1986 mariner 90hp inline 6 problems-update-motor

[njrextreme]

Hello, my Name is Nick and new to this site. I hope someone can help me w/ a few questions.

A couple seasons ago I replaced my stator, triger, switch boxes, and rectifire. The reason I did is because the motor was running on only 3cyls. So I get it running great and took it out on the river a couple times. The second trip, I was WOT on my way to the dock and the motor wound down and died. It was hard to start but it did and now seems to have the same problem as before. It runs like its half power and wont bring the boat to a plane. Also, there is a ticking noise. Not like a rod, just a faint tick. Any ideas on why the ing. system would fail, and then fail again. Also, what could the tick be. Im going to check the spark and see if its a switch box again. I still have one good box left thats original.
Thanks, Nick

 

[Lone Duck]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

Check under your flywheel, something may be loose.

 

[achris]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

Also check for bad grounds... That will kill switchboxes very fast...

About your 'tick'.. Noises are incredibly difficult to diagnose without hearing them... One person's tick may be another person's knock... If you could get a video of it (with the sound of cause) and post it up on something like you-tube, and link it here we MAY be able to help.... As I said, noises are difficult....

Chris.....

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

Also check for bad grounds... That will kill switchboxes very fast...

About your 'tick'.. Noises are incredibly difficult to diagnose without hearing them... One person's tick may be another person's knock... If you could get a video of it (with the sound of cause) and post it up on something like you-tube, and link it here we MAY be able to help.... As I said, noises are difficult....

Chris.....

What kind of puller do I need to get the fly wheel off. Will a auto style one work? I had a tech pop it off last time for me. I replaced the stator and triger so it could be somthing loose. It does not sound like a knock. First thing im going to do is see if it lost spark on three again, and maybe get a quick vid on my phone for the tick. I dont have a nice vid cam yet.Thanks for the replys

 

[bzajdek]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

As far as I know they ended production of inline six motors in 1986 on 90 HP models, the 1987 + were 3 cylinders for the 90HP.

 

[arsenalpsu]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

Have you checked compression? I know exactly what you're saying when you had "loss of power"- my 115hp tower detonated last year which caused a piece of the piston to short out a spark plug and *poof*. AND after that I noticed a knocking noise- so I spent all winter rebuilding her. If it's making a knocking that's bad, you?re getting "piston slap"- either from missing rings or worn out pistons. You can still get compression and be missing a ring- two of my pistons were like that.

IF this truly is knocking it may come and go, but will eventuially come back with a vengeance- before the old girl throws a rod and becomes scrap metal- tear her down and rebuild it, "the grim reaper is knocking at your Mercs door"

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

Ill post up what I find this sunday or monday. Ive never rebuilt a boat motor but wouldnt mind trying. Last time the boat ran like this I had it inspected, and comp. was all in check. Carbs hold there prime. It was a loss of spark on three cyl's last time. I think it happened again. I hope it dont need rebuilt. Its old, but im sure low hrs. on it. I will need to find out why it burt another switch box up.

 

[arsenalpsu]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

I had never either but had fun learing and doing it- depends on what that noise really is. If you don't have spark in a cylinder it could be as simple as a bad connection- since you just replaced all your electronics last year i would hope none of them have failed already!

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

As far as I know they ended production of inline six motors in 1986 on 90 HP models, the 1987 + were 3 cylinders for the 90HP.

Ill check for sure but was told its a 87 motor.

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

Ok, so i did some checking it out yest.. I have good spark on all six cyl.. The motor # is 0A969248--- if anyone could tell me the yr for sure. It starts and runs but feels a little ruff. I took a cell phone vid. but I dont think I need to post it. I started to pull plug wires when it was running. It would stumble and want to die on the first two. Then # 3 did not change the way it was running. I pulled the spark plug and it had small chunks of metalic on it =(.
How much to rubild one of these motors if I do it myself? I know I would need machine work most likely. Is it worth rebuilding or should I be looking for a used motor or replacement powerhead? Not the news I wanted, just my luck. Im going to have more in the motor than the boats worth.

 

[achris]

Re: 1989 mariner 90hp inline 6 problems-electrical

Re: 1989 mariner 90hp inline 6 problems-electrical

It's a 1986 model....

As for chunks of metal on the spark plug, that's a piston coming apart. DON'T run the engine any longer. At this point you may not need to bore and will get away with a hone and a new piston, maybe. Run it any longer and you will need a new piston and a bore.

Causes of detonation... The list is actually quite long, but the one I'd look at would be your carb jets. The inline 6 engines of that era had a coating on the water jacket side of the block and they had a little trouble getting heat out. A few years back I had one that did 3 pistons in short succession. Always the same piston. We check the timing, every time.... We changed the jets to the next size bigger, problem solved.

Chris........

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

So what is my best route to go. Does the power head unbolt from the rest of it Then pull the case apart and start inspecting? Ive never done a motor like this. Any help would be great. Thanks for telling me the year of it.
Nick

 

[achris]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

Hi Nick,

You're welcome..

So what is my best route to go. Does the power head unbolt from the rest of it

Yes...

Then pull the case apart and start inspecting?

Well, after you've removed a whole heap of other stuff, yes.

Ive never done a motor like this.

There's a first time for every thing.

Any help would be great.

That's why you're here...

VERY FIRST THING!!!! Get a factory manual. If you have a friendly local Merc dealer, then the part number is 90-86134--3, or go on-line. The factory manual is more expensive than the seloc or clymer, but worth every extra cent, and then some!

Chris.......

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-electrical

Re: 1986 mariner 90hp inline 6 problems-electrical

Hi Nick,

You're welcome..



Yes...



Well, after you've removed a whole heap of other stuff, yes.



There's a first time for every thing.



That's why you're here...

VERY FIRST THING!!!! Get a factory manual. If you have a friendly local Merc dealer, then the part number is 90-86134--3, or go on-line. The factory manual is more expensive than the seloc or clymer, but worth every extra cent, and then some!

Chris.......

Thanks Chris. Im sure I will be on here asking questions and posting progress pics very soon.

 

[arsenalpsu]

Re: 1986 mariner 90hp inline 6 problems-update-motor

Nick,

If you have any mechanical sence it's pretty easy. (especially when you have people on here that have done it) That cylinder that you found metal is in is the piston head coming apart. Could be for many reasons....but do you have an oil injected system in yours? If so get rid of it and start mixing your own. Also get rid of your idle stabilizer. (small black box on the front cow support) Timing should be 18 (20 at cranking) and 1-3BTDC on your 90hp. Impeller should be no more than 5 years old MAX and WOT should be 5500-5800, they like to spin and hate to be laged. If it is just one or two pistons and you don't have to bore I have two good used ones from my rebuild I'll sell to you for cheep.(new is like $100 each on here) I put 6 new sem-keystone rings on mine. ANYWAY we can get into that stuff later...first thing is getting a flywheel puller and a manual. Here's the puller i used http://cgi.ebay.com/ebaymotors/Merc...0794054QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

I got my OEM manual on e-bay for 20 bucks, i don't see any now and I'm sure they'll be a pretty penny at the dealer.

Depending on what is wrong, it should be worth it for you. Look at how much the new crap is going for. This engine lasted almost 25 years before an overhaul, with care and rebuild it should last you another 25 years. AND you could buy another used one and it could have the same problems. Depending on if it needs to be bored and how many pistons, you'll looking between 200 and 700 bucks for parts if you do it yourself. (no you don't need the special ring compressors to do this as many may say) You would pay a shop $2500+.....if you want to do a powerhead swap, Clamscasino can do it for around 1100 + shipping. You just send him your block and he'll send you a rebuild one. PM me if you're interested in that.

Let us know when you get the puller and your book.

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-update-motor

Im no pro, but not a noob either when it comes to motors. I will check back when I get the book and puller. I hope it only needs a piston. It does have the orig oil inj. unit on it. I will get rid of it for sure when I fix the motor. What black box are you talking about? Not sure if mine has that or not. Ill have to look to be sure.

 

[arsenalpsu]

Re: 1986 mariner 90hp inline 6 problems-update-motor

It's a small black box, about the size of a deck of cards, that is supposed to aid the idle but they are known to go bad and screw up timing at WOT (wide open throttle) which will cause detonation. Take it out and throw it away. It will have 3 wires going to your switch boxes, just remove them.

How much metal was on your spark plug? Do a compression check and compair how bad that cylinder is compaired to the rest. IF it was just a few SMALL pieces and you still have compression you might be able to put off a rebuild. The small metal pieces could have shorted out your spark plug.

Check compression and report back.....

 

[njrextreme]

Re: 1986 mariner 90hp inline 6 problems-update-motor

Not alot of metal. A few tiny chunks. That was going to be my next step, comp test. I never heard of shorting out a spark plug. Interesting. I know the wire is getting power, but I didnt check the plug. The plug and head were warm so I think its firing. With the ticking/knocking going on, I would think somthing internal is not good. Ill report back.