1986 225 hp - what would make the potting of a coil melt?

[cfauvel]

I may have several issues at the same time.

Normally the motor at WOT runs at 5800 rpm and jumps on plane in <4 seconds. (as recently as two weeks ago).

what I have done since then is a whole thread on the VRO's oil mechanism and test on the assembly. So that assembly has been taken apart to see the diaphragms and put back together and run at idle in the yard.

also the voltage regulator was changed due to lack of tach pulse and over charge to batteries.

So those are the things I've done prior to today.

Symptom:
mashing the throttle the boat wouldn't get up on plane and die, so checked the connections to the fuel pump, played with primer bulb and got it hard and tried again numerous times

It finally went, but it got only to 4000 rpm
(temp rose above normal (gauge), but didn't blow horn)

then it died again and did same song and dance as before....

...out of the blue it would act near normal and get up on plane and run to 5000rpm +....BUT if you slowed down for a no-wake zone it would die and take a lot of effort to get it running again....then out of the blue it would work again.
(when it acted near normal it wouldn't jump on plane as expected)


once we got done with the no-wake zones and it acted normally we took it for a 20+ mile cruise from 3000 - 4400 rpm with no problems at all... cruised at 25mph, 35 mp and 40 mph without a hitch...so seemed like a low speed issue.

When I got home just now I took out the three starboard plugs,....the two bottom ones were a nice brown, the top one was a little wet, when I noticed melted coil potting onto a water tube.

I Imagine a coil going out would show itself as a lack of expected power.

What would cause the coil to heat up so bad to melt the potting?

Going outside right now to check the port side and do my stator OHM and voltage tests...I'll probably make a video and take photos of that,.....


At first my gut said fuel pump as that was one of the last things I played with....but being able to run at 4000+ rpm for a few hours kind of leads me away from that....right?

 

[cfauvel]

Results of ignition tests

COILS ohm tests
Primary lead post to ground
1 - .0 ohm 4 - .0 ohm
2 - .0 ohm 5 - .0 ohm
3 - .0 ohm 6 - .0 ohm

Secondary lead post to ground
1 - 259.3 ohm 4 - 256 ohm
2 - 263.2 ohm 5- 261.2 ohm
3 - 264.3 ohm 6 - 256.5 ohm

NOTE: coil 1,2,3 and 4 show signs of potting melting....but mainly #4

NOTE: Port powerpack ground lead was broken from its terminal (crimped on new terminal)

Recharge/Stator coil tests
Yellow lead to Yellow lead 0 ohms
Continuity between yellow wires (what I'd expect)
NO continuity between either yellow wire to ground (what I'd expect)

using DVA adapter on multimeter set to DC. - motor running
port yellow wire to ground - 19-20 volts
strbd yellow wire to ground - 20-30 volts
switched wires and the reading were the same...rechecked that the magnets had not come loose as last time I got those readings

Regulator is new.

Charge Coil tests - ohms
Port stbd
Pin A(brown) to Pin B (brown) Pin A(brown) to Pin B (brown)
1.07Kohms 1.07Kohms

DVA adapter meter set to DC
port stbd
160+ cranking 160+ cranking
292+ running at idle 273+ running at idle

Sensor Coil test - ohms
port stbd
D-A 43.5 ohm D-A 47 ohm
D-B 43.7 ohm D-B 47.3 ohm
D-C 44.1 ohm D-C 47.4 ohm

Volts cranking with DVA, meter set to DC
D-A .5v D-A .6v
D-B .615v D-B .6v
D-C .606v D-C .6- .8v

I'm leaning towards fuel pump....grrr..what did I do?

BUT can the fuel pump be problematic at less than 2500 rpm, then work perfectly above that? That doesn't sound plausible to me.

 

[Bosunsmate]

Not sure how fuel pump could cause coil potting. Have you seen any potting there before and is there any sign of any heat damage on the top of the head? Such as blurred paint.
Bad grounds can do all sorts of things, so have you tested it with the powerpack ground reattached? I dont like crimping in places that vibrate, the old school technique of twisting wires together seems to work better for me.
You may of had some gunk get into your carbs during the vro inspection. Id remove the lanyard line so you dont get spark, clean all your plugs then reinstall and turn the engine over with the starter for about 6 seconds then remove all the plugs and check that they are all wet from fuel.

 

[Bosunsmate]

I would also check that you have spark on that top cylinder, the one that was wet especially.
You could also manually prime fuel bulb at low speeds to confirm if it is the pump, you of course need to do that constantly not just get it hard once and try

 

[oldboat1]

Overheating could obviously cause the melting. The rectifier/regulator is water cooled. If it failed, it might have done so from overheating due to a water flow issue -- same issue affecting the coil, potentially.

 

[cfauvel]

I would also check that you have spark on that top cylinder, the one that was wet especially.
You could also manually prime fuel bulb at low speeds to confirm if it is the pump, you of course need to do that constantly not just get it hard once and try

while the symptom was occurring, we pumped the primer bulb constantly, one time it would stall the engine, the next time it would do nothing
(to stall the engine, the float must NOT have been working or my primer solenoid is leaking ....that latter is unlikely as I just replaced the gasket and valve seat on the solenoid...)

then the next time the symptom occurred I tried the primer solenoid and got a little difference in the engine, but nothing to get me on plane.

then out of the blue just fine after 2500....and for hours after that ....BUT for the hours after that I didn't bring it down to idle for fear the symptoms would reoccur.

I'll check for spark on the top right tomorrow....I am pretty sure I got spark at idle...

Not sure how fuel pump could cause coil potting.

yeah was more thinking of the overall symptoms experienced, since I'v been playing with the pump

Have you seen any potting there before and is there any sign of any heat damage on the top of the head? Such as blurred paint.

other than the melted potting there is no apparent heat damage.
I have never really noticed before...just struck me as odd that this coil had the most apparent signs of heat and its plug was the wettest of the 6...in fact all others were dry.

NOTE: these coils are probably 31 years old or 20 years old....I don't recall ever replacing them.....maybe it is simply time to.

odd that <2500 rpm initially in the day, the motor started to get too warm....then once it was back to normal I could go for hours at 4000+ and my temp gauge was back to normal (in the middle)...not sure if this motor has a SLOW mode, I don't think it does. It has been a while since I tested the temp sensors.

Bad grounds can do all sorts of things, so have you tested it with the powerpack ground reattached? I don't like crimping in places that vibrate, the old school technique of twisting wires together seems to work better for me.

I have retested on land at idle with ground fixed, but No I haven't re-tested on the water after finding the ground issue ....the powerpack with the ground issue was not the same side as the coil with the melted potting....ugh

AND I just read on the CDI site that for at least two bolts you MUST scrape off the paint and use a stainless washer to properly ground the regulator...I did NOT do that...ugh....I suck...to be fair...that's an instruction manual and men don't read instruction manuals

I will try to water test tomorrow...I need a second set of hands to dunk the boat.

You may of had some gunk get into your carbs during the vro inspection. Id remove the lanyard line so you dont get spark, clean all your plugs then reinstall and turn the engine over with the starter for about 6 seconds then remove all the plugs and check that they are all wet from fuel.

the gunk option may explain why the pumping of primer bulb stalled the engine that one time.

good idea to verify that each cylinder is getting gas.

I did scope out each cylinder and the top of each piston are looking much drier than before..still has carbon deposits...but they've always been wet carbon deposits as being too rich in oil.

initially the symptom of not getting past 2500 or on plane sounded like stator problem, as I have seen that before on this motor, but that went out the door when it ran fine for hours >2500.


NOTE: plenty of smoke being produced, I am not scared that it is NOT getting oil.

BTW I just a saw a picture of my stator...I've been thinking the knobbers COMPLETELY wrong....the Charge Coils the one that make the 160-300 volts are the two back knobs/coils the ones facing the regulator....the recharge coil (yellow wires) have 9 knobbers/coils that go all the way around....

 

[cfauvel]

Overheating could obviously cause the melting. The rectifier/regulator is water cooled. If it failed, it might have done so from overheating due to a water flow issue -- same issue affecting the coil, potentially.

All valid points...

the old reg was nearly about 8 years old, and I suspect that a bad cell in my AGM starting battery is ultimate what made the regulator act weird....CDI doesn't support AGM batteries (at least for this regulator)

any thoughts on why the motor worked great above 3000 rpm for hours after an hour's worth of initially having wonky symptoms?

note the broken ground for port side power pack and note that the coils are really old....what should the coil's ohm reading be on the secondary plug?

update: found them in my manual
Primary should be .1 +/- .05....I'm at 0...so close
Secondary should be 275 +/- 50....I'm around the 260s for all, so good there (except for the melted potting)

Sensor coil
40+/- 10ohms....i'm in the 43-45 range ...so good there
min cranking volts .3 ...I'm in the .6 range....so good there

Charge Coil
ohms 970 +/- 15...I'm at 1070....so that;s not within range per manual, but CDI states theirs should be approximately 900-1100...I'm at the upper end of their range.

Power pack
min output cranking 100
min output running 230
have to confess I didn't do a test for this...going to read about it right now..

 

[cfauvel]

UPDATE:
well did the following
1 - with the pump in place took of the air motor pulse line to see if fuel was in the line...none was found

took the pump off and took off the air motor side. Saw some moistness, but not full on wet and it didn't smell of gas.

whilst apart I tried to figure out how the smaller spring pushes on the poppet to release vacuum that sends oil piston and everything connected back to starting position. I still don't get it.

there are two part numbers for VRO pump, one for < 50 hp and one for > 50 hp....I think I got the < 50 hp one as it seems to over oil.....I found no part number and I don't have the receipt for 1999.

I used 23.3 gallons of fuel and used 166 oz of oil.
23.3 * 128 = 2982 oz divided by the 166 ox of oil used I'm running 18:1 ratio....

I suspect what governs the amount of oil pulses is the smaller spring...not sure if for the larger motors if the poppet spring is longer or stiffer or both.

well I just followed the tests in this flow chart


The air motor holds air pressure to 15psi no problem..
BUT if I cap the fuel outlet and rapidly remove the pressure, the pump clicks....tells me to replace fuel pump diaphragms though it looks fine....


Something tells me the excessive oil is attributed to whatever is allowing the system to CLICK when pressure is released.

 

[Bosunsmate]

Ive never held one but id suspect diaphram whipping back is the click and if it clicks with outlet covered it means its got a leak allowing it to depressurise against springs force, id check the seating areas for it too.
Was just harzarding a guess there

 

[cfauvel]

Ive never held one but id suspect diaphram whipping back is the click and if it clicks with outlet covered it means its got a leak allowing it to depressurise against springs force, id check the seating areas for it too.
Was just harzarding a guess there

The springs is on the air motor side...If I pull a vacuum, it puts pressure on the spring....and that keeps vacuum just fine
if put 15 psi on the air motor side, it too holds pressure, and the spring pressure is reduced since the air pressure is going in the same direction as the spring.

rapidly releasing the pressure would momentarily bring the diaphragm and spring to natural position.

thus there is some flapper on the fuel side that is not sealing in that moment (I guess as that is what they are telling me to replace) and allowing the smaller spring/poppet do it's thing.... I finally see the poppet but don't get how the smaller spring works the poppet..and at which stroke...

I would love to put a see through port in the air motor, fuel pump area on the side closest to air motor and fuel pump closest to oil mixing area.

going to get the fuel pump repair kit...but honestly I don't think that was my boating woes....I think the pump has been acting like this for years and every time it clicks it dumps oil into the mix...that would explain the excessive smoke for years.


as far as my issues on Friday...I think it is either the bad ground on the power pack or one or more bad coils.

 

[jakedaawg]

Usually, we do not take apart the oil side and put it back on the boat. Newer manuals forbid this. Or we were told in class, but either way....

 

[cfauvel]

Usually, we do not take apart the oil side and put it back on the boat. Newer manuals forbid this. Or we were told in class, but either way....

the oil side is super simple...maybe they are talking about the electronics

here is the oil side.


this is the opposite mating service...there is an o-ring that seals the oil chamber.

 

[V153]

Melted potting can mean only one thing. Bad pot ...

 

[Faztbullet]

OMC coils use a powdered iron core and overtightening mounting bolts can break it internally which can cause a spark issue possibly overheat, coil mounting ground washer improperly mounted(star washer) and bad springs in boot of spark wire could cause coil to overheat.

 

[cfauvel]

OMC coils use a powdered iron core and overtightening mounting bolts can break it internally which can cause a spark issue possibly overheat, coil mounting ground washer improperly mounted(star washer) and bad springs in boot of spark wire could cause coil to overheat.

can you tell me the proper way to mount these coils? as in what washers do I use?

I see some with the following
engine mounting hole -> coil -> flat stainless washer -> start washer -> bolt

 

[cfauvel]

Update:

Got some primary lead extenders for the coils and have the following results with the engine running at 1100 rpm using DVA adapter

Port side output from power pack are in the 205v DC range.
starboard side output from power packs are in the 195v DC range

Does that sound acceptable?

the Evinrude manual states it should be about 250 whilst running....

UPDATE: CDI Electronics (which these packs are) state that a minimum of 150v whilst running....so I think we are good here.


Did buy new coils, but won't put them on until I get out on the water to see if me replacing, what seemed perfectly fine, fuel diaphragms in the VRO makes the difference.

VRO does seem to use 1 inch column of oil in a clear 1/4 ID vinyl tube in three pulses.

my manual states that at WOT a 1 inch column should be used in three pulses and at 800 rpm a 1 inch column used in 9 pulses or so....my manual is for a 1986 motor, but my pump is from 1999, making it an OMS....I suspect that i'm running at the expected 50:1 at all RPMS rather being variable....

We''l see if the symptom goes away this Friday.

 

[Bosunsmate]

good luck, id imagine it was the diaphragm. I had the same headscratcher on my water pump a month ago.
The pressure switch wouldnt activate yet the diaphragm and everything else looked fine, I ended up buying a replacement unit and it worked straight away, Even with all the hours of looking and testing it i couldnt find the fault and all that it is is that wasnt functioning is as simple as a water channel up to a rubber diaphragm

 

[cfauvel]

finally was able to get the boat to test it...been raining so much....today was a great day.


performance was back to normal, getting on plane and WOT.

Here is what was done.

• replaced the fuel pump diaphragm of the VRO. as it failed one of the tests in the VRO test flow chart. (which was probably why I was using too much oil).
• found broken ground on one power pack and fixed it. Though I don't think that was it as at speed the motor ran for hours just fine (3000+ rpm)
• cleaned out my fuel filter of some varnish granules that came from front fuel tank. And sucked more granules from front tank until I got clean glass again.

Not sure which thing I did was the fix....I don't think it was the fuel pump as the motor ran fine at above 3000 rpms for hours even at WOT 5600+ rpms. But the fuel diaphragm should lower my oil consumption....

went ahead and bought 6 new coils as mine are from 1993....will put them on this weekend......didn't want to add too many changes in determining what was the cause.