TOPIC: Merc 1500 with power T&T

Just picked up the motor below that has been sitting in the barn for 6+ years. Looks like some "biodegradeable" wiring to be addressed, and I did not do a full compression test. I did pop the top and turn the crankshaft without the plugs. Felt pretty solid and smooth.

Here are some pics Merc experts - let me know what you think and what else you need to see.









Wires need some work





Some issues with the distributor

Missing the switchbox or did you get one of those with it? The wiring is typical, you can try cutting it back to see if there's any good wire left in the harness.

If it's repairable, the best way is to splice the new wires in using solderless splice clips (crimp connection). Then solder each connection and cover with shrink sleeving. The result is a mechanically strong splice, that's also good electrically, since you soldered.

Note on the switchbox, you can use a 4-cyl or 6-cyl box and either will work. But the 4-cyl box won't drive a Merc S/S tach. No big deal there, since modern tachs are driven off the alternator output, at the rectifier.

Here's a switchbox on eBay for $30 shipped if no one else bids on it:



An excellent upgrade for these is the CDI replacement box which is a combined switchbox/coil in one unit. So you can eliminate the large orange/red ign coil mounted in the cowling, the CDI setup just bolts right in place of the Merc switchbox. A bit $$$ though, $245+ on eBay.

You got the hoses for PT&T, that's good, 'cause they're quite expensive. You may be able to use some shrink sleeving over the hoses to make them look better.

Now the fun time begins, and you've got a nice kicker motor to play with, to boot!

Cheers......ed

Thanks Ed - what you see in the pics is what I got. I got a box of Merc and OMC parts from an auction earlier this year. I will need to troll through and see if any of the parts and see if they will fit. IF you send me your email I will send you the spreadsheet. It is on Glassifieds too.

I just put a bid on that switchbox. Hopefully the price stays low for the next 2 days

I really need to look at my Merc parts inventory and see what I have that can be used. I would hate to buy something that I have sitting on a shelf but don't know about it. I am not against upgrading the ignition to CDI - the goal is to have a cool looking tower on the back of the GT, but no one will seek that it is upgraded if they can't catch up to me!!!!

Sniped that switch at the last second. There is one thing down on the list of parts I will need

Got the switch today in the mail. Spent the day working on the 110 and cleaning the garage for the arrival of the '74 Marlin tomorrow. Hopefully sometime next week I will get around to starting the process of rebuilding the wiring on the 1500. What should I use for replacement wire? Its not single core, but what gauge is being used?

Wanted to bump this again as I am stopping for plugs for the 110. What gauge of wire should I pick up to wire up the Merc? I am assuming filament core, but wouldn't solid core hold up better?

63LStriton wrote:

Wanted to bump this again as I am stopping for plugs for the 110. What gauge of wire should I pick up to wire up the Merc? I am assuming filament core, but wouldn't solid core hold up better?

No, these use a solid-core copper-stranded wire. You don't want to use automotive-grade wires on these or any resistor-type wiring, it won't work.

Merc used to use Packard 440 ign wires but the electronic ign's develop such high voltage that they weren't good enough.

IMHO unless the yellow Merc ign wires are cracked or messed-up at the end that threads into the distributor, I wouldn't replace them.

Or, replace with new, equivalent wires. You can get lengths of this wire, and the crimp-ends, to make your own.

Sierra Marine sells a universal plug wire kit with 25-ft of 7mm hypalon rubber, copper marine-grade wire, and various crimp fittings. You'd need a special crimper for the screw-in fittings at the distributor cap, as well.

P/N 18-5225 and $35 on eBay:



But I wouldn't even bother with replacing the spark plug wires until you get the ign working and then running the motor to evaluate if it's worth fixing or not.......ed

Ed,

One of these days you are going to take a hammer to me because of my poor communication skills on this site. I keep sending everyone down different rabbit trails because I am not being clear enough.

I am not talking about replacing the plug wires - yet. I am talking about what I need to re-wire the bio-degradable Merc wiring so I can think about putting in the "new" switchbox and hooking up the rest of the wiring harness.

As you can see from earlier posts, some of the wires that go to the box are in pretty tough shape. You had mentioned cutting back to find good wire, and then butt splicing, soldering, and shrink wrapping. I just wasn't sure what kind of wire to put in place for the repair. I would think solid core would hold up better, but I imagine they used stranded core for its flexibility. Just wanted some guidance on what to buy since I really only want to do this once on this motor.

BTW - I will thinking about buying white coated wire so that I could use markers to replicate the original wiring color striping. That would give me good reference info in the future, just in case I needed to pull things apart.

Thanks for your help, and sorry for the multiple questions and false starts!!

Buy marine wire. It's stranded and tinned for the best corrosion protection. Don't splice, just run all new, it'll be fun once you get started! Find out what size and colors you need and then buy it online. After the initial price shock, go to West and see what they charge... then you'll feel much better! Use liquid electrical tape over all crimped connections, then cover that with heat shrink. Use dielectric grease at all screw and plug connections. A good ratchet crimper is a smart investment too, online for 50 bucks or so. The split accordion wire bundling stuff (sorry, not sure what it's called) available at auto parts stores makes a nice job and won't hold moisture in if it gets in. Oh yeah, use tinned connectors too, wherever you get the crimper from, for instance.

I would check with CDI the people who make the ing. parts they sell the internal wiring harness for most motors spendy but worth the money

The ebay item id given is invalid, no result has been sentBe sure to solder any connections that you crimp.

The bigger wires are probably 12-gauge. I think the smaller, control-type wires (such as choke, etc) are probably 16-AWG but it wouldn't hurt to run 14-gauge instead.

When you're cutting the rotten wires back to solid material, you can measure the AWG with your wire stripper. If you don't have one, I highly recommend it! I've had a Sears stripper/crimper that's the same as the old "Super Champ" brand wire stripper, for 40 years and it's still a useful tool.



I found this seller on eBay with a lot of marine-grade electrical stuff, including rolls of wire. If you come home from West Marine with a case of sticker shock, check out this guy:

www.ebay.com/sch/m.html?item=291565494304&_ssn=gregsmarine&_sop=15

I found some good-quality heat shrink tubing on eBay, this particular brand was reasonably-priced and there are 100' rolls available in the 1/8" and 1/4" sizes (or smaller amounts, too). A 100' roll for well under $20 might last a lifetime!

Didn't think about putting the crimper on to check the size - I only have 3 or 4 shuffling around in the garage looking for work!! I had run over to the local Menards and picked up some 14 ga tinned wire along with solder, butt joints, tape, etc. I will check the size of the ignition cables as I don't want to be too small for what they need. Only want to do this once - hopefully.

Probably won't get to this until Friday or Sat. At least now I have a fuel line that will fit so I can test run it on a stand with some muffs. I will see if I have fire and then work over the carbs. but first I have to look over the busted up distributor cap. If it is screwed up, can I scavenge parts from the 65 1000? I might have a new rotor in my boxes of goodies from the auction. Just need to cross-reference some numbers.

Sorry, when I read your post, I didn't catch that it was just the engine wiring. So yes, you will need to make butt slices where you have molded-in wires coming from devices. There are two schools of thought on soldering, and many experts advise against it because the vibration will stress the point where the flexible wire joins the hard solder joint. I personally feel soldering is ok as long as the wire is supported well on both sides of the joint. Don't use the connectors with the little plastic insulator on them. You can't get a good crimp through the insulator. Sometimes that's all you can get in a pinch so just slit with a box knife and remove them. The heat shrink over liquid electrical tape is the best insulation and waterproofing you can get. For closed connectors, meaning it has been already formed into a round tube to insert the wire, crimp best with a crimper jaw that is semicircle on one side and a dimple point on the other. If you can find open connectors, that have been formed in a u shape, that you can lay the wire in, use a crimper with a semicircle on one side and a "double barrel" shape on the other, kind of like the shape of the lower half of boobs... those are the very best as it will curve the loose ends of the connector back into the center, and stuff them into the wire. You can swing on those connections and they won't come apart! Oh, and be sure on the closed connectors that you put the dimple in the side opposite of the seam. Hope my explanation didn't lose you...

All I can remember is boobs......

I try to use descriptions that stick with you

I think you need to concentrate a little mor..... LOOK, A SQUIRREL!!!!!!!

Bill, lol

I'm still chasing the squirrel......

Bounced around looking for the manual for my 1350 and the 1500. I had previously bought a manual for the 65 1000 from www.servicemanualvault.com , and had really good luck with their stuff. Found a manual for the 1350, my '77 115 Johnyrude, and '57 Big Twin 35 - bought all three for under $15.

Did not see a manual for the 77 1500. That site listed a 1500 manual for 74-76 and did not include my serial number in the listing of motors covered. I was going to order it, but I wasn't sure if there was a re-design for my model that changed something significantly. As it is, the manual that I ordered for the 1350 is probably the same one that I was about to order for the 76 1500.

Gurus - any thoughts on a manual for my 77 1500?

www.boatinfo.no/lib/mercury/manuals/mercury_1965-1989_40-115.html#/0

Thanks Ed!!