My intermittent Johnson...V4...88???

[captaingaff]

I have learned so much from this site but this is my first post. One thing I notice is that knowone ever posts how there problem was resolved... believe me if you guys can help I'll be sure to let u know what happened..this originally a 1997 90hp SPL but was rebuilt with a late 80's block...maybe 110hp??? twin powerpack...anyways...

2 months ago i was runnin WOT and she drop a cylinder...started poor mans troubleshooting which has always worked in the past...visual inspection of spark and swaping out has always faithfully led me to bad coil, plug wire or plug...not this time...i narrowed it to the wire from the PP to the bottom starboard cylinder...tryn to cut time to make a fishin trip I jumped the gun and bought a new PP and replaced all spark plugs...still no spark on that cylinder...swapped PPs and dremeled ALL grounds...sparks on all cylinders!!! Ran great for 20 min on all 4...then died...like key was turned off!!! no restart...towed in..now both on 2 port side cylinders wont spark...it followed the brand new pack...bought ANOTHER pack AND replaced timer base plugs AND had resistance tests done on stator and timer base...all sparked good...took it out..ran great on all 4 then it died in almost the same spot...but restarted this time and i limped home w/ 8mph top speed...didnt check spark...read some more posts on here and figured it must be my stator...bought a used stator...started good...idled out of the canal...but again wouldnt jump up on plane...limped home...didnt check spark...read more posts...gettn pretty good at poppn that flywheel off so i decided to trade my used stator for a used timer base...but tmrw is when Im gonna install and test it...but could a timer base be intermittent like that if the resistance tests good??? Gonna get a spark tester tmrw...I know my procedures are p!ss-poor at best but Ive had this boat for alot of years and feel pretty confident that plugs,wires,coils, pp, and stator are not the issue...any other points in the right direction would be appreciated...rectifier??? grouper season is gettn ready to close for 2 months...help!!!

 

[Joe Reeves]

Re: My intermittent Johnson...V4...88???

Remove spark plugs, disconnect main electrical cable at engine (no connections forward to console/controls).

Check spark (must jump 7/16" gap) by using jumper from battery terminal of starter solenoid to small solenoid 3/8" terminal that energizes the solenoid (starter circuit).

If spark is okay during above test BUT not with main electrical connectors attached, the usual culprit is a intermitently shorted ignition switch, in which case, replace it.

 

[captaingaff]

Re: My intermittent Johnson...V4...88???

considered ignition but didnt suspect anything in-line before the timer base...and could the ignition cause intermittent behavior on diff plugs??? know where the starter solenoid is but not sure about the small solenoid...will a spark tester tell me the AMOUNT of gap jump??? For over a year my engine intermitently wont shut off with the key(have to flood it w choke)...but its never been this kinda issue

 

[surrender]

Re: My intermittent Johnson...V4...88???

If your key has been giving you trouble all this time anyway that would be a good thing to replace first. May not have needed any of that other stuff. The ignition assembly is not that expensive or hard to swap out. Do it then start testing everything else.

 

[Joe Reeves]

Re: My intermittent Johnson...V4...88???

There is no "small solenoid"...... there is a "small 3/8" nut terminal" on the starter solenoid.

Do the test as mentioned so as not to assume the ignition switch or the related instrument wiring harness is faulty or not.

 

[captaingaff]

Re: My intermittent Johnson...V4...88???

Thanks to everyone for the suggestions but I found it...could have saved myself alot of grief and money if I just would have bought a $10 compression tester...picked one up today and this is what I found...

Portside...bottom=118...top=120 (plugs look good)
Starboardside...bottom=0(plug caked)...top=75(plug fouled)

All the times I checked the plugs they were fine but hadnt checked them since my last time out...the boat had been starting and idling great too...ugh!!! Could a bad PP or stator have caused these cylinders to fail???

Now what??? Rebuild???
Ive had my motor rebuilt before but it wouldnt even start...didnt think this sort of problem could be intermittent
Still think I have a spark issue but I'll deal with that later...bought a spark tester too so I can properly check my spark

 

[bktheking]

Re: My intermittent Johnson...V4...88???

Pull the head on the starboard side and check the condition of the head gasket and no a bad PP or stator does not directly blow a head gasket or take out a ring, mechanical vs electric in that case, the 2 aren't related. If the headgasket looks good then check the cylinder walls for evidence of metal or scoring.
Over heating a motor typically takes out a head gasket and poor fuel oil mixture (not enough or forgetting to add oil) into the cylinder due to dirty or bad carbs take out a ring.

I suppose if you ran the motor long enough without having spark in that one cylinder it would eventually take out the head gasket due to the pressure build up but lets face it an explosion with more force occurs less than every second when that motor's running so it's hard to justify the logic.

 

[captaingaff]

Re: My intermittent Johnson...V4...88???

ok did it...the cylinder walls appear smooth and unworn but the ends of the pistons themselves look bad...the top one looks like someone took a chizel to it and the bottom one looks corroded...the piece I unbolted has gouges on the top cylinder but the bottom looks fine...
Both pistons move smoothly in and out when I manually turn the flywheel...and both pistons only have the slightest wiggle inside the cylinder...
The head gasket seems ok although Im not sure what to look for...
I have pics if that will help or just tell me Im screwed and save me the trouble

 

[CharlieB]

Re: My intermittent Johnson...V4...88???

Your descriptions sound as tho a broken ring tattoo'd the upper cyl, but the lower sounds like a lean carb melting the piston top.

You know the old saying about a picture is worth a thousand words. That applies here, seeing the damage will enable us to make a better diagnosis of the problem.

I would also suggest removing the exhaust cover and checking the rings, see if any are broken, gently press on each one to feel for any 'spring tension'.

Post your pictures or a link to another photo hosting site.

 

[bktheking]

Re: My intermittent Johnson...V4...88???

Like Charlie said, sounds like it ate a ring! Post pics

 

[captaingaff]

Re: My intermittent Johnson...V4...88???

Top starboard

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Bottom starboard

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Outter housing

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Top outter housing close up

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[CharlieB]

Re: My intermittent Johnson...V4...88???

Looks exactly like the lower carb leaned out, melting the piston top and snagging a ring. Part of the ring bounced back thru the exhaust into the upper cyl and tattoo'd the piston and head.

Sorry but you are needing to replace both pistons, rings, and the head.

Rebuild the carbs, while you are at it, a fuel pump recon and water pump are good insurance to protect your freshly built motor.