Outboard Engine Stator Repair: New Coils

Electrical and electronic topics for small boats
Oldslowandugly
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Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Mon May 09, 2022 6:03 pm

I am about to remove the flywheel on my 1996 48SPL to see if I can splice in new stator wire leads. The insulation at the terminals has deteriorated to the point of shorting out. I thought that in case I need to replace the entire stator, I researched buying one. It seems the original design which incorporates the laminated steel mount has been discontinued. They offer as a replacement two coils and the wiring. The directions say that you need to install the coils onto your old laminations.

Q1: how are new coils installed into the laminated steel frame assembly?

Q2: what material are the blobs on the original coils?

Q3: are the blobs insulators?

Q5: how are the coils held in place?

The OEM stator and the new replacement coils are shown below.

584341.jpg
Fig. 1. Original stator assembly.
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ReplacementCoils.jpg
Fig. 2. Replacement kit with only lighting coils.
ReplacementCoils.jpg (35.26 KiB) Viewed 3797 times
Last edited by Oldslowandugly on Tue May 10, 2022 10:42 am, edited 1 time in total.

jimh
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Re: Outboard Engine Stator Repair: New Coils

Postby jimh » Mon May 09, 2022 7:16 pm

Before removing the old coils from the steel frame assembly, be certain you have observed the wiring orientation and have recorded it or taken a detailed photograph of it.

The dark gray blobs in the OEM assembly appear to be adhesive that captures the spices between the yellow flexible wires and the solid enameled winding wires and holds the splices in place so they don't move under vibration.

The white nylon coil bobbins should be enough insulation.

The supplier (CDI) should have provided instructions. Or, perhaps there is a service manual that discusses the installation.

The steel frame is part of the coil winding magnetic pole.

Oldslowandugly
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Joined: Fri Jan 15, 2016 11:19 pm
Location: Queens NY

Re: Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Tue May 10, 2022 10:41 am

I haven't removed the stator from the timing plate yet. I was hoping that I could splice new wires to the OEM wires right after they exit just under the timing plate. At that spot they seem to be more intact. Testing shows that the coils are not shorted to ground but I need to separate them from the protective sleeves so I can do a resistance test. If you look at the backs of the OEM coils it looks like some sort of plastic wrap secures them to the frame. The pic of the new coils shows three tie wraps included so maybe that is how they are retained. After taking the flywheel off I see there is some melted potting material that dripped and hardened under the charge coil. That is usually a sign that the motor has been over-heated. I may be replacing all of the lighting coils, charge coil, and trigger coil.

Oldslowandugly
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Joined: Fri Jan 15, 2016 11:19 pm
Location: Queens NY

Re: Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Tue May 10, 2022 1:54 pm

I took the entire timing plate off. The charge coil has definitely melted and the ohm meter test says open circuit. The trigger coil is OK and the lighting coils on the stator are good too. Just the wiring is crumbling. The original charge coil had a stainless steel faceplate that must have come off and was being dragged around by the flywheel. Much damage ensued, so I decided to purchase an entire used timing plate complete with all the coils and with solid wiring from Green Bay Prop. The base plate is the same part number as mine so it will bolt right on. I will still splice in new wires to the original stator coils so as to have a spare.

timing plate.jpg
Fig. 3. A used timing plate with all coils and wiring.
timing plate.jpg (121.69 KiB) Viewed 3777 times

Oldslowandugly
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Location: Queens NY

Re: Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Tue May 10, 2022 4:01 pm

Here is clear indication that either the charge coil or the motor have over-heated. I have read that either occurrence can cause this melting of the potting material. The coil shows an open circuit so it is unusable.

IMG_0405.JPG
Fig. 4. Melted potting material from overheated charge coil.
IMG_0405.JPG (186.59 KiB) Viewed 3770 times


To allow the charge coil and trigger coil to be removed from the timing plate, their electrical connector must be disassembled. Lacking the OMC tool, I found that a 1/8-inch hex key tool fit perfectly to push out the pins. Be sure to lubricate both ends of the connector with isopropyl alcohol which will leave no residue. Once the connector is removed then the wires will pass out of the timing plate.

IMG_0406.JPG
Fig. 5. A 1/8-inch hex key tool will push the pins out of the connector.
IMG_0406.JPG (124.36 KiB) Viewed 3770 times

Oldslowandugly
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Location: Queens NY

Re: Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Tue May 10, 2022 7:20 pm

JIMH--upon investigation I see that the thin coated wire from the coil does in fact enter the blob (as you suggested) and the thicker marine grade wire exits the blob. The blobs are sealing the connection and securing them against movement. [The blobs are] a hard substance similar to automotive seam sealer.

I also see a few nylon tie-wraps securing the wiring at various spots, and they are probably to keep the wires from being hit by the flywheel.

The coils are wrapped around plastic spools [bobbins] that have two flaps on one side that hold the coils tight to the laminated core. I would guess that those replacement coils should have that same set of flaps.
Last edited by Oldslowandugly on Wed May 11, 2022 8:48 pm, edited 1 time in total.

jimh
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Re: Outboard Engine Stator Repair: New Coils

Postby jimh » Wed May 11, 2022 9:20 am

Re the rubber-body electrical connector shown above in Figure 5:

Using alcohol on the rubber connector body will act as a great temporary lubricant to ease the friction that is retaining the metal contacts. When mating large rubber-body electrical connectors, a bit of alcohol on the mating surfaces will permit easier assembly, particularly with the large red rubber Amphenol connector for the main engine harness.

As shown in Figure 1 and Figure 3, the actual coil windings are made with solid copper wire with a thin insulation. The insulation material is generically called "enamel" insulation; there is a trade-name material called Formvar. The general problem with these insulating materials is their melting temperature. If the coil becomes too hot, the insulation begins to soften. If a short circuit occurs between windings, this is know as a shorted-loop. A shorted loop in a magnetic current field creates a problem, usually leading to more heat being generated.

In the OEM coils seen in Figure 3, the spice between solid wire and better insulated stranded wire is made very close to the coil winding. In Figure 1, showing an aftermarket coil, the splice is made away from the coil winding. If refurbishing the OEM coils by attaching new insulated stranded wire to the solid wires of the coil, you could consider unwinding perhaps one turn in order to move the splice junction a bit farther away from the coil, as was done in the aftermarket coil in Figure 1. Note the extended solid copper wire is protected by a flexible insulating sheath, which is probably rather heat resistant. Finding where one could get that material is an unknown to me at this moment. I would not use radiated-shrink tube material. It would be very stiff. The best way to reduce mechanical movement of the wire when there are vibrations trying to excite the wire into motion is to not have a stiff wire. A stranded wire with significant insulation around it will tend to be damped and won't vibrate as much as a stiff wire.

Oldslowandugly
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Joined: Fri Jan 15, 2016 11:19 pm
Location: Queens NY

Re: Outboard Engine Stator Repair: New Coils

Postby Oldslowandugly » Wed May 11, 2022 8:47 pm

jimh wrote:Note the extended solid copper wire is protected by a flexible insulating sheath, which is probably rather heat resistant. Finding where one could get that material is an unknown to me at this moment.

I think the heat resistant sheath that they use on stove and oven wiring would do the job. It is a fiberglass cloth that the wiring is routed through when it passes near hot sections of the appliance. It is easily salvaged from an old stove igniter.
wire shield.jpg
Stove igniter wire with heat shield.
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