What the Merc dealer says

[Btuvi]

Re: What the Merc dealer says

CaptJason, I have taken note of one of your comments that is coming home to me. That is that you have to fix the problems you find and keep going.

Once the identified problems have been addressed I will test drive and provide feedback.

Thanks again for increasing my understanding of the whole.

 

[Btuvi]

Re: What the Merc dealer says

Well, according to NGK tech the plugs installed weren't wrong. The gap was wrong.

Five of the plugs in my engine were gapped at .028 and one at .020 (probably dropped and closed up) but best gap for plug is .040

See my post: Regarding 225 optimax plugs.

 

[reelfishin]

Re: What the Merc dealer says

From the description of your problem, my first guess would be that the motor is dropping a cylinder at times. A bad spark plug, plug wire, coil, or possibly reeds can cause this.
The most likely cause is either fouled spark plugs, bad plug wires or ends, or cracked coils.
I'd fix the cross threaded plug for now, even if an insert is needed, just to see what else your dealing with. Once this is done, you can get a good compression reading. If the there's signs of leakage at any gasket, fix it. Its all only nuts and bolts. Then make sure the plug wires are good, have clean contacts and give it a test run. I tend to test plug wires with a spray bottle with some water. If misting water over the wires creates a mist, then they need to be replaced.
I'm not familiar with your exact motor but all engines need good spark, fuel and air, plus good compression to run. Without the basics, you have nothing.

If I were to relate or compare working on an outboard to anything else, having worked on boats, cars and motorcycles for years, I'd say outboards are more like a motorcycle motor than an automotive engine.
Both in size and compact design. What usually gets most auto mechanics is having to deal with integral alternators, reed plates and the lack of moving parts, and the often corroded parts.

 

[JustJason]

Re: What the Merc dealer says

CaptJason, I have taken note of one of your comments that is coming home to me. That is that you have to fix the problems you find and keep going.

That's why I keep on saying it my friend. if it's your boat then you can do whatever you want.... But if I'm fixing a boat for somebody... it's got to be 100% before I send a customer back out on the water with it.

 

[j_martin]

Re: What the Merc dealer says

btuvi,
Yer on the right track. The two plug types are basically interchangable. One is a platinum tip, and one is irridium. The trailing letter is the gap size. Otherwise they are the same plug. I think folks have found the .040 gap works the best. Be careful you don't touch the center electrode. It is very brittle precious metal. (but it can take a heckofa fire without damage)

You need good plug threads because plugs are a consumable item, and need to be changed.

Believe it or not, these motors ain't rocket science. They are high performance (power density) and very compact, which can be intimidating, but there is nothing a shade tree mechanic can't do on em if he's willing to be careful and do things right, at least until you split the cases and start pulling pistons and rods. The motors themselves are about half as complicated as a car motor mechanically, and much simpler than a modern car motor control (engine management) wise.

The plugs as you described them indicate a real hack has been working on it. If you pull the heads, take a look around for scoring and such, clean things up, have any cracks welded and properly machined, threads cleaned up and/or repaired. (one way to repair the plug hole is to heliarc weld it up, drill and rethread it.) and put it back together making sure bolts are clean and straight, and use yer torque wrench. I've found I need 3 different torque wrenches. I torque every bolt, even the small ones.

Ask a lot of questions. For instance it's been found by most that if you reuse the head bolts, don't stretch them as the book says for new ones, just torque them.

The factory maintainance manual is worth it's weight in gold.

The first Mercury engine I ever owned is a V6. I've never seen under the cover of one before. I went through carbs, exhaust chest, reeds, and all the electrics the first winter. I found a lot of little things wrong and fixed them. It runs like a scalded dog.

I ramble on.
If it were mine, I'd get the cross threaded plug out, and run a compression check. I wouldn't even repair the threads before that, maybe just chase em with a greasy tap. If it's good, then go for it. It'll be worth it.

hope it helps
John

 

[j_martin]

Re: What the Merc dealer says

Just an afterthought

When you have a question, start a new thread with the question clearly in the title. That way folks all over the world have the actual question bounced off'n them, and one with the answer is likely to respond quickly.

"what the Merc dealer says" really has little to do with the subject matter of this thread. There are a multitude of actual subjects in this thread, like
"Spark plug thread repair"
"head bolt torque"
"plug specs for an optimax"
"repairing a small crack in ??????" (be detailed)

hope it helps
John

 

[Btuvi]

Re: What the Merc dealer says

Thanks, John. Good advice.