Dead Cylinder - Decayed Stator wires

[astroglass_81]

I just aquired a 1981 Mercury 90 HP Outboard. I really don't know anything about the history of this motor and have never heard it run, but does not look too bad. With that said, Compression on all 6 cyls is about 135. I replaced water pump impeller and checked spark on all cylinders. All cyls were good at 1/4" gap except #5-dead. Swapped (+) coil wires between #5 & #6. #5 coil then fired, #6 didn't. Is the switchbox dead on that cyl only? and I also found ground screw connection loose for #5 coil. Would that have caused switchbox to fail on that cyl? Engine has been sitting atleast a couple years. Removed gas tank and cleaned crud out of bottom and installed a new sender. Went through carbs, cleaned stale fuel out. I need to know if a harmonic balancer puller will work as well as the mercury thread in puller for flywheel removal. I have decided to replace my stator due to rotten wires. I feel that if I go thru the trouble to remove it, I'd replace it. When I get in there, if trigger wires are rotten too, I guess I need to replace it too. Id like tips and in put on what kind of job im getting into here. If the stator was the problem for #5 cyl being dead, maybe I won't have to install a new switchbox too?? I'm ready to hear this thing run, but I want it right to avoid further part failures. If stator knocked out switchbox, will switchbox knock out new stator or trigger? I'm not a "parts changer" per say, reason I'm replacing stator, wires are badly decayed. Also, is the top crankshaft seal hard to replace, Seloc manual says if its leaking, replace it. Sorry thread so long. Thanks for all the help.

 

[Laddies]

Re: Dead Cylinder - Decayed Stator wires

Chances are the reason you don't have spark on #5 is either a switchbox or a coil which I doubt, but a a coil is a slight possibility. The story about stators burning out boxes and triggers is a story started by inept repair shops and poor quality replacement parts from Mercury use Rapair parts and save yourself a lot of grief

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

As I stated in previous post, I swapped (+) coil wires between #5 & #6. #5 coil then fired, #6 didn't. So that tells me #5 coil is good, and I am assuming the (per say) #5 place on switchbox is not sending voltage to coil. Is there an effective way to check switchbox, without swapping boxes? I also intend on fully checking stator and trigger resistance readings when I breakdown for stator replacement to possibly determine if either one of those are the culprit of problem. Again, I need to know if a harmonic balancer puller will work as well as a mercury flywheel puller. I really don't want to damage my flywheel. Thanks for all the input.

 

[Laddies]

Re: Dead Cylinder - Decayed Stator wires

The only way to test a box is with a DVA and test input and output voltage or as you say swap the boxes

 

[j_martin]

Re: Dead Cylinder - Decayed Stator wires

Generally speaking, if the stator is bad, all cylinders will be affected, except on a 6, where half will be affected. If a trigger is bad, 2 opposite cylinders (in the timing sequence) will be affected. Switchbox is a crap shoot. Coil affects only one cylinder. You've eliminated the coil with a swap procedure, so that leaves the switchbox as the most likely culprit.

Before I changed the switchbox, I'd check the integrity of the #5 coil wire.

hope it helps
John

 

[hkeiner]

Re: Dead Cylinder - Decayed Stator wires

The below link contains some troubleshooting guidance that may help you.

Good luck


http://dolphinmarineservice.homestead.com/ign5.html

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

I am very thankful for all the input. I need to get some time on a couple days without rain, and grab this thing by the horns and "git 'er dunne" . If anyone knows if a harmonic balancer puller will work as well as the mercury flywheel puller to remove flywheel, please post a thread. I dont want a horror story with my flywheel. Thanks again all, I'll be in touch.

 

[j_martin]

Re: Dead Cylinder - Decayed Stator wires

I am very thankful for all the input. I need to get some time on a couple days without rain, and grab this thing by the horns and "git 'er dunne" . If anyone knows if a harmonic balancer puller will work as well as the mercury flywheel puller to remove flywheel, please post a thread. I dont want a horror story with my flywheel. Thanks again all, I'll be in touch.

Use the Mercury type puller only. Anything else will cause damage. They're only about 25 bucks on eBay. Be sure you get the fine thread one. Usually the combination puller/lifter uses a coarse thread push bolt. It's less effective. You can always use a fine thread bolt and a loop of chain to make an engine lifter out of it.

hope it helps
John

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

Thanks j martin, I will keep that in mind. I thought the harmonic balancer puller I already have would work. Another guy posted to use a steering wheel puller. My thoughts were a 3 point puller would be better than a 2 point puller. Guess I'd better be safe than sorry.

 

[Chris1956]

Re: Dead Cylinder - Decayed Stator wires

Astro - A harmonic balancer puller is fine for pulling the flywheel. Remove 3 or the 8, 5/16 fine thread bolts that surround the flywheel nut and thread longer bolts thru the puller, into the flywheel. It will work just fine..

 

[j_martin]

Re: Dead Cylinder - Decayed Stator wires

Astro - A harmonic balancer puller is fine for pulling the flywheel. Remove 3 or the 8, 5/16 fine thread bolts that surround the flywheel nut and thread longer bolts thru the puller, into the flywheel. It will work just fine..

Just be sure you mark the position, or go nuts trying to time it later.

John

 

[CharlieB]

Re: Dead Cylinder - Decayed Stator wires

I've seen a number of those old stators successfully saved with MULTIPLE layers of liquid tape or silicone built up thick enough to contain the voltage.

As a shop I of coarse recommend that the stator be replaced but depending on your budget that call is yours.

You have already proven that your ignition fault is the switchbox feeding #5 cyl.

If the stator OR the trigger were the fault you would have lost spark on at leaast one more cyl, the problem is ONLY on #5 and you have proved #5 coil is good.

A poor grouond to complete the circuit WILL KILL a switchbox, no doubt there that loose ground on #5 coil is the cause of the switchbox's early death.

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

This was posted to me on another thread. I was wondering if I should be concerned about knocking out a new switchbox using the existing trigger. I am going to replace the stator because it has a shorted charge coil (1 ohm meter reading) and the rectifier is shorted. Isn't the charge coil supposed to be 1000 ohms? Anyhow that's why I thought the yellow wires from stator to rectifier were decayed...guess they were cooked and falling apart. And yes, I'm replacing rectifier too. I just don't want a vicious cycle here

 

[CharlieB]

Re: Dead Cylinder - Decayed Stator wires

Using the DVA Meter as a testing tool to verify the stator output will determine weather you NEED a stator or NOT.

If one of two switboxes drops all 3 cyl's then the manual states to DISCONNECT the bias wire between the boxes and retest for spark

If there is now spark on ALL cyl's THEN replace BOTH switchboxes as the bias on the working box has caused the problem, replacing only the non-working box will seriously shorten its life because of the bad bias in the working box.

Regulators die and get replaced, a bad regulator can cause ignition faults, disconnect the regulator and retest for spark, if all cyl's spark then replace the regulator.

Ohms test alone do not necessarily condemn a stator UNLESS any wire ohms to ground. DVA tests determine stator output.

Cranking DVA test and running DVA tests BOTH are necessary for correct diagnosis, otherwise you may buy parts that you may NOT need.

 

[CharlieB]

Re: Dead Cylinder - Decayed Stator wires

A switchbox dropping only one cyl is only a defective switchbox. HOWEVER, remove the Bias wire and retest, if #5 now fires then there IS a problem in the other box, replace both. Mark these boxes as 3 Cyl ONLY, they will work fine on a 3 cyl 75 to 90 HP.

Cooked charging coil wires to the regulator only shows that you have a shorted regulator. If those wires may be repaired AND the charging coils pass the DVA test then the stator can still be good.

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

A switchbox dropping only one cyl is only a defective switchbox. HOWEVER, remove the Bias wire and retest, if #5 now fires then there IS a problem in the other box, replace both. Mark these boxes as 3 Cyl ONLY, they will work fine on a 3 cyl 75 to 90 HP.

Cooked charging coil wires to the regulator only shows that you have a shorted regulator. If those wires may be repaired AND the charging coils pass the DVA test then the stator can still be good.

So in this case, if I unhook the bias wire and recheck spark, and #5 then fires, both boxes will need to be replaced? Am I to understand that both these boxes (ones I take off) will operate correctly on a 3 cyl? Eventhough they won't work together?

 

[j_martin]

Re: Dead Cylinder - Decayed Stator wires

So in this case, if I unhook the bias wire and recheck spark, and #5 then fires, both boxes will need to be replaced? Am I to understand that both these boxes (ones I take off) will operate correctly on a 3 cyl? Eventhough they won't work together?

Yup.

 

[astroglass_81]

Re: Dead Cylinder - Decayed Stator wires

Alrightythen, removed stator & repaired charge coil wires. I did check resistance from blue, red, blue/white, & red/white to ground (stator mounting ring, had stator laying on table) and I did get resistance readings. Ain't I supposed to get readings from those wires to ground? I don't remember getting a reading to ground from the two yellow charge coil wires, I don't think I'm supposed to on them two. Anyhow, today I put that sucker back on and did a DVA test on the trigger wires with the cranking motor. Spark plugs were in, plug wires were on my spark tester, & battery had a good charge. Chart said all 3 trigger tests were supposed to be 4v or more. Mine were about 3.6v on each test. Is that ok or does it need to be more? When I first did a spark test on this engine, I had the spark gap set at 1/4" and the spark looked kinda red or orange (color blind) Is the spark supposed to be hot blue? Is 1/4" gap ok? Thanks in advance for any help.