gasket set for entire engine, and I ordered a nice used fresh water block while I could get it that if we don’t need he is going to store for later.

Thanks for all the help,
Joe

• This reply was modified 3 years, 8 months ago by joesnuffy.
• This reply was modified 3 years, 8 months ago by joesnuffy.
• This reply was modified 3 years, 8 months ago by joesnuffy.

[joesnuffy]

I did do this test today to see how compression ratios were per pull. I have had that original head gasket off engine then reinstalled it but problem was already happening with lower cylinder not firing. Just some food for thought.

Cylinder 1 per pull
55lbs
81
100
105
110

Cylinder 2 per pull
55lbs
72
89
95
95

Trying to see if major difference by pull.

Thank You,
Joe

• This reply was modified 3 years, 8 months ago by joesnuffy.

[fleetwin]

Good work Joe, you have confirmed the water ingestion for sure….
OK, now to try to pinpoint the actual leak….Do you have a little inspection light you can peek inside the lower cylinder with? With the engine off and plugs out, turn on the water gently while peeking inside the cylinder with the light, perhaps you can see exactly where/how the water is getting into the lower cylinder. Many possibilities here. Perhaps the owner will get lucky and you will find that just the cylinder head is gouged/porous. Or, maybe water is leaking by the SS exhaust/water baffle somehow…
I remember a case where a V4 block was actually porous right near one of the exhaust ports, and the water was dribbling back into the cylinder. This fellow wasn’t so lucky…
Once you have pinpointed the leak area, go ahead and restart the engine with no water going through it, to expel the water that got sprayed inside…
It sounds like you have already found another powerhead for this engine, hopefully you won’t need to replace the powerhead….Let me know if I can help with any other parts…D
Your compression report would indicate that water is getting by the head gasket somehow, unless the rings have gotten stuck after getting wet all the time….

• This reply was modified 3 years, 8 months ago by fleetwin. Reason: addition

[joesnuffy]

Fleetwin,
Thank you I will inspect it today.

Joe

[joesnuffy]

Fleetwin,

I looked into the bottom cylinder yesterday with water on and a flashlight and could not see anything very well. I took a paper towel and twisted it up tightly like a wick and tilted the motor forwards a bit hopping to see if water was coming from head not the exhaust port or seal area and put the piston at almost TDC so I could put twisted paper towel into the cylinder and let it touch the bottom of cylinder. I then turned on the water for a few minutes and pulled out the paper towel. It had absorbed a small amount of water making the end of it wet a little and black about 1/8 inch up the paper towel. I did it again and got the same result.

I decided to pull the cylinder head and I had already done this once and the fire rings on the head gasket looked good but this time I took a razor and removed the head gasket trying not to damage it but it was very brittle and pieces of it came off. After I got it off the block side of the engine it did not look so good I mean the tops of the cylinder where the wear ring on head gasket seat were rusted I am going to post a pic. The water jackets were also due for a good cleaning. I think with motor running the piston acted like a vacuum and was pulling water into the bottom cylinder.

Looking at the cylinder head in the bottom corner you can see where the carbon has been slightly washed away and that is about where I had the paper towel. Also in the exhaust area it looks like the water was leaving the bottom cylinder and washing the lower exhaust area.

The gasket kit is suppose to be here this afternoon our mail runs about 2-4pm so hopefully the new head gasket will fix the issue. I also removed the exhaust cover and have cleaned all that up and inspected it also and its ready for new gaskets.

Thanks,
Joe

• This reply was modified 3 years, 8 months ago by joesnuffy.
• This reply was modified 3 years, 8 months ago by joesnuffy.

[fleetwin]

Kinda hard to tell much about the head gasket from your pictures…But, it does look “brittle” perhaps from overheating…And yeah, the passages need to be cleaned out….Back to your previous comment about the head bolts, be sure that cylinder head surface is flat. “Dress” the head with some fine emery on a surface plate/flat surface to ensure it is flat prior to reassembly. And yes, replace the exhaust manifold gaskets as well. Did you figure out if you were missing parts from the thermostat?
Am hoping that resurfacing the cylinder head with a new head gasket will solve this issue…
Keep in mind what I said about overheat issues on these engines. Probably time for a water pump, and possibly the troublesome upper water tube grommet as well…But, for now, let’s be sure the water leakage issue is resolved…Again, any signs of overheat? Melted coils, wiring harness?

[joesnuffy]

Fleetwin,
I am going to work on it today. The gasket kit got here late yesterday.

Thanks for the help,
Joe

[joesnuffy]

Fleetwin,
Got some bad, good, and great news. First the bad news I put all the new gaskets on the exhaust, new head gasket and I still had the same problem not running on bottom cylinder. I know after tearing into the motor those gaskets and the water jackets and exhaust plate area needed cleaning so that’s the good news.

I set down and started thinking what the heck could be going on with this motor. Maybe it has a hole in the block or maybe it is sucking water into the engine from the bottom. Now for the great news I thought before pulling the power head I will try and tighten the bottom bolts that hold it on. 6 bolts and I turned them all 1/4 to 1/2 turn tighter closer to 1/2 turn per bolt. I put the motor back in the water and boom it was running on the bottom cylinder and more water was coming out the blubber holes so water had to be spraying into the motor some how?

I got all the gaskets for the engine. I think the next step should be to pull the power head and inspect everything under there put new gaskets on etc?? Also put in a new impeller and thermostat etc.

Thanks for the help,
Joe
https://www.youtube.com/watch?v=LUKRtCkrCjc

https://www.youtube.com/watch?v=mNC1su3s5Xg

https://www.youtube.com/watch?v=F-RvGMcnr28

• This reply was modified 3 years, 8 months ago by joesnuffy.

[fleetwin]

Well, hard to say…Doesn’t really make sense, cuz nothing was leaking out between the exhaust housing and powerhead….But, “never say never” is what I have learned over the years…
Now, if the bolts that hold the inner exhaust housing to the powerhead were loose, then that could easily explain a water leak into the powerhead. I know it is hard to tell, but does it look like the powerhead has been off before? At this point, I would pull the powerhead and gearcase….The upper water tube grommets on these engines are always suspect, and perhaps the inner exhaust housing bolts are loose. That overboard spray doesn’t look real strong, and this is a salt water motor, so it is time to do the grommet job…This is a great opportunity to lube up all the fasteners so they will never get stuck/seized also. Once you have the inner exhaust housing off, we can discuss how to trim the grommet to make sure it doesn’t get crushed in the future….
I’m glad there is no horrible defect causing the water leak…

[Author]

Posts