engine wire springs/coils

[mdidomenico]

i'm going to start the wiring on my engine soon, i noticed in pictures here and can recall before i removed all the wiring that several of wires had coils in them near the devices.  are these coils important or just strain/vibration relief?  if important, how do you get the wire to stay in a spring like shape?

i suspect these springs/coils are largely irrelevant, but i was curious, figured i'd ask

[Stu Jackson]

i'm going to start the wiring on my engine soon, i noticed in pictures here and can recall before i removed all the wiring that several of wires had coils in them near the devices.  are these coils important or just strain/vibration relief?  if important, how do you get the wire to stay in a spring like shape?

i suspect these springs/coils are largely irrelevant, but i was curious, figured i'd ask

They are "...just strain/vibration relief."  Not irrelevant, but very useful.  Everything connected to the ngine vibrates, and alternator connections do so even more, like the tach and field wires.

Coil them up around a pencil, make them much longer than you think you'll need to offset any tendency to "unwind."  Practice on some samples first.

[mark_53]

I don't have wire coils. Never had one come lose but if I did, I'd use a lock washer.  Wire is pretty flexible on it's own.

[Ron Hill]

Guys : Like Stu said they are for strain/vibration.  Those coils also act as a "service loop" with extra wire in that run.

They are VERY handy, because they give you some extra wire incase you need to put a new connector on the end.  I just use a wooden dowel to wind the wire around to get that coil! 

A few thoughts

[KWKloeber]

Md

[edited]

When wiring different alternator optional models on Universals the terminals were in different locations and the harnesses weren't customized.  Leaving them a little long and putting the coil in there is a professional look rather than having them a little long and drooping, or worse a little tight. 
It's one thing if you're terminating each wire individually after pulling a harness, but if you pull a harness with the wires already terminated it's nearly impossible to get every one precisely to the correct length.  And then what if you change alternators?  Or the pigtail on  REPLACEMENT fuel pump is an inch shorter?  Butt crimp on an extension? NOT professional.

They're no so much strain relief - they're strain prevention.

Are you making up a harness yourself?  What are you planning for fusing the harness? How are you powering the fuel pump and alternator field excite?
Are you wiring right to the panel or to a terminal strip?

Note that the OEM Westerbeke (XPA) engine harness was SAE stiff wire (and current engines STILL ARE not flexible Type 3 marine wire. So, the coils are a little more difficult to stay put on new (flexible) wiring than on the old (stiff) harness.

PS: there's no such engine as an mxp-25a.
If you have an M-25XPA it's wired differently than the M-25 and M-25XP.
If it's truly an "A" she has the convoluted wiring scheme (suggest you consider changing it WHILE you're rewiring anyway.
ALSO, be mindful of the issue with the oil switch terminals on the A (and B) engines, and issue with the starter solenoid terminal  connection.

[mdidomenico]

Are you making up a harness yourself?  What are you planning for fusing the harness? How are you powering the fuel pump and alternator field excite?
Are you wiring right to the panel or to a terminal strip?

PS: there's no such engine as an mxp-25a.
If you have an M-25XPA it's wired differently than the M-25 and M-25XP.

If it's truly an "A" she has the convoluted wiring scheme (suggest you consider changing it WHILE you're rewiring anyway.
ALSO, be mindful of the issue with the oil switch terminals on the A (and B) engines, and issue with the starter solenoid terminal  connection.

all good questions.  i'm starting from total scratch so the world is my oyster.  hopefully i can do it correctly.  over the next couple of weeks i'll likely be starting a few threads on the issues/clarification (fusing is one i plan to start with).  i'm working my way through all the engine electrical threads, some of it's hard to follow and buried in multiple threads, so it's taking a bit to digest it all

i put the engine moniker in my sig before i knew anything after just getting the boat.  i'm pretty sure it's an m-25xp.  unfortunately most of the stickers peeled off before i got her and when the yard painted the engine last fall they scrapped off what remained.

[Ron Hill]

mdid : I'm sure that you have a M25XP engine made by Medilest in Oshkosh.
 
Just make sure that you use marine grade (tined) wire and a good grade of connectors like a name brand - Blue Sea or Anchor or Cole Hersee - to name a few.  Also a good grade crimper will help.   
Don't do like someone I saw - he got great deal on a roll of green marine grade wire.  You guessed it - all of his wiring was green!!   

A few thoughts 

[KWKloeber]

Telltales:

The engine displacement is embossed onto the block, above/behind the secondary fuel filter:
855cc = M25
927cc = M25XP or XPA or XPA(C)

Does your fuel return line come off the front of the engine (cyl #1 injector banjo) or rear (#3 injector banjo)?

Is your oil pressure alarm switch on the block, above back end of the starter (one wire running to it)? = M-25 or XP.
Or mounted to a plate attached to the unused port side engine mount holes (two wires running to it)? = XPA or XPA(C)

Is there a preheat solenoid and push button circuit breaker mounted aft end of engine, stbd side? = XPA or XPA(C)

[Ron Hill]

Ken : I don't know of a C34 that Catalina made that didn't have a Medalist M25 or M25XP engine.  I believe the same holds true for the C36s.

A thought

[KWKloeber]

Ken : I don't know of a C34 that Catalina made that didn't have a Medalist M25 or M25XP engine.  I believe the same holds true for the C36s.

A thought

Ron

Your point escapes me. We're discussing whether the engine is an m25, an XP, an XPA, or an XPA(C).  Are you saying the latter two were never installed in a 34?

[Ron Hill]

ken : The only 2 "M25" engines that I know of that were installed in a Mk I C34 were the M25 and M25XP.   Later in the MK I they installed the M35 and in the MKII the M35BC engine.

A thought

[KWKloeber]

ken : The only 2 "M25" engines that I know of that were installed in a Mk I C34 were the M25 and M25XP.   Later in the MK I they installed the M35 and in the MKII the M35BC engine.

A thought

Ok gotcha. Thx for that heads up Ron.
Mike Brown has a 35A (dunno if it's original.).

So if there were no XPAs installed it seems that MD doesn't have an xpa.

Ken