Merc 115 inline timing, I THINK I got it

[Bob37814]

Ok guys, Finally got my tower 115 going today.....long journey, good help though from Clams and emckelvy, Definately a learning experience!!!!! I wanna make sure I got this right because next saturday, Im taking her to the water. At cranking speed with a timing light, throttle arm at WOT, it flashes it at 21 degrees. I have also marked this with a paint marker and I see it also while cranking. With the throttle arm at idle position, the timing light flashes it at about 2 or 3 BTDC. It starts and runs, may have to redo fuel pump, Just want to make sure I dont barbecue my pistons. This motor sounds really good and just want to make sure that I did it right with the timing issue

 

[Chris1956]

Re: Merc 115 inline timing, I THINK I got it

Bob, The Max timimg sounds right. However, the idle timing spec is set when the throttle arm just touches the carb, just when it starts to open the carb butterfly.

Also, the idle pickup spec is different depending on whether the motor has ADI or Distributor ignition.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

Chris, My motor im guessing as ADI or what Clams calls direct charge, well anyways, it does not have the distributor.Also, in Clams' link and sync notes, He speaks of a first minor throttle pickup. Is this what you mean by when the throttle arm just touches the top carb????? If im right and understand correctly on all this, advance the main throttle arm til it just touches, and adjust the trigger screw until my timing light reads it at 3-4 degrees? Also I noticed behind the trigger screw there is another screw, Noticed it does somekinda trigger adjustment whilst the bigger screw seems to stop it at a point. Forgive me if I sound like a complete moron on the subject as I am only here to learn. Try this out and let me know whats up, Im going to say the larger screw that I mentioned earlier is used to stop the trigger advancement. The one behind this, smaller screw is whats used for the timing adjustment for the first minor throttle pickup. Thats just an educated guess from me only after much trial and error...PLEASE clarify this for me. I think im at a point that I can actually fix this thing with that info...Thanks - Bob

 

[Chris1956]

Re: Merc 115 inline timing, I THINK I got it

Bob, If you have the six coils, the ignition is an ADI type. The idle pickup timing is usually a few degrees ATDC, so you might like to look it up. My '93 V6 is 4 degrees after TDC.

To set the idle pickup timing, the throttle arm should just be touching the arm that opens the top carb. Using a timing light, adjust the trigger screw so it reads properly. I usually push up the cold start lever until the throtle arm just touches the carb arm, and then shoot the timing.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

Chris, Just got in from jury duty with the rest of the day off work. Im fixing to go out and see what I can do with this thing. Hopefully after reading the link and sync that Clams posted, and with your wealth of good info. I just might be able to get this bad boy right this time. Also, if I pump the primer bulg really really hard, should raw fuel drip out of the top carb? I mean you REALLY gotta bear down on the bulb to get it to dribble out but its just a very small bit. Thanks- Bob

 

[Chris1956]

Re: Merc 115 inline timing, I THINK I got it

Bob, the carb is likely good. As long as it doesn't drip easily, you should be OK.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

Goody Chris, Thats one thing i am glad to hear of. I am about to go out now and tinker with her a little bit, was waiting for my battery to charge up.....hooked up the charger last night forgot to plug it in LOL. As for the timing, I'm close. dead close. But here in East TN, no rainfall and they lower the lake levels, As for a shakedown cruise, may have to wait for next spring when the lakes go back up....BUMMER!!!! But wintertime I can take it easy and really give this old 115 a good thorogh checkout, throw money at it whereever needed, and hopefully have a nicer than average boat....Ill keep you posted on the results later this evening or tomorrow afternoon once I see hopefully how this timing issue works out. Manual on the way so that will make things a world of difference easier(i hope) Appreciate all the help and God Bless - Bob

 

[AMD Rules]

Re: Merc 115 inline timing, I THINK I got it

What's your serial number?

I'll check my manual for factory timing spec.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

The s/n is 5416341 making it a 1979 ADI motor...Just as an update to all, after a minor fuel problem, the engine now starts again after link and sync with specific posted directions from Clams Canino. Sounds real smooth and revs really nice and returns to a neutral idle at about 800rpms(if the tach is accurate) Now another problem is, I cannot get it to start unless I manual prime the carbs with fuel/oil mixture in a squirt can. If I do this it starts and runs quite well. Bulb is nice and firm, electric choke works(but there is a little more than a 1/4 inch gap between the plastic choke plates and the carbs when the e choke is engaged) But now, the engine fires up warm is a touch of the key. In my past experiences with a Merc 402 40hp and a 500 50hp with the easy warm starting, this definately sounds like I am on the right road to somewhere

 

[AMD Rules]

Re: Merc 115 inline timing, I THINK I got it

Sounds like you're making progress....

Factory Specs for the 115hp ADI:

Timing Maximum Advance: 18? BTDC (20? at Cranking Speed)
Throttle Primary Pickup: 5? - 7? ATDC
Full Throttle RPM: 5000-5500 RPM
Idle RPM (in Gear): 550 - 650 RPM
Water Pressure (at Cylinder Block): 2 to 5 psi @ 2000 RPM

These inlines motors are notoriously difficult to cold start. Be sure to prime bulb until firm then another squeeze for fun. Don't over do it though because you can stretch the fuel pump diaphram. Be sure that choke is working. Any leaks in the fuel lines or fittings and you'll be cursing that system forever. They need fuel to start, and like the taste of it.

If it never gets better, you might consider converting over to a newer enrichment system from the mid-80's onward. My motors typically start up quite easily. That enrichment system works well.

Good luck.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

Another thing I noticed last evening was all the fuel lines on the block itsself and some on the fuel pump were held on my what appears to me to be zip ties. What do you guys think???? Change them over to the metal automotive type for good measure or leave the plastic zip tie ones alone?

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

alright guys, hold the phone Started it up and ran beautifully for about 5 minutes. then it went clink and now theres a knock in the powerhead......you can hear it slap vigorosely with every revolution....woe is me!!!!!! It sounds like a rod, may be a bearing i dunno....In you alls opinion, being a 79 model motor whats the best course of action??? Is it worth the time and cost rebuilding, or should I part it out and repower? Man I tell ya this feels worse then a swift kick in the n&t$...If its not worth fixing, what does anyone need???? Clams, may have some parts for ya

 

[AMD Rules]

Re: Merc 115 inline timing, I THINK I got it

The black plastic ties are likely Merc's ties and are ok. Could be a sign those fuel lines have never been changed though.

Best course of action is to determine why its knocking. One way to check for bearing slop is to use a screwdriver. Take all the plugs out, using the flywheel rotate just past TDC on any piston then using the screwdriver push down on that piston and see if you can feel extra play. There's always a little bit, but if its knocking due to bearings you shoudl be able to feel it on the corresponding piston.

Have you re-checked compression since the noise started?

Pulling the inspection covers on the intake side doesn't take much time, and can give you a visual on the condition of the cylinders/pisons/rings.

Good luck.

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

i checked for bearing slop and found nothing Everything seems good and tight, Compression on all 6 still in the neighborhood of 120If I turn it over with a socket wrench at the flywheel, it hangs up at one point, but with a little more force, it will move past this point and you can hear an obvoius THOMP. It just seems like something is hanging up. I am gonna pull the carb/intake manifold/front cover today to expose the entire crank and rotate it again to see whats causing it. Laddies said it may have got hot and dropped a piece of carbon in a bore...I'll look for that too. I will post later this evening and let you all know my findings....I am praying to the Cods its fixable

 

[Bob37814]

Re: Merc 115 inline timing, I THINK I got it

Ouch guys......Dont know what to say but does anyone need any used inline 6 parts???? Removed entire powerhead from engine today, removed carbs, intake. basically everything to get inside it. I have a noise like a wrist pin bearing in the #6 cylinder, and the bottom end cap bearing poured ball bearings upon removal. after fishing them out with a telescopic magnet, I noticed the bearing balls themselved were badly beaten and scored with flat spots. Also in my findings, the bearing races were scored up very badly and had a few burrs on them. Now for the real kicker....The bottom of the crankshaft where the bearing rides is completely beat up. I can tell now when the engine would hang up that one of the steel balls must have ran off track and wore a really nasty groove(which was probably what was making my motor hard to turn at one point) I wanna appreciate all of you helping me out with the timing and sync of the ignition and carb problems, trigger problems, and other trial and error but I wont be fixing this motor afterall. Think I'm gonna part this motor out on ebay and craigslist and save them funds and put back a little dough and repower around the first of the year when I might be able to find a good used outboard on a deal

 

[AMD Rules]

Re: Merc 115 inline timing, I THINK I got it

Sorry to hear that. Best of luck with your next motor.